Authors: Audrey French, Carl E Hjelmen
Mentors: Carl E Hjelmen
Insitution: Utah Valley University
Chromosome numbers are often one of the first pieces of genetic information we collect about the genome of an organism. These chromosome numbers vary widely across the tree of life and will change due to fission and fusion events, where the number increases or decreases, respectively (Blackmon and Demuth 2015, Perkins et al. 2019, Sylvester et al. 2020, Morelli et al. 2022). As the Drosophila species group has been a model for more than 100 years, there is a plethora of information on their karyotypes, including number, chromosome shapes, and sex chromosome systems. The shapes of chromosomes vary and can be described as metacentric (v), submetacentric (j), telocentric (rod), and small and heterochromatic (dot). In the Drosophila genus, sex chromosome systems can be neo-sex, XY, and X0. The numerous species of Drosophila can be compiled into the major subgenera of Drosophila and Sophophora, which have diverged for around 40-65 million years. The karyotype data of the Drosophila genus has been compiled into an open-source database. I am using this database to find the rates of chromosome number change in the Drosophila genus. This analysis is done through the chromePlus package in R (Blackmon et al., 2019) which will perform a comparative phylogenetic analysis, and a phylogeny of 152 species in the Drosophila genus (Hjelmen et al., 2019). Using these available tools, I can compare rates of fusion and fission between sex chromosome systems and subgenera. This could expand the knowledge on evolution of chromosomes and genomes.