51. Extremely low nucleotide diversity in the X-linked region of papaya caused by a strong selective sweep
- Author
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Ray Ming, Richard C. Moore, Jennifer Han, Robert VanBuren, Zhicong Lin, Ching Man Wai, Jisen Zhang, Ming Li Wang, Zhenyang Liao, Jie Arro, Deborah Charlesworth, Francis Zee, and Qingyi Yu
- Subjects
0301 basic medicine ,Genetics ,education.field_of_study ,Dioecy ,Haplotype ,Population ,Gynodioecy ,Biology ,Nucleotide diversity ,03 medical and health sciences ,030104 developmental biology ,Evolutionary biology ,Genetic variation ,Selective sweep ,Domestication ,education ,human activities - Abstract
The papaya Y-linked region showed clear population structure, resulting in the detection of the ancestral male population that domesticated hermaphrodite papayas were selected from. The same populations were used to study nucleotide diversity and population structure in the X-linked region. Diversity is very low for all genes in the X-linked region in the wild dioecious population, with nucleotide diversity π syn = 0.00017, tenfold lower than the autosomal region (π syn = 0.0017) and 12-fold lower than the Y-linked region (π syn = 0.0021). Analysis of the X-linked sequences shows an undivided population, suggesting a geographically wide diversity-reducing event, whereas two subpopulations were observed in the autosomes separating gynodioecy and dioecy and three subpopulations in the Y-linked region separating three male populations. The extremely low diversity in the papaya X-linked region was probably caused by a recent, strong selective sweep before domestication, involving either the spread of a recessive mutation in an X-linked gene that is beneficial to males or a partially dominant mutation that benefitted females or both sexes. Nucleotide diversity in the domesticated X samples is about half that in the wild Xs, probably due to the bottleneck when hermaphrodites were selected during domestication. The extreme low nucleotide diversity in the papaya X-linked region is much greater than observed in humans, great apes, and the neo-X chromosome of Drosophila miranda, which show the expected pattern of Y-linked genes
- Published
- 2016
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