Convergent Evolution
Evolution in Sulfidic Environments
I worked with a group of collaborators on a project integrating datasets across multiple levels of biological organization to identify the mechanisms underlying convergent evolution of tolerance to hydrogen sulfide (H2S)—a toxicant that impairs mitochondrial function—across evolutionarily independent populations of sulfide spring Poecilia mexicana in southern Mexico, as well as other lineages of poeciliid fishes inhabiting sulfidic habitats across the Americas and Caribbean. We found that P. mexicana from sulfide springs are able to maintain mitochondrial function in the presence of H2S due to convergent adaptations in the primary toxicity target and a major detoxification enzyme. These convergent adaptations arose from both selection on standing genetic variation and de novo mutations.
We also investigated convergent evolution in a broader taxonomic sampling of Poeciliids spanning 40 million years of evolution using comparative transcriptomics. We found that sulfide tolerance in 10 independent lineages of sulfide spring poeciliids is correlated with the convergent modification of and expression changes in genes associated with H2S toxicity and detoxification. Click here to check out the full study.
