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Thesis defense : William TOUBIANA

When Sep 20, 2019
from 09:30 AM to 12:00 PM
Where Amphi G2 (IFSA, 50, Avenue Tony Garnier 69007 Lyon)
Contact Name
Contact Phone 04 2673 1335
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On Friday 20th of September, William TOUBIANA (Khila team) will defend his thesis:

Towards an adaptive and genomic understanding of an exaggerated secondary sexual character in water striders

Note the defense will be head at the I.F.S.A. (Institut de Science Financière et d'Assurances) Amphi G2, located at 50, Avenue Tony Garnier (it's the building after Bioaster when you are walking from the IGFL).




From the DNA molecule to the more complex phenotypes, variation is a universal process in life and living organisms. The innumerable differences that exist between species are probably one of the most manifest examples. Yet, all this diversity would never have occurred in nature without some pre-existing divergence within species. One of the most striking examples of intraspecies variation appears in sexual organisms, between males and females. Understanding the environmental and genetic factors influencing sexual divergence is a longstanding question in evolutionary biology. To this end, I focus here on a new insect model system, Microvelia longipes, which has the particularity to have evolved an extreme case of sexual dimorphism in the rear legs. Males display exaggerated long rear legs compared to females but also an extreme variability in these leg lengths from one male to another. We identified that M. longipes males use their exaggerated legs as weapons during male-male competition. Males with longer legs have more chance to access females on egg-laying sites and therefore increase their reproductive success. Moreover, fitness assays and comparative studies between Microvelia species revealed that the intensity of male competition was associated with the exaggeration and hypervariability of the rear legs in M. longipes males. In a second approach, we studied the developmental and genomic basis of this sexual dimorphism through a comparative transcriptomic analysis and identified genes and genomic regions associated with male exaggerated legs and ultimately with sexual selection. Overall, the integrative approach used in this work allows to establish Microvelia longipes as a promising new model system to study the influence of sexual selection in adaptive evolution.