Sympatric speciation is often envisioned as a series of stages from panmixis to reproductive incompatibility. Empirical studies of this process have either been retrospective or have focused on the specific stage of divergence of their focal study populations/species. These approaches have an important limitation; the mechanisms, genes and phenotypic traits driving the initial split in the ancestral population are likely to be different from those acting at later stages of speciation. It may thus be difficult elucidate the complex eco-evolutionary dynamics leading to divergence and reproductive isolation.
One potential solution to this problem is to follow populations as they go through the different stages of speciation. Although this is not feasible in most natural systems, we are now in a position that allows us to do just that. We have recently found that whitefish (Coregonus lavaretus) introduced into lakes with pike (Esox lucius) evolve sympatric, genetically distinct ecotypes in less than 150 years. This short time scale, in combination with the availability of historical samples and data from more than 50 introduced populations that diverged during the last 230 years, allows us to study replicated and parallel speciation “in action” for the first time in a natural system.
In this project we use data from introduced populations of different age to construct a timeline that describes the ecological and genetic processes contributing to phenotypic divergence and reproductive isolation during subsequent stages of a sympatric speciation process.