XY sex chromosomes in Boa and Python

[Warren_Booth]

Up until now, we have largely believed that all snakes possessed ZW sex chromosomes, with females carrying ZW and males ZZ. Doubt was caste in recent years as to the validity of this, with the proposal that the banana/coral trait acted like an XY related trait. From the literature published, I myself did not believe, in part due to the quality of the data collected to generate this hypothesis and due to the published literature. The joy about being a scientist is that your opinion can change following a re-investigation. Therefore, following an extensive review of that literature and the new availability of genomic methods to identify sex chromosomes that lack morphological differentiation (they are the same size in most boas and pythons, whereas in advanced snakes they can easily be identified as they show size differentiation), we undertook an extensive genomic analysis of boa constrictor, Burmese python, and the western diamondback rattlesnake. Our results identified XY sex chromosomes in boa and python, which may have evolved from different origins, whereas the rattlesnake has ZW sex chromosomes. This is an exciting and important discovery in understanding the evolution of sex chromosomes in snakes, and now explains why we see only female parthenogens in boas and pythons, and only male parthenogens in advances snakes. The work was published in the journal Current Biology.

http://www.the-scientist.com/?articles.view/articleNo/49814/title/Snake-Sex-Determination-Dogma-Overturned/

Enjoy,

Warren