TY - JOUR

T1 - Runaway GC evolution in gerbil genomes

AU - Parcana, Rodrigo

AU - Hargreaves, Adam D.

AU - Mulley, John

AU - Holland, Peter W. H.

N1 - © The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

PY - 2020/8/1

Y1 - 2020/8/1

N2 - Recombination increases the local GC-content in genomic regions through GC-biased gene conversion (gBGC). The recent discovery of a large genomic region with extreme GC-content in the fat sand rat Psammomys obesus provides a model to study the effects of gBGC on chromosome evolution. Here, we compare the GC-content and GC-to-AT substitution patterns across protein-coding genes of four gerbil species and two murine rodents (mouse and rat). We find that the known high-GC region is present in all the gerbils, and is characterised by high substitution rates for all mutational categories (AT-to-GC, GC-to-AT and GC-conservative) both at synonymous and nonsynonymous sites. A higher AT-to-GC than GC-to-AT rate is consistent with the high GC-content. Additionally, we find more than 300 genes outside the known region with outlying values of AT-to-GC synonymous substitution rates in gerbils. Of these, over 30% are organised into at least 17 large clusters observable at the megabase-scale. The unusual GC-skewed substitution pattern suggests the evolution of genomic regions with very high recombination rates in the gerbil lineage, which can lead to a runaway increase in GC-content. Our results imply that rapid evolution of GC-content is possible in mammals, with gerbil species providing a powerful model to study the mechanisms of gBGC.

AB - Recombination increases the local GC-content in genomic regions through GC-biased gene conversion (gBGC). The recent discovery of a large genomic region with extreme GC-content in the fat sand rat Psammomys obesus provides a model to study the effects of gBGC on chromosome evolution. Here, we compare the GC-content and GC-to-AT substitution patterns across protein-coding genes of four gerbil species and two murine rodents (mouse and rat). We find that the known high-GC region is present in all the gerbils, and is characterised by high substitution rates for all mutational categories (AT-to-GC, GC-to-AT and GC-conservative) both at synonymous and nonsynonymous sites. A higher AT-to-GC than GC-to-AT rate is consistent with the high GC-content. Additionally, we find more than 300 genes outside the known region with outlying values of AT-to-GC synonymous substitution rates in gerbils. Of these, over 30% are organised into at least 17 large clusters observable at the megabase-scale. The unusual GC-skewed substitution pattern suggests the evolution of genomic regions with very high recombination rates in the gerbil lineage, which can lead to a runaway increase in GC-content. Our results imply that rapid evolution of GC-content is possible in mammals, with gerbil species providing a powerful model to study the mechanisms of gBGC.

UR - https://oup.silverchair-cdn.com/oup/backfile/Content_public/Journal/mbe/37/8/10.1093_molbev_msaa072/1/msaa072_supplementary_figures_tables.pdf?Expires=1618051685&Signature=Lsdkk1M4TBF2XWkmDFaknswzRam0tHGFH3v5GpqhWT4H45KNwesPgKkQYM1snxTlWuAAWh8mxuKBtsdeerQyoBQfWvp70VlduCkVeAOp7nHQ8GgOl3U60ezXrUe-fw1hq7N5LJDR~kHI~feWvbu-6nQhQzdIu8wBsBArOzXkZ~yZRI3izKL8OdgKZMYYHFIbL48bSnBPGK5Ec4rvv0lmemkCY-abdH0DNGEUECB8xr1MgZ6AbTzORWcoK32x22ck-8ov0qmIDq7e3TccbW4tu6TatGk1Gzcgf7U7u~H1bd1gX8HOeBiCLy~5meVIexcm2cyfEfTWfet-1shHsuQX7g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA

U2 - 10.1093/molbev/msaa072

DO - 10.1093/molbev/msaa072

M3 - Article

C2 - 32170949

VL - 37

SP - 2197

EP - 2210

JO - Molecular Biology and Evolution

JF - Molecular Biology and Evolution

SN - 0737-4038

IS - 8

M1 - msaa072

ER -