Molecular evidence for adaptive evolution of olfactory-related genes in cervids.

Abstract

Cervids have evolved very successful means for survival and thriving to adapt to various climates and environments. One of these successful means might be the effective and efficient way of communication. To support this notion, cervids are well equipped with a variety of skin glands that distribute in different body regions. However, studies relevant to adaptive evolution in cervids, particularly on olfactory reception at the molecular level, have thus far not been reported. To provide valuable insights into molecular evidence for the adaptive evolution of olfactory-related gene in cervids. Based on recently sequenced genomes of cervids and closely-related-species, we performed comparative genomic analysis at genome level using bioinformatics tools. Tree topology strongly supported that Bovidae was the sister group of Moschidae and both formed a branch that was then clustered with Cervidae. Expansion of heavy chain genes of the dynein family and 51 rapidly evolving genes could be associated with adaptation of cilia that serve as sensory organelles and act as cellular antennae. Based on the branch-site model test along the deer branch spanning 7-21 mammalian species, 14 deer olfactory receptor genes were found to be undergoing positive selection pressure and 89 positive selection sites (probability > 60%) had amino acid substitutions unique to deer. This study, for the first time, provides significant molecular evidence for adaption of olfactory-related genes of cervids according to their olfactory behavior.