Can temperature and water availability contribute to the maintenance of latitudinal diversity by increasing the rate of biotic interactions

Abstract

Environmental gradients (such as average annual temperature increasing towards the tropics) are numerous across the globe. Here I propose a theory, comprised of progressive hypotheses, which links temperature and water availability to the maintenance of high genetic and phenotypic diversity in the tropics through enhanced biotic interactions. In terrestrial ecosystems higher temperatures and water availability, by allowing higher rates of mobility, growth and reproduction of organisms, should lead to higher rates of encounter among individuals in communities. Due to this, interactions in wet and warm environments, such as tropical rainforests, should be both more frequent and more diverse regardless of the number of species present. This diversity of interactions is illustrated at the genotype level, stressing whether genotypes interact positively or negatively with other genotypes, and considering species, as well as individuals, as genotypes. Such biotic interactions in environments can generate strong genotype-environment interactions that can promote the maintenance of high levels of (functional) genetic and phenotypic diversity. This can subsequently facilitate coexistence and speciation processes. The paper finishes by proposing future research to test the hypotheses and hence the overall theory presented here.