Cape ground squirrel site comparison dataset

Male mating strategies respond to female availability such that variation
in resources that affect spatial distribution can also alter cost-benefit
tradeoffs within a population. In arid-adapted species, rainfall alters
reproduction, behavior, morphology, and population density such that
populations differing in resource availability may also differ in
successful reproductive strategies. Here we compare two populations of
Cape ground squirrels (Xerus inauris), a sub-Saharan species with
year-round breeding and intense mating competition. Unlike most mammals
where males resort to aggressive interactions over females, male X.
inauris are tolerant of one another, relying instead on other
non-aggressive pre- and post-copulatory strategies to determine
reproductive success. Our findings suggest that differences in resource
availability affect female distribution which ultimately leads to
intraspecific variation in male reproductive tactics and sexual
morphology. Sperm competition, assessed by reproductive morphometrics, was
more pronounced in our high resource site where females were distributed
evenly across the landscape whereas dominance seemed to be an important
determinant of success in our low resource site where females were more
aggregated. Both sites had similar mating intensities, and most males did
not sire any offspring. However, our low resource site had a higher
variance in fertilization success with fewer males siring multiple
offspring compared to our high resource site where more individuals were
successful. Our results lend support to resource models where variations
in female spatial distribution attributed to environmental resources
ultimately impact male reproductive behaviors and morphology.