Ten Years of Evolutionary Research on the Yosemite Toad (Anaxyrus canorus): What Can the Past and Present Tell Us About Their Future?

Yosemite toads (Anaxyrus canorus) are extremely vulnerable to ongoing climate change. Adults exclusively breed in the transient and exceptionally shallow ponds of mountain meadows making them highly dependent upon seasonal snowpack and associated groundwater and runoff levels. Tadpoles regularly face high desiccation mortality exacerbated by opportunistic parasites and predators. Adults and subadults are sensitive to temperature-induced reduction in body fat levels that can influence their overwintering survival and fecundity. Over the past decade, we have used genomic, climate, and landscape data to elucidate how this iconic species has previously adapted alongside climate experienced during the Pleistocene and present-day, to predict the future fate of the species. Pleistocene ice sheets have fractured their distribution into several “pure” and “fused” lineages, while modern-day populations are further divided into “hub” and “satellite” populations. In two recent publications, we forecast how 21st century climate change will encourage range shifts upward in elevation, while simultaneously favoring the adaptive success of certain higher elevation lineages. Our simulations predict a 29% demographic reduction over 90 years of climate scenario RCP 8.5, consistent with previous estimates. Our novel landscape genomic approach offers practical conservation suggestions, such as identifying climate refugia, protecting migrational corridors, and combining low-diversity lineages with similar adaptations into one conservation unit.