Divergence in heritable life history traits suggests potential for local adaptation and trade‐offs associated with a coal ash disposal site

Abstract

Globally, human activities have resulted in rapid environmental changes that present unique challenges for wildlife. However, investigations of local adaptation in response to simultaneous exposure to multiple anthropogenic selection pressures are rare and often generate conflicting results. We used an in situ reciprocal transplant design within a quantitative genetic framework to examine how adaptive evolution and phenotypic plasticity contribute to the persistence of an amphibian population inhabiting an environment characterized by high levels of multiple toxic trace elements. We found evidence of phenotypic divergence that is largely consistent with local adaptation to an environment contaminated with multiple chemical stressors, tied to potential trade‐offs in the absence of contaminants. Specifically, the population derived from the contaminated environment had a reduced risk of mortality and greater larval growth and in the contaminated environment, relative to offspring from the naïve population. Further, while survival in the uncontaminated environment was not compromised in offspring from the contaminant‐exposed population, they did show delayed development and reduced growth rates over larval development, relative to the naïve population. We found no evidence of reduced additive genetic variation in the contaminant‐exposed population, suggesting long‐term selection in a novel environment has not reduced the evolutionary potential of that population. We also saw little evidence that past selection in the ASH environment had reduced trait plasticity in the resident population. Maternal effects were prominent in early development, but we did not detect any trends suggesting these effects were associated with the maternal transfer of toxic trace elements. Our results demonstrate the potential for adaptation to multiple contaminants in a wild amphibian population, which may have facilitated long‐term persistence in a heavily impacted environment.

Bioenergetic Effects of Polycyclic Aromatic Hydrocarbon Resistance Manifest Later in Life in Offspring of Fundulus heteroclitus from the Elizabeth River

“…3 Additionally, the Southern toad (Anaxyrus terrestris) has undergone local adaptation in the Savannah River Site in Aiken County, South Carolina to survive coal ash pollution, with the physiological trade-off of delayed development and reduced larval growth. 4 Despite the emerging evidence of trade-offs of pollution adaptation, mechanisms of trade-off manifestation and the potential to regain physiological homeostasis remain unclear.…”

“…Physiological trade-offs to pollution adaptation have been demonstrated in many species across multiple taxa. − For example, populations of Daphnia longispina have developed tolerance to copper and zinc through adaptation to acid mine drainage from an abandoned cupric pyrite mine in Portugal, with the fitness trade-off of lower feeding rates and reduced survival in clean conditions . Additionally, the Southern toad (Anaxyrus terrestris) has undergone local adaptation in the Savannah River Site in Aiken County, South Carolina to survive coal ash pollution, with the physiological trade-off of delayed development and reduced larval growth . Despite the emerging evidence of trade-offs of pollution adaptation, mechanisms of trade-off manifestation and the potential to regain physiological homeostasis remain unclear.…”