Environmental exposure does not explain putative maladaptation in road-adjacent populations.

Area of Science:

• Evolutionary Biology
• Ecology
• Conservation Biology

Background:

• Roads are significant human alterations to environments, influencing ecological processes.
• Their role as agents of natural selection, potentially driving local adaptation or maladaptation, is understudied.
• Wood frog tadpoles near roads exhibit reduced survival, contrary to expected local adaptation.

Purpose of the Study:

• To investigate if early embryonic exposure to roadside pond water causes the observed survival disadvantage in wood frogs.
• To determine if the survival disadvantage is genetically or environmentally mediated by parents.

Main Methods:

• A reciprocal transplant experiment was conducted.
• Embryonic exposure to roadside pond water was controlled to isolate its effect.
• Survival rates of tadpoles from roadside and non-roadside populations were compared.

Main Results:

• Reduced tadpole survival persisted even when embryonic exposure to roadside pond water was controlled.
• The survival disadvantage is not induced by embryonic exposure to roadside water.
• Parental mediation (genetic or inherited environmental effects) is indicated as the cause of reduced survival.

Conclusions:

• The survival disadvantage in roadside wood frog populations is parentally mediated, suggesting potential genetic maladaptation or later-life stage local adaptation.
• Understanding these maladaptive responses is crucial for conservation given the ubiquity of roads.
• Further research is needed to fully elucidate the mechanisms behind these evolutionary responses to roads.