Inexorable spread: inexorable death? The fate of neo-XY chromosomes of grasshoppers

CLAUDIO J. BIDAU, DARDO A. MARTÍ & ELIO R. CASTILLO

JOURNAL OF GENETICS

INDIAN ACAD SCIENCES

Lugar: Bangalore ; Año: 2011 vol. 90 p. 397 - 400

0022-1333

In a recent article, Veltsos et al. (2008) proposed a hypothesis for the spread of a newly arisen Y chromosome throughout the range of a species using as a model the alpine acridid grasshopper Podisma pedestris that has two chromosomal forms: a standard X0/XX and a  neo-XY/neo-XX race, which form a hybrid zone in the Southern Alps (Hewitt 1975). Veltsos et al. (2008) made computer simulations based on the premise that, although Y chromosomes have an evolutionary tendency towards erosion and eventual loss (Charlesworth 1978, 2002; Charlesworth and Charlesworth 2000; Charlesworth et al. 2005), there is a continuous recycling of Y chromosomes by de novo formation and fixation of neo-Y chromosomes. The model clearly explains the possible spread of a new Y chromosome throughout the geographic range of the species (Veltsos et al. 2008; Pannell and Pujol 2009), but it does not take into account the evolutionary fate of the neo-chromosomes. We discuss here that, although neo-XY chromosomes of grasshoppers may be a useful model to explain the spread of a new chromosomal rearrangement, they are not a predictive example of sex-chromosome evolution and recycling.