Open AccessAbrupt shortening of bird W chromosomes in ancestral Neognathae
Author(s) -
Gorelick Root,
Fraser Danielle,
Mansfield Melissa,
Dawson Jeff W.,
Wijenayake Sanoji,
Bertram Susan M.
Publication year - 2016
Publication title -
biological journal of the linnean society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.906
H-Index - 112
eISSN - 1095-8312
pISSN - 0024-4066
DOI - 10.1111/bij.12832
Subject(s) - heterogametic sex , biology , extant taxon , recombination , chromosome , evolutionary biology , phylogenetic tree , w chromosome , genetics , evolution of sexual reproduction , zoology , karyotype , gene
As a result of suppressed recombination, heterogametic sex chromosomes (either Y or W) are usually assumed to gradually shorten over evolutionary time as a way to remove accumulated mutations. However, suppressed recombination removes the most obvious mechanism for excising portions of sex chromosomes. We examined ratios of W/Z chromosome size across 224 bird species from 146 genera. Much of the data were obtained from a previous study (Rutkowska et al . 2012. Biology Letters 8 : 636–638), who, similar to ourselves, found no gradual decrease in W chromosome length over evolutionary time. However, we show an abrupt decrease in W chromosome length at or just after the phylogenetic split between the two extant bird superorders, Paleognathae and Neognathae, indicating that the key to understanding sex chromosome evolution may have little to do with gradual suppression of recombination.