Genetic researcher Nathan Clark spoke about research his team at the University of Pittsburgh conducted on evolutionary genetics. The seminars are hosted weekly by the University of Wisconsin Genetics Department at the Biotechnology Center.
The Clark Lab works on examining the genetics behind convergent evolution, where animals adapt similar characteristics despite being distantly related. Clark’s lab specializes in comparing these distant species and seeing how genetic changes correlate to phenotypic or trait changes.
Clark tracks these changes by measuring different phenomena, which help explain the relationship between the genetic changes and the phenotypic ones. One of these methods is tracking the rate at which related genes mutate.
The lab investigated the changing genes in aquatic mammals in separate families like dolphins, seals, manatees and otters. They filtered related genes evolving at faster rates and grouped them into either genes pushed into rapid mutation due to positive selection or genes in a relaxed state.
Positive selection refers to genes evolving to adapt to serious risks and threats. Genes can also evolve rapidly in situations where they are not critical to the survival of an individual.
While examining genes evolving rapidly and with high selection pressure, Clark noticed genes associated with lung function and skin tissues had increased rates of evolution. His lab then sought to test two theories on why these genes were being pressured to adapt. Their investigation indicated that the rapid evolution was due to adaptations to living in an aquatic environment as opposed to pathogens necessitating changes.
Clark’s lab also looked at which genes were being lost in aquatic mammals. They found similarities to the relaxed genes evolving at high rates, but also an extreme outlier. In the analysis they ran, PON1 — a gene that creates a protein responsible for breaking down certain fat molecules and organophosphate pesticides — was being lost at a very high rate in aquatic mammals but never in terrestrial ones.
Expanding their search, Clark’s lab found none of the terrestrial mammals they surveyed had lost function of the PON1 gene, while almost every aquatic mammal had. More analysis revealed that PON1 seemed to be expressed at increasingly low levels in recently evolved aquatic mammals before the gene would slowly degrade and stop being expressed at all.
Clark then moved on to his lab’s research on subterranean mammals. They found most of the genes evolving at high rates were related to eyesight.
Clark said looking at the regions that regulate gene expression in moles could help predict their involvement in human eye diseases.
“Our hope [is that] eventually, we might be able to use some of this evolutionary information, some of these new regions, into the fold, but we’re happy to find them wherever they may lie,” Clark said.