A legacy of human-induced ecosystem changes: spatial processes drive the taxonomic and functional diversities of testate amoebae in Sphagnum peatlands of the Galápagos

Fournier, Bertrand; Coffey, Emily E. D.; van der Knaap, Willem Oscar; Fernández, Leonardo D.; Bobrov, Anatoly; Mitchell, Edward A. D. (2016). A legacy of human-induced ecosystem changes: spatial processes drive the taxonomic and functional diversities of testate amoebae in Sphagnum peatlands of the Galápagos. Journal of Biogeography, 43(3), pp. 533-543. Wiley 10.1111/jbi.12655

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Aim

Our aims were to compare the composition of testate amoeba (TA) communities from Santa Cruz Island, Galápagos Archipelago, which are likely in existence only as a result of anthropogenic habitat transformation, with similar naturally occurring communities from northern and southern continental peatlands. Additionally, we aimed at assessing the importance of niche-based and dispersal-based processes in determining community composition and taxonomic and functional diversity.
Location

The humid highlands of the central island of Santa Cruz, Galápagos Archipelago.
Methods

We survey the alpha, beta and gamma taxonomic and functional diversities of TA, and the changes in functional traits along a gradient of wet to dry habitats. We compare the TA community composition, abundance and frequency recorded in the insular peatlands with that recorded in continental peatlands of Northern and Southern Hemispheres. We use generalized linear models to determine how environmental conditions influence taxonomic and functional diversity as well as the mean values of functional traits within communities. We finally apply variance partitioning to assess the relative importance of niche- and dispersal-based processes in determining community composition.
Results

TA communities in Santa Cruz Island were different from their Northern Hemisphere and South American counterparts with most genera considered as characteristic for Northern Hemisphere and South American Sphagnum peatlands missing or very rare in the Galápagos. Functional traits were most correlated with elevation and site topography and alpha functional diversity to the type of material sampled and site topography. Community composition was more strongly correlated with spatial variables than with environmental ones.
Main conclusions

TA communities of the Sphagnum peatlands of Santa Cruz Island and the mechanisms shaping these communities contrast with Northern Hemisphere and South American peatlands. Soil moisture was not a strong predictor of community composition most likely because rainfall and clouds provide sufficient moisture. Dispersal limitation was more important than environmental filtering because of the isolation of the insular peatlands from continental ones and the young ecological history of these ecosystems.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Palaeoecology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

van der Knaap, Willem Oscar

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0305-0270

Publisher:

Wiley

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

04 Apr 2016 15:01

Last Modified:

20 Dec 2016 11:44

Publisher DOI:

10.1111/jbi.12655

Uncontrolled Keywords:

biodiversity, dispersal, disturbance, environmental filtering, island biogeography, microbial ecology, soil protozoa, functional trait

BORIS DOI:

10.7892/boris.79594

URI:

https://boris.unibe.ch/id/eprint/79594

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