Role of Chromosomal Reorganisations in the Human–Chimpanzee Speciation

Abstract

The elucidation of how recombination is shaping the genomic architecture of organisms and, more in particular, how this affects the speciation process has been a long‐standing question in evolutionary biology. Large‐scale genomic changes such as inversions, translocations, fusions and fissions contribute to the reshuffling of genomes, providing new chromosomal forms on which natural selection can work. Despite large efforts employed in the last decade, few empirical data are available on the mechanisms by which genome reshuffling contribute to the formation of new species. Here, the authors discuss on the models of chromosomal evolution and the contribution of chromosomal reorganisations in mammalian chromosome evolution, and more specifically, during the human–chimpanzee speciation event. Key Concepts: The evolutionary process by which new biological species arise (speciation) is a complex process that requires the understanding of many mechanisms such as reproductive isolation, patterns of species diversity, together with the genetic basis underlying the process. Understanding the mechanisms by which reproductive isolation (breakdown of gene flow between two populations) is achieved, is fundamental for speciation. Genetic speciation makes references to the group of genes that are involved in maintaining reproductive isolation between species. Chromosomal reorganisations may contribute to speciation due to the underdominant fitness effects associated with meiotic abnormalities when occurring in heterozygotes. Chromosome rearrangements, such as inversions, can suppress recombination thus contributing to a reduction of gene flow across genomic regions and the accumulation of genetic incompatibilities.

Comparison of Compression-Based Measures with Application to the Evolution of Primate Genomes

“…Recombination and mobile genetic elements, such as retrotransposons, shape the genomic architecture, namely through large alteration events such as inversions, translocations, fusions, and fissions, being a major factor for genome reshuffling [ 161 ]. However, rearranged chromosomes present significantly lower recombination rates than chromosomes that have been maintained since the last common ancestor of great apes [ 162 ], mostly because inverted regions have lower recombination rates than collinear and noninverted regions, independently of the effect of centromeres [ 162 ].…”