Degeneration, Expression Evolution, and Functional Specialization of Young Sex Chromosomes in the Plant Rumex hastatulus

Young Y chromosomes, such as those found in many plant species, provide valuable insights into the early stages of processes such as Y chromosome degeneration. Investigating these processes empirically may allow for evaluation of both classic and more recent theoretical models of sex chromosome evolution. In my thesis, I use new high-quality genomic resources along with large transcriptomic and genomic datasets to investigate sex chromosome evolution in Rumex hastatulus, a dioecious plant where the males have two Y chromosomes in one subtype (the XYY cytotype) and one Y chromosome in the other subtype (the XY cytotype). In Chapter 2, I show that significant Y chromosome degeneration resulting in gene loss and loss of synteny occurs at evolutionarily recent timescales (