Assistant Professor Louisiana State University Baton Rouge, Louisiana, United States
Abstract: Competition plays a vital role in shaping biodiversity. Multiple mechanisms, such as character displacement, density-dependent selection, and mass effects, can drive competition to act on species traits. However, because the strengths of these mechanisms are often context-dependent, it remains difficult to predict how competition influences trait variation, and whether there are underlying ecological factors that interact with competition to contribute to trait variation.
Here, we conducted a meta-analysis with 2887 relevant literature to examine whether the effect of competition on trait variation is context-dependent. We focused on three ecological factors, organism (micro/macro), competition (intraspecific/interspecific), and trait (discrete/continuous) types, in our meta-analysis. Despite these factors being recognized as potential modifiers of competition in previous research, syntheses of their role in shaping trait variation are lacking.
Our results showed that competition overall favored greater trait variation. All three considered factors significantly modified the competitive effects on trait variation. When considering organism types, the effect size of competition on trait variation was higher in microorganisms than in macroorganisms. When considering competition types, intraspecific competition showed a stronger effect than interspecific competition; as when individuals within a species share similar traits, it could lead to great trait variation. Furthermore, we discovered that discrete traits, controlled by single or small number of genes, were more sensitive to competition and showed greater variation, compared to continuous traits, which were often controlled by multiple genes.
In conclusion, our meta-analysis provides strong evidence for the crucial role of competition in trait variation. By demonstrating the impact of competition on traits and identifying the relevant factors that contribute to this impact, our study sheds new light on the mechanisms by which competition shapes trait diversity of ecological communities.
