Data from: Socio-ecological context modulates significance of territorial contest competition in Drosophila prolongata

The intensity and direction of sexual selection is intricately linked to
the social and ecological context. Both operational sex ratios (OSRs) and
population densities can affect the ability of males to monopolize
resources and mates, and thus the form and intensity of sexual selection
on them. Here, we studied how the mating system of the promiscuous and
strongly sexually dimorphic fruit fly Drosophila prolongata responds to
changes in the OSR and population density. We recorded groups of flies
over five days and quantified territory occupancy, mating success, and
competitive fertilization success. Although sexual selection was stronger
under male-biased than even OSRs but unrelated to density, realized
selection on morphological traits was higher under even OSRs and increased
with density. Larger and more territorial males achieved both higher
mating success and competitive fertilization success, but only under even
OSRs. Our combined results also support a shift in the mating system from
territorial contest competition to scramble competition under male-biased
OSRs and potentially at low density, where there was no clear contribution
of the measured traits to reproductive success. Our study emphasizes the
limitations of traditional selection metrics and the role of the
socio-ecological context in predicting adaptation to a changing
environment.