Apes possess two sex chromosomes-the male-specific Y chromosome and the X chromosome, which is present in both males and females. The Y chromosome is crucial for male reproduction, with deletions being linked to infertility. The X chromosome is vital for reproduction and cognition. Variation in mating patterns and brain function among apes suggests corresponding differences in their sex chromosomes. However, owing to their repetitive nature and incomplete reference assemblies, ape sex chromosomes have been challenging to study. Here, using the methodology developed for the telomere-to-telomere (T2T) human genome, we produced gapless assemblies of the X and Y chromosomes for five great apes (bonobo (Pan paniscus), chimpanzee (Pan troglodytes), western lowland gorilla (Gorilla gorilla gorilla), Bornean orangutan (Pongo pygmaeus) and Sumatran orangutan (Pongo abelii)) and a lesser ape (the siamang gibbon (Symphalangus syndactylus)), and untangled the intricacies of their evolution. Compared with the X chromosomes, the ape Y chromosomes vary greatly in size and have low alignability and high levels of structural rearrangements-owing to the accumulation of lineage-specific ampliconic regions, palindromes, transposable elements and satellites. Many Y chromosome genes expand in multi-copy families and some evolve under purifying selection. Thus, the Y chromosome exhibits dynamic evolution, whereas the X chromosome is more stable. Mapping short-read sequencing data to these assemblies revealed diversity and selection patterns on sex chromosomes of more than 100 individual great apes. These reference assemblies are expected to inform human evolution and conservation genetics of non-human apes, all of which are endangered species.
A native of Ukraine, Kateryna Makova received her PhD degree from Texas Tech University, where she studied the genetic consequences of the Chernobyl Nuclear Power Plant accident. She then completed her postdoctoral studies at the University of Chicago, where she investigated differences in mutation rates between males and females, among other topics. She has been a Professor at the Penn State University Department of Biology since 2003. Her laboratory conducts research in evolutionary and medical genomics. Current topics of interest include mitochondrial mutations, regional variation in mutation rates, sex chromosome evolution, evolution of non-B DNA, and childhood obesity. The research in Kateryna’s laboratory is highly interdisciplinary and collaborative. The group collaborates with statisticians, computer scientists, and biochemists. During her career, Kateryna has mentored 15 PhD students and 11 postdoctoral fellows, and has authored over 100 scientific manuscripts. Kateryna’s research has been continuously funded by the NIH since 2004. She currently directs the Center for Medical Genomics, which brings together researchers from the University Park and Hershey campuses of Penn State University. She serves as an Editor of Genome Research and as the Past President of the Society for Molecular Biology and Evolution.