Experimental manipulation of sexual antagonism in Drosophila melanogaster

Lund-Hansen, Katrine Koch (2017) Experimental manipulation of sexual antagonism in Drosophila melanogaster. Doctoral thesis (PhD), University of Sussex.

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Despite the benefits of sexual reproduction, sharing a genome can put constraints on
the evolvability of a species. This is due to sexual conflict, where the interests of each
sex is in direct opposition to one another, and the benefit of one sex can be the cost of
the other sex (i.e. sexual antagonism). Sex chromosomes have been the focus of much
of the research done on sexual conflict due to their unique nature and are particularly
interesting in the context of sexually antagonistic variance.

In the first experiment (Chapter 2), I used experimental evolution to
investigate the standing sexually antagonistic variation on the X-chromosome of the
common vinegar fly, Drosophila melanogaster. Unlike most other experimental
evolution experiments where selection has been limited to males, I limited the
inheritance of the X-chromosome to females only. I used a non-recombining Xchromosome
balancer to control the inheritance of the female-limited X-chromosome.
Throughout the evolution experiment, I tested different phenotypic traits that have
previously been shown to be sexual antagonistic, as well as investigating how the
transcriptome changed through female-limited selection (Chapter 3). The results
were mixed but indicated that limiting selection of the X-chromosome to females
could, to some extent, change the antagonistic variation and move traits towards the
female optimum. In the second experiment (Chapter 4), I exchanged sex
chromosomes between populations with divergent geographic origins. I used flies
with special genetic constructs (e.g. autosomal balancers, fused-X chromosomes) to
control the population crosses, so that sex chromosomes were introduced into a new
background without any prior interaction. I found that introducing a novel sex
chromosome increased male reproductive fitness through improved sperm
competition at the cost of offspring viability. 25 generations after introducing the
novel sex chromosome (Chapter 5), the increase in male fitness was undetectable and
their fitness was again the same as the wild types. Collectively, this indicates an
antagonistic coevolution between the sex chromosomes.

Together, these two experiments shed new light on sexual conflict and the
antagonistic coevolution between the sexes at the genetic level, both between and
within the sex chromosomes. These novel insights could help further the
understanding of how sex chromosomes may affect speciation.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Biology and Environmental Science
Subjects: Q Science > QL Zoology > QL0360 Invertebrates > QL0434 Arthropoda > QL0463 Insects > QL0531 Diptera (Flies) > QL0537.A-Z Systematic divisions. By family > QL0537.D76 Drosophilidae (Vinegarflies)
Depositing User: Library Cataloguing
Date Deposited: 13 Sep 2017 11:35
Last Modified: 13 Sep 2017 11:35
URI: http://sro.sussex.ac.uk/id/eprint/70184

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