Frederik Hendrickx (RBINS)
Carl Vangestel and Gontran Sonet
Descriptions of new species, in particular those of arthropods, generally rely on the description of differences in traits related to sexual selection (SSTs). The rationale for this approach is that (i) differences in sexual traits might act as a reproductive barrier between populations differing in these traits and (ii) that sexual traits, especially those expressed in males, are under very strong directional selection and, hence, subject to rapid evolution and to be highly differentiated even among closely related species. However, this represents a paradox as strong directional selection for particular traits is also expected to deplete genetic variation underlying these traits. This observation suggests that the evolution of sexual traits could be of a rather saltatorial type. To investigate this, we recently started to explore the genomic basis of an extreme male dimorphism in SSTs observed in the dwarf spider Oedothorax gibbosus. Spiders of this genus, and dwarf spiders (Erigoninae) in general, are characterised by conspicious variation in male head morphologies related to sexual selection. For the species O. gibbosus, a clear dimorphism is present with gibbosus males possessing a profound hump, while tuberosus males lack these features and resemble females. The varation observed within this species, which is inherited according to Mendelian expectations, even exceeds the variation seen among species. Although the evolutionary mechanism that led to this dimorphisms is relatively well understood, there is only very limited information of the molecular basis underlying this dimorphism. Hence, this system represents a unique opportunity to explore the genomic basis of extreme morphological variation.
Lab work progress:
Whole genome resequencing: completed