Environmental adaptations as windows on molecular evolution.
Changes in gene regulation may play an important role in adaptive evolution, particularly during adaptation to a changing environment. However, little is known about the molecular mechanisms underlying adaptively significant variation in gene regulation. To address this question, we are using environmental adaptations in populations of a fish, Fundulus heteroclitus as a window into the molecular evolution of gene regulation. F. heteroclitus are found along the East Coast of North America, with populations distributed along a steep thermal gradient. At the extremes of the species range, populations have undergone local adaptation to their habitat temperatures. A variety of genes differ in their regulation between these populations. We have determined the mechanism responsible for changes in lactate dehydrogenase-B (Ldh-B) gene regulation. A limited number of mutations in the regulatory sequence of this gene result in changes in its expression. Both the phenotypic (increased LDH activity) and genotypic (changes in Ldh-B regulatory sequences) differences between populations have been shown to be affected by natural selection, rather than genetic drift. Therefore, even a small number of mutations within important regulatory sequences can provide evolutionarily significant variation and have an impact on environmental adaptation.
Schulte
P M
PM
Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada, N2L 3G1. pschulte@sciborg.uwaterloo.ca
D000222:Adaptation, Physiological; D000818:Animals; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D005809:Genes, Regulator; D007527:Isoenzymes / Q000235:genetics; D007770:L-Lactate Dehydrogenase / Q000235:genetics
D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; C409667:lactate dehydrogenase 1