CIFAR

New Paper on Evolution and Salmon Bioenergetics

March 3, 2015

We are pleased to report that the “Editor’s Choice” paper in the February 2015 issue of the Journal of Zoological Systematics and Evolutionary Research is a direct result of CIFAR’s support of a UAF Global Change Student Research Grant Competition award. The paper, which focuses on mitochondrial DNA analysis, describes research that followed a surprising find made by first author Michael Garvin as he began work on his CIFAR-funded student grant project.

Changes in mitochondrial DNA over time can be used to describe the genealogies of populations or species (like a family tree) and also as a clock to date different events along the branches of the tree. For instance, this information has been used to determine which groups of humans migrated out of Africa and when. For his CGC project, Mike planned to do this type of analysis with populations of chum salmon to determine when and how they colonized Western Alaska. As a first step he tested to make sure that mitochondrial DNA behaved “neutrally,” i.e., that the changes in the DNA were not part of the evolutionary process.

“To my surprise, the tests I ran determined that one site in particular had undergone ‘positive selection’ and was very likely important for the evolution of different species of Pacific salmon.” Mike notes that, coincidently, scientists at Cambridge in the UK published the three-dimensional structure of the protein complex that was encoded by the gene that he found to be under selection (Efremov et al., Nature 465:441–447, 2010).

“The complex is central to the production of energy in all animals and the specific site I found in salmon was located in a ‘piston armature’ that appears to coordinate the energy producing pumps of the large complex.”

In a follow-up study, Mike and his collaborators found that this armature has been important in the evolution of many other taxa including bears and whales. “We proposed that the changes alter how efficiently energy is used so that individuals can adapt to ecosystems like Alaska where food is plentiful in the spring and summer but not in the winter. The efficiency is directly related to how long they have to rely on stored energy when food is unavailable.” This analysis formed the basis of the new JZSER article.

Mike is now analyzing the mitochondrial DNA variation of nearly 600 chum salmon to determine if he can gain some insight into how they adapted to western Alaskan drainages.

“An initial small project funded by CIFAR has expanded into areas I never imagined!”

Garvin, M.R., J.P. Bielawski, L.A. Sazanov and A.J. Gharrett. 2015. Review and meta-analysis of natural selection in mitochondrial complex I in metazoans. Journal of Zoological Systematics and Evolutionary Research, 53(1):1–17. doi:10.1111/jzs.12079.

Mike Garvin’s CGC project “Whole mitochondrial genome analysis to uncover detailed genetic structure of chum salmon populations and possible historical refugia” was funded by CIFAR in 2010.

Contact: Michael Garvin