Uncovering evolutionary processes

Figure from Hodge & Bellwood, 2015 illustrating the evolutionary process of peripheral budding.

Figure modified from Hodge & Bellwood, 2015 illustrating the evolutionary process of peripheral budding.

One such evolutionary processes that I have identified through my research is the concept of peripheral budding. This process came to light when examining the geographical relationships of closely related species in the genus Anampses. The process involves successive divergence events from a single species and results in a phylogenetic tree topology where the divergence time is underestimated for that species. In the figure above, the successive divergences are illustrated as founder events (although they could occur via any mode of speciation) at times t1, t2 and t3 and the age of the species from which they diverged is estimated from the phylogeny as t3. This is an underestimation of the true species age, which is more accurately estimated as t1, or as t-zero, if the phylogeny contained more taxa. Peripheral budding is potentially prevalent among fishes and other organisms with comparable dispersal capabilities, like birds and insects.

My research has also described methods for further analysis of species-age estimates that overcome their misidentification in the case of peripheral budding, and tackle issues of pseudoreplication. The application of these methods revealed an increase in the geographical range area of coral reef fish species with age.



Figure from Hodge & Bellwood, 2015 showing an increase in species geographical range area with age.