Though recent trends have led many evolutionary ecologists to studying not only how ecological interactions can alter evolutionary processes, but also how the dynamic evolution of traits as well as the historical contingency of lineages can alter species ecology, most life history evolution studies remain focused on populations and are not concerned with community ecology. Those that do consider community ecology typically deal with how life history traits, such as maturation rate and age at first reproduction, affect the ecology of a species, such as ecological niche and competitive ability. Few life history evolution studies have considered how the community ecology of a species affects the evolution of its life history traits.
One of the most robust predictions made by life history theory is when adult mortality increases, age at maturity should decrease to maximize reproductive success. In this study, I test the hypothesis that increasing the strength of interspecific competition on a population leads to a decrease in age at maturity based on the assumption that increasing competition will induce higher mortality. I constructed an optimization model based on a Lotka-Volterra competition framework and identified the age at maturity that optimized fitness across a range of competition coefficients.
Results/Conclusions
Contrary to my expectation, age at maturity increased with the strength of competition. One possible explanation is that increasing interspecific competition reduced the density of the focal population and, in so doing, also reduced intraspecific competition. Another possibility is that incorporating density-dependence into models of age at maturity alters our classic expectations. Classic models of life history evolution assume that there is no density-dependence on the traits being considered, while this model assumes that there is density dependence because both focal and competitor population densities are in the equations used to optimize fitness.
It is both important and interesting to consider how life history traits evolve in the context of the ecological community. The results of this model suggest that, when considered in a community context, classical predictions about how life history traits should evolve are altered or even reversed. This leads to even more questions of how these predictions will play out in heterogeneous environments, whether asymmetries in competitive ability can lead to differences life history traits between competitors, and if the evolution of different life history traits can be a way for competitors to partition niche space.