Abstract
The isolation and defined boundaries of marine islands make them ideal natural laboratories of evolution, representing excellent case studies to unravel evolutionary processes that have shaped current biodiversity. However, we still do not understand why some island lineages have radiated spectacularly, while others remained species-poor or did not radiate at all. Identifying the drivers that promote diversification is one of the key objectives in biodiversity research. Models have been developed to assess the effect of species traits on diversification, but these methods require densely sampled and well-resolved phylogenetic trees. Such trees are often not available, especially not for species-rich clades that have undergone remarkable radiations. In this project proposal, we will develop a novel model of trait-dependent diversification that is specifically tailored for islands, implying that only information from island representatives and their continental relatives is required, and thereby greatly reducing the sampling and sequencing effort for lineages with a global distribution. To do so, PhD student 1 will merge two of our previously developed diversification models (DAISIE for species diversification on islands and SECSSE for trait-dependent diversification) into one integrated model, which has the great combined advantage of allowing the exploration of the effect of multiple species traits on insular rates of speciation and extinction, while requiring a much lower phylogenetic sampling than existing trait-dependent methods. PhD student 2 will test this novel framework via self-generated empirical data on plants – i.e. molecular phylogenies generated with hybrid sequencing, and trait data on growth form, flower and fruit traits – focusing on the largest plant family that has undergone radiations in an insular setting (Asteraceae) on one of the best studied archipelagos (Canary Islands; ca 50 colonisation events leading to 229 native species). The major outcomes of our proposal are twofold: (1) a tested, freely available, user-friendly software that will allow evolutionary biologists to investigate which traits drive (plant and animal) diversification in an insular context, and (2) identification of plant traits that have triggered radiation in the most successful island lineage.
Netherlands