Sunday, February 23, 2014
Genetic Convergence among Echolocating Taxa
Parker et al. report in Nature that the genomes of several echolocating species show remarkable convergence at the amino acid level, especially in hearing-related genes. Echolocating bats do not form a monophyletic clade, indicating that echolocation has evolved more than once in the bat order. Parker et al. sequenced and assembled the genomes of four bats, including echolocating and non-echolocating species, and aligned these sequences to the mammalian genomes available on Ensembl, including those of other bats and the bottlenose dolphin, an echolocating cetacean. They estimated a likelihood value for each amino acid position's fit to the accepted species tree. Sites with poor fit where the amino acid residue present was concordant among echolocating species were considered evidence of convergence. Seven known hearing-related genes ranked high among loci containing the greatest numbers of convergent amino acids among echolocating bats and between bats and dolphins. Interestingly, so did several genes related to vision, likely reflecting adaptation to low light levels in both bats and dolphins.