Is variation in female aggressiveness across Drosophila species associated with reproductive potential?

Aggression is a key determinant of fitness in many species, mediating
access to mates, food, and breeding sites. Variation in intrasexual
aggression across species is likely driven by variation in resource
availability and distribution. While males primarily compete over access
to mates, females are likely to compete over resources to maximize
offspring quantity and/or quality, such as food or breeding sites. To
date, however, most studies have focused on male aggression, and we know
little about drivers of female aggression across species. To investigate
potential reproductive drivers of female aggression, we tested the
relationship between three reproductive traits and aggression in eight
Drosophila species. Using machine learning classifiers developed for D.
melanogaster, we quantified aggressive behaviours displayed in the
presence of yeast for mated and unmated females. We found that female
aggression was correlated with ovariole number across species, suggesting
that females that lay more eggs are more aggressive. A need for resources
for egg production or oviposition sites may therefore be drivers of female
aggression, though other potential hypotheses are discussed.