Evidence for Faster X Chromosome Evolution in Spiders
(2019) In Molecular biology and evolution 36(6). p.1281-1293- Abstract
- In species with chromosomal sex determination, X chromosomes are predicted to evolve faster than autosomes because of positive selection on recessive alleles or weak purifying selection. We investigated X chromosome evolution in Stegodyphus spiders that differ in mating system, sex ratio, and population dynamics. We assigned scaffolds to X chromosomes and autosomes using a novel method based on flow cytometry of sperm cells and reduced representation sequencing. We estimated coding substitution patterns (dN/dS) in a subsocial outcrossing species (S. africanus) and its social inbreeding and female-biased sister species (S. mimosarum), and found evidence for faster-X evolution in both species. X chromosome-to-autosome diversity (piX/piA)... (More)
- In species with chromosomal sex determination, X chromosomes are predicted to evolve faster than autosomes because of positive selection on recessive alleles or weak purifying selection. We investigated X chromosome evolution in Stegodyphus spiders that differ in mating system, sex ratio, and population dynamics. We assigned scaffolds to X chromosomes and autosomes using a novel method based on flow cytometry of sperm cells and reduced representation sequencing. We estimated coding substitution patterns (dN/dS) in a subsocial outcrossing species (S. africanus) and its social inbreeding and female-biased sister species (S. mimosarum), and found evidence for faster-X evolution in both species. X chromosome-to-autosome diversity (piX/piA) ratios were estimated in multiple populations. The average piX/piA estimates of S. africanus (0.57 [95% CI: 0.55–0.60]) was lower than the neutral expectation of 0.75, consistent with more hitchhiking events on X-linked loci and/or a lower X chromosome mutation rate, and we provide evidence in support of both. The social species S. mimosarum has a significantly higher piX/piA ratio (0.72 [95% CI: 0.65–0.79]) in agreement with its female-biased sex ratio. Stegodyphus mimosarum also have different piX/piA estimates among populations, which we interpret as evidence for recurrent founder events. Simulations show that recurrent founder events are expected to decrease the piX/piA estimates in S. mimosarum, thus underestimating the true effect of female-biased sex ratios. Finally, we found lower synonymous divergence on X chromosomes in both species, and the male-to-female substitution ratio to be higher than 1, indicating a higher mutation rate in males. (Less)
- Abstract (Swedish)
- In species with chromosomal sex determination, X chromosomes are predicted to evolve faster than autosomes because
of positive selection on recessive alleles or weak purifying selection. We investigated X chromosome evolution in
Stegodyphus spiders that differ in mating system, sex ratio, and population dynamics. We assigned scaffolds to X
chromosomes and autosomes using a novel method based on flow cytometry of sperm cells and reduced representation
sequencing. We estimated coding substitution patterns (dN/dS) in a subsocial outcrossing species (S. africanus) and its
social inbreeding and female-biased sister species (S. mimosarum), and found evidence for faster-X evolution in both
species. X chromosome-to-autosome... (More) - In species with chromosomal sex determination, X chromosomes are predicted to evolve faster than autosomes because
of positive selection on recessive alleles or weak purifying selection. We investigated X chromosome evolution in
Stegodyphus spiders that differ in mating system, sex ratio, and population dynamics. We assigned scaffolds to X
chromosomes and autosomes using a novel method based on flow cytometry of sperm cells and reduced representation
sequencing. We estimated coding substitution patterns (dN/dS) in a subsocial outcrossing species (S. africanus) and its
social inbreeding and female-biased sister species (S. mimosarum), and found evidence for faster-X evolution in both
species. X chromosome-to-autosome diversity (piX/piA) ratios were estimated in multiple populations. The average piX/
piA estimates of S. africanus (0.57 [95% CI: 0.55–0.60]) was lower than the neutral expectation of 0.75, consistent with
more hitchhiking events on X-linked loci and/or a lower X chromosome mutation rate, and we provide evidence in
support of both. The social species S. mimosarum has a significantly higher piX/piA ratio (0.72 [95% CI: 0.65–0.79]) in
agreement with its female-biased sex ratio. Stegodyphus mimosarum also have different piX/piA estimates among
populations, which we interpret as evidence for recurrent founder events. Simulations show that recurrent founder
events are expected to decrease the piX/piA estimates in S. mimosarum, thus underestimating the true effect of femalebiased
sex ratios. Finally, we found lower synonymous divergence on X chromosomes in both species, and the male-tofemale
substitution ratio to be higher than 1, indicating a higher mutation rate in males. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/e3b5eed5-0e06-4f26-9556-1bbeef139b87
- author
- Bechsgaard, Jesper ; Schou, Mads Fristrup LU ; Vanthournout, Bram ; Hendrickx, Frederik ; Knudsen, Bjarne ; Settepani, Virginia ; Schierup, Mikkel Heide and Bilde, Trine
- organization
- publishing date
- 2019
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- faster-x,female bias,sex chromosome,social spider
- in
- Molecular biology and evolution
- volume
- 36
- issue
- 6
- pages
- 1281 - 1293
- publisher
- Oxford University Press
- external identifiers
-
- scopus:85066456149
- pmid:30912801
- ISSN
- 0737-4038
- DOI
- 10.1093/molbev/msz074
- language
- English
- LU publication?
- yes
- id
- e3b5eed5-0e06-4f26-9556-1bbeef139b87
- date added to LUP
- 2019-06-28 16:12:21
- date last changed
- 2025-04-04 15:06:51
@article{e3b5eed5-0e06-4f26-9556-1bbeef139b87,
abstract = {{In species with chromosomal sex determination, X chromosomes are predicted to evolve faster than autosomes because of positive selection on recessive alleles or weak purifying selection. We investigated X chromosome evolution in Stegodyphus spiders that differ in mating system, sex ratio, and population dynamics. We assigned scaffolds to X chromosomes and autosomes using a novel method based on flow cytometry of sperm cells and reduced representation sequencing. We estimated coding substitution patterns (dN/dS) in a subsocial outcrossing species (S. africanus) and its social inbreeding and female-biased sister species (S. mimosarum), and found evidence for faster-X evolution in both species. X chromosome-to-autosome diversity (piX/piA) ratios were estimated in multiple populations. The average piX/piA estimates of S. africanus (0.57 [95% CI: 0.55–0.60]) was lower than the neutral expectation of 0.75, consistent with more hitchhiking events on X-linked loci and/or a lower X chromosome mutation rate, and we provide evidence in support of both. The social species S. mimosarum has a significantly higher piX/piA ratio (0.72 [95% CI: 0.65–0.79]) in agreement with its female-biased sex ratio. Stegodyphus mimosarum also have different piX/piA estimates among populations, which we interpret as evidence for recurrent founder events. Simulations show that recurrent founder events are expected to decrease the piX/piA estimates in S. mimosarum, thus underestimating the true effect of female-biased sex ratios. Finally, we found lower synonymous divergence on X chromosomes in both species, and the male-to-female substitution ratio to be higher than 1, indicating a higher mutation rate in males.}},
author = {{Bechsgaard, Jesper and Schou, Mads Fristrup and Vanthournout, Bram and Hendrickx, Frederik and Knudsen, Bjarne and Settepani, Virginia and Schierup, Mikkel Heide and Bilde, Trine}},
issn = {{0737-4038}},
keywords = {{faster-x,female bias,sex chromosome,social spider}},
language = {{eng}},
number = {{6}},
pages = {{1281--1293}},
publisher = {{Oxford University Press}},
series = {{Molecular biology and evolution}},
title = {{Evidence for Faster X Chromosome Evolution in Spiders}},
url = {{http://dx.doi.org/10.1093/molbev/msz074}},
doi = {{10.1093/molbev/msz074}},
volume = {{36}},
year = {{2019}},
}