Investigating the relative role of dispersal and demographic traits in
predictive phylogeography
Abstract
Many studies suggest that aside from environmental variables, such as
topography and climate, species-specific ecological traits are relevant
to explain the geographic distribution of intraspecific genetic
lineages. Here, we investigated whether and to what extent incorporating
such traits systematically improves the accuracy of random forest models
in predicting genetic differentiation among pairs of localities. We
leveraged available ecological datasets for birds and tested the
inclusion of two categories of ecological traits: dispersal-related
traits (i.e., morphology and foraging ecology) and demographic traits
(such as species survival rate and generation length). We estimated
genetic differentiation from published mitochondrial DNA sequences for
31 species of birds (1,801 total genetic samples, 526 localities) in the
Atlantic Forest of South America. Aside from the aforementioned
ecological traits, we included geographic, topographic and climatic
distances between localities as environmental predictors. We then
created models using all available data to evaluate model uncertainty
both across space and across the different categories of predictors.
Finally, we investigated model uncertainty in predicting genetic
differentiation individually for each species (a common challenge in
conservation biology). Our results show that while environmental
conditions are the most important predictors of genetic differentiation,
model accuracy largely increases with the addition of ecological traits.
Additionally, the inclusion of dispersal traits improves model accuracy
to a larger extent than the inclusion of demographic traits. Similar
results are observed in models for individual species, although model
accuracy is highly variable. We conclude that ecological traits improve
predictive models of genetic differentiation, refining our ability to
predict phylogeographic patterns from existing data. Additionally,
demographic traits may not be as informative as previously hypothesized.
Finally, prediction of genetic differentiation for species with
conservation concerns may require further careful assessment of the
environmental and ecological variations within the species range.