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New publication: Finding a population genetic fingerprint of coevolution

A red milkweed beetle, Tetraopes tetrophthalmus, on its host plant. (jby)

A new paper from the lab — coauthored with all three of the Yoder Lab’s graduate student alumni — is now online ahead of print in the journal Evolution Letters. In it, we analyze population genetic data from 20 pairs of plants and herbivores, parasites, and mutualists that live intimately on those plants to test for evidence that the associate species’ population genetic structure aligns with that of their host plants. This is an expected result if adaptation to the host plant drives diversification of the associates — and we found that it is indeed a recurring pattern. Here’s the “Impact statement” published with the paper:

Natural selection created by intimate association with plants is thought to be responsible for the evolution of some highly diverse groups like beetles and butterflies, but we are still learning exactly when and how plant-associate interactions promote the formation of new species. One way to examine the process of plant-associate diversification up close is to look at the genetic variation of populations within a single species of associates and its host plant. We compiled this kind of data from published studies of 20 plant-associate pairs, and tested for evidence that populations of associates from less genetically similar populations of their host plant were themselves less genetically similar—a possible consequence of natural selection created by close association with the host plant, and a first step towards the formation of new species. We found evidence for this pattern in a majority of the plant-associate pairs we examined, and we found that the pattern was somewhat stronger for antagonistic associates than for mutualistic ones. 

This work stands on the shoulders of a long history of studies examining how host plants may drive the diversification of associate species, and we’re excited to have this new contribution finally published. It’s possibly the start of a longer-term project for the lab, because (as we note in the paper) plants are far from alone in hosting intimate associate species; you could imagine a similar analysis of, for instance, animal hosts and microbial symbionts, or parasites like lice. Stay tuned for the next stage — or get in touch if you want to pitch in as an undergraduate researcher or a graduate student.