Source code for dynamic models and simulations of mate sampling behavior

Theory predicts that the strength of sexual selection (i.e., how well a
trait predicts mating or fertilization success) should increase with
population density, yet empirical support remains mixed. We explore how
this discrepancy might reflect a disconnect between current theory and our
understanding of the strategies individuals use to choose mates. We
demonstrate that the density-dependence of sexual selection predicted by
previous theory arises from the assumption that individuals automatically
sample more potential mates at higher densities. We provide an updated
theoretical framework for the density-dependence of sexual selection by
(1) developing models that clarify the mechanisms through which
density-dependent mate sampling strategies might be favored by selection
and (2) using simulations to determine how sexual selection changes with
population density when individuals use those strategies. We find that
sexual selection may increase strongly with density if sampling strategies
change adaptively in response to density-dependent sampling costs, whereas
within-individual plasticity in sampling over time (e.g., due to
adaptation to increasing sampling costs as the breeding season progresses)
produces weaker density-dependent sexual selection. Our findings suggest
that density-dependence of sexual selection depends on the ecological
context in which mate sampling has evolved.