Assessing positive selection in centromere-associated kinetochore proteins across Metazoan groups.

Centromeres are comprised of long stretches of repetitive DNA that evolve rapidly in organisms across the tree of life. Consistent selfish centromere evolution can also have cascading effects - driving rapid evolution in interacting kinetochore proteins - possibly to maintain centromere-kinetochore compatibility. Effects of selfishly evolving centromeres on interacting proteins are most heavily studied in the inner kinetochore and assembly proteins including the constitutive centromere-associated network proteins CENP-A and CENP-C with some exploration of the extended effects to other kinetochore-associated protein complexes. While rapid evolution of the centromere has been broadly studied in many organisms, studies assessing positive selection in centromere-associated kinetochore proteins have largely focused on Drosophila. Here, we tested the hypothesis that signatures of positive selection would be present in outer kinetochore and condensin genes in diverse animal groups. We selected two protein complexes -the Condensin I complex and the Mis12 Complex - to test for positive selection in parasitic wasps, two groups of ray-finned fishes (including the amazon molly an asexual diploid exempt from centromere drive), and two groups of primates. We did not find selection using any test in any protein in the amazon molly but did find sporadic positive selection in proteins in both complexes across all groups.