Widespread disruptive selection in the wild is associated with intense resource competition

• Published in: BMC evolutionary biology Vol. 12; no. 1; p. 136
• Main Authors: Martin, Ryan A, Pfennig, David W
• Format: Journal Article
• Language: English
• Published: London BioMed Central 02.08.2012; BioMed Central Ltd; BMC
• Subjects: Amphibia; Animal reproduction; Animal Systematics/Taxonomy/Biogeography; Animals; Anura - anatomy & histology; Anura - genetics; Biomedical and Life Sciences; Competition; Competition (Biology); Competitive Behavior; Disruptive selection; Entomology; Environmental aspects; Evolution; Evolutionary Biology; Fish; Frogs; Genetic aspects; Genetic Fitness; Genetics and Population Dynamics; Life Sciences; Natural populations; Natural selection; Phenotype; Quadratic selection; Research Article; Resource polymorphism; Selection differential; Selection, Genetic; Spadefoot toad; Spea multiplicata; Studies; Surveys; Tadpoles; United States; Competition; Selection differential; Disruptive selection; Resource polymorphism; Spadefoot toad; Quadratic selection
• ISSN: 1471-2148; 1471-2148
• DOI: 10.1186/1471-2148-12-136

Background Disruptive selection has been documented in a growing number of natural populations. Yet, its prevalence within individual systems remains unclear. Furthermore, few studies have sought to identify the ecological factors that promote disruptive selection in the wild. To address these issues, we surveyed 15 populations of Mexican spadefoot toad tadpoles, Spea multiplicata, and measured the prevalence of disruptive selection acting on resource-use phenotypes. We also evaluated the relationship between the strength of disruptive selection and the intensity of intraspecific competition—an ecological agent hypothesized to be an important driver of disruptive selection. Results Disruptive selection was the predominant mode of quadratic selection across all populations. However, a directional component of selection favoring an extreme ecomorph—a distinctive carnivore morph—was also common. Disruptive selection was strongest in populations experiencing the most intense intraspecific competition, whereas stabilizing selection was only found in populations experiencing relatively weak intraspecific competition. Conclusions Disruptive selection can be common in natural populations. Intraspecific competition for resources may be a key driver of such selection.