Snakes and the evolution of sex chromosomes

Abstract

Chromosomal sex determination has appeared on many separate occasions in evolution. A common denominator appears to be that specialized sex chromosomes tend to accumulate particular highly repeated nucleotide sequences in many unrelated species, including snakes, birds, mammals and insects. In snake species where the sex-determining W chromosome apparently has evolved relatively recently, the distribution of these evolutionary conserved sequences in the genome and on the sex chromosomes has provided a new perspective on how these chromosomes may evolve and what their significance may be for the evolutionary process itself.