Kavli Affiliate: Scott Small
| Authors: Gabrielle C. Coffing, Silas Tittes, Scott T. Small, Jeremea O. Songco-Casey, Denise M. Piscopo, Judit R. Pungor, Adam C Miller, Cristopher Niell and Andrew D. Kern
| Summary:
Sex chromosomes are critical elements of sexual reproduction in many animal and plant taxa, however they show incredible diversity and rapid turnover even within clades. Here, using a chromosome-level assembly generated with long read sequencing, we report the first evidence for genetic sex determination in cephalopods. We have uncovered a sex chromosome in California two-spot octopus (Octopus bimaculoides) in which males/females show ZZ/ZO karyotypes respectively. We show that the octopus Z chromosome is an evolutionary outlier with respect to divergence and repetitive element content as compared to other chromosomes and that it is present in all coleoid cephalopods that we have examined. Our results suggest that the cephalopod Z chromosome originated between 455 and 248 million years ago and has been conserved to the present, making it the among the oldest conserved animal sex chromosomes known.