Expression Evolution of Ancestral XY Gametologs across All Major Groups of Placental Mammals
Mónica Martínez-Pacheco, Mariela Tenorio, Laura Almonte, Vicente Fajardo, Alan Godínez, Diego Fernández, Paola Cornejo‐Páramo, Karina Díaz-Barba, Jean Halbert, Angélica Liechti, Tamás Székely, Araxi O. Urrutia, Diego Cortez
Abstract
Placental mammals present 180 million-year-old Y chromosomes that have retained a handful of dosage-sensitive genes. However, the expression evolution of Y-linked genes across placental groups has remained largely unexplored. Here, we expanded the number of Y gametolog sequences by analyzing ten additional species from previously unexplored groups. We detected seven remarkably conserved genes across 25 placental species with known Y repertoires. We then used RNA-seq data from 17 placental mammals to unveil the expression evolution of XY gametologs. We found that Y gametologs followed, on average, a 3-fold expression loss and that X gametologs also experienced some expression reduction, particularly in primates. Y gametologs gained testis specificity through an accelerated expression decay in somatic tissues. Moreover, despite the substantial expression decay of Y genes, the combined expression of XY gametologs in males is higher than that of both X gametologs in females. Finally, our work describes several features of the Y chromosome in the last common mammalian ancestor.