Insights into avian incomplete dosage compensation : Sex-biased gene expression coevolves with sex chromosome degeneration in the common whitethroat
Sigeman, Hanna LU ; Ponnikas, Suvi LU ; Videvall, Elin LU ; Zhang, Hongkai ; Chauhan, Pallavi LU ; Naurin, Sara LU and Hansson, Bengt LU
(2018)
In Genes
9(8).
- Abstract
Non-recombining sex chromosomes (Y and W) accumulate deleterious mutations and degenerate. This poses a problem for the heterogametic sex (XY males; ZW females) because a single functional gene copy often implies less gene expression and a potential imbalance of crucial expression networks. Mammals counteract this by dosage compensation, resulting in equal sex chromosome expression in males and females, whereas birds show incomplete dosage compensation with significantly lower expression in females (ZW). Here, we study the evolution of Z and W sequence divergence and sex-specific gene expression in the common whitethroat (Sylvia communis), a species within the Sylvioidea clade where a neo-sex chromosome has been formed by a fusion... (More)
Non-recombining sex chromosomes (Y and W) accumulate deleterious mutations and degenerate. This poses a problem for the heterogametic sex (XY males; ZW females) because a single functional gene copy often implies less gene expression and a potential imbalance of crucial expression networks. Mammals counteract this by dosage compensation, resulting in equal sex chromosome expression in males and females, whereas birds show incomplete dosage compensation with significantly lower expression in females (ZW). Here, we study the evolution of Z and W sequence divergence and sex-specific gene expression in the common whitethroat (Sylvia communis), a species within the Sylvioidea clade where a neo-sex chromosome has been formed by a fusion between an autosome and the ancestral sex chromosome. In line with data from other birds, females had lower expression than males at the majority of sex-linked genes. Results from the neo-sex chromosome region showed thatWgametologs have diverged functionally to a higher extent than their Z counterparts, and that the female-to-male expression ratio correlated negatively with the degree of functional divergence of these gametologs. We find it most likely that sex-linked genes are being suppressed in females as a response to W chromosome degradation, rather than that these genes experience relaxed selection, and thus diverge more, by having low female expression. Overall, our data of this unique avian neo-sex chromosome system suggest that incomplete dosage compensation evolves, at least partly, through gradual accumulation of deleterious mutations at the W chromosome and declining female gene expression.
(Less)
- author
- Sigeman, Hanna
LU
; Ponnikas, Suvi
LU
; Videvall, Elin
LU
; Zhang, Hongkai
; Chauhan, Pallavi
LU
; Naurin, Sara
LU
and Hansson, Bengt
LU
- organization
- publishing date
- 2018-08-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Degeneration, Dosage compensation, Gene expression, Recombination, Sex chromosomes
- in
- Genes
- volume
- 9
- issue
- 8
- article number
- 373
- publisher
- MDPI AG
- external identifiers
-
- scopus:85050796961
- pmid:30049999
- ISSN
- 2073-4425
- DOI
- 10.3390/genes9080373
- language
- English
- LU publication?
- yes
- id
- a91bb644-45b0-4f7a-b977-b12b0aa0483e
- date added to LUP
- 2018-08-22 11:41:29
- date last changed
- 2024-04-15 10:26:19
@article{a91bb644-45b0-4f7a-b977-b12b0aa0483e,
abstract = {{<p>Non-recombining sex chromosomes (Y and W) accumulate deleterious mutations and degenerate. This poses a problem for the heterogametic sex (XY males; ZW females) because a single functional gene copy often implies less gene expression and a potential imbalance of crucial expression networks. Mammals counteract this by dosage compensation, resulting in equal sex chromosome expression in males and females, whereas birds show incomplete dosage compensation with significantly lower expression in females (ZW). Here, we study the evolution of Z and W sequence divergence and sex-specific gene expression in the common whitethroat (Sylvia communis), a species within the Sylvioidea clade where a neo-sex chromosome has been formed by a fusion between an autosome and the ancestral sex chromosome. In line with data from other birds, females had lower expression than males at the majority of sex-linked genes. Results from the neo-sex chromosome region showed thatWgametologs have diverged functionally to a higher extent than their Z counterparts, and that the female-to-male expression ratio correlated negatively with the degree of functional divergence of these gametologs. We find it most likely that sex-linked genes are being suppressed in females as a response to W chromosome degradation, rather than that these genes experience relaxed selection, and thus diverge more, by having low female expression. Overall, our data of this unique avian neo-sex chromosome system suggest that incomplete dosage compensation evolves, at least partly, through gradual accumulation of deleterious mutations at the W chromosome and declining female gene expression.</p>}},
author = {{Sigeman, Hanna and Ponnikas, Suvi and Videvall, Elin and Zhang, Hongkai and Chauhan, Pallavi and Naurin, Sara and Hansson, Bengt}},
issn = {{2073-4425}},
keywords = {{Degeneration; Dosage compensation; Gene expression; Recombination; Sex chromosomes}},
language = {{eng}},
month = {{08}},
number = {{8}},
publisher = {{MDPI AG}},
series = {{Genes}},
title = {{Insights into avian incomplete dosage compensation : Sex-biased gene expression coevolves with sex chromosome degeneration in the common whitethroat}},
url = {{http://dx.doi.org/10.3390/genes9080373}},
doi = {{10.3390/genes9080373}},
volume = {{9}},
year = {{2018}},
}