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Sexually antagonistic selection: evidence and proximate mechanisms

Gesuchsteller/in Roulin Alexandre
Nummer 120517
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Département d'Ecologie et d'Evolution Faculté de Biologie et de Médecine Université de Lausanne
Hochschule Universität Lausanne - LA
Hauptdisziplin Oekologie
Beginn/Ende 01.07.2008 - 30.06.2011
Bewilligter Betrag 570'000.00
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Keywords (8)

Melanin-based coloration; Colour polymorphism; Sexually antagonistic selection; Sexual and natural selection; ASIP; behavioural ecology; melanin; POMC

Lay Summary (Englisch)

Lead
Lay summary
The evolutionary stability of sexual dimorphism is a central issue of sexual selection theory. The usual situation is when males are sexually selected to be more conspicuous, while females are naturally selected to be cryptic. Sexual dimorphism can also be maintained if the underlying genes have positive effects in one sex but negative effects in the other sex. In the present project, my research group studies the causes and consequences of sexually antagonistic selection in the barn owl, a species displaying a melanin-based colour trait to a larger extent in females than in males, and blacker females are of higher quality. This project is divided in four subprojects. (i) Sexually antagonistic selection: using a 14-year dataset in a population of wild barn owls we investigate whether the degree of eumelanism is positively selected in females and negatively selected in males. Using modern techniques, this large dataset allow us to consider several key fitness components such as survival at different age classes and several reproductive parameters. (ii) Consequences of sexually antagonistic selection: if selection on eumelanism is positive in females and negative in males, nestling sex ratio may be associated with the degree of parental eumelanism. This prediction will be tested using the same long-term dataset. (iii) Physiological causes of sexually antagonistic selection: because sex-hormones probably mediate positive selection on the degree of female eumelanism and negative selection on the degree of male eumelanism, we measure these hormones in relation to this plumage trait in both nestlings and adults. In a second stage, we will manipulate hormone level to demonstrate that sex hormones causally mediate sexually antagonistic selection on eumelanism. (iv) Genetic basis of sexually antagonistic selection: we identify the genes that underlie sexually antagonistic selection (i.e. genes coding for melanin-based coloration and the associated phenotypic qualities). We identified a polymorphism and we measure the expression of the pro-opiomelanocortin (POMC) gene. This gene simultaneously regulates melanogenesis and sexual behaviour, exocrine gland activity, aggressiveness, hypothalamic-pituitary-adrenal stress response, immune function, and energy homeostasis. The present project has the potential to pinpoint the full range of causes and consequences of sexually antagonistic selection from the ultimate (i.e. natural and sexual selection) to proximate level (i.e. physiological and genetic mechanisms). This knowledge will offer us an answer to why male-like traits are counter-selected in females and female-like traits in males.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Verbundene Projekte

Nummer Titel Start Förderungsinstrument
102913 Evolution, maintenance and signalling function of genetic polymorphism in colour traits 01.07.2004 SNF-Förderungsprofessuren
135757 Sexually antagonistic selection: evidence and proximate mechanisms 01.07.2011 Projektförderung (Abt. I-III)
102913 Evolution, maintenance and signalling function of genetic polymorphism in colour traits 01.07.2004 SNF-Förderungsprofessuren

Abstract

The evolutionary stability of sexual dimorphism is a central issue of sexual selection theory. The usual situation is when males are sexually selected to be larger or more conspicuous, while females are naturally selected to be cryptic during the reproductive period. Sexual dimorphism can also be maintained if the underlying genes have positive effects in one sex but negative effects in the other sex. These genes are often located on sex chromosomes because sexually antagonistic selection favours sex-specific gene expression with this gene tending to be less expressed in the sex in which gene products have negative effects. In the present project, I intend to study the causes and consequences of sexually antagonistic selection in the barn owl, a species displaying a melanin-based colour trait to a larger extent in females than in males, and blacker females are of higher quality; the gene creating variation in this trait is located on the Z sex chromosome. This project is divided in four complementary subprojects. (i) Sexually antagonistic selection: using a 12-year dataset in a population of wild barn owls we will investigate whether the degree of eumelanism is positively selected in females and negatively selected in males. Using modern techniques, this big dataset will allow us to consider several key fitness components such as survival at different age classes and several reproductive parameters. (ii) Consequences of sexually antagonistic selection: if selection on eumelanism is positive in females and negative in males, I predict nestling sex-ratio to be associated with the degree of parental eumelanism. This prediction will be tested using the same long-term dataset but also with data collected during the study period covered by the SNF grant. (iii) Physiological causes of sexually antagonistic selection: because sex-hormones probably mediate positive selection on the degree of female eumelanism and negative selection on the degree of male eumelanism, I intend to measure these hormones in relation to this plumage trait in both nestlings and adults. In a second stage, we will manipulate hormone level to demonstrate that sex hormones causally mediate sexually antagonistic selection on eumelanism. (iv) Genetic basis of sexually antagonistic selection: I intend to identify the genes that underlie sexually antagonistic selection (i.e. genes coding for melanin-based coloration and the associated phenotypic qualities). To this end, we will assess polymorphism and expression of the pro-opiomelanocortin (POMC) gene. This gene is a good candidate because it simultaneously regulates melanogenesis and sexual behaviour, exocrine gland activity, aggressiveness, hypothalamic-pituitary-adrenal stress response, immune function, and energy homeostasis. The present project has the potential to pinpoint the full range of causes and consequences of sexually antagonistic selection from the ultimate (i.e. natural and sexual selection) to proximate level (i.e. physiological and genetic mechanisms). This knowledge will offer us an answer to why masculine traits are counter-selected in females and feminine traits in males. The project is therefore of interest beyond the scientific community.
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