| Title: | Lineage-specific differences in evolutionary mode in a salamander courtship pheromone |
| Author(s): | Palmer CA; Watts RA; Gregg RG; McCall MA; Houck LD; Highton R; Arnold SJ; |
| Address: | "Department of Zoology, Oregon State University, USA. palmerc@science.oregonstate.edu" |
| ISSN/ISBN: | 0737-4038 (Print) 0737-4038 (Linking) |
| Abstract: | "Functionally equivalent genes may evolve heterogeneously across closely related taxa as a consequence of lineage-specific selective pressures. Such disparate evolutionary modes are especially prevalent in genes that encode postcopulatory reproductive proteins, presumably as a result of sexual selection. We might therefore expect genes that mediate reproduction prior to insemination to evolve in a similar manner. Plethodontid receptivity factor (PRF), a proteinaceous salamander pheromone produced by the male, increases female receptivity during courtship interactions. To test for lineage-specific differences in PRF's evolution, we intensively sampled PRF genes across the eastern Plethodon phylogeny (27 spp.; 34 populations) to compare gene diversification, rates of evolution, modes of selection, and types of amino acid substitution. Our analyses indicate that PRF evolutionary dynamics vary considerably from lineage to lineage. Underlying this heterogeneity, however, are two well-defined transitions in evolutionary mode. The first mode is representative of a typical protein profile, wherein neutral divergence and purifying selection are the dominant features. The second mode is characterized by incessant, cyclical evolution driven by positive selection. In this mode, the positively selected sites are bound by a limited assortment of acceptable amino acids that appear to evolve independently of other sites, resulting in a tremendous number of unique PRF alleles. Several of these selected sites are implicated in receptor binding. These sites are apparently involved in a molecular tango in which the male signal and female receptors coevolve within a confined molecular space. PRF's lineage-specific evolutionary dynamics, in combination with evidence of a molecular tango, highlight the molecular action of sexual selection on a chemical signal that is used during courtship" |
| Keywords: | "Amino Acid Sequence Animals Base Sequence Cluster Analysis *Evolution, Molecular Female *Genetic Variation Likelihood Functions Male Models, Genetic Molecular Sequence Data *Phylogeny *Selection, Genetic Sequence Alignment Sequence Analysis, DNA Sex Attra;" |
| Notes: | "MedlinePalmer, Catherine A Watts, Richard A Gregg, Ron G McCall, Maureen A Houck, Lynne D Highton, Richard Arnold, Stevan J eng Comparative Study Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2005/07/22 Mol Biol Evol. 2005 Nov; 22(11):2243-56. doi: 10.1093/molbev/msi219. Epub 2005 Jul 20" |
