Modern mammals are descended from ancestors that lived about 180 million years ago. The organization of the animal's genome has been reconstructed by a team of researchers. The work is in a journal.
Harris Lewin is a professor of evolution and ecology at the University of California, Davis and senior author on the paper.
23 of the 26 known orders of mammals have their genomes drawn on by the researchers. Chimpanzees, wombats, rabbits, and domestic cattle were included. Chicken and alligator genomes were included in the analysis. As part of the Earth BioGenome Project, some of these genomes are being produced. The Earth BioGenome Project has a working group chaired by Lewin.
Joana Damas, the first author on the reconstruction, said that the mammal's ancestors had 19 autosomal chromosomes, which control the inheritance of an organisms characteristics outside of those controlled by sexlinked chromosomes. The team found 1, 215 blocks of genes that were the same on all 32 genomes. The genes that are critical to developing a normal embryo are contained in the building blocks of all mammals.
Over 300 million years, chromosomes have been stable.
The order of genes in birds' and mammals' chromosomes are the same.
Lewin said that the evolutionary stability of the order and orientation of the genes on the chromosomes was shown.
The regions between the blocks were more prone to breakages, rearrangements and sequence duplications.
Ancestral genome reconstructions can be used to understand where and why pressures vary. Professor William Murphy of Texas A&M University was not an author on the paper. The foundation for assessing the role of natural selection in the evolution of the mammal's chromosomes is provided by this.
The researchers were able to observe the ancestral and common ancestors. There was a difference in the rate of chromosomes being rearranged between mammals. The rise of mammals was caused by an asteroid impact 66 million years ago that killed off the dinosaurs.
The results will help understand the genetics behind the adaptation that has allowed mammals to live on a changing planet.
More information: Joana Damas et al, Evolution of the ancestral mammalian karyotype and syntenic regions, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2209139119 Journal information: Proceedings of the National Academy of Sciences
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