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Island biogeography of young land uplift islands - viewed through the lens of bryophytes in a northern Swedish archipelago
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Landskapsekologi)
2016 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Öbiogeografi hos unga landhöjningsöar - betraktad ur ett mossperspektiv. (Swedish)
Abstract [en]

Increasing habitat fragmentation and rapid global warming is changing the conditions for species populations and ecological communities around the world. This presents challenges for the maintenance of biodiversity and a dominant paradigm for conservation in fragmented habitats is given by island biogeography and metapopulation (or metacommunity) ecology.

In this thesis I approach key concepts (area, connectivity and community assembly) in island biogeography and metacommunity ecology within the context of a dynamic land uplift archipelago. The presented work consists of two interwoven themes: (i) A methodological theme in which statistical approaches are developed to deal with the complexities of multispecies dynamic systems, and (ii) an applied theme dealing with community assembly and island biogeography of bryophytes on young land uplift islands.

To describe island connectivity for entire species assemblages, an approach using functional principal component analysis (fPCA) on patch connectivity functions (the connectivity of an island as a continuous function of a variable representing the spatial scale of species dispersal capacities) was developed. In addition, a new statistical method, functional co-inertia analysis (fCoIA), for analyzing co-variation between multivariate species data and continuous functions was developed and applied to the relation between bryophyte species incidences and the island age/area-dynamics.

Primarily asexual bryophyte species are dispersal limited and presence probabilities are related to island connectivity. No such patterns were found for species, at least occasionally, producing spores. Our results suggest that bryophyte dispersal is regulated by the contribution of spores to a regional spore rain and that bryophyte species with low spore output at the landscape level may be extra vulnerable under habitat fragmentation and loss. Having specialized asexual propagules increases the presence probabilities on islands, partly compensating for the dispersal limitation in asexual species. This suggests a trade-off between dispersal and establishment capacity, but also points to the importance of local dispersal for maintaining populations under the succession driven spatial turnover of microsites on the islands. Bryophyte colonization is strongly limited by habitat availability when a given habitats is rare, but there seems to exist a threshold over which other processes (e.g. dispersal limitation) become more important. Species with more vagile life history strategies appear to be stronger affected by the area of available habitats than many perennial species

Place, publisher, year, edition, pages
Umeå: Umeå University , 2016. , 59 p.
Keyword [en]
functional data analysis, metacommunity, isolation, mosses, liverworts, sporophyte production, dispersal-establishment trade-off
National Category
Ecology Botany Probability Theory and Statistics
Research subject
Ecological Botany; Conservation Biology; Statistics
Identifiers
URN: urn:nbn:se:umu:diva-121239ISBN: 978-91-7601-495-0 (print)OAI: oai:DiVA.org:umu-121239DiVA: diva2:932336
Public defence
2016-09-23, Björken, Sveriges Lantbruksuniversitet, Umeå, 09:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council Formas, 215-2010-998
Available from: 2016-06-03 Created: 2016-05-30 Last updated: 2016-06-17Bibliographically approved
List of papers
1. Exploring Connectivity across Spatial Scales Using Functional Principal Component Analysis
Open this publication in new window or tab >>Exploring Connectivity across Spatial Scales Using Functional Principal Component Analysis
(English)Article in journal (Refereed) Submitted
Abstract [en]

The interplay between organism dispersal and habitat patch connectivity is crucial for the distribution and dynamics of populations and communities. However, the appropriate spatial scales of connectivity analysis vary among species, populations and individuals, depending on their capacity and propensity to move. This scale dependence poses problems when studying assemblages including species with different appropriate scales or when the scale for a species varies or is difficult to determine. To address these problems, we develop an approach summarizing among-patch variation in structural connectivity across a continuum of scales. We do this by first treating a connectivity metric (e.g. habitat area around a patch) as a continuous function of a scale-defining variable (e.g. distance) for a number of patches. We then extract and summarize information present in the shapes of the resulting collection of “patch connectivity functions”, using methods for functional data analysis (functional principal component analysis, fPCA). We apply the approach to a data set of 36 islands and show that it is possible to effectively summarize the among-patch variation in structural patch connectivity across spatial scales using only a small number of functional principal components. We also show how our functional data analysis approach to connectivity metrics can be useful (i) as an information tool for decisions regarding the design of protected area networks and (ii) in designing spatially explicit ecological studies including multiple species (e.g. metacommunity studies). We explore relationships with widely used methods in landscape ecology and show how continuous function representations can reveal information hidden in single value applications of metrics. The usefulness of the approach for analyses of functional connectivity is discussed. We conclude that the approach provides a powerful methodology to represent variation in connectivity across spatial scales that will serve many purposes within spatial ecology and biogeography

Keyword
Spatial scale, Metacommunities, Metapopulations, Multispecies conservation, Functional data analysis, Functional PCA, Connectivity, Isolation, Island biogeography, Landscape context, Conservation planning, Study design
National Category
Ecology
Research subject
Conservation Biology
Identifiers
urn:nbn:se:umu:diva-121232 (URN)
Funder
Swedish Research Council Formas, 215-2010-998
Available from: 2016-06-01 Created: 2016-05-30 Last updated: 2016-06-01
2. Analyzing co-variation patterns between functional and multivariate ecological data – the functional co-inertia analysis
Open this publication in new window or tab >>Analyzing co-variation patterns between functional and multivariate ecological data – the functional co-inertia analysis
(English)Manuscript (preprint) (Other academic)
Abstract [en]
  1. Ecological phenomena are often better represented by mathematical functions than by discrete values. Examples include population trends, temperatures curves, functional responses of predators and seed size distributions. A collection of such functions describing the same phenomenon in different sites or at different points in time constitutes a functional data set. To facilitate the use of functional data sets, we develop a statistical method that allows for the analysis of co-variation between functional and multivariate data sets.
  2. We extend the multivariate co-inertia analysis framework for analyzing common variation structure between datasets to cases when one or both datasets consist of functional data. We use basis expansions of functions and weighted inner products to extend the concepts of inertia and co-inertia to functional data and present an extension of the RV-coefficient for quantifying the association between datasets. We then derive the functional co-inertia analysis (fCoIA) as a special case of the multivariate method. Using metrics derived from the functions in the basis expansion we express the fCoIA as a multivariate co-inertia analysis of basis expansion coefficients. The new approach is illustrated by coupling non-functional bryophyte species data with a functional dataset describing age-area distributions of young land-uplift islands.
  3. The technique efficiently summarizes the co-variation structure between the two datasets and provides quantifications and visualizations of the contributions from each data set to the co-variation..An important feature of the results is the graphical illustration of the common variation patterns through plots of approximations of cross-covariance function shapes describing the detailed co-variation of each variable in the multivariate data with the functional data.
  4. The methodology provides ecologists (potentially also evolutionary biologists) with a new tool for incorporating functional data into ordination analyses and considerably extends the realm of questions that can be addressed. In the future, the approach might be extended to other multivariate methods (e.g….) building on the co-inertia framework (e.g RLQ analysis) and we envision analyses matching environmental data to function valued species traits (e.g “reaction norms” of plastic phenotypic expressions).
Keyword
functional data analysis, fCoIA, bryophytes, land uplift, co-inertia
National Category
Ecology Probability Theory and Statistics
Research subject
Ecological Botany; Statistics
Identifiers
urn:nbn:se:umu:diva-121235 (URN)
Funder
Swedish Research Council Formas, 215-2010-998
Available from: 2016-06-01 Created: 2016-05-30 Last updated: 2016-06-01
3. Bryophyte community assembly on young land uplift islands – dispersal and habitat filtering assessed using species traits
Open this publication in new window or tab >>Bryophyte community assembly on young land uplift islands – dispersal and habitat filtering assessed using species traits
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The combined challenges from rapid landscape transformations and climate change have actualize the need to understand community assembly processes in order to efficiently conserve threatened species in changing landscapes. In this study we focus on community assembly in bryophytes and use species traits to examine habitat filtering and dispersal limitation during colonization of islands recently created by land uplift processes in the Bothnian bay in northern Europe. The bryophyte floras of 20 islands differing in age, area, connectivity and habitat composition were assessed through field inventories and we compiled information across several sources to create a list of all species in the regional species pool. Data on traits related to habitat affiliations (substrate, light, moisture and pH) and dispersal/colonization ability (e.g regional abundance, spore size, sporophyte frequency) were collected and, for 420 species (94% of the regional pool) with available data, we used multivariate models to compare trait effects on species occurrence probabilities across the 20 islands. We found that occurrence probabilities depended strongly on the availability of different habitats across the islands and that regionally rare species and predominantly asexual species had sharply reduced probabilities of being present on islands compared to regionally abundant and /or sexual species, Having specialized asexual propagules had a positive effect on occurrence probabilities, but compensated only partly for the reductions in asexual species. No effects of spore size were detected. A comparison of trait effects on occurrence probabilities across island connectivity and area gradients, revealed reduced habitat filtering on larger islands and that the negative effects on occurrence probabilities in the asexual species decreased with island connectivity. An absence of connectivity relationships for sexual species, suggest that their colonization is regulated by habitat availability and the contributions of each species landscape level spore output to a “regional spore rain” from which species recruited. Conservation strategies, aimed at conserving and increasing the frequency of regional propagule sources, irrespective of their spatial configuration, could therefore be useful in this group. For asexual species, our results instead suggest a strategy aimed at spatially concentrating the conservation and restoration of habitats in order to increase metapopulation persistence.

National Category
Ecology
Research subject
Ecological Botany; Conservation Biology
Identifiers
urn:nbn:se:umu:diva-121236 (URN)
Funder
Swedish Research Council Formas, 215-2010-998
Available from: 2016-06-01 Created: 2016-05-30 Last updated: 2016-06-01

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Karlsson Tiselius, Andreas

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