Genetic and environmental influences on fitness-related traits in an endangered shorebird population

Adaptation depends on the additive genetic variance for fitness and its component traits. Yet estimating additive genetic variance and heritability for wild populations is challenging because determining relatedness of individuals is difficult. We used 20 years (1994-2013) of phenotypic records from mark-recapture data and a multi-generational pedigree to estimate quantitative genetic variation in three fitness-related traits in Great Lakes piping plovers (Charadrius melodus), an endangered wild shorebird. Genetic and environmental components of variance as well as heritabilities were estimated using Bayesian inference for animal models. Phenotypic variation in age-corrected chick mass was composed of a significant additive genetic component (h2 = 0.27; 95% credible interval: 0.16-0.38), and hatch year, common maternal environment, and hatch site effects. Conversely, natal dispersal distance and female breeding time were not significantly heritable (h2 = 0.03; 95% CI: 0.0-0.11; h2 = 0.08, 95% CI: 0.0-0.22, respectively). Rather, environmental factors (e.g., breeding site) are the main sources of variation in these two traits. Variation in female breeding time was minimally influenced by her mate and was moderately repeatable. The low potential for natal dispersal and breeding time to evolve may limit the ability of this population to adapt to climate change long-term. However, trait alteration could occur by a phenotypically plastic response, allowing rapid adjustment to novel environmental conditions and short-term persistence. Depending on the relative contribution of genetic and environmental influences on the trait(s) of interest, results from quantitative genetic studies can also help identify management priorities for endangered populations.