de Almeida Afonso Abranches Nunes, LG; (2017) New methods for testing phylogenetic niche conservatism with an application to the Squamates of Madagascar. Doctoral thesis , UCL (University College London).

Preview

Text laura-nunes-thesis.pdf Download (3MB) | Preview

Abstract

Phylogenetic niche conservatism (PNC), whereby closely-related species share similar ecological preferences, is often assumed to play a role in speciation processes. However, this trend is challenged by cases of phylogenetic niche divergence (PND), whereby closely-related species diverge in their ecological preferences. I examine the incidence of PNC and PND in the endemic scaled reptiles (Order, Squamata) of Madagascar. Firstly, I develop new tools to test for PNC and PND for a pair of species or populations. I introduce a novel measure of niche overlap and a null biogeographic test. I begin by comparing their performance with existing methods and case studies and I find the outputs from this new methodology to be consistent with evolutionary theory. I then conduct an assessment on the sensitivity of these tools to common sources of uncertainty identified in other niche-based methodologies. The methodology shows sensitivity to environmental spatial autocorrelation but not size of background region or sampling bias. I then applied these tools to sister taxa of squamates in Madagascar. I find cases of both PNC and PND and a tendency for niche conservatism in regions of high topographic complexity. In order to have an understanding of factors driving species divergence at a local scale, I also test for character displacement. I find character displacement to also be positively associated with topographic complexity. These findings suggest potential shifts in local scale niche traits and conservatism of broad scale niche traits. Overall in this thesis, I describe novel approaches to the study of PNC and PND. I also propose topographic complexity as an important factor in speciation processes in Madagascar. These findings provide hypotheses on the ecological processes involved in speciation on topographic complex regions while the tools presented in this thesis can be applied to many study systems.

Download activity - last month

Export as JSONCSVXML

Download activity - last 12 months

Export as XMLCSVJSON

Downloads by country - last 12 months

Export as JSONCSVXML

Archive Staff Only

View Item