11/10/19 - Séminaire de Lucas MARIE-ORLEACH
Le vendredi 11 octobre 2019 à 13h00, salle de conférences de l'OSUR, bâtiment 14b, Campus de Beaulieu, UR1
Sexual selection is known to drive the evolution of striking pre- and postmating traits, and may affect macroevolution processes such as adaptation, speciation, or extinction. Here, I will present two studies on the role of sexual selection on speciation, and on the quantification of sexual selection on pre- and postmating episodes of selection. First, to assess the role of sexual selection in speciation, we used standard measures of sexual selection (Bateman metrics) to investigate whether the strength of sexual selection predicts species richness across the Animal Kingdom. We found a correlation between male Bateman gradients and species richness, which suggests that sexual selection promotes speciation and/or protects against species extinction. Second, to understand the relative importance of pre- and postmating sexual selection, we used a transgenic line of the transparent flatworm, Macrostomum lignano, that expresses green fluorescent protein (GFP) in all cell types, including sperm cells, enabling in vivo sperm tracking and easy paternity analysis. Thus, we could observe and quantify usually cryptic traits, and ask how mating success, sperm-transfer efficiency and sperm-fertilising efficiency contributed to male reproductive success. We found that a large part of variance in male reproductive success arose from the postmating episodes, during which individuals with larger testes managed to successfully transfer more sperm per copulation. Ongoing analyses aim to distinguish the stochastic from the repeatable components of variance in individual success, and to investigate fitness landscapes in a multivariate trait space along the different episodes of selection.
Contact : Lucas MARIE-ORLEACH