Research

Evolution of chromosome number

Genome structure, at a fundamental level, can be described by the division of the genome into a discrete number of chromosomes and further divided into autosomes and sex chromosomes. An array of mechanisms or selection pressures can lead to changes in both of these characteristics of genomes. Meiotic drive, segregation mechanisms, sexual antagonism, epistasis, benefits of higher or lower recombination, and drift have all been invoked to explain changes in the number of chromosomes and the proportion of the genome that is sex linked through sex chromosomes. Despite over a century of work, this level of genome organization has been resistant to broad generalizations that can explain the striking variation we observe among species. I will use large comparative phylogenetic approaches to determine the degree to which rates of chromosome number and sex chromosome system evolution vary among orders of insects. I will also use these approaches to infer whether mutations that have led to divergence in chromosome number are deleterious, neutral, or beneficial.