White-eyes are a widespread group in the Old World Tropics. They have the highest documented rate of diversification among vertebrates (Moyle et al 2009), and are particularly interesting because they have radiated across so many habitats while maintaining a relatively conserved morphology. The entire radiation of White-eyes is estimated to be about 2 million years old (Moyle et al 2009). The Southern African White-eyes are under a million years old and there are 3 or 4 species in the group. In South Africa, the three species occur in different biomes. Along the biome boundaries, hybrid individuals have been found (Oatley et al. 2012).
We recently completed a study that examines gene flow among the South African lineages to better understand the extent of and timing of gene flow among lineages (Oatley et al. in prep). We used a combination of statistical approaches to estimate gene flow and also to evaluate the role of contemporary landscape features (habitat, rivers) on patterns of genetic diversity across South Africa. I was able to implement an approximate Bayesian computational framework to further validate our estimates of gene flow among lineages and also to evaluate population size demographics. Here is a preview of some of the demographic models we evalauted.
To further our understanding of speciation dyanmics among Southern African white-eyes, I am using Rad sequencing to investigate hybrid zone dynamics and introgression across species boundaries. This work builds on the population genetic and hybridization work already in place in this system, and will add a genomic perspective. Our preliminary findings have already found some genomic regions that may form “islands of divergence”. We are also further exploring the spatial context of diversification and hybridization in this system. This work is in collaboration with Graeme Oatley, Ke Bi, Rauri Bowie, and Gary Voelker . I recently presented some results of this work at the Evolution Conference in Raleigh NC.
To gain an understanding of the spatial dynamics of each species I generated species distribution models for each species covering the past 120 ky
(62 time slices).