Intraspecific Competition Can Promote Population-Level Specialization

The hypothesis of competitive diversification asserts that increased intraspecific competition will cause a population to generalize in resource use. The reasoning is that as preferred resources are depleted, individuals which use alternative resources become more fit, leading to an overall broadening of resource use. However, recent studies have shown instances of the opposite effect: increased intraspecific competition leading to increased population resource specialization. We explored how intraspecific competition could affect population resource specialization by creating an evolutionary game theoretic consumer-resource model in which individuals have both resource use preference and resource use breadth which are flexible and adaptable. Using this model, we see how the consumer’s population specialization changes in response to increases in population size and therefore intensity of intraspecific competition. We show that greater population specialization can result from intraspecific competition particularly at low population densities. We hypothesize that this may be because specialization offers a competitive advantage as more specialized individuals can acquire more of the preferred resources without greatly sacrificing alternative resources. This competitive advantage becomes magnified under certain ecological and evolutionary conditions, such as a low diversity of resources and a high benefit of specialization.