Environments impacted by mining and mining-related activities can often be characterized by high levels of toxic trace metals. These pollutants present unique challenges for wildlife, often resulting in profound evolutionary changes. However, evolutionary mechanisms such as local adaptation and life history trade-offs in response to these anthropogenic selection pressures are still poorly understood. We conducted a reciprocal transplant experiment with Rana pipiens tadpoles from three populations to test if adaptive or maladaptive evolution occurs in amphibians inhabiting mining-impacted environments. We also assessed the potential role of global warming on the evolutionary outcome of these impacted tadpole groups by using two different temperature regimes.
Results/Conclusions
Our results showed evidence of growth and mortality rate variation largely consistent with life-history trade-offs associated with local adaptation to environments impacted by multiple chemical stressors. Specifically, tadpoles from the environment with the highest amount of metals showed reduced risk of mortality, but lower larval growth rate in their original environment relative to tadpoles from naïve populations. We also observed that as temperature increased, tadpoles from the most impacted environment had a lower mortality rate than tadpoles from the less impacted environments when raised in the less impacted environments. Our study demonstrates the potential for amphibian populations to adapt to mining-impacted environments and confirms the effect of additional stressors in influencing mortality rates in these populations.
