Chromosomal Fusions and Evolutionary Forces: Exploring the Neo-Sex Chromosome System of Anolis distichus
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
The evolutionary dynamics of sex chromosomes differ from autosomes due to their unique pattern of in-heritance and regions of hemizygosity in non-recombining areas. However, the study of sex chromosomes and sex-linked gene evolution has been limited by the rarity of truly novel sex chromosome complements in model systems. Recent advances in next-generation sequencing have enabled the identification of neo-sex chromosomes, created by the fission or fusion of autosomes with sex chromosomes, providing a new avenue to investigate the dynamics of sex chromosome evolution. Squamate reptiles, particularly Anolis lizards, are an excellent system for studying the consequences of sex-linkage due to their frequent sex chromosome-autosome fusions. The Hispaniolan Bark Anole, Anolis distichus , has experienced two sex chromosome and autosome fusions that led to a multiple sex chromosome system (X 1 X 2 Y). We present a high-quality whole-genome assembly and annotation of a male A. distichus (X 1 X 2 Y), enabling a detailed analysis of all three of its neo-sex chromosomes. We identify scaffolds associated with X 1 , X 2 , and Y chromosomes using an integra-tive approach and estimate degeneration and selection strength. Our results support long-held theories of differential evolutionary pressures in sex chromosomes, such as the Fast X effect and Y degeneration. Additionally, we find that chromosome 12 has become sex-linked independently in two different Anolis species, suggesting that some autosomes may be more likely to become sex-linked. Altogether, our genome adds to the diversity of available taxa sequenced and enables novel comparative analyses in a variety of fields, including speciation, chromosomal synteny, and sex chromosome evolution.
