The voltage-gated potassium channel subfamily KQT member 4 (KCNQ4) displays parallel evolution in echolocating bats.

LIU YANG; HAN NAIJIAN ; FRANCHINI LUCÍA FLORENCIA; XU HUIHUI ; PISCIOTTANO FRANCISCO; ELGOYHEN ANA BELÉN; RAJAN EMMANUVEL KOILMANI; ZHANG SHUYI

MOLECULAR BIOLOGY AND EVOLUTION

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2012 p. 1441 - 1450

0737-4038

Bats are the only mammals that use highly developed laryngeal echolocation, a sensory mechanism based on the ability toemit laryngeal sounds and interpret the returning echoes to identify objects. Although this capability allows bats toorientate and hunt in complete darkness, endowing them with great survival advantages, the genetic bases underlying theevolution of bat echolocation are still largely unknown. Echolocation requires high-frequency hearing that in mammals islargely dependent on somatic electromotility of outer hair cells. Then, understanding the molecular evolution of outer haircell genes might help to unravel the evolutionary history of echolocation. In this work, we analyzed the molecularevolution of two key outer hair cell genes: the voltage-gated potassium channel gene KCNQ4 and CHRNA10, the geneencoding the a10 nicotinic acetylcholine receptor subunit. We reconstructed the phylogeny of bats based on KCNQ4 andCHRNA10 protein and nucleotide sequences. A phylogenetic tree built using KCNQ4 amino acid sequences showed thattwo paraphyletic clades of laryngeal echolocating bats grouped together, with eight shared substitutions among particularlineages. In addition, our analyses indicated that two of these parallel substitutions, M388I and P406S, were probably fixedunder positive selection and could have had a strong functional impact on KCNQ4. Moreover, our results indicated thatKCNQ4 evolved under positive selection in the ancestral lineage leading to mammals, suggesting that this gene might havebeen important for the evolution of mammalian hearing. On the other hand, we found that CHRNA10, a gene that evolvedadaptively in the mammalian lineage, was under strong purifying selection in bats. Thus, the CHRNA10 amino acid tree didnot show echolocating bat monophyly and reproduced the bat species tree. These results suggest that only a subset ofhearing genes could underlie the evolution of echolocation. The present work continues to delineate the genetic bases ofecholocation and ultrasonic hearing in bats.