Name: Paúl MJ

Biodeserts supervisors: Carvalho S

Co-supervisors: Dan Rosauer (ANU College of Science)

Title: Drivers of amphibian phylogenetic and phylogeographic diversity in the Iberian Peninsula

Institution: University of Porto, Portugal

Status: Completed

Abstract

Understanding the ecological and evolutionary processes that drive biodiversity and allow its persistence is of upmost importance, given the on-going biodiversity crisis. Many hypotheses have been proposed to explain spatial diversity patterns, including: water-energy availability, isolation, habitat heterogeneity and historical climatic stable refugia.
The main goal of this study was to identify the potential drivers of spatial diversity patterns, using Iberian amphibians as a case study. We hypothesized that both contemporary and historical topographic and climatic predictors are major drivers of phylogenetic diversity and endemism.
We calculated spatial patterns of phylogenetic diversity and endemism using a previously published ultrametric phylogenetic tree and distribution data. We also calculated two null models (‘tip shuffle’ and ‘independent swap’) to assess if species in a community are more distantly related than expected, since phylogenetic diversity and phylogenetic endemism are commonly correlated with species richness and endemism. Furthermore, we compiled spatial data on topographic and climatic variables related to the energy, water availability, altitude, habitat heterogeneity and historical climatic instability hypotheses. To test our hypotheses, we used Spatial Autoregressive Models, in a model selection framework and selected the best model to explain diversity patterns based on Akaike Information Criterion scores.
According to our results, spatial patterns of phylogenetic diversity and endemism, are aggregated in biodiversity hotspots, although they are highly correlated with species richness. Water, energy and historical climatic instability are the most important drivers (out of the ones tested) of amphibian diversity in Iberia. However, the best models had a low goodness-of-fit, suggesting that those predictors provide a significant, but not sufficient, explanation for diversity patterns. We hypothesize that the low goodness-of-fit obtained might be related to: i) different assembly processes occurring at global and regional scales, ii) limitations regarding our variables, iii) lack of appropriate predictors, iv) the inclusion of a partial a phylogeny and range distributions. Given these hypotheses, further research incorporating predictors and diversity metrics not accounted for in the present study and at different evolutionary scales (inter and intra-specific) is needed to properly understand the processes driving amphibian biodiversity.