Unusual Ways to Lose a Y Chromosome and Survive with Changed Autosomes: a Story of Mole Voles Ellobius (Mammalia, Rodentia)

Abstract

When does reproduction start? An old question of the chicken and the egg is even more complicated in relation to mole voles Ellobius. First, ‘chicken’ should be a female, and males are obviously involved in reproduction too because zygote is a result of sperm and oocyte fusion. But nobody knows how males appear in Ellobius lacking the Y chromosome and key testis-determining Sry gene (X0♂/X0♀ or XX♂/XX♀). Second, it is unclear, how balanced gametes form in complex heterozygous hybrids, whose parents carry Robertsonian translocations with partial homology. Here we review studies of sex determination and meiotic mechanisms in mammals with the exceptional diversity of sex chromosomes and autosomes, mole voles Ellobius.