Genomics | Evolutionary/Comparative Genetics
Contrasted GC-content dynamics across 33 mammalian genomes: influence of body mass and chromosome size
Society for Molecular Biology and Evolution 2010 meeting, 4 - 8 Jul 2010, P-S04-24
The origin, evolution and functional relevance of isochores (genomic variations in GC-content) is a long-debated topic, especially in mammals. Such variations in GC-content could be explained by recombination hotspots, where reparation systems could promote the fixation of GC alleles: The Biased Gene Conversion Model. Most of the existing literature, however, has focused on a small number of model species and/or limited sequence datasets.
We analyzed more than 1000 orthologous genes in 33 fully-sequenced mammalian genomes, reconstructed their ancestral isochore organization in the maximum likelihood framework, and explored the evolution of third-codon position GC-content in representatives of 16 orders and 27 families.
We showed that the previously-reported erosion of GC-rich isochores is not a general trend. Several species (e.g. shrew, microbat, tenrec, rabbit) have independently undergone a marked increase in GC-content, with a widening gap between the GC-poorest and GC-richest classes of genes. The intensively studied apes and (especially) murids do not reflect the general placental pattern. We correlated GC-content evolution with species life-history traits and cytology. Significant effects of body mass and genome size were detected, with each being consistent with the GC-biased gene conversion model.
No relevant conflicts of interest declared.
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