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  • 1. Balint, Miklos
    et al.
    Pfenninger, Markus
    Grossart, Hans-Peter
    Taberlet, Pierre
    Vellend, Mark
    Leibold, Mathew A.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bowler, Diana
    Environmental DNA time series in ecology2018In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 33, no 12, p. 945-957Article, review/survey (Refereed)
    Abstract [en]

    Ecological communities change in time and space, but long-term dynamics at the century-to-millennia scale are poorly documented due to lack of relevant data sets. Nevertheless, understanding long-term dynamics is important for explaining present-day biodiversity patterns and placing conservation goals in a historical context. Here, we use recent examples and new perspectives to highlight how environmental DNA (eDNA) is starting to provide a powerful new source of temporal data for research questions that have so far been overlooked, by helping to resolve the ecological dynamics of populations, communities, and ecosystems over hundreds to thousands of years. We give examples of hypotheses that may be addressed by temporal eDNA biodiversity data, discuss possible research directions, and outline related challenges.

  • 2. Bellard, Celine
    et al.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hugueny, Bernard
    Biotic and abiotic drivers of species loss rate in isolated lakes2019In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 88, no 6, p. 881-891Article in journal (Refereed)
    Abstract [en]

    Today, anthropogenic impacts are causing a serious crisis for global biodiversity, with rates of extinction increasing at an unprecedented rate. Extinctions typically occur after a certain delay, and understanding the mechanisms causing delays is a key challenge for both fundamental and applied perspectives. Here, we make use of natural experiments, the isolation of lakes by land uplift in Northern Scandinavia, to examine how yearly extinction rates are affected by time since isolation and a range of abiotic and biotic factors. In this aim, we adapted a model of delayed species loss within isolated communities to test the effects of time since isolation, area, pH, depth and the presence/absence of piscivores on extinction rates. As expected, we found that small and/or young lakes experience a higher annual rate of extinctions per species than larger and/or older ones. Compared to previous studies that were conducted for either young (few thousand years ago) or very old (>10,000 years ago) isolates, we demonstrated over a large and continuous temporal scales (50-5,000 years), similar relationship between extinction rates and age. We also show that extinction rates are modified by local environmental factors such as a strong negative effect of increasing pH. Our results urge for the need to consider the time since critical environmental changes occurred when studying extinction rates. In a wider perspective, our study demonstrates the need to consider extinction debts when modelling future effects of climate change, land-use changes or biological invasions on biodiversity.

  • 3.
    Bergström, Ulf
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial scale, heterogeneity and functional responses2004In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 73, no 3, p. 487-493Article in journal (Refereed)
    Abstract [en]

    1. In a laboratory experiment, we studied the effect of arena size on the functional response of the mysid shrimp Neomysis integer preying on the cladoceran Polyphemus pediculus. The aim of the study was to examine mechanisms that cause the functional response to be scale-dependent, by documenting the spatial distribution and the movement behaviour of predator and prey.

    2. The attack rate was significantly higher in large arenas, while the handling time did not differ between arena sizes. The difference in attack rate could be explained by differences in aggregative behaviour of predator and prey and in swimming activity of the predator. It is suggested that distributions of animals are often affected by the walls of the experimental arenas and that this spatial heterogeneity is scale-dependent, which may have a considerable impact on estimates of ecological process rates.

    3. A method of correcting attack rate estimates for artefacts caused by such spatial heterogeneity is presented.

  • 4. Bergström, Ulf
    et al.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Leonardsson, Kjell
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Plugging space into predator-prey models: an empirical approach.2006In: Am Nat, ISSN 1537-5323, Vol. 167, no 2, p. 246-59Article in journal (Refereed)
  • 5. Dessborn, Lisa
    et al.
    Elmberg, Johan
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Pike predation affects breeding success and habitat selection of ducks2011In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 56, no 3, p. 579-589Article in journal (Refereed)
    Abstract [en]

    1. Fish and ducks often belong to the same local food web, and several studies indicate that there is a general negative effect of fish on breeding ducks. This pattern has so far been addressed mainly within the framework of competition for common invertebrate prey, while predation by large fish as a force behind settlement and abundance patterns in ducks remains largely unknown. This is the first study to address the effect of fish predation on breeding ducks, isolated from that of competition, and the first experiment to explore the ability of ducks to identify and avoid lakes with high risk of fish predation.

    2. We used a before–after control–impact design and 11 naturally fishless lakes. Waterfowl on the lakes were surveyed during the breeding season of 2005. Large adult pike (Esox lucius) were added to two lakes in early spring 2008, and waterfowl surveys were repeated on all 11 lakes.

    3. Pike introduction did not affect the number of pairs on lakes during the nesting season in any of three focal duck species (mallard Anas platyrhynchos, teal Anas crecca, and goldeneye Bucephala clangula). During the brood-rearing season, however, there was a decrease in duck days in teal and goldeneye in lakes with pike, with similar trends observed in mallard. The number of goldeneye ducklings was also significantly lower in lakes with pike. We were unable to determine whether the response was attributable to direct pike predation or to broods leaving experimental lakes, but in either case, our study demonstrates high fitness costs for ducks breeding on lakes with pike.

    4. The apparent inability of nesting ducks to detect pike and the clear fitness implications may influence the annual recruitment of ducks on a larger scale as pike are both common and widespread. Vegetation complexity and food abundance are likely to be of overriding importance when breeding ducks are choosing a nesting site. As pike have a strong influence on breeding birds, relying on vegetation and cues of food abundance, while ignoring indicators of predation risk from fish, could lead to lakes with pike acting as an ecological trap.

  • 6. Dessborn, Lisa
    et al.
    Englund, Goran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Elmberg, Johan
    Arzel, Celine
    Innate responses of mallard ducklings towards aerial, aquatic and terrestrial predators2012In: Behaviour, ISSN 0005-7959, E-ISSN 1568-539X, Vol. 149, no 13-14, p. 1299-1317Article in journal (Refereed)
    Abstract [en]

    Reproductive success in ducks is strongly influenced by predation on the breeding grounds. Ducklings are targeted by a range of terrestrial, aerial and aquatic predators, giving a strong selective advantage to individuals and broods that have effective ways to avoid predation. In experiments on naive mallard (Anas platyrhynchos) ducklings without an accompanying adult female we investigated the innate ability to identify and avoid threats at varying intensity from aerial, aquatic and terrestrial predators. Ducklings displayed increased vigilance in response to pre-recorded calls of predatory birds, representing a low level of threat. They did not react to visual and olfactory stimuli generated by motionless northern pike (Esox lucius). Neither did they show a strong response to caged American mink (Neovison vison) (visual and olfactory stimuli), although they avoided the area with the mink, indicating a certain level of recognition. High intensity threats were simulated by staging attacks from aerial (goshawk, Accipiter gentilis) and aquatic predators (northern pike). The aerial attack made ducklings dive and scatter under water, whereas the response to attack by pike was to run on the water and scatter in different directions. The lack of response to a 'passive' pike and the rather weak avoidance of mink indicate that olfactory cues are not as important in identifying a potential predatory threat by ducklings as are auditory cues. Visual cues appear to be of little importance unless they are combined with movement, and a clear response is only triggered when the intensity of predator threat is high. Mallard ducklings, thus, show an innate capacity to adjust anti-predator behaviour to different predator types and to threat intensity. Our study highlights the general trade-off between foraging needs and predator avoidance, but also second-order trade-offs in which innate avoidance behaviour towards one type of predator may increase predation risk from another.

  • 7. Elmberg, Johan
    et al.
    Dessborn, Lisa
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Presence of fish affects lake use and breeding success in ducks2010In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 641, no 1, p. 215-223Article in journal (Refereed)
    Abstract [en]

    Several previous studies indicate that presence of fish has negative effects on waterbirds breeding on lakes, owing either to competition for common invertebrate prey or fish predation on ducklings/chicks. However, others have reported results to the contrary and it remains unresolved what factors trigger, inhibit, and modulate fish-waterbird interactions. The present study was designed to test the effect of fish presence per se, with a minimum of variation in possibly confounding environmental variables. Thus, after stratifying for area, depth, altitude, pH, and total phosphorus we compared 13 lakes with and 12 without fish (mainly pike Esox lucius and perch Perca fluviatilis) with respect to (i) general species richness of waterbirds, (ii) species-specific utilization and breeding success of two dabbling ducks (mallard Anas platyrhynchos and teal Anas crecca) and a diving duck (goldeneye Bucephala clangula). General species richness of waterbirds was higher on fishless lakes. Overall use (bird days) and brood number of teal and goldeneye were higher on fishless lakes. The latter also had more benthic and free-swimming prey invertebrates compared to lakes with fish. Mallard use, mallard brood number, and abundance of emerging insects did not differ between lake groups. Generalized linear models including fish presence as factor and considering seven environmental variables as covariates, confirmed that all waterbird variables except mallard days and broods were negatively correlated to fish presence. There was also a residual positive relationship of lake area on general species richness, teal days, and teal broods. Our data demonstrate a stronger effect of fish presence on diving ducks and small surface feeding ducks than on large surface-feeding ducks. We argue that observed patterns were caused by fish predation on ducks rather than by fish-duck competition for common prey.

  • 8.
    Englund, G
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Scale dependent effects of predatory fish on stream benthos2005In: Oikos, Vol. 111, p. 19-30Article in journal (Refereed)
  • 9.
    Englund, G
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Hambäck, P
    Scale dependence of emigration rates2004In: Ecology, Vol. 85, p. 320-327Article in journal (Refereed)
  • 10.
    Englund, G
    et al.
    Umeå University.
    Hambäck, P
    Scale dependence of movement rates in stream invertebrates2004In: Oikos, Vol. 105, p. 31-40Article in journal (Refereed)
  • 11.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Competition in caddis larvae1992Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with behavioural strategies used by caddis larvae in pairwise contests and when selecting microhabitats. Effects of caddis larvae on survival and habitat selection of other insect taxa have also been studied.

    The behaviours used by Arctopsyche ladogensis larvae fighting for nets, and Agrypnia pagetana larvae fighting for cases, agreed well with predictions from the sequential assessment game, which is an ESS model of animal fighting behaviour.

    Establishment by net-spinning Hydropsyche siltalai larvae on artificial substrates was highest at intermediate densities of residents. Emigration/mortality was density independent, and it was higher at a poor site (low food availability) than at a rich site. Establishment was unaffected by site quality. Growth was density dependent because larvae in upstream positions reduced both current velocity and concentration of food particles for larvae in downstream positions.

    A field experiment involved manipulations of the density of H. siltalai larvae and their nets in a lake outlet stream. H. siltalai larvae affected all abundant taxa, but the mechanism involved varied between taxa. Rhyacophila nubila (Trichoptera) and chironomid larvae benefited from the presence of H. siltalai nets. Negative effects on nymphs of the mayfly Ephemerella ignita were due to predation by H. siltalai larvae, while a combination of predation and increased emigration in response to nets depressed densities of Simulium truncatum blackfly larvae.

  • 12.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Eriksson, Håkan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Mats B.
    The birth and death of lakes on young landscapes2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 7Article in journal (Refereed)
    Abstract [en]

    Ongoing land uplift caused by postglacial isostatic rebound creates strong landscape-age gradients alongside the Gulf of Bothnia, northern Scandinavia. Lakes are continuously generated on this dynamic landscape as the uplift isolates bays from sea inundation. However, concomitant with this process older lakes are lost as the basins are filled with sediments, creating a continuum of lake ages on the landscape. We studied the lake size and depth distributions and lake densities, along an age gradient covering 0-4500 years. Map data on the density, area, and elevation of lakes were combined with field-based measurements of maximum basin depth. We find that young lake populations are densely distributed and dominated by small and shallow lakes. Over time, small and shallow lakes are lost by complete sediment filling, resulting in lower lake density and a shift in size and depth distributions towards larger, deeper lakes. Since lake filling is a universal process, we propose that these findings can be generalized to other gradients in landscape age.

  • 13.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Hambäck, Peter A.
    Scale dependence of immigration rates: models, metrics and data2007In: Journal of Animal Ecology, Vol. 76, p. 30-35Article in journal (Refereed)
    Abstract [en]

    1.

    We examine the relationship between immigration rate and patch area for different types of movement behaviours and detection modes. Theoretical models suggest that the scale dependence of the immigration rate per unit area (I/A) can be described by a power model I/A = i*Areazeta, where ζ describes the strength of the scale dependence.

    2.

    Three types of scaling were identified. Area scaling (ζ = 0) is expected for passively dispersed organisms that have the same probability of landing anywhere in the patch. Perimeter scaling (−0·30 > ζ > −0·45) is expected when patches are detected from a very short distance and immigrants arrive over the patch boundary, whereas diameter scaling (ζ = −0·5) is expected if patches are detected from a long distance or if search is approximately linear.

    3.

    A meta-analysis of published empirical studies of the scale dependence of immigration rates in terrestrial insects suggests that butterflies show diameter scaling, aphids show area scaling, and the scaling of beetle immigration is highly variable. We conclude that the scaling of immigration rates in many cases can be predicted from search behaviour and the mode of patch detection.

  • 14.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Hambäck, Peter A.
    Top-down and bottom-up effects on the spatiotemporal dynamics of cereal aphids: Testing scaling theory for local density2007In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 76, no 1, p. 30-35Article in journal (Refereed)
    Abstract [en]
    • 1.We examine the relationship between immigration rate and patch area for different types of movement behaviours and detection modes. Theoretical models suggest that the scale dependence of the immigration rate per unit area (I/A) can be described by a power model I/A = i*Areaζ, where ζ describes the strength of the scale dependence.
    • 2.Three types of scaling were identified. Area scaling (ζ = 0) is expected for passively dispersed organisms that have the same probability of landing anywhere in the patch. Perimeter scaling (−0·30 > ζ > −0·45) is expected when patches are detected from a very short distance and immigrants arrive over the patch boundary, whereas diameter scaling (ζ = −0·5) is expected if patches are detected from a long distance or if search is approximately linear.
    • 3.A meta-analysis of published empirical studies of the scale dependence of immigration rates in terrestrial insects suggests that butterflies show diameter scaling, aphids show area scaling, and the scaling of beetle immigration is highly variable. We conclude that the scaling of immigration rates in many cases can be predicted from search behaviour and the mode of patch detection.
  • 15.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Olofsson, P
    Salonsaari, J
    Öhman, Johanna
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Predation leads to assembly rules in fragmented fish communities2009In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 12, p. 663-671Article in journal (Refereed)
    Abstract [en]

    Diamond [Assembly of species communities. In: Ecology and Evolution of Communities (eds Cody, M.L. & Diamond, J.M.). Harvard University Press, Cambridge, pp. 342–444] proposed that resource competition leads to checkerboard-like distributions of competing species. This proposal prompted research that revealed checkerboard patterns within a wide range of communities, but the mechanisms that generate such patterns are still poorly understood. Here we present whole-lake natural experiments and analyses of species–environment relationships in small coastal lake fish communities that were fragmented when land uplift isolated these lakes from the Baltic Sea, showing that a combination of predation and habitat suitability generated checkerboard distributions. Checkerboard patterns developed because two piscivores, northern pike and Eurasian perch, caused the extinction of several prey species in deep lakes. Conversely, low oxygen levels in shallow lakes caused extinction of the piscivores, and these areas served as a refuge for tolerant prey species. Based on these findings, we suggest that habitat suitability and biotic interactions should be viewed simultaneously in null models of assembly rules.

  • 16.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Leonardsson, Kjell
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Scaling up the functional response for spatially heterogeneous systems.2008In: Ecology Letters, ISSN 1461-0248, Vol. 11, no 5, p. 440-9Article in journal (Refereed)
    Abstract [en]

    Scale transition theory is a framework for predicting regional population dynamics from local process functions and estimates of spatial heterogeneity. Using this framework, we estimated regional scale functional responses for a benthic predator-prey system in the Baltic Sea. Functional responses were based on laboratory experiments or field observations of stomach contents, and prey densities measured at a local scale (0.1 m(2)) or a regional scale (300 km(2)). Laboratory data overestimated consumption at high prey densities, whereas predictions based on local scale data tallied closely with consumption observed at the regional scale. The predicted regional functional response was different for increasing and decreasing prey densities, reflecting that predator and prey densities, as well as the covariance between them, exhibit oscillatory dynamics. We conclude that it is important to validate laboratory data with small-scale field observations and that scale transition is a powerful tool for scaling-up process functions in heterogeneous systems.

  • 17.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Rydberg, Cecilia
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Leonardsson, Kjell
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Long-term variation of link strength in a simple benthic food web.2008In: Journal of Animal Ecology, ISSN 1365-2656, Vol. 77, no 5, p. 883-90Article in journal (Refereed)
    Abstract [en]

    1. The predatory isopod Saduria entomon (L.) and its amphipod prey Monoporeia affinis (Lindström) are key components of the food web in the northern Baltic Sea, together representing 80-90% of the macrobenthic biomass. We use 20 years of stomach content data for Saduria to investigate how diet dynamics affect the stability of the interaction between Saduria and Monoporeia.

    2. Consumption of the main prey, Monoporeia, fitted a type III functional response. Consumption rates of the most important alternative prey, mysids, were found to be unrelated to mysid densities but negatively related to the density of Monoporeia. The fit of consumption data to a model that assumes passive prey selection was poor. Thus we conclude that some form of active choice is involved.

    3. The effect of consumption of mysids, the alternative prey, on the stability of this system was investigated using a ‘one predator-two prey' model with stochastic environmental variation. Analysis of the model suggests that feeding on mysids leads to a decreased extinction risk for the predator, Saduria, and reduced density oscillations for both Saduria and its main prey, Monoporeia

  • 18.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Sjödin, Henrik
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bonsall, Michael
    Oxford University.
    Cianelli, Lorenzo
    Oregon State University.
    Frank, Kenneth
    Bedford Institute of Oceanography.
    Heino, Mikko
    University of Bergen.
    Janssen, Arne
    University of Amsterdam.
    Leonardsson, Kjell
    Swedish University of Agricultural Science.
    van der Meer, Jaap
    Royal Netherlands Institute for Sea Research.
    Nachman, Gösta
    Copenhagen University.
    Yu, Jun
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Density dependence induced by the spatial covariance between predators and preyManuscript (preprint) (Other academic)
  • 19.
    Englund, Göran
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Öhlund, Gunnar
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hein, Catherine L
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Diehl, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Temperature dependence of the functional response2011In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 14, no 9, p. 914-21Article in journal (Refereed)
    Abstract [en]

    The Arrhenius equation has emerged as the favoured model for describing the temperature dependence of consumption in predator-prey models. To examine the relevance of this equation, we undertook a meta-analysis of published relationships between functional response parameters and temperature. We show that, when plotted in lin-log space, temperature dependence of both attack rate and maximal ingestion rate exhibits a hump-shaped relationship and not a linear one as predicted by the Arrhenius equation. The relationship remains significantly downward concave even when data from temperatures above the peak of the hump are discarded. Temperature dependence is stronger for attack rate than for maximal ingestion rate, but the thermal optima are not different. We conclude that the use of the Arrhenius equation to describe consumption in predator-prey models requires the assumption that temperatures above thermal optima are unimportant for population and community dynamics, an assumption that is untenable given the available data.

  • 20. Hambäck, P
    et al.
    Englund, G
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Patch area, population density and the scaling of migration rates: the resource concentration hypothesis revisited2005In: Ecology Letters, Vol. 8, p. 1057-1065Article in journal (Refereed)
  • 21. Hambäck, Peter A
    et al.
    Summerville, Keith S
    Steffan-Dewenter, Ingolf
    Krauss, Jochen
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Crist, Thomas O
    Habitat specialization, body size, and family identity explain lepidopteran density-area relationships in a cross-continental comparison.2007In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 104, no 20, p. 8368-73Article in journal (Refereed)
    Abstract [en]

    Habitat fragmentation may strongly affect species density, species interactions, and the rate of ecosystem processes. It is therefore important to understand the observed variability among species responses to fragmentation and the underlying mechanisms. In this study, we compare density-area relationships (DARs) for 344 lepidopteran species belonging to 22 families (butterflies and moths). This analysis suggested that the DAR(slope) is generally positive for moths and negative for butterflies. The differences are suggested to occur because moths are largely olfactory searchers, whereas most butterflies are visual searchers. The analysis also suggests that DARs vary as a function of habitat specialization and body size. In butterflies, generalist species had a more negative DAR(slope) than specialist species because of a lower patch size threshold. In moths, the differences in DAR(slope) between forest and open habitat species were large for small species but absent for large species. This difference is argued to occur because the DAR(slope) in large species mainly reflects their search mode, which does not necessarily vary between moth groups, whereas the slope in small species reflects population growth rates.

  • 22.
    Hein, Catherine L
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Öhlund, Gunnar
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Dispersal through stream networks: modelling climate-driven range expansions of fishes2011In: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 17, no 4, p. 641-651Article in journal (Refereed)
    Abstract [en]

    Aim To incorporate dispersal through stream networks into models predicting the future distribution of a native, freshwater fish given climate change scenarios. Location Sweden. Methods We used logistic regression to fit climate and habitat data to observed pike (Esox lucius Linnaeus) distributions in 13,476 lakes. We used GIS to map dispersal pathways through streams. Lakes either (1) contained pike or were downstream from pike lakes, (2) were upstream from pike lakes, but downstream from natural dispersal barriers, or (3) were isolated from streams or were upstream from natural dispersal barriers. We then used climate projections to model future distributions of pike and compared our results with and without including dispersal. Results Given climate and habitat, pike were predicted present in all of 99,249 Swedish lakes by 2100. After accounting for dispersal barriers, we only predicted pike presence in 31,538 lakes. Dispersal barriers most strongly limited pike invasion in mountainous regions, but low connectivity also characterized some relatively flat regions. Main conclusions The dendritic network structure of streams and interconnected lakes makes a two-dimensional representation of the landscape unsuitable for predicting range shifts of many freshwater organisms. If dispersal through stream networks is not accounted for, predictions of future fish distributions in a warmer climate might grossly overestimate range expansions of warm and cool-water fishes and underestimate range contractions of cold-water fishes. Dispersal through stream networks can be modelled in any region for which a digital elevation model and species occurrence data are available.

  • 23.
    Hein, Catherine L.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impacts Research Centre, Abisko Scientific Research Station, Abisko, Sweden .
    Öhlund, Gunnar
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Fish introductions reveal the temperature dependence of species interactions2014In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 281, no 1775, p. 20132641-Article in journal (Refereed)
    Abstract [en]

    A major area of current research is to understand how climate change will impact species interactions and ultimately biodiversity. A variety of environmental conditions are rapidly changing owing to climate warming, and these conditions often affect both the strength and outcome of species interactions. We used fish distributions and replicated fish introductions to investigate environmental conditions influencing the coexistence of two fishes in Swedish lakes: brown trout (Salmo trutta) and pike (Esox lucius). A logistic regression model of brown trout and pike coexistence showed that these species coexist in large lakes (more than 4.5 km(2)), but not in small, warm lakes (annual air temperature more than 0.9-1.5 degrees C). We then explored how climate change will alter coexistence by substituting climate scenarios for 2091-2100 into our model. The model predicts that brown trout will be extirpated from approximately half of the lakes where they presently coexist with pike and from nearly all 9100 lakes where pike are predicted to invade. Context dependency was critical for understanding pike-brown trout interactions, and, given the widespread occurrence of context-dependent species interactions, this aspect will probably be critical for accurately predicting climate impacts on biodiversity.

  • 24.
    Hein, Catherine L.
    et al.
    Abisko Sci Res Stn, CIRC, Abisko, Sweden.
    Öhlund, Gunnar
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Future distribution of Arctic Char Salvelinus alpinus in Sweden under climate change: Effects of temperature, lake size and species interactions2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 303-312Article in journal (Refereed)
    Abstract [en]

    Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95 % of 467 Swedish lakes. We predicted that Arctic char will lose 73 % of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.

  • 25.
    Henriksson, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Rydberg, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Failed and successful intentional introductions of fish species into 821 Swedish lakes2016In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 97, no 5, p. 1p. 1364-1364Article in journal (Refereed)
    Abstract [en]

    Introductions of fish into lakes can be viewed as whole system experiments, which can be used to study the principles of community assembly and factors determining the outcome of species invasions. Freshwater fish species have been translocated by humans for centuries in Sweden, and this activity has been documented by national and regional authorities starting at the end of the 19th century. Based on this documentation and additional interviews with local fishermen, we have compiled a data set that includes 1157 intentional introductions of 26 freshwater fish species into 821 Swedish lakes. The data include both successful and failed introductions; where a successful introduction means that the introduced fish species was present in the lake for ≥20 yr or that reproduction was observed earlier than that. The oldest introduction is from 1658 and the latest from 2002. Additionally, the data set includes species composition, water temperature sum, maximum water temperature, lake area, elevation, longitude, and latitude for all lakes. These data have been used to test hypotheses about biotic resistance and invasion success in three papers. We found the presence or absence of specific species predicted invasion success better than the species richness of the lakes. We also found that species with high invasion success tend to make a large contribution to biotic resistance, which will make communities more resistant in the future as they are invaded by additional species.

  • 26.
    Henriksson, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Rydberg, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Failed and successful introductions of fish species into 821 Swedish lakesManuscript (preprint) (Other academic)
    Abstract [en]

    Introductions of fish into lakes can be viewed as whole system experiments, which can be used to study the principles of community assembly and factors determining the outcome of species invasions. Freshwater fish species have been translocated by humans for centuries in Sweden and this activity has been documented by national and regional authorities starting at the end of the 19th century. Based on this documentation and additional interviews with local fishermen we have compiled a dataset that includes 1158 introductions of 26 freshwater fish species into 821 Swedish lakes. The data includes both successful and failed introductions; where a successful introduction means that the introduced fish species was present in the lake for ≥20 years or that reproduction was observed earlier than that. The oldest introduction is from 1658 and the latest from 2002. Additionally, the dataset includes species composition, temperature sum, maximum temperature, lake area, elevation, longitude and latitude for all lakes. This data has been used to test hypotheses about biotic resistance and invasion success in three papers. We found the presence or absence of specific species predicted invasion success better than the species richness of the lakes. We also found that species with high invasion success tend to make a large contribution to biotic resistance, which will make communities more resistant in the future as they are invaded by additional species.

  • 27.
    Henriksson, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wardle A., David
    Swedish University of Agriculture Sciences, Department of Forest Vegetation Ecology.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Diehl, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Strong invaders are strong defenders: implications for the resistance of invaded communities2016In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 19, no 4, p. 487-494Article in journal (Refereed)
    Abstract [en]

    Many ecosystems receive a steady stream of non-native species. How biotic resistance develops over time in these ecosystems will depend on how established invaders contribute to subsequent resistance. If invasion success and defence capacity (i.e. contribution to resistance) are correlated, then community resistance should increase as species accumulate. If successful invaders also cause most impact (through replacing native species with low defence capacity) then the effect will be even stronger. If successful invaders instead have weak defence capacity or even facilitative attributes, then resistance should decrease with time, as proposed by the invasional meltdown hypothesis. We analysed 1157 introductions of freshwater fish in Swedish lakes and found that species' invasion success was positively correlated with their defence capacity and impact, suggesting that these communities will develop stronger resistance over time. These insights can be used to identify scenarios where invading species are expected to cause large impact.

  • 28.
    Henriksson, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Yu, Jun
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Wardle A., David
    Swedish University of Agriculture Sciences, Department of Forest Vegetation Ecology.
    Trygg, Johan
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Weighted species richness outperforms species richness as predictor of biotic resistance2016In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 97, no 1, p. 262-271Article in journal (Refereed)
    Abstract [en]

    The species richness hypothesis, which predicts that species-rich communities should be better at resisting invasions than species-poor communities, has been empirically tested many times and often poorly supported. In this paper we contrast the species richness hypothesis with four alternative hypotheses with the aim of finding better descriptors of invasion resistance. These alternative hypotheses state that resistance to invasions is determined by abiotic conditions, community saturation (i.e., the number of resident species relative to the maximum number of species that can be supported), presence/absence of key species, or weighted species richness. Weighted species richness is a weighted sum of the number of species, where each species' weight describes its contribution to resistance. We tested these hypotheses using data on the success of 571 introductions of four freshwater fish species into lakes throughout Sweden (i.e., Arctic char (Salvelinus alpinus), tench (Tinca tinca), zander (Sander lucioperca), and whitefish (Coregonus lavaretus)). We found that the weighted species richness best predicted invasion success. The weights describing the contribution of each resident species to community resistance varied considerably in both strength and sign. Positive resistance weights, which indicate that species repel invaders, were as common as negative resistance weights, which indicate facilitative interactions. This result can be contrasted with the implicit assumption of the original species richness hypothesis, that all resident species have negative effects on invader success. We argue that this assumption is unlikely to be true in natural communities, and thus that we expect that weighted species richness is a better predictor of invader success than the actual number of resident species.

  • 29.
    Henriksson, Anna
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Yu, Jun
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Wardle, David A.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Biotic resistance in freshwater fish communities: species richness, saturation or species identity?2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 8, p. 1058-1064Article in journal (Refereed)
    Abstract [en]

    Some communities are susceptible to invasions and some are not. Why? Elton suggested in 1958 that the ability of the community to withstand invading species - its biotic resistance - depends on the number of resident species. Later contributors have emphasized the habitat's ability to support species, as well as the contribution of individual species to the resistance. In this study we use information from 184 introductions of Arctic char into Swedish lakes to study both abiotic and biotic aspects of the resident community's ability to resist introductions. We find that the best model included the proportion of forest cover and the proportion of agricultural land cover in the watershed in combination with the presence versus absence of northern pike. Thus, the most important biotic factor to explain the outcome of introductions of Arctic char is the presence of northern pike, a large piscivore. This means that one single species explains the outcome of the introductions better than does the species richness or the saturation level of the community.

  • 30.
    Holm, Stig-Olov
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Increased ecoefficiency and gross rebound effect: Evidence from USA and six European countries 1960-20022009In: Ecological Economics, ISSN 0921-8009, E-ISSN 1873-6106, Vol. 68, no 3, p. 879-887Article in journal (Refereed)
    Abstract [en]

    Despite increased efficiency in the use of natural resources, the use of these resources continues to increase in most societies. This paper examines the discrepancy between the potential decrease of use of natural resources, as an effect of increased efficiency, and actual use. During the period 1960–2002, this difference was found to grow faster in the USA than the mean for six West European countries. Possible reasons for this difference between the two regions are analysed. To reduce the anthropogenic flows of energy and material, and the consequent deleterious effects on the biosphere, it will become necessary to adapt consumption to degree of efficiency in the use of natural resources. Based on the comparison between the two regions, some economic aspects of this issue are discussed.

  • 31. Hunsicker, Mary E.
    et al.
    Ciannelli, Lorenzo
    Bailey, Kevin M.
    Buckel, Jeffrey A.
    White, J. Wilson
    Link, Jason S.
    Essington, Timothy E.
    Gaichas, Sarah
    Anderson, Todd W.
    Brodeur, Richard D.
    Chan, Kung-Sik
    Chen, Kun
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Frank, Kenneth T.
    Freitas, Vania
    Hixon, Mark A.
    Hurst, Thomas
    Johnson, Darren W.
    Kitchell, James F.
    Reese, Doug
    Rose, George A.
    Sjödin, Henrik
    Umeå University, Faculty of Science and Technology, Umeå Marine Sciences Centre (UMF).
    Sydeman, William J.
    van der Veer, Henk W.
    Vollset, Knut
    Zador, Stephani
    Functional responses and scaling in predator-prey interactions of marine fishes: contemporary issues and emerging concepts2011In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 14, no 12, p. 1288-1299Article, review/survey (Refereed)
    Abstract [en]

    Predatorprey interactions are a primary structuring force vital to the resilience of marine communities and sustainability of the worlds oceans. Human influences on marine ecosystems mediate changes in species interactions. This generality is evinced by the cascading effects of overharvesting top predators on the structure and function of marine ecosystems. It follows that ecological forecasting, ecosystem management, and marine spatial planning require a better understanding of food web relationships. Characterising and scaling predatorprey interactions for use in tactical and strategic tools (i.e. multi-species management and ecosystem models) are paramount in this effort. Here, we explore what issues are involved and must be considered to advance the use of predatorprey theory in the context of marine fisheries science. We address pertinent contemporary ecological issues including (1) the approaches and complexities of evaluating predator responses in marine systems; (2) the scaling up of predatorprey interactions to the population, community, and ecosystem level; (3) the role of predatorprey theory in contemporary fisheries and ecosystem modelling approaches; and (4) directions for the future. Our intent is to point out needed research directions that will improve our understanding of predatorprey interactions in the context of the sustainable marine fisheries and ecosystem management.

  • 32.
    Johansson, Frank
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Brodin, Tomas
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Gardfjell, Hans
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Species abundance models and patterns in dragonfly communities: effects of fish predation2006In: Oikos, Vol. 114, p. 27-36Article in journal (Refereed)
  • 33.
    Jonsson, Micael
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wardle, David A.
    Direct and indirect effects of area, energy and habitat heterogeneity on breeding bird communities2011In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 38, no 6, p. 1186-1196Article in journal (Refereed)
    Abstract [en]

    Aim To compare the ability of island biogeography theory, niche theory and species–energy theory to explain patterns of species richness and density for breeding bird communities across islands with contrasting characteristics.

    Location Thirty forested islands in two freshwater lakes in the boreal forest zone of northern Sweden (65°55′ N to 66°09′ N; 17°43′ E to 17°55′ E).

    Methods We performed bird censuses on 30 lake islands that have each previously been well characterized in terms of size, isolation, habitat heterogeneity (plant diversity and forest age), net primary productivity (NPP), and invertebrate prey abundance. To test the relative abilities of island biogeography theory, niche theory and species–energy theory to describe bird community patterns, we used both traditional statistical approaches (linear and multiple regressions) and structural equation modelling (SEM; in which both direct and indirect influences can be quantified).

    Results Using regression-based approaches, area and bird abundance were the two most important predictors of bird species richness. However, when the data were analysed by SEM, area was not found to exert a direct effect on bird species richness. Instead, terrestrial prey abundance was the strongest predictor of bird abundance, and bird abundance in combination with NPP was the best predictor of bird species richness. Area was only of indirect importance through its positive effect on terrestrial prey abundance, but habitat heterogeneity and spatial subsidies (emerging aquatic insects) also showed important indirect influences. Thus, our results provided the strongest support for species–energy theory.

    Main conclusions Our results suggest that, by using statistical approaches that allow for analyses of both direct and indirect influences, a seemingly direct influence of area on species richness can be explained by greater energy availability on larger islands. As such, animal community patterns that seem to be in line with island biogeography theory may be primarily driven by energy availability. Our results also point to the need to consider several aspects of habitat quality (e.g. heterogeneity, NPP, prey availability and spatial subsidies) for successful management of breeding bird diversity at local spatial scales and in fragmented or insular habitats.

  • 34. Liao, Jinbao
    et al.
    Lu, Hui
    Li, Zhenqing
    Meng, Xinzhu
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The dynamical models of activated sludge system: stochastic cellular automaton and differential equations2012In: International Journal of Biomathematics, ISSN 1793-5245, Vol. 5, no 5, p. 1250048-Article in journal (Refereed)
    Abstract [en]

    A stochastic cellular automaton (CA) model for activated sludge system (ASS) is formulated by a series of transition functions upon realistic treatment processes, and it is tested by comparing with ordinary differential equations (ODEs) of ASS. CA system performed by empirical parameters can reflect the characteristics of fluctuation, complexity and strong non-linearity of ASS. The results show that the predictions of CA are approximately similar to the dynamical behaviors of ODEs. Based on the extreme experimental system with complete cell recycle in model validation, the dynamics of biomass and substrate are predicted accurately by CA, but the large errors exist in ODEs except for integrating more spatially complicated factors. This is due to that the strong mechanical stress from spatial crowding effect is ignored in ODEs, while CA system as a spatially explicit model takes account of local interactions. Despite its extremely simple structure, CA still can capture the essence of ASS better than ODEs, thus it would be very useful in predicting long-term dynamics in other similar systems.

  • 35.
    Mobley, Kenyon B.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lussetti, Daniel
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bokma, Folmer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Morphological and genetic divergence in Swedish postglacial stickleback (Pungitius pungitius) populations2011In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 11, p. 287-Article in journal (Refereed)
    Abstract [en]

    Background: An important objective of evolutionary biology is to understand the processes that govern phenotypic variation in natural populations. We assessed patterns of morphological and genetic divergence among coastal and inland lake populations of nine-spined stickleback in northern Sweden. Coastal populations are either from the Baltic coast (n = 5) or from nearby coastal lakes (n = 3) that became isolated from the Baltic Sea (< 100 years before present, ybp). Inland populations are from freshwater lakes that became isolated from the Baltic approximately 10,000 ybp; either single species lakes without predators (n = 5), or lakes with a recent history of predation (n = 5) from stocking of salmonid predators (~50 ybp).

    Results: Coastal populations showed little variation in 11 morphological traits and had longer spines per unit of body length than inland populations. Inland populations were larger, on average, and showed greater morphological variation than coastal populations. A principal component analysis (PCA) across all populations revealed two major morphological axes related to spine length (PC1, 47.7% variation) and body size (PC2, 32.9% variation). Analysis of PCA scores showed marked similarity in coastal (Baltic coast and coastal lake) populations. PCA scores indicate that inland populations with predators have higher within-group variance in spine length and lower within-group variance in body size than inland populations without predators. Estimates of within-group PST (a proxy for QST) from PCA scores are similar to estimates of FST for coastal lake populations but PST > FST for Baltic coast populations. PST > FST for PC1 and PC2 for inland predator and inland no predator populations, with the exception that PST < FST for body size in inland populations lacking predators.

    Conclusions: Baltic coast and coastal lake populations show little morphological and genetic variation within and between groups suggesting that these populations experience similar ecological conditions and that time since isolation of coastal lakes has been insufficient to demonstrate divergent morphology in coastal lake populations. Inland populations, on the other hand, showed much greater morphological and genetic variation characteristic of long periods of isolation. Inland populations from lakes without predators generally have larger body size, and smaller spine length relative to body size, suggesting systematic reduction in spine length. In contrast, inland populations with predators exhibit a wider range of spine lengths relative to body size suggesting that this trait is responding to local predation pressure differently among these populations. Taken together the results suggest that predation plays a role in shaping morphological variation among isolated inland populations. However, we cannot rule out that a causal relationship between predation versus other genetic and environmental influences on phenotypic variation not measured in this study exists, and this warrants further investigation.

  • 36.
    Mobley, Kenyon B.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ruiz, Rocio Colas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Johansson, Frank
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bokma, Folmer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    No evidence that stickleback spines directly increase risk of predation by an invertebrate predator2013In: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 15, no 2, p. 189-198Article in journal (Refereed)
    Abstract [en]

    Background: Some populations of stickleback have a reduced number and/or relative size of spines. Hypothesis: Macroinvertebrate predators such as dragonfly larvae cause selective pressure against spines by capturing more stickleback with pelvic spines than stickleback that are spineless. Organisms: Ninespine stickleback (Pungitius pungitius) and dragonfly larvae (Aeshna grandis). Methods: We used 10 stickleback, five with pelvic spines and five with their pelvic spines removed. We put them in containers with two dragonfly larvae. Every day for 4 days we monitored how many stickleback were captured by the larvae. We repeated this experiment ten times at two different densities of fish and predators. We also developed a model to determine whether selection for spinelessness can be distinguished from drift. Results: Dragonfly larvae caught as many stickleback with spines as without. The absence of spines was not associated with a decrease in predation risk. We substituted Bayesian estimates of the selection coefficient into quantitative genetic models of allele frequency change, and the results of the models suggest that the selective advantage of spine loss is so small that its effects cannot be distinguished from drift.

  • 37.
    Nonaka, Etsuko
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Metapopulation Research Centre, Department of Biosciences, University of Helsinki, Helsinki, Finland.
    Svanbäck, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Ecology and Genetics/Limnology, Uppsala University.
    Thibert-Plante, Xavier
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Mechanisms by which phenotypic plasticity affects adaptive divergence and ecological speciation2015In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 186, no 5, p. E126-E143Article in journal (Refereed)
    Abstract [en]

    Phenotypic plasticity is the ability of one genotype to produce different phenotypes depending on environmental conditions. Several conceptual models emphasize the role of plasticity in promoting reproductive isolation and, ultimately, speciation in populations that forage on two or more resources. These models predict that plasticity plays a critical role in the early stages of speciation, prior to genetic divergence, by facilitating fast phenotypic divergence. The ability to plastically express alternative phenotypes may, however, interfere with the early phase of the formation of reproductive barriers, especially in the absence of geographic barriers. Here, we quantitatively investigate mechanisms under which plasticity can influence progress toward adaptive genetic diversification and ecological speciation. We use a stochastic, individual-based model of a predator-prey system incorporating sexual reproduction and mate choice in the predator. Our results show that evolving plasticity promotes the evolution of reproductive isolation under diversifying environments when individuals are able to correctly select a more profitable habitat with respect to their phenotypes (i.e., adaptive habitat choice) and to assortatively mate with relatively similar phenotypes. On the other hand, plasticity facilitates the evolution of plastic generalists when individuals have a limited capacity for adaptive habitat choice. We conclude that plasticity can accelerate the evolution of a reproductive barrier toward adaptive diversification and ecological speciation through enhanced phenotypic differentiation between diverging phenotypes.

  • 38.
    Olajos, Fredrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bokma, Folmer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bartels, Pia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Myrstener, Erik
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Rydberg, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Öhlund, Gunnar
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bindler, Richard
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wang, Xiao-Ru
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Zale, Rolf
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Estimating species colonization dates using DNA in lake sediment2018In: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 9, no 3, p. 535-543Article in journal (Refereed)
    Abstract [en]
    1. Detection of DNA in lake sediments holds promise as a tool to study processes like extinction, colonization, adaptation and evolutionary divergence. However, low concentrations make sediment DNA difficult to detect, leading to high false negative rates. Additionally, contamination could potentially lead to high false positive rates. Careful laboratory procedures can reduce false positive and negative rates, but should not be assumed to completely eliminate them. Therefore, methods are needed that identify potential false positive and negative results, and use this information to judge the plausibility of different interpretations of DNA data from natural archives.
    2. We developed a Bayesian algorithm to infer the colonization history of a species using records of DNA from lake-sediment cores, explicitly labelling some observations as false positive or false negative. We illustrate the method by analysing DNA of whitefish (Coregonus lavaretus L.) from sediment cores covering the past 10,000 years from two central Swedish lakes. We provide the algorithm as an R-script, and the data from this study as example input files.
    3. In one lake, Stora Lögdasjön, where connectivity with the proto-Baltic Sea and the degree of whitefish ecotype differentiation suggested colonization immediately after deglaciation, DNA was indeed successfully recovered and amplified throughout the post-glacial sediment. For this lake, we found no loss of detection probability over time, but a high false negative rate. In the other lake, Hotagen, where connectivity and ecotype differentiation suggested colonization long after deglaciation, DNA was amplified only in the upper part of the sediment, and colonization was estimated at 2,200 bp based on the assumption that successful amplicons represent whitefish presence. Here the earliest amplification represents a false positive with a posterior probability of 41%, which increases the uncertainty in the estimated time of colonization.
    4. Complementing careful laboratory procedures aimed at preventing contamination, our method estimates contamination rates from the data. By combining these results with estimates of false negative rates, our models facilitate unbiased interpretation of data from natural DNA archives.
  • 39. Pauchard, Anibal
    et al.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Albihn, Ann
    Alexander, Jake
    Burgess, Treena
    Daehler, Curtis
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Essl, Franz
    Evengård, Birgitta
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
    Greenwood, Gregory B.
    Haider, Sylvia
    Lenoir, Jonathan
    McDougall, Keith
    Muths, Erin
    Nunez, Martin A.
    Olofsson, Johan
    Pellissier, Loic
    Rabitsch, Wolfgang
    Rew, Lisa J.
    Robertson, Mark
    Sanders, Nathan
    Kueffer, Christoph
    Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation2016In: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 18, no 2, p. 345-353Article in journal (Refereed)
    Abstract [en]

    Cold environments at high elevation and high latitude are often viewed as resistant to biological invasions. However, climate warming, land use change and associated increased connectivity all increase the risk of biological invasions in these environments. Here we present a summary of the key discussions of the workshop 'Biosecurity in Mountains and Northern Ecosystems: Current Status and Future Challenges' (Flen, Sweden, 1-3 June 2015). The aims of the workshop were to (1) increase awareness about the growing importance of species expansion-both non-native and native-at high elevation and high latitude with climate change, (2) review existing knowledge about invasion risks in these areas, and (3) encourage more research on how species will move and interact in cold environments, the consequences for biodiversity, and animal and human health and wellbeing. The diversity of potential and actual invaders reported at the workshop and the likely interactions between them create major challenges for managers of cold environments. However, since these cold environments have experienced fewer invasions when compared with many warmer, more populated environments, prevention has a real chance of success, especially if it is coupled with prioritisation schemes for targeting invaders likely to have greatest impact. Communication and co-operation between cold environment regions will facilitate rapid response, and maximise the use of limited research and management resources.

  • 40. Petersen, John E
    et al.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Dimensional approaches to designing better experimental ecosystems: a practitioners guide with examples.2005In: Oecologia, ISSN 0029-8549, Vol. 145, no 2, p. 216-24Article in journal (Refereed)
  • 41.
    Petrin, Zlatko
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Malmqvist, Björn
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Contrasting effects of anthropogenic and natural acidity in streams: a meta-analysis.2008In: Proceedings of the Royal Society B: Biological Sciences, ISSN 0962-8452, Vol. 275, no 1639, p. 1143-8Article in journal (Refereed)
    Abstract [en]

    arge-scale human activities including the extensive combustion of fossil fuels have caused acidification of freshwater systems on a continental scale, resulting in reduced species diversity and, in some instances, impaired ecological functioning. In regions where acidity is natural, however, species diversity and functioning seem less affected. This contrasting response is likely to have more than one explanation including the possibility of adaptation in organisms exposed to natural acidity over evolutionary timescales and differential toxicity due to dissimilarities in water chemistry other than pH. However, empirical evidence supporting these hypotheses is equivocal. Partly, this is because previous research has mainly been conducted at relatively small geographical scales, and information on ecological functioning in this context is generally scarce. Our goal was to test whether anthropogenic acidity has stronger negative effects on species diversity and ecological functioning than natural acidity. Using a meta-analytic approach based on 60 data sets we show that macroinvertebrate species richness and the decomposition of leaf litter - an important process in small streams - tend to decrease with increasing acidity across regions and across both acidity categories. Macroinvertebrate species richness, however, declines three times more rapidly with increasing acidity where it is anthropogenic than where it is natural, in agreement with the adaptation hypothesis and the hypothesis of differences in water chemistry. In contrast, the loss in ecological functioning differs little between categories, probably because increases in the biomass of taxa remaining at low pH compensate for losses in functionality that would otherwise accompany losses of taxa from acidic systems. This example from freshwater acidification illustrates how natural and anthropogenic stressors can differ markedly in their effects on species diversity and one aspect of ecological functioning.

  • 42.
    Sjödin, Henrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Space race functional responses2015In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1801, article id 20142121Article in journal (Refereed)
    Abstract [en]

    We derive functional responses under the assumption that predators and prey are engaged in a space race in which prey avoid patches with many predators and predators avoid patches with few or no prey. The resulting functional response models have a simple structure and include functions describing how the emigration of prey and predators depend on interspecific densities. As such, they provide a link between dispersal behaviours and community dynamics. The derived functional response is general but is here modelled in accordance with empirically documented emigration responses. We find that the prey emigration response to predators has stabilizing effects similar to that of the DeAngelis-Beddington functional response, and that the predator emigration response to prey has destabilizing effects similar to that of the Holing type 11 response. A stability criterion describing the net effect of the two emigration responses on a Lotka-Volterra predator-prey system is presented. The winner of the space race (i.e. whether predators or prey are favoured) is determined by the relationship between the slopes of the species' emigration responses. It is predicted that predators win the space race in poor habitats, where predator and prey densities are low, and that prey are more successful in richer habitats.

  • 43.
    Sjödin, Henrik
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Söderquist, Mårten
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Population-level consequences of heterospecific density-dependent movements in predator-prey systems2014In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 342, p. 93-106Article in journal (Refereed)
    Abstract [en]

    In this paper we elucidate how small-scale movements, such as those associated with searching for food and avoiding predators, affect the stability of predator-prey dynamics. We investigate an individual-based Lotka-Volterra model with density-dependent movement, in which the predator and prey populations live in a very large number of coupled patches. The rates at which individuals leave patches depend on the local densities of heterospecifics, giving rise to one reaction norm for each of the two species. Movement rates are assumed to be much faster than demographics rates. A spatial structure of predators and prey emerges which affects the global population dynamics. We derive a criterion which reveals how demographic stability depends on the relationships between the per capita covariance and densities of predators and prey. Specifically, we establish that a positive relationship with prey density and a negative relationship with predator density tend to be stabilizing. On a more mechanistic level we show how these relationships are linked to the movement reaction norms of predators and prey. Numerical results show that these findings hold both for local and global movements, i.e., both when migration is biased towards neighbouring patches and when all patches are reached with equal probability.

  • 44. Spens , J.
    et al.
    Englund , Göran
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Lundqvist , H.
    Network connectivity and dispersal barriers: Using geographical information system (GIS) tools to predict landscape scale distribution of a key predator (Esox lucius) among lakes2007Article in journal (Refereed)
    Abstract [en]

    The keystone piscivore northern pike Esox lucius can structure fish communities, and models predicting pike-focused connectivity will be important for management of many waters. We explored the ability of pike to colonize upstream locations and modelled presence-absence in lakes based on landscape features derived from maps. An upstream connectivity model (UC model) was generated using data from 87 lakes. We validated the UC model with retrospective whole-lake experiments involving introductions (n = 49) and extirpations (by rotenone) of pike (n = 96), as well as with the natural distribution of pike in lakes (n = 1365) within 26 drainage basin networks in northern Sweden. The UC model predicted the incidence of pike in lakes with stream-connections with 95.4% accuracy, based mainly on a single variable, S-V5max, that measures the minimum distance found between 5 m elevation intervals (= maximum stream slope) along watercourses from nearest downstream source of potential immigrants. Recolonizations of pike in rotenone lakes generated a near-identical classification tree, as in the UC model. The classification accuracy of pike presence in the external validation procedure ranged from 88.7 to 98.7% between different drainage basins. Predictions of pike absence were not as accurate, due possibly to undetected introductions, but still lead to 86.6% overall accuracy of the external validation. Most lakes lacking pike, but misclassified as having pike based on low S-V5max, were isolated from downstream sources of pike by subsurface stream flow through bouldery areas (SSB). Synthesis and applications. The variable S-V5max provides managers with a tool for revealing the location and severity of natural dispersal barriers to pike (and logically also barriers to other species with equivalent or less dispersal capacity). Because presented models only require map-based information, and have high predictive power, they may have the potential to be of fundamental use in predicting distribution of freshwater fish. These predictions may provide the means for prioritizing in risk assessment and control programmes to combat pike invasions, as well as contribute to determining a reference state of species incidence in specific lakes. Our results also point towards a possibility that, even where stream slope is low, long-term effective barriers may be designed that mimic natural SSB.

  • 45.
    Strengbom, J
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Englund, G
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Ericson, L
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Experimental scale and precipitation modify effects of nitrogen addition on a plant pathogen2006In: Journal of Ecology, Vol. 94, no 1, p. 227-233Article in journal (Refereed)
  • 46. Svanbäck, Richard
    et al.
    Rydberg, Cecilia
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Leonardsson, Kjell
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Diet specialization in a fluctuating population of Saduria entomon: a consequence of resource or forager densities?2011In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, no 6, p. 848-854Article in journal (Refereed)
    Abstract [en]

    Intraspecific competition has been shown to favor diet specialization among individuals. However, the question whether the competition takes the form of interference or exploitative in driving diet specialization has never been investigated. We investigated individual diet specialization in the isopod Saduria entomon, in relation to forager and resource biomasses in a system that exhibits predator–prey fluctuations in density. We found that individual diet specialization was only affected by the biomass of their preferred prey (Monoporeia affinis) and not by Saduria biomass; diet specialization was higher when Monoporeia biomass was low compared to when there were high Monoporeia biomass. Population diet breadth increased at low Monoporeia biomass whereas individual diet breadths were marginally affected by Monoporeia biomass. Overall, this led to the increase in diet specialization at low Monoporeia biomass. This study shows that predator–prey dynamics might influence diet specialization in the predator and that resource biomass, not forager biomass might be important for individual diet specialization.

  • 47.
    Uszko, Wojciech
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Diehl, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Amarasekare, Priyanga
    Effects of warming on predator-prey interactions - a resource-based approach and a theoretical synthesis2017In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 20, no 4, p. 513-523Article in journal (Refereed)
    Abstract [en]

    We theoretically explore consequences of warming for predator-prey dynamics, broadening previous approaches in three ways: we include beyond-optimal temperatures, predators may have a type III functional response, and prey carrying capacity depends on explicitly modelled resources. Several robust patterns arise. The relationship between prey carrying capacity and temperature can range from near-independence to monotonically declining/increasing to hump-shaped. Predators persist in a U-shaped region in resource supply (=enrichment)-temperature space. Type II responses yield stable persistence in a U-shaped band inside this region, giving way to limit cycles with enrichment at all temperatures. In contrast, type III responses convey stability at intermediate temperatures and confine cycles to low and high temperatures. Warming-induced state shifts can be predicted from system trajectories crossing stability and persistence boundaries in enrichment-temperature space. Results of earlier studies with more restricted assumptions map onto this graph as special cases. Our approach thus provides a unifying framework for understanding warming effects on trophic dynamics.

  • 48.
    Uszko, Wojciech
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Diehl, Sebastian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Amarasekare, Priyanga
    Effects of warming on predator-prey interactions: a resource-based approach and a theoretical synthesisManuscript (preprint) (Other academic)
  • 49.
    Valinia, Salar
    et al.
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Moldan, Filip
    IVL Swedish Environmental Research Institute, Göteborg, Sweden.
    Futter, Martyn N.
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Kohler, Stephan J.
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bishop, Kevin
    Department of Earth Sciences, Uppsala University, Uppsala, Sweden and Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Folster, Jens
    Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Assessing anthropogenic impact on boreal lakes with historical fish species distribution data and hydrogeochemical modeling2014In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 20, no 9, p. 2752-2764Article in journal (Refereed)
    Abstract [en]

    Quantifying the effects of human activity on the natural environment is dependent on credible estimates of reference conditions to define the state of the environment before the onset of adverse human impacts. In Europe, emission controls that aimed at restoring ecological status were based on hindcasts from process-based models or paleolimnological reconstructions. For instance, 1860 is used in Europe as the target for restoration from acidification concerning biological and chemical parameters. A more practical problem is that the historical states of ecosystems and their function cannot be observed directly. Therefore, we (i) compare estimates of acidification based on long-term observations of roach (Rutilus rutilus) populations with hindcast pH from the hydrogeochemical model MAGIC; (ii) discuss policy implications and possible scope for use of long-term archival data for assessing human impacts on the natural environment and (iii) present a novel conceptual model for interpreting the importance of physico-chemical and ecological deviations from reference conditions. Of the 85 lakes studied, 78 were coherently classified by both methods. In 1980, 28 lakes were classified as acidified with the MAGIC model, however, roach was present in 14 of these. In 2010, MAGIC predicted chemical recovery in 50% of the lakes, however roach only recolonized in five lakes after 1990, showing a lag between chemical and biological recovery. Our study is the first study of its kind to use long-term archival biological data in concert with hydrogeochemical modeling for regional assessments of anthropogenic acidification. Based on our results, we show how the conceptual model can be used to understand and prioritize management of physico-chemical and ecological effects of anthropogenic stressors on surface water quality.

  • 50.
    Yu, Jun
    et al.
    SLU, Centre of Biostochastics.
    Englund, Göran
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Predator-Prey Covariance with predator aggregative responses2010Report (Other academic)
    Abstract [en]

    The spatial covariance between prey and predator densities is closely related to the rate of encounters, and thus to predation rates. To include the effect of covariance in dynamic predator–prey models it is useful to express the spatial covariance as a function of predator and prey densities. Here we derive mean–covariance relationships for a scenario where predators show an aggregative response, i.e., they respond behaviorally by aggregating in patches with high prey densities. Prey, on the otherhand, do not respond to predator densities. Some explicit expressions are obtained when the prey distribution is clumped or random. It is shown that the prey-predator covariance can be expressed only through the distributional information of prey. In particular when the prey distributionis clumped or random, this covariance depends only on the mean prey density.

12 1 - 50 of 54
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