séminaire du PEV – vendredi 19 décembre 2014

Sex ratio drive and polyandry

Nina Wedell, Centre for Ecology & Conservation Biosciences, University of Exeter - UK

vendredi 19 décembre, 11 heures, amphi Monge

 

 

Selfish Genetic Elements (SGEs) are genes, organelles or microorganims present within the genome or cell of an organism that employ various tactics to increase their transmission rate relative to the rest of the host genome to the next generation. SGEs are ubiquitous in living organisms and often associated with fitness cost to the bearer including reduced male fertility. ‘Sex Ratio’ (SR) drive in Drososphila pseudoobscura is an example of an SGE that result in female only broods due to elimination of Y-bearing sperm. However, SR-carrying males are poor sperm competitors and, as a consequence, polyandrous females sire a higher proportion of males. Experimental evolution experiments show that females rapidly evolve increased remating rates in SR populations, as predicted if polyandry is a strategy to reduce the risk of siring offspring carrying SGEs. In addition, polyandry also reduces the risk of population extinction due to lack of males, as it effectively decreases the frequency of SR. These results reveal intimate interactions between an SGE (sex ratio drive) and female mating behaviour and indicate polyandry may be able to directly regulate the frequency of SGEs in natural populations.