Link to the paper: https://onlinelibrary.wiley.com/doi/full/10.1111/mec.15126
Differentiated sex chromosomes such as XX/XY chromosomes of viviparous mammals and ZZ/ZW sex chromosomes of birds with highly degenerated Y and W, respectively, evolved in animals multiple times. Their noteworthy convergent characteristic is the evolutionary stability, documented among amniotes for dozens of millions of years in mammals, birds, and some lineages of lizards, snakes and turtles. The differentiation of sex chromosomes stemming from the cessation of recombination between them is assumed to be largely a one-way process. We found that the differentiated ZZ/ZW sex chromosomes with highly degenerated W of the Madagascan geckos of the genus Paroedura were likely present in the common ancestor of the genus. However, the subclade of the genus seems to reverse the for a considerable evolutionary time highly differentiated ZZ/ZW sex chromosomes back to poorly differentiated state and thus represents a rare case of the loss of once highly differentiated sex chromosomes. Notably, the differentiated ZZ/ZW sex chromosomes of these geckos share genes with the XX/XY sex chromosomes of viviparous mammals and the ZZ/ZW sex chromosomes of lacertid lizards, as well as with the XX/XY sex chromosomes of iguanas and ZZ/ZW sex chromosomes of softshell turtles. Along with other analogous cases which we summarize in our contribution, this finding reinforces the observation that particular chromosomes are repeatedly co -opted for the function of sex chromosomes in amniotes.