Methods in Biogeography

The International Biogeography Society has just held their 5th meeting in Crete and I thought I would pick some highlights that are methods relevant.  This meeting brings together a range of researchers from the intersection of ecology, evolutionary biology, geography, geology and systematics: a truly diverse grouping.

Biogeography is, in essence concerned with the distributions of species and how these change with time. It is no surprise then that phylogenetic analysis was the focus of many talks. Indeed, if there is one thing that sets the talks I saw at this meeting apart from those at more ‘ecological’ meetings, it is the heavy reliance on phylogenetic methods. Relatively recently developed methods for looking at phylogenetic structure in ecological communities were particularly in evidence.

Three talks were particularly methods focussed and described really interesting new approaches and perspectives.

Andy Purvis of Imperial College, UK, looked at how macroevolutionary questions could be tested using different methods and data. His talk emphasised that evolutionary models can be varied and that broad-scale analyses that assume single models could be misleading. For example, using data on all mammal species he showed that the evolution of body mass could be described using an ‘early burst’ model; however when broken up into individual orders, the picture was a highly variable one with different models fitting best to some orders rather than others, and very different rates across groups.

Andy also dealt with niche conservatism, another big theme at this meeting. Niche conservatism is the idea that closely related species share their niches because they inherit them from ancestors. If niches are generally conserved then this is important because, for example, changes to climate or habitat may affect taxonomic groups of species that share similar requirements, or that are historically slow to adapt. Andy made the good point that current definitions are sometimes at odds with each other, and that notions of niche conservatism need to be clearly spelled out.

Also from Imperial, Ally Phillimore took a different perspective. The aim in his research is to link small-scale ecological processes with macroevolution. He described an elegant method for linking within and between population spatial and temporal variation to explore the degree to which adaptation and plasticity drive phenological responses to climate change. Using data on data gathered by the public on egg laying dates in frogs in the UK, Ally showed how his approach could be used to predict how fast populations need to evolve in order to keep up with climate change.

A major issue in the analyis of biogeographical and macroecological data is how to deal with spatialautocorrelation. Pedro Peres Neto from the University of Quebec and Montréal described simulation results that showed how autocorrelation affects the outcomes of statistical tests, and provided some guidelines on the expected outcome of methods. He pointed out that the strength of a relationship between two variables and the source of dependency (whether in the residuals or the predictors) could be factors. One point well made was that spatial and phylogenetic methods for trait data analysis share a lot of similarity and there is a lot of potential for interchange.

These are just three talks I have highlighted as I found them particularly stimulating (and methods relevant), overall the meeting was really enjoyable interesting. And, following the coldest UK December in 100 years, I really do have to congratulate the organisers on their choice of Crete a venue!

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