bioRxiv preprint doi: https://doi.org/10.1101/505610; this version posted January 23, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. 1 A BIRD'S WHITE-EYE VIEW ON AVIAN SEX 2 CHROMOSOME EVOLUTION 3 4 Thibault Leroy1, Yoann Anselmetti1, Marie-Ka Tilak1, Sèverine Bérard1, Laura Csukonyi1,2, Maëva 5 Gabrielli2, Céline Scornavacca1, Borja Milá3, Christophe Thébaud2, Benoit Nabholz1* 6 7 1 ISEM, Univ Montpellier, CNRS, IRD, EPHE, Montpellier, France 8 2 Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174 CNRS – Université Paul Sabatier – IRD, Toulouse, 9 France 10 3 National Museum of Natural Sciences (MNCN), Spanish National Research Council (CSIC), Madrid, Spain 11 * Corresponding author:
[email protected] 12 13 14 41 diversity in both translocated regions and, as expected, 15 ABSTRACT 42 even more so on the neoW chromosome. In order to 16 43 compare the rates of molecular evolution in genomic 44 regions of the autosomal-to-sex transitions, we then 17 Chromosomal organization is relatively stable 45 estimated the ratios of non-synonymous to 18 among avian species, especially with regards to sex 46 synonymous polymorphisms (πN/πS) and substitutions 19 chromosomes. Members of the large Sylvioidea clade 47 (dN/dS). Based on both ratios, no or little contrast 20 however have a pair of neo-sex chromosomes which is 48 between autosomal and Z genes was observed, thus 21 unique to this clade and originate from a parallel 49 representing a very different outcome than the higher 22 translocation of a region of the ancestral 4A 50 ratios observed at the neoW genes.