Convergence in hearing-related genes between echolocating birds and mammals

Abstract

Echolocation, the detection of objects by means of sound waves, has evolved independently in diverse animals. Echolocators include not only mammals such as toothed whales and yangochiropteran and rhinolophoid bats but also Rousettus fruit bats, as well as two bird lineages, oilbirds and swiftlets. In whales and yangochiropteran and rhinolophoid bats, positive selection and molecular convergence has been documented in key hearing-related genes, such as prestin ( SLC26A5 ), but few studies have examined these loci in other echolocators. Here, we examine patterns of selection and convergence in echolocation-related genes in echolocating birds and Rousettus bats. Fewer of these loci were under selection in Rousettus or birds compared with classically recognized echolocators, and elevated convergence (compared to outgroups) was not evident across this gene set. In certain genes, however, we detected convergent substitutions with potential functional relevance, including convergence between Rousettus and classic echolocators in prestin at a site known to affect hair cell electromotility. We also detected convergence between Yangochiroptera, Rhinolophidea, and oilbirds in TMC1, an important mechanosensory transduction channel in vertebrate hair cells, and observed an amino acid change at the same site within the pore domain. Our results suggest that although most proteins implicated in echolocation in specialized mammals may not have been recruited in birds or Rousettus fruit bats, certain hearing-related loci may have undergone convergent functional changes. Investigating adaptations in diverse echolocators will deepen our understanding of this unusual sensory modality.

Estimates of molecular convergence reveal pleiotropic genes underlying adaptive variation across teleost fish

“…Identifying molecular signatures of convergence is integral to understanding the genetic basis behind the evolution of phenotypes, as well as aiding in recognising adaptive developmental processes across diverse groups of animals 19–21 . Indeed, studies of molecular convergence have provided insights into the origin of traits like echolocation in birds and mammals, toxin resistance in beetles, and carnivory in plants, just to name a few 22–24 .…”

“…As methodologies for detecting molecular convergence events have improved, scientists have been able to re-examine and enhance prior studies to identify or confirm general trends of convergent evolution associated with phenotypes 18,24–27 . A notable recent development is the CSUBST (Combinatorial SUBSTitutions) algorithm introduced by Fukushima and Pollock 28 .…”