Genomic Correlates of Disease Recovery in Natural Populations of the Sierra Nevada Yellow-Legged Frog (Rana sierrae)

In our rapidly changing world, evolution is likely to play an important role in facilitating the resilience of wildlife populations. The Sierra Nevada yellow-legged frog (Rana sierrae) provides a rare example of recovery following severe declines caused by the amphibian chytrid fungus (Batrachochytrium dendrobatidis). However, the role of evolution in facilitating this recovery remains circumstantial. In this study, we sought to gain insights into the potential role of evolution by comparing genomes of frogs from naive and recovering populations located in close proximity. Using multiple methods to scan frog genomes for signatures of selection, our study reveals several genomic variants associated with frog recovery. Specifically, we identify outlier gene variants across genes related to skin integrity and intracellular regulation, an interferon-related gene and a recovery-associated variant in RIN3-a gene that may play a critical role in disease defence and wound healing. Finally, we report no differences in genetic diversity between naive and recovering populations. Our study provides a rare example from natural populations that suggests that evolution can produce individuals that harbour adaptive alleles and allow population recovery in the presence of novel stressors. These findings complement recent research on rapid amphibian evolution in response to disease and provide mechanistic hypotheses for how individuals can prove resilient to disease outbreaks.