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The genomic basis of the response to female-limited X-chromosome evolution

Manat, Yesbol LU (2021)
Abstract
In this thesis, I attempted to achieve a better understanding of the nature of X-linked polymorphic loci using a female-limited X chromosome (FLX) experimental evolution in Drosophila melanogaster. I expected that expressing the evolved X chromosome will result in an increase in female fitness and a decrease in male fitness. I first investigated the effect of an experimentally evolved female-limited X chromosome on male reproductive traits (Paper I). Secondly, I examined how the genome-wide expression pattern responds to the presence of the evolved X chromosome (Paper II), and then I analysed the changes in allele frequencies across the genome (Paper III). Finally, I attempted to study the changes in genetic variances and covariances in... (More)
In this thesis, I attempted to achieve a better understanding of the nature of X-linked polymorphic loci using a female-limited X chromosome (FLX) experimental evolution in Drosophila melanogaster. I expected that expressing the evolved X chromosome will result in an increase in female fitness and a decrease in male fitness. I first investigated the effect of an experimentally evolved female-limited X chromosome on male reproductive traits (Paper I). Secondly, I examined how the genome-wide expression pattern responds to the presence of the evolved X chromosome (Paper II), and then I analysed the changes in allele frequencies across the genome (Paper III). Finally, I attempted to study the changes in genetic variances and covariances in sexually homologous traits in response to FLX evolution, as well as change in the cross-sex genetic correlations for these sexually homologous traits (Paper IV).
Contrary to the initial expectation, I found evidence of trade-offs between various components of male reproductive success rather than an overall decline (Paper I). However, I identified a more ‘feminized’ gene expression profile as the result of FLX evolution (Paper II) and found evidence of adaptation in the methodological control treatment which was a necessary part of the experimental design. The analysis of differences in allele frequencies between selection regimes showed no evidence of overrepresentation of SA loci on the X chromosome, but these results suggest an interesting avenue for future study of sexual conflict over sensory ability (Paper III). Finally, I found evidence of a breakdown in the intersexual genetic correlation for locomotory activity in FLX populations compared to control populations (Paper IV).
These results indicate that the X chromosome may not possess as many SA mutations as previously thought, and they are by nature difficult to study in a species with old, already highly degenerated sex chromosomes. However, the results presented here highlight the importance of sex-specific selection pressures in shaping the genetic architecture of many traits.
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author
supervisor
opponent
  • Associate professor Friberg, Urban, Linköping University, Sweden
organization
publishing date
type
Thesis
publication status
published
subject
keywords
X chromosome, Sex chromosome, Drosophila melanogaster, Experimental evolution, sexual selection, intralocus sexual conflict
pages
158 pages
publisher
Lund University (Media-Tryck)
defense location
Blå hallen, Ekologihuset, Sölvegatan 37, Lund Join via zoom: https://lu-se.zoom.us/j/62973176994
defense date
2021-05-07 09:00:00
ISBN
978-91-7895-830-6
978-91-7895-829-0
language
English
LU publication?
yes
id
fa20afdc-9672-43e4-83b6-513cf4cce288
date added to LUP
2021-03-31 21:40:36
date last changed
2021-04-13 12:53:33
@phdthesis{fa20afdc-9672-43e4-83b6-513cf4cce288,
  abstract     = {{In this thesis, I attempted to achieve a better understanding of the nature of X-linked polymorphic loci using a female-limited X chromosome (FLX) experimental evolution in Drosophila melanogaster. I expected that expressing the evolved X chromosome will result in an increase in female fitness and a decrease in male fitness. I first investigated the effect of an experimentally evolved female-limited X chromosome on male reproductive traits (Paper I). Secondly, I examined how the genome-wide expression pattern responds to the presence of the evolved X chromosome (Paper II), and then I analysed the changes in allele frequencies across the genome (Paper III). Finally, I attempted to study the changes in genetic variances and covariances in sexually homologous traits in response to FLX evolution, as well as change in the cross-sex genetic correlations for these sexually homologous traits (Paper IV).<br/>Contrary to the initial expectation, I found evidence of trade-offs between various components of male reproductive success rather than an overall decline (Paper I). However, I identified a more ‘feminized’ gene expression profile as the result of FLX evolution (Paper II) and found evidence of adaptation in the methodological control treatment which was a necessary part of the experimental design. The analysis of differences in allele frequencies between selection regimes showed no evidence of overrepresentation of SA loci on the X chromosome, but these results suggest an interesting avenue for future study of sexual conflict over sensory ability (Paper III). Finally, I found evidence of a breakdown in the intersexual genetic correlation for locomotory activity in FLX populations compared to control populations (Paper IV). <br/>These results indicate that the X chromosome may not possess as many SA mutations as previously thought, and they are by nature difficult to study in a species with old, already highly degenerated sex chromosomes. However, the results presented here highlight the importance of sex-specific selection pressures in shaping the genetic architecture of many traits.<br/>}},
  author       = {{Manat, Yesbol}},
  isbn         = {{978-91-7895-830-6}},
  keywords     = {{X chromosome; Sex chromosome; Drosophila melanogaster; Experimental evolution; sexual selection; intralocus sexual conflict}},
  language     = {{eng}},
  publisher    = {{Lund University (Media-Tryck)}},
  school       = {{Lund University}},
  title        = {{The genomic basis of the response to female-limited X-chromosome evolution}},
  url          = {{https://lup.lub.lu.se/search/files/96153411/The_genomic_basis_of_the_response_to_female_limited_Xchromosome_evolution.pdf}},
  year         = {{2021}},
}