Joseph R. Shaw, Ph.D.; Bruce Stanton, Ph.D.; Celia Chen, Ph.D.
Indiana University, Dartmouth College
NIEHS Grants R01ES019324, P42ES007373
Research funded in part by the NIEHS has identified genes and gene regulation processes that allow killifish to transform the function and structure of its freshwater gills for use in salt water. These findings provide insight into how genes might interact with the environment and evolve toward the development of traits that can more easily respond to environmental changes.
The researchers previously observed that killifish are more vulnerable to arsenic during changes in salinity. Since arsenic prevents killifish from shifting between freshwater and seawater, they reasoned that arsenic could be used to identify which genes orchestrate these changes. The researchers exposed killifish to arsenic while they were acclimating to saltwater, and found that the many genes orchestrating the killifish response are maintained at precise levels. These results suggest strict regulatory control of these genes may be a general feature of plastic responses in other organisms.
The investigators also found that plasticity-enabling genes seem to be organized in unusually simple networks. Natural selection acts on these networks differently, depending on the degree of plasticity required. Thus, killifish living in stable environments have less precise regulatory control over plasticity-enabling genes than those living in the least stable environments.
Citation: Shaw JR, Hampton TH, King BL, Whitehead A, Galvez F, Gross RH, Keith N, Notch E, Jung D, Glaholt SP, Chen CY, Colbourne JK, Stanton BA. 2014. Natural selection canalizes expression variation of environmentally induced plasticity-enabling genes. Mol Biol Evol 31(11):3002-3015.