Ecological consequences of heritable intraspecific variation

Trait variation among individuals of a population is now considered to be an important part of biodiversity. Many empirical studies have quantified this variation and showed that it can change over time. These studies have also made it clear that intraspecific variation is important in determining a population's response to disturbances. Heritable changes in traits that determine how species interact with its biotic and abiotic environment lead to eco-evolutionary feedbacks. Mathematical models that integrate some aspects of evolutionary models with those of ecological models are required to study these feedbacks. In this dissertation, I build and extend a series of population dynamics models focusing on heritable intraspecific variation in continuously varying traits. My models capture trait-based ecological interactions as well as stabilizing natural selection. With this mathematical approach I study (i) two-species competition, exploiter-victim interaction and mutualism, and (ii) biotic-abiotic interactions with a conditionable or a consumable abiotic factor. I show that (i) weak stabilizing selection promotes stable coexistence in two-species interactions and (ii) population dynamics and trait evolution are significantly different when a species interacts with a conditionable abiotic factor and a consumable abiotic factor. In a special case of the biotic-abiotic interaction, I show that smaller body size is intrinsically beneficial in a competition for space. Overall, my results point that heritable intraspecific variation has important ecological consequences and could significantly change our expectations relative to those based on purely ecological models.