COS 169-1 - Plasticity in resource consumption traits shape community structure and the strength of niche and neutral processes in competitive communities

Abstract: Resource competition theory has overlooked the feedbacks that emerge from organisms shaping their environment through resource consumption, which in turn, shape plastic changes in traits in direct response to environmental variation. Community ecology has yet to integrate this feedback to predictions of community structure that include functional diversity and relative abundance distributions. Here we study how plasticity in resource consumption traits, defined by individual energy allocation constraints, shape community structure. We adopt a model incorporating plasticity in classic consumer-resource models where consumption strategies are dynamic by optimizing organism growth, underpinned by investment constraints in physiological machinery for acquisition of resources. Our results predict how plasticity in resource consumption strategies results in trait dynamics that let species avoid competitors while maximizing its efficiency on available resources. Interestingly this plastic optimization in even just one species in a community allows all other non-plastic species to coexist, a case of positive facilitation with pure competitive interactions. Additionally, we build a simple linear model based on plasticity maximizing resource uptake while minimizing competition that is predictive of relative species abundances so long as a geometric characteristic that we define as community supply vector distance is above a certain threshold. We study two cases, one where species consumption strategies are predictive of species abundances (niche), and a second in which consumption strategies are not predictive of species abundances (neutral). In the first case, we find that initial consumption strategies are more predictive of species abundances than equilibrium consumption strategies, highlighting the importance of the consumption strategy species have when colonizing a new environment in determining community structure when these traits are dynamic. Our study suggests that plasticity constrained by individual energy allocation provides a mechanism of facilitation that promote coexistence as well determines the relative strength of niche and neutral processes as drivers of community structure.