Restricting Recombination

In this post, I review the evolution of recombination rate between the sex chromosomes. As considered in previous posts, low rates, and more often absence, of crossover between parts of the X and the Y plays an important role in sex chromosome evolution and is frequently considered a defining characteristic of sex chromosomes. Wide variation in [...]

Why the X and Y don’t match

Because X-Y heteromorphism allowed for the sex chromosomes to be followed through meiotic division, it was the first marker to be correlated with the segregation and inheritance of a phenotype (sex). Still today, molecular differences between X and Y are used to identify the sex chromosomes in genetic sequencing studies. Because of its pivotal role [...]

Early Studies in Sex Chromosome Evolution

The discovery of sex chromosomes, at the turn of the twentieth century, significantly shaped not only how we study sex chromosomes today but also the fields of genetics and evolution more broadly. The first heteromorphic chromosomes to be correlated with sex phenotypes were observed in insects. In 1905, cytological study led N. Stevens to find [...]