Dr. Mercedes Burns, Department of Biological Sciences
The ancestral mating system in Sclerosomatidae is thought to be solicitation-based, scramble-competition polygynandry, however, multiple sclerosomatid groups are notable for having evolved traits indicative of sexual coercion. Current knowledge of the genus Leiobunum (Opiliones) indicates a potential role of reproductive seasonality (i.e., grouping of reproductive events during a specific time of the year due to environmental constraints) in the evolution of sexual conflict. Coercive traits and strategies only occur in species from northern latitudes, while species in tropical locations retain traits associated with solicitous breeding, such as nuptial gift sacs. This trend may apply to other genera, but inter- and intraspecific variation in genital morphology and its impact in mating interactions is one area of research where knowledge is comparatively limited. This dearth of information is compounded by a general research bias towards northern-temperate regions, and the fact that many tropical species of sclerosomatid Opilliones lack even basic genital morphological descriptions. Using phylogenetic and morphological analyses we will evaluate variations in reproductive structures along a continuous transect of increasing breeding season length, with the expectation that populations from highly seasonal locations will display evidence of increased sexual antagonism.