Meeting Abstract

P2.103  Saturday, Jan. 5  Signatures of natural selection across the mitochondrial genome in Tachycineta swallows. STAGER, M.*; CHEVIRON, Z. A.; Univ. of Illinois at Urbana-Champaign stager2@illinois.edu

Over the last century, latitudinal variation in avian life-history traits has formed the foundation for general theories of life-history evolution. This variation can be summarized as a slow-fast continuum such that tropical species fall on one end, exhibiting low reproductive rates, slow development, and long lifespans, while on the opposing end, temperate species exhibit the opposite traits. Tachycineta swallows exemplify this pattern across their broad latitudinal range (Alaska to Cape Horn), making them an ideal group to investigate the mechanistic basis of avian life history variation. Because much of the temperate-tropical variation in avian life histories is tied to differences in rates of energy expenditure, studies of metabolic traits are particularly well-suited to establish mechanistic links between physiological and life-history traits. The vertebrate mitochondrial genome contains 13 protein-coding genes that are central to aerobic metabolism, making it a promising candidate locus for studying the mechanistic basis of metabolic trait differences that may underlie life-history variation among closely related species. We took advantage of a robust nuclear DNA phylogeny and complete mitochondrial genome sequences that were recently published for all nine species of Tachycineta swallows to test for signatures of natural selection across the entire mitochondrial genome. Our preliminary results suggest that although purifying selection is the dominant selective force influencing the evolution of the mitochondrial genome in Tachycineta , several mitochondrial genes contain regions that exhibit signatures of positive diversifying selection, suggesting that they may contribute to metabolic differences between temperate and tropical species.