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  • 51.
    Rossberg, Axel
    et al.
    Queen’s University Belfast School of Biological Sciences Belfast BT9 7BL Northern Ireland UK.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Dieckmann, Ulf
    International Institute for Applied Systems Analysis (IIASA) Evolution and Ecology Program Schlossplatz 1 2361 Laxenburg Austria.
    How trophic interaction strength depends on traits: A conceptual framework for representing multidimensional trophic niche spaces2010Inngår i: Theoretical Ecology, ISSN 1874-1738 (Print) 1874-1746 (Online), Vol. 3, nr 1, s. 13-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A key problem in community ecology is to understand how individual-level traits give rise to population-level trophic interactions. Here, we propose a synthetic framework based on ecological considerations to address this question systematically. We derive a general functional form for the dependence of trophic interaction coefficients on trophically relevant quantitative traits of consumers and resources. The derived expression encompasses—and thus allows a unified comparison of—several functional forms previously proposed in the literature. Furthermore, we show how a community’s, potentially low-dimens ional, effective trophic niche space is related to its higher-dimensional phenotypic trait space. In this manner, we give ecological meaning to the notion of the “dimensionality of trophic niche space.” Our framework implies a method for directly measuring this dimensionality. We suggest a procedure for estimating the relevant parameters from empirical data and for verifying that such data matches the assumptions underlying our derivation.

  • 52. Rossberg, Axel G
    et al.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Dieckmann, Ulf
    Food-web structure in low- and high-dimensional trophic niche spaces2010Inngår i: Journal of the Royal Society Interface, ISSN 1742-5689, E-ISSN 1742-5662, Vol. 7, nr 53, s. 1735-1743Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A question central to modelling and, ultimately, managing food webs concerns the dimensionality of trophic niche space, that is, the number of independent traits relevant for determining consumer-resource links. Food-web topologies can often be interpreted by assuming resource traits to be specified by points along a line and each consumer's diet to be given by resources contained in an interval on this line. This phenomenon, called intervality, has been known for 30 years and is widely acknowledged to indicate that trophic niche space is close to one-dimensional. We show that the degrees of intervality observed in nature can be reproduced in arbitrary-dimensional trophic niche spaces, provided that the processes of evolutionary diversification and adaptation are taken into account. Contrary to expectations, intervality is least pronounced at intermediate dimensions and steadily improves towards lower- and higher-dimensional trophic niche spaces.

  • 53. Sasaki, Tatsuya
    et al.
    Brännstrom, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Dieckmann, Ulf
    Sigmund, Karl
    The take-it-or-leave-it option allows small penalties to overcome social dilemmas2012Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, nr 4, s. 1165-1169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Self-interest frequently causes individuals engaged in joint enterprises to choose actions that are counterproductive. Free-riders can invade a society of cooperators, causing a tragedy of the commons. Such social dilemmas can be overcome by positive or negative incentives. Even though an incentive-providing institution may protect a cooperative society from invasion by free-riders, it cannot always convert a society of free-riders to cooperation. In the latter case, both norms, cooperation and defection, are stable: To avoid a collapse to full defection, cooperators must be sufficiently numerous initially. A society of free-riders is then caught in a social trap, and the institution is unable to provide an escape, except at a high, possibly prohibitive cost. Here, we analyze the interplay of (a) incentives provided by institutions and (b) the effects of voluntary participation. We show that this combination fundamentally improves the efficiency of incentives. In particular, optional participation allows institutions punishing free-riders to overcome the social dilemma at a much lower cost, and to promote a globally stable regime of cooperation. This removes the social trap and implies that whenever a society of cooperators cannot be invaded by free-riders, it will necessarily become established in the long run, through social learning, irrespective of the initial number of cooperators. We also demonstrate that punishing provides a "lighter touch" than rewarding, guaranteeing full cooperation at considerably lower cost.

  • 54. Seehausen, Ole
    et al.
    Butlin, Roger K.
    Keller, Irene
    Wagner, Catherine E.
    Boughman, Janette W.
    Hohenlohe, Paul A.
    Peichel, Catherine L.
    Saetre, Glenn-Peter
    Bank, Claudia
    Brannström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Brelsford, Alan
    Clarkson, Chris S.
    Eroukhmanoff, Fabrice
    Feder, Jeffrey L.
    Fischer, Martin C.
    Foote, Andrew D.
    Franchini, Paolo
    Jiggins, Chris D.
    Jones, Felicity C.
    Lindholm, Anna K.
    Lucek, Kay
    Maan, Martine E.
    Marques, David A.
    Martin, Simon H.
    Matthews, Blake
    Meier, Joana I.
    Most, Markus
    Nachman, Michael W.
    Nonaka, Etsuko
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Rennison, Diana J.
    Schwarzer, Julia
    Watson, Eric T.
    Westram, Anja M.
    Widmer, Alex
    Genomics and the origin of species2014Inngår i: Nature reviews genetics, ISSN 1471-0056, E-ISSN 1471-0064, Vol. 15, nr 3, s. 176-192Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Speciation is a fundamental evolutionary process, the knowledge of which is crucial for understanding the origins of biodiversity. Genomic approaches are an increasingly important aspect of this research field. We review current understanding of genome-wide effects of accumulating reproductive isolation and of genomic properties that influence the process of speciation. Building on this work, we identify emergent trends and gaps in our understanding, propose new approaches to more fully integrate genomics into speciation research, translate speciation theory into hypotheses that are testable using genomic tools and provide an integrative definition of the field of speciation genomics.

  • 55.
    Sjödin, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Dieckmann, Ulf
    Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Mazzucco, Rupert
    Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Contingent dispersal and the formation of cooperative groupsManuskript (preprint) (Annet vitenskapelig)
  • 56.
    Sjödin, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Englund, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Space race functional responses2015Inngår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, nr 1801, artikkel-id 20142121Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 57.
    Sjödin, Henrik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria.
    Söderquist, Mårten
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Englund, Göran
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Population-level consequences of heterospecific density-dependent movements in predator-prey systems2014Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 342, s. 93-106Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 58. Sumpter, David
    et al.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Synergy in social communication2008Inngår i: Sociobiology of communication: an interdisciplinary perspective / [ed] Patrizia d'Ettorre and David P. Hughes, Oxford: Oxford University Press , 2008Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Synergy is where the interactions of a group of individuals becomes more than the sum of their parts. In this chapter we review how, through the use of social communication, foraging animals can increase their rate of finding food. We discuss how mechanisms such as pheromone trails, dancing, and other signals act to increase group, and thus individual, success. We also discuss how social dilemmas can arise where costly signalling can be exploited by non-signallers. We show that under a range of conditions, specifically when group success increases more than linearly with group size, cooperative signalling can evolve without kin selection or reciprocity. This study serves to emphasise the importance in linking mechanism with function when studying collective behaviour of animals.

  • 59. Swami, Viren
    et al.
    Frederick, David A
    Aavik, Toivo
    Alcalay, Lidia
    Allik, Jüri
    Anderson, Donna
    Andrianto, Sonny
    Arora, Arvind
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. International Institute for Applied Systems Analysis, Austria.
    Cunningham, John
    Danel, Dariusz
    Doroszewicz, Krystyna
    Forbes, Gordon B
    Furnham, Adrian
    Greven, Corina U
    Halberstadt, Jamin
    Hao, Shuang
    Haubner, Tanja
    Hwang, Choon Sup
    Inman, Mary
    Jaafar, Jas Laile
    Johansson, Jacob
    Umeå universitet. International Institute for Applied Systems Analysis, Austria.
    Jung, Jaehee
    Keser, Aşkın
    Kretzschmar, Uta
    Lachenicht, Lance
    Li, Norman P
    Locke, Kenneth
    Lönnqvist, Jan-Erik
    Lopez, Christy
    Loutzenhiser, Lynn
    Maisel, Natalya C
    McCabe, Marita P
    McCreary, Donald R
    McKibbin, William F
    Mussap, Alex
    Neto, Félix
    Nowell, Carly
    Alampay, Liane Peña
    Pillai, Subash K
    Pokrajac-Bulian, Alessandra
    Proyer, René T
    Quintelier, Katinka
    Ricciardelli, Lina A
    Rozmus-Wrzesinska, Malgorzata
    Ruch, Willibald
    Russo, Timothy
    Schütz, Astrid
    Shackelford, Todd K
    Shashidharan, Sheeba
    Simonetti, Franco
    Sinniah, Dhachayani
    Swami, Mira
    Vandermassen, Griet
    van Duynslaeger, Marijke
    Verkasalo, Markku
    Voracek, Martin
    Yee, Curtis K
    Zhang, Echo Xian
    Zhang, Xiaoying
    Zivcic-Becirevic, Ivanka
    The Attractive Female Body Weight and Female Body Dissatisfaction in 26 Countries Across 10 World Regions: Results of the International Body Project I2010Inngår i: Personality and Social Psychology Bulletin, ISSN 0146-1672, E-ISSN 1552-7433, Vol. 36, nr 3, s. 309-325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study reports results from the first International Body Project (IBP-I), which surveyed 7,434 individuals in 10 major world regions about body weight ideals and body dissatisfaction. Participants completed the female Contour Drawing Figure Rating Scale (CDFRS) and self-reported their exposure to Western and local media. Results indicated there were significant cross-regional differences in the ideal female figure and body dissatisfaction, but effect sizes were small across high-socioeconomic-status (SES) sites. Within cultures, heavier bodies were preferred in low-SES sites compared to high-SES sites in Malaysia and South Africa (ds = 1.94-2.49) but not in Austria. Participant age, body mass index (BMI), and Western media exposure predicted body weight ideals. BMI and Western media exposure predicted body dissatisfaction among women. Our results show that body dissatisfaction and desire for thinness is commonplace in high-SES settings across world regions, highlighting the need for international attention to this problem.

  • 60. Takahashi, Daisuke
    et al.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis (IIASA), Austria.
    Mazzucco, Rupert
    Yamauchi, Atsushi
    Dieckmann, Ulf
    Abrupt community transitions and cyclic evolutionary dynamics in complex food webs2013Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 337, s. 181-189Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding the emergence and maintenance of biodiversity ranks among the most fundamental challenges in evolutionary ecology. While processes of community assembly have frequently been analyzed from an ecological perspective, their evolutionary dimensions have so far received less attention. To elucidate the eco-evolutionary processes underlying the long-term build-up and potential collapse of community diversity, here we develop and examine an individual-based model describing coevolutionary dynamics driven by trophic interactions and interference competition, of a pair of quantitative traits determining predator and prey niches. Our results demonstrate the (1) emergence of communities with multiple trophic levels, shown here for the first time for stochastic models with linear functional responses, and (2) intermittent and cyclic evolutionary transitions between two alternative community states. In particular, our results indicate that the interplay of ecological and evolutionary dynamics often results in extinction cascades that remove the entire trophic level of consumers from a community. Finally, we show the (3) robustness of our results under variations of model assumptions, underscoring that processes of consumer collapse and subsequent rebound could be important elements of understanding biodiversity dynamics in natural communities.

  • 61. Takahashi, Daisuke
    et al.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program , International Institute for Applied Systems Analysis, Laxenburg, Austria.
    Mazzucco, Rupert
    Yamauchi, Atsushi
    Dieckmann, Ulf
    Cyclic transitions in simulated food-web evolution2011Inngår i: Journal of Plant Interactions, ISSN 1742-9145, E-ISSN 1742-9153, Vol. 6, nr 2-3, s. 181-182Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Eco-evolutionary food-web models help elucidate the processes responsible for the emergence and maintenance of complex community structures. Using an individual-based model of evolving trophic and competitive interactions, we highlight a pattern of community macroevolution involving two meta-stable states, corresponding to a plant-herbivore community and a plant community, respectively. On the evolutionary timescale, our model exhibits cyclic transitions between these alternative community states. The model also helps understand the eco-evolutionary mechanisms underlying these recurrent rapid transitions, which end intermittent periods of near-stasis or punctuated equilibrium.

  • 62. van Leeuwen, E.
    et al.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Int Inst Appl Syst Anal, Evolut & Ecol Program, A-2361 Laxenburg, Austria.
    Jansen, V. A. A.
    Dieckmann, U.
    Rossberg, A. G.
    A generalized functional response for predators that switch between multiple prey species2013Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 328, s. 89-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We develop a theory for the food intake of a predator that can switch between multiple prey species. The theory addresses empirical observations of prey switching and is based on the behavioural assumption that a predator tends to continue feeding on prey that are similar to the prey it has consumed last, in terms of, e.g., their morphology, defences, location, habitat choice, or behaviour. From a predator's dietary history and the assumed similarity relationship among prey species, we derive a general closed-form multi-species functional response for describing predators switching between multiple prey species. Our theory includes the Holling type II functional response as a special case and makes consistent predictions when populations of equivalent prey are aggregated or split. An analysis of the derived functional response enables us to highlight the following five main findings. (1) Prey switching leads to an approximate power-law relationship between ratios of prey abundance and prey intake, consistent with experimental data. (2) In agreement with empirical observations, the theory predicts an upper limit of 2 for the exponent of such power laws. (3) Our theory predicts deviations from power-law switching at very low and very high prey-abundance ratios. (4) The theory can predict the diet composition of a predator feeding on multiple prey species from diet observations for predators feeding only on pairs of prey species. (5) Predators foraging on more prey species will show less pronounced prey switching than predators foraging on fewer prey species, thus providing a natural explanation for the known difficulties of observing prey switching in the field. (C) 2013 Elsevier Ltd. All rights reserved.

  • 63.
    Wickman, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Dieckmann, Ulf
    Evolution and Ecology Program, International Institute for Applied Systems Analysis (IIASA).
    Hui, Cang
    Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University; Mathematical and Physical Biosciences, African Institute for Mathematical Sciences.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    How geographic productivity patterns affect food-web evolutionManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    It is well recognized that spatial heterogeneity and overall productivity have important consequences for the diversity and community structure of food webs. Yet, few, if any, studies have considered the effects of heterogeneous spatial distributions of primary production. Here, we theoretically investigate how the variance and autocorrelation length of primary production affect properties of evolved food webs consisting of one autotroph and several heterotrophs. We report the following findings. (1) Diversity increases with landscape variance and is unimodal in autocorrelation length. (2) Trophic level increases with high landscape variance and is unimodal in autocorrelation length. (3) The extent to which the spatial distribution of heterotrophs differ from that of the autotroph increases with variance and decreases with autocorrelation length. (4) Components of initial disruptive selection experienced by the ancestral heterotroph predict properties of the final evolved communities. Prior to our study reported here, several authors had hypothesized that diversity increases with the variance of productivity. Our results support their hypothesis and contributes new facets by providing quantitative predictions that also account for autocorrelation length and additional properties of the evolved communities.

  • 64.
    Wickman, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Diehl, Sebastian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Blasius, Bernd
    Klausmeier, Christopher A.
    Ryabov, Alexey B.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Determining Selection across Heterogeneous Landscapes: A Perturbation-Based Method and Its Application to Modeling Evolution in Space2017Inngår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 189, nr 4, s. 381-395Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spatial structure can decisively influence the way evolutionary processes unfold. To date, several methods have been used to study evolution in spatial systems, including population genetics, quantitative genetics, moment-closure approximations, and individual-based models. Here we extend the study of spatial evolutionary dynamics to eco-evolutionary models based on reaction-diffusion equations and adaptive dynamics. Specifically, we derive expressions for the strength of directional and stabilizing/disruptive selection that apply both in continuous space and to metacommunities with symmetrical dispersal between patches. For directional selection on a quantitative trait, this yields a way to integrate local directional selection across space and determine whether the trait value will increase or decrease. The robustness of this prediction is validated against quantitative genetics. For stabilizing/disruptive selection, we show that spatial heterogeneity always contributes to disruptive selection and hence always promotes evolutionary branching. The expression for directional selection is numerically very efficient and hence lends itself to simulation studies of evolutionary community assembly. We illustrate the application and utility of the expressions for this purpose with two examples of the evolution of resource utilization. Finally, we outline the domain of applicability of reaction-diffusion equations as a modeling framework and discuss their limitations.

  • 65.
    Wickman, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Diehl, Sebastian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria.
    Evolution of resource specialisation in competitive metacommunities2019Inngår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 22, nr 11, s. 1746-1756Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Spatial environmental heterogeneity coupled with dispersal can promote ecological persistence of diverse metacommunities. Does this premise hold when metacommunities evolve? Using a two-resource competition model, we studied the evolution of resource-uptake specialisation as a function of resource type (substitutable to essential) and shape of the trade-off between resource uptake affinities (generalist- to specialist-favouring). In spatially homogeneous environments, evolutionarily stable coexistence of consumers is only possible for sufficiently substitutable resources and specialist-favouring trade-offs. Remarkably, these same conditions yield comparatively low diversity in heterogeneous environments, because they promote sympatric evolution of two opposite resource specialists that, together, monopolise the two resources everywhere. Consumer diversity is instead maximised for intermediate trade-offs and clearly substitutable or clearly essential resources, where evolved metacommunities are characterised by contrasting selection regimes. Taken together, our results present new insights into resource-competition-mediated evolutionarily stable diversity in homogeneous and heterogeneous environments, which should be applicable to a wide range of systems.

  • 66.
    Wickman, Jonas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Diehl, Sebastian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Patterns of diversity in evolved metacommunities of resource competitorsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Spatial heterogeneity in environmental conditions coupled with moderate dispersal can promote ecological persistence of diverse metacommunities. We explored whether this premise holds when metacommunities can evolve. Using a model of competition for two resources, we studied the evolution of resource-uptake specialization as a function of resource type (substitutable to essential) and the shape of the trade-off in resource uptake affinities (generalist- to specialist-favoring). In homogeneous environments, evolutionarily stable coexistence of consumers is only possible for sufficiently substitutable resources and specialist-favoring trade-offs. Remarkably, these same conditions yield comparatively low diversity in heterogeneous environments, where consumer diversity is instead maximized for clearly substitutable or clearly essential resources and intermediate trade-offs. When resources are weakly interactively essential, at most two consumers persist evolutionarily in spite of high spatial variance in resource supply ratios. We explain these patterns based on analytical results for the limiting case of a spatially homogeneous system.

  • 67.
    Zhang, Lai
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Dieckmann, Ulf
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis, A-2361 Laxenburg, Austria.
    On the performance of four methods for the numerical solution of ecologically realistic size-structured population models2017Inngår i: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 8, nr 8, s. 948-956Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. Size-structured population models (SSPMs) are widely used in ecology to account for intraspecific variation in body size. Three characteristic features of size-structured populations are the dependence of life histories on the entire size distribution, intrinsic population renewal through the birth of new individuals, and the potential accumulation of individuals with similar body sizes due to determinate or stunted growth. Because of these three features, numerical methods that work well for structurally similar transport equations may fail for SSPMs and other transport-dominated models with high ecological realism, and thus their computational performance needs to be critically evaluated.

    2. Here, we compare the performance of four numerical solution schemes, the fixed-mesh upwind (FMU) method, the moving-mesh upwind (MMU) method, the characteristic method (CM), and the Escalator Boxcar Train (EBT) method, in numerically solving three reference problems that are representative of ecological systems in the animal and plant kingdoms. The MMU method is here applied for the first time to SSPMs, whereas the three other methods have been employed by other authors.

    3. Our results show that the EBT method performs best, except for one of the three reference problems, in which size-asymmetric competition affects individual growth rates. For that reference problem, the FMU method performs best, closely followed by the MMU method. Surprisingly, the CM method does not perform well for any of the three reference problems.

    4. We conclude that life-history features should be carefully considered when choosing the numerical method for analyzing ecologically realistic size-structured population models.

  • 68.
    Zhang, Lai
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. School of Mathematical Science, Yangzhou University 225002, Yangzhou, China.
    Thibert-Plante, Xavier
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ripe, Jorgen
    Svanback, Richard
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik. Evolution and Ecology Program, International Institute for Applied Systems Analysis A-2361, Laxenburg, Austria.
    Biodiversity loss through speciation collapse: Mechanisms, warning signals, and possible rescue2019Inngår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 73, nr 8, s. 1504-1516Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Speciation is the process that generates biodiversity, but recent empirical findings show that it can also fail, leading to the collapse of two incipient species into one. Here, we elucidate the mechanisms behind speciation collapse using a stochastic individual-based model with explicit genetics. We investigate the impact of two types of environmental disturbance: deteriorated visual conditions, which reduce foraging ability and impede mate choice, and environmental homogenization, which restructures ecological niches. We find that: (1) Species pairs can collapse into a variety of forms including new species pairs, monomorphic or polymorphic generalists, or single specialists. Notably, polymorphic generalist forms may be a transient stage to a monomorphic population; (2) Environmental restoration enables species pairs to reemerge from single generalist forms, but not from single specialist forms; (3) Speciation collapse is up to four orders of magnitude faster than speciation, while the reemergence of species pairs can be as slow as de novo speciation; (4) Although speciation collapse can be predicted from either demographic, phenotypic, or genetic signals, observations of phenotypic changes allow the most general and robust warning signal of speciation collapse. We conclude that factors altering ecological niches can reduce biodiversity by reshaping the ecosystem's evolutionary attractors.

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