Ecological Speciation

How we get new species is one of the oldest questions in biology. We now know there are a few different ways, one of which is ecological speciation, where different populations become adapted to different environments, causing divergence, barriers to gene flow, and eventually reproductive isolation. But we still don't always understand why some populations complete that process and others remain the same species. To study that process, we need to watch speciation in action.

But what happens when we populations from both of these ecotypes back into the same lake? How close are they to becoming different species?

We can infer evidence of speciation through mating patterns. If these populations have made progress towards speciation, we would expect that benthic fish would be more likely to mate with benthic fish, and limnetic with limnetic. 

To track mating patterns, we can use genetic data to see how often we find admixed individuals (or hybrid) in our experimental lakes. Specially, we have extracted DNA from each fish and are using genotyping of population-specific markers to infer ancestry.  After identifying those hybrids, we can compare the frequencies of hybrids to what we might expect under different assumptions of mating patterns to see if there is significant mate preference by ecotype.

Inferring mating patterns will allow us to see if these diverged ecotypes have made any progress towards becoming different species.