The Consequences of Genetic Diversity in Competitive Communities

Abstract

Several lines of evidence suggest that the species diversity and composition of communities should depend on genetic diversity within component species, but there has been very little effort to directly assess this possibility. Here I use models of competition among genotypes and species to demonstrate a strong positive effect of the number of genotypes per species on species diversity across a range of conditions. Genetic diversity allows species to respond to selection imposed by competition, resulting in both functional convergence and divergence among species depending on their initial niche positions. This ability to respond to selection promotes species coexistence and contributes to a reduction in variation in species composition among communities. These models suggest that whenever individual fitness depends on the degree of functional similarity between a focal individual and its competitors, genetic diversity should promote species coexistence; this prediction is consistent with the few relevant empirical data collected to date. The results point to the importance of considering the genetic origin and diversity of material used in ecological experiments and in restoration efforts, in addition to highlighting potentially important community consequences of the loss of genetic diversity in natural populations.

Effects of competition on phylogenetic signal and phenotypic plasticity in plant functional traits

“…Facultative character displacement could result in individuals with greater trait divergence when they cooccur than when they grow alone (Vellend 2006). Alternatively, coexisting individuals across species could converge on an optimal trait value (e.g., Grant 1972, Abrams 1986, Vellend 2006, Fox and Vasseur 2008, if the environment strongly favors specific trait values.…”

Application of Model of Plant Population Structure and Phenotypic Divergence

“…At the start of each year, the adults will select habitat according to the expected fitness rewards in each habitat. A species has up to 10 genotypes, and each genotype has a fixed position along the niche axis according to the method of Vellend (2006) (Fig. 2).…”

“…The classic Lotka-Volterra model of competition community ecology, and continues to provide importance insights in contemporary studies (Vellend, 2006). For both models, a given "run" of simulations consisted of 10 localities simulated at each of five levels of genotypic richness (GR); 1, 2, 4, 7, or 10 genotypes.…”

Can Temperature and Water Availability Contribute to the Maintenance of Latitudinal Diversity by Increasing the Rate of Biotic Interactions?

“…Furthermore, given the growing evidence that developmental plasticity may also contribute to the generation of novelty and speciation (West-Eberhard 2003), the overall amount of phenotypic diversity (both from constitutive genes as well as from plasticity) may be an important determinant of diversification. Second, from an ecological point of view, species coexistence may largely depend on the available genetic diversity within interacting populations (Vellend and Heber 2005, Vellend 2006, Hughes et al 2008, as well as on the degree of phenotypic plasticity (Peacor et al 2006). Thus, understanding how temperature and humidity can affect biotic interactions and the maintenance of genetic diversity has the potential to alter our current view on how global warming and climate change could be linked to the maintenance of biodiversity on Earth.…”

“…Furthermore, more species can be maintained in the tropics because higher genetic and phenotypic diversity can also increase species coexistence (e.g. Vellend and Heber 2005;Peacor et al 2006;Vellend 2006;Hughes et al 2008), and can facilitate the establishment of populations in novel habitats by their use of previously unutilized resources (e.g. Jasmin and Kassen 2007).…”