Ecological genomics is a rapidly growing field that aims to understand the genetic mechanisms responsible for the adaptive responses of organisms to their environment. I’m jumping into this area of research as a postdoc in the Kelly Lab at Louisiana State University and last weekend I attended the 12th annual Ecological Genomics Symposium hosted by the Ecological Genomics Institute at Kansas State University. The talks and posters presented at EGS covered a broad range of questions, critters, and data types- both phenotypic and genomic, but the common goal of many of the projects was to determine how genotype and environment influence the evolution of phenotypes. In this post I’ll highlight a small cross section of the exciting research I heard about at the meeting.
Dr. Zac Cheviron at the University of Illinois and Dr. Catherine Linnen at the University of Kentucky both study the (adorable) deer mouse Peromyscus maniculatus, but they focus on different adaptive traits that have evolved in this species. Deer mice have the broadest elevational distribution of any North American mammal, occurring from sea level to 4300 meters, and Zac studies how mouse populations have adapted to life at such extreme heights. His recent work has shown that under the hypoxic (i.e. low oxygen) conditions expected at high elevation, mice from the highlands outperform lowland mice by, generally speaking, using oxygen more efficiently. You can read about the very cool details of this work here and here.
The Deer mouse, Peromyscus maniculatus. Photo courtesy of J. N. Stuart, Flickr
Deer mice found at lower elevation in the Nebraska Sand Hills have multiple traits, including light colored fur, that help them blend in with the light colored soil and avoid detection by avian predators. Catherine presented results from a recent Science paper showing that in light colored mice different phenotypic traits correspond to different mutations within a single gene called Agouti. This work is a great example of how single nucleotide polymorphisms (SNPs) can determine phenotype.
While changes in coat color in the deer mouse are driven by mutations in a protein-coding gene, Daniel Gates, a PhD candidate at the University of Nebraska, presented a poster showing a different mechanism controls color change in the Peruvian plant genus Iochroma. The ancestral flower color in Iochroma is blue but white flowers have evolved in Iochroma loxense. Dan used RNAseq data to show a transcription factor called R3 MYB represses the expression of genes that determine flower color in I. loxense. You might expect changes in flower color to be associated with changes in which species pollinate the plants and previous work from the Smith Lab has investigated the role of pollinators in Iochroma flower evolution (see here and here).
Iochroma loxense (left) with derived flower color and Iochroma cyaneum (right) with ancestral flower color. Photos courtesy of Stacey Smith
Dr. Tara Marriage, a postdoc in the Olson Lab at Kansas State University uses RNAseq data to study the transition from single to multicellularity in Volvocine algae. Multicellularity has evolved at least 25 times across the tree of life and we are still learning about the mechanisms responsible for this transition. From an adaptive point of view, a multicellular phenotype offers an advantage over unicellularity because cells can develop specialized roles and diffusion and predation become less of a problem as organism size increases. The work Tara presented on the single celled Chlamydomonas reinhardtii and the multicellular Gonium pectorale suggests the transition to multicellularity was accomplished through changes in cell cycle regulation and through differential expression of genes involved in cell wall modification and cell-cell adhesion.
The Volvocine algae Chlamydomonas reinhardtii (left) and Gonium pectorale (right). Photos courtesy of The Protist Information Server
Taken together, the results presented a the Ecological Genomics Symposium showed how phenotypes are influenced by the environment and can evolve through many different genetic pathways, ranging from point mutations in coding genes to changes in transcription and gene expression. EGS was a great opportunity to learn about the emerging questions and methods in ecological genomics. Because the meeting was on the small side (about 85 participants), it was easy to meet people, ask them more about their work, and get feedback on my own research. I talked to people in every career stage from undergraduates to tenured faculty and the gender ratio was close to even (about 43% of participants were women). I recommend this meeting to anyone interested in ecological genomics and I’m excited to go back next year!
(On a note unrelated to science, if you’re ever in Kansas City, don’t miss the chance to visit the Nelson-Atkins Museum of Art)
Cheviron ZA, Connaty AD, McClelland GB, Storz JF (2014) Functional genomics of adaptation to hypoxic cold-stress in high-altitude deer mice: transcriptomic plasticity and thermogenic performance. Evolution 68:48-62 http://doi.org/10.1111/evo.12257
Cheviron ZA, Bachman GC, Connaty AD, McClelland GB, Storz JF (2012) Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice. Proceedings of the National Academy of Sciences 109:8635-8640 http://.doi.org/10.1073/pnas.1120523109
Linnen CR, Poh Y-P, Peterson BK, Barrett RDH, Larson JG, Jensen JD, Hoekstra HE (2013) Adaptive Evolution of Multiple Traits Through Multiple Mutations at a Single Gene. Science 339:1312-1316 http://doi.org/10.1126/science.1233213
Muchhala N, Johnsen S, Smith SD (2014) Competition for hummingbird pollination shapes flower color variation in Andean Solanaceae. Evolution 68:2275-2286 http://dx.doi.org/10.1111/evo.12441
Smith SD, Ané C, Baum DA (2008) The role of pollinator shifts in the floral diversification of Iochroma (Solanaceae). Evolution 62:793-806 http://dx.doi.org/10.1111/j.1558-5646.2008.00327.x