Capturing the Contribution of Rare and Common Species to Turnover: A Multi-Site Version of Generalised Dissimilarity Modelling

Post provided by Guillaume Latombe and Melodie A. McGeoch

Understanding how biodiversity is distributed and its relationship with the environment is crucial for conservation assessment. It also helps us to predict impacts of environmental changes and design appropriate management plans. Biodiversity across a network of local sites is typically described using three components:

  1. alpha (α) diversity, the average number of species in each specific site of the study area
  2. beta (β) diversity, the difference in species composition between sites
  3. gamma (γ) diversity, the total number of species in the study area.
Two tawny frogmouths, a species native to Australia. ©Marie Henriksen.

Two tawny frogmouths, a species native to Australia. ©Marie Henriksen.

Despite the many insights provided by the combination of alpha, beta and gamma diversity, the ability to describe species turnover has been limited by the fact that they do not consider more than two sites at a time. For more than two sites, the average beta diversity is typically used (multi-site measures have also been developed, but suffer shortcomings, including difficulties of interpretation). This makes it difficult for researchers to determine the likely environmental drivers of species turnover.

We have developed a new method that combines two pre-existing advances, zeta diversity and generalised dissimilarity modelling (both explained below). Our method allows the differences in the contributions of rare versus common species to be modelled to better understand what drives biodiversity responses to environmental gradients. Continue reading

Disentangling Ecosystem Functions: Our Imagination is the Limit


Studies of Action

Studies of ecosystem function are studies of action: of insects pollinating flowers, of predators killing pests – and in our case (well, more often than not) of beetles disposing of dung. To isolate the effects of the critters that we think will matter, we need to selectively include or exclude them. If we think a particular species or species group is responsible for a certain function, then we test this by keeping it in or out of enclosures. If we want to look at effects of species diversity, then we create communities of different species richness.

Research on dung beetles is far from boring. © Kari Heliövaara.

Research on dung beetles is far from boring. © Kari Heliövaara.

Depending on the target organism, this is sometimes easy and sometimes difficult. But it almost invariably proves to be fun! We enjoy the challenge of inventing new techniques for unravelling ecosystem functions sustained by insects. Working on dung beetles – as we tend to do – can be messy, but it’s definitely never boring.

In targeting ecosystem functions, the real trick is to make the experiments relevant. What we want to understand are the effects of changes occurring in the real world. All too often studies of ecosystem functions have been focused on artificial species pools in artificial settings. To see how we have solved this, we’ll give you a quick look at our dungy portfolio of approaches to date. Continue reading

New Associate Editors

Over the next few weeks we will be welcoming three new Associate Editors to Methods in Ecology and Evolution. Susan Johnston (University of Edinburgh, UK) became a member of the Associate Editor Board on Monday 5 October. She will be joined on 19 October by Natalie Cooper (Natural History Museum, London, UK) and finally by Luísa Carvalheiro (University of Brasília, Brazil) on 2 November. You can find out more about all three of our new Associate Editors below.

Susan Johnston

Susan Johnston“My research focuses on using genomic information to understand evolution in natural populations. I adapt mixed model approaches to determine the genetic architecture of interesting traits (e.g. estimating heritability, genome-wide association studies, outlier analyses) to examine its relationship with fitness or importance in local adaptation. I am interested in the potential of affordable genomics to answer evolutionary and ecological questions in wild systems, and how to deal with various statistical issues arising from such studies in small and/or structured populations.”

Susan’s most recently published article is ‘Low but significant genetic differentiation underlies biologically meaningful phenotypic divergence in a large Atlantic salmon population‘, co-authored with T. Aykanat, P. Orell, E. Niemelä, J. Erkinaro and C.R. Primmer. The findings suggest that different evolutionary processes affect sub-populations of Atlantic salmon and that hybridization and subsequent selection may maintain low genetic differentiation without hindering adaptive divergence. This article was published in Molecular Ecology.

Natalie Cooper

Natalie Cooper“I am an evolutionary biologist, focusing mainly on macroevolution and macroecology. My interests include phylogenetic comparative methods, morphological evolution, using museum specimens in research, and integrating neontological and palaeontological data and approaches for understanding broad-scale patterns of biodiversity.”

Natalie has recently been published in Molecular Phylogenetics and Evolution (‘Effects of missing data on topological inference using a Total Evidence approach‘ with T. Guillerme) and in Evolution (‘Investigating evolutionary lag using the species-pairs evolutionary lag test (SPELT)‘ with C.L. Nunn). She was also a speaker at the Methods in Ecology and Evolution 5th Anniversary Symposium. Her presentation, ‘Limitations of Phylogenetic Comparative Methods‘, is freely available on YouTube.

Luísa Carvalheiro

Luisa Carvalheiro“My research focuses on community ecology & conservation. I have particular interest in the study of dynamics of biodiversity through time and space; and on the evaluation of how such biotic changes affect ecosystem functioning and ecosystem services, considering how the complex network of ecological interactions in which species are integrated mediates such changes.”

Earlier this year Luísa’s article ‘Susceptibility of pollinators to ongoing landscape changes depends on landscape history‘ (with J. Aguirre-Gutiérrez, J.C. Biesmeijer, E.E. van Loon, M. Reemer, and M.F. Wallis De Vries) was published in Diversity and Distributions. The article emphasizes the limited value of a one-size-fits-all biodiversity conservation measures and highlights the importance of considering landscape history when planning biodiversity conservation actions. This article is Open Access. Luísa was also the lead author of ‘The potential for indirect effects between co-flowering plants via shared pollinators depends on resource abundance, accessibility and relatedness‘ an Open Access article published in Ecology Letters last year.

We are thrilled to welcome Susan, Natalie and Luísa to the Associate Editor Board and we look forward to working with them over the coming years.

Issue 2.6

Our last issue for 2011 is out. Issue 2.6 is packed with the latest methodological developments.

We have four new articles on monitoring: from positional accuracy in the field by Mike Dodd to distance sampling butterflies by Nick Isaac and colleagues, to how to account for non-independent detection of individuals by Julien Martin and collaborators and, finally, to a class of spatial capture-recapture models for ‘search-encounter’ data by Andrew Royle, Marc Kéry and Jérôme Guélat.

Two articles focus on modelling distributions. Darryl MacKenzie and colleagues present their work on modelling habitat and species distribution dynamics and Peter Wilson introduces an analytical framework applying a distance-based approach to the ordination and analysis of maps produced by species distribution modelling tools.

Kristen L. Granger and collaborators explain their extraction and assay methods on seed chemistry while Adam Davis et al look at seed predation rates.

Also, Joseph Chipperfield et al model dispersal kernels, Alexandre Bec and co-authors assess the reliability of fatty acid–specific stable isotope analysis for trophic studies. Jeroen Groot and Walter Rossing review recent developments in systems modelling which support learning by creating a salient diversity of management alternatives and by translating science-based results into stakeholder perspectives.

Nicholas J. Gotelli, Werner Ulrich and Fernando T. Maestre explore randomization tests for quantifying species importance to ecosystem function and their article takes the front cover.

Finally, the issue contains two free Application articles. In the first Conrad Stack, Luke Harmon and Brian O’Meara detail RBrownie, an R package for testing hypotheses about rates of evolutionary change. In the second, Stefan Prost and Christian Anderson present TempNet, a method to display statistical parsimony networks for heterochronous DNA sequence data.

Ask your librarian to get free access in perpetuity to the first two years of Methods in Ecology and Evolution by completing this request form or learn about how to access the journal in 2012.