Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles
Island populations often experience different ecological and demographic conditions than their counterparts on the continent, resulting in divergent evolutionary forces affecting their genomes. Random genetic drift and selection both may leave their imprints on island populations, although the relat...
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fthighwire:oai:open-archive.highwire.org:genome:34/6/851 2024-09-15T18:18:47+00:00 Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles Wang, Xuejing Heckel, Gerald 2024-06-01 00:00:00.0 text/html http://genome.cshlp.org/cgi/content/short/34/6/851 https://doi.org/10.1101/gr.278487.123 en eng Cold Spring Harbor Laboratory Press http://genome.cshlp.org/cgi/content/short/34/6/851 http://dx.doi.org/10.1101/gr.278487.123 Copyright (C) 2024, Cold Spring Harbor Laboratory Press RESEARCH TEXT 2024 fthighwire https://doi.org/10.1101/gr.278487.123 2024-07-30T15:49:43Z Island populations often experience different ecological and demographic conditions than their counterparts on the continent, resulting in divergent evolutionary forces affecting their genomes. Random genetic drift and selection both may leave their imprints on island populations, although the relative impact depends strongly on the specific conditions. Here we address their contributions to the island syndrome in a rodent with an unusually clear history of isolation. Common voles ( Microtus arvalis ) were introduced by humans on the Orkney archipelago north of Scotland >5000 years ago and rapidly evolved to exceptionally large size. Our analyses show that the genomes of Orkney voles were dominated by genetic drift, with extremely low diversity, variable Tajima's D , and very high divergence from continental conspecifics. Increased d N / d S ratios over a wide range of genes in Orkney voles indicated genome-wide relaxation of purifying selection. We found evidence of hard sweeps on key genes of the lipid metabolism pathway only in continental voles. The marked increase of body size in Orkney—a typical phenomenon of the island syndrome—may thus be associated to the relaxation of positive selection on genes related to this pathway. On the other hand, a hard sweep on immune genes of Orkney voles likely reflects the divergent ecological conditions and possibly the history of human introduction. The long-term isolated Orkney voles show that adaptive changes may still impact the evolutionary trajectories of such populations despite the pervasive consequences of genetic drift at the genome level. Text Microtus arvalis HighWire Press (Stanford University) Genome Research 34 6 851 862 |
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RESEARCH Wang, Xuejing Heckel, Gerald Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles |
topic_facet |
RESEARCH |
description |
Island populations often experience different ecological and demographic conditions than their counterparts on the continent, resulting in divergent evolutionary forces affecting their genomes. Random genetic drift and selection both may leave their imprints on island populations, although the relative impact depends strongly on the specific conditions. Here we address their contributions to the island syndrome in a rodent with an unusually clear history of isolation. Common voles ( Microtus arvalis ) were introduced by humans on the Orkney archipelago north of Scotland >5000 years ago and rapidly evolved to exceptionally large size. Our analyses show that the genomes of Orkney voles were dominated by genetic drift, with extremely low diversity, variable Tajima's D , and very high divergence from continental conspecifics. Increased d N / d S ratios over a wide range of genes in Orkney voles indicated genome-wide relaxation of purifying selection. We found evidence of hard sweeps on key genes of the lipid metabolism pathway only in continental voles. The marked increase of body size in Orkney—a typical phenomenon of the island syndrome—may thus be associated to the relaxation of positive selection on genes related to this pathway. On the other hand, a hard sweep on immune genes of Orkney voles likely reflects the divergent ecological conditions and possibly the history of human introduction. The long-term isolated Orkney voles show that adaptive changes may still impact the evolutionary trajectories of such populations despite the pervasive consequences of genetic drift at the genome level. |
format |
Text |
author |
Wang, Xuejing Heckel, Gerald |
author_facet |
Wang, Xuejing Heckel, Gerald |
author_sort |
Wang, Xuejing |
title |
Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles |
title_short |
Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles |
title_full |
Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles |
title_fullStr |
Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles |
title_full_unstemmed |
Genome-wide relaxation of selection and the evolution of the island syndrome in Orkney voles |
title_sort |
genome-wide relaxation of selection and the evolution of the island syndrome in orkney voles |
publisher |
Cold Spring Harbor Laboratory Press |
publishDate |
2024 |
url |
http://genome.cshlp.org/cgi/content/short/34/6/851 https://doi.org/10.1101/gr.278487.123 |
genre |
Microtus arvalis |
genre_facet |
Microtus arvalis |
op_relation |
http://genome.cshlp.org/cgi/content/short/34/6/851 http://dx.doi.org/10.1101/gr.278487.123 |
op_rights |
Copyright (C) 2024, Cold Spring Harbor Laboratory Press |
op_doi |
https://doi.org/10.1101/gr.278487.123 |
container_title |
Genome Research |
container_volume |
34 |
container_issue |
6 |
container_start_page |
851 |
op_container_end_page |
862 |
_version_ |
1810456854845718528 |