SEX RATIO AND EVOLUT · Consequences of strongly blased sex ratios for evolution and ecology
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2004-04-01 → 2006-03-31
- EU contribution
- €168,232
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - SEX RATIO AND EVOLUT (Consequences of strongly blased sex ratios for evolution and ecology)
Many natural plant and animal populations harbour selfish genetic elements that distort the sex ratio of the host population. By their effect on the sex ratio, these elements alter the direction and intensity of competition and conflict between male and female hosts and are hence expected to have a profound influence on host traits associated with reproduction. This project investigated the effect of sex ratio distorters on the evolution of reproductive characters of their hosts. Taking an experimental approach, we subjected populations of a standard laboratory model organism, the fruit fly Drosophila melanogaster, to different degrees of sex ratio bias. This was done over roughly thirty generations, during which the populations could adapt to the altered conditions. Our work has shown that sex ratio distortion has a significant effect on host reproductive biology. Despite the relatively short duration of our experiment, we observed changes in both behaviour and reproductive morphology of the flies in response to sex ratio bias. These changes were found to increase the overall productivity of populations harbouring sex ratio distorters. This means that adaptation to a biased sex ratio tends to stabilise populations and reduce elevated extinction risk otherwise associated with sex ratio bias. Importantly, our results also showed that adaptation can be impeded by the increase of genetic drift associated with sex ratio bias. In population with a very uneven sex ratio, evolutionary change can be dominated by stochastic fluctuations in gene frequencies. In small populations or with extreme sex ratio bias, these random effects can outweigh directional evolutionary change and prevent a response to selection. Our experiments demonstrated that, in agreement with this theoretical expectation, adaptation to sex ratio bias requires a large population size.
Data: CORDIS, © European Union
Project objective
The sex ratio is a key factor in the evolution of male and female reproductive function. First, the serration determines the strength of selection that mate competition and mate choice impose on sexual characters, such as testes size, ejaculate size and the production of accessory gland peptides inhales or the rate of mating and egg production in females. Second, the sex ratio determines the effective size of the population under selection. Biased sex ratios lower the effective population size, thereby increasing the force of genetic drift and constraining adaptive evolution. The present project aims to investigate the evolution of male and female sexual characters under strongly female-biased sex ratios. Strong female bias occurs naturally in a number of systems through the action of selfish genetic elements. An experimental evolution approach using Drosophilamelanogaster will be employed to study change in reproductive characters associated with biased population sex ratio. Treatments manipulating the sex ratio while controlling either the numerical or the effective population size will be performed to disentangle the effect of selection imposed by the serration from the effect of effective population size in constraining adaptive evolution. The project proposed will provide genuine scientific advance by combining evolutionary biology, quantitative genetics and behavioural ecology in examining the design and function of different aspects of reproductive biology. Besides the direct scientific merits, the fellowship will allow to complete the applicant\'s training by providing experience with the Drosophilae system, one of the most important animal models in molecular and organism biology. Further, transactional mobility of the applicant to the host institution UCL will guarantee knowledge transfer and networking within the EU.
Original text from CORDIS.
Participants
- UNIVERSITY COLLEGE LONDON · LONDONCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union