Experimental evolution results in a new sex chromosome

Science

(Dan Eastwood) #1

Paolo Franchini explains further: “We found out that introgression – the movement of genetic material from one species to another – and the selection of pigmentation phenotypes results in the retention of an unexpectedly large maternally derived genomic region.” During the hybridisation process, the sex-determining region on the X chromosome of one parent was transferred to an autosome of the hybrid fish. This transfer led to the evolution of a completely new sex chromosome. “Our results show above all the complexity of factors that contribute to patterns observed in hybrid genomes including such fundamental issues such as sex determination,” summarises Paolo Franchini. The work proves that hybridisation can catalyse the rapid evolution of a new sex chromosome and thus makes an essential contribution to an experiment launched more than 30 years ago.