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Oyler-McCance, S.J., Ryan, M.J., Sullivan, B.K. et al. Genetic connectivity in the Arizona toad (Anaxyrus microscaphus): implications for conservation of a stream dwelling amphibian in the arid Southwestern United States. Conserv Genet (2024).


The Arizona Toad (Anaxyrus microscaphus) is restricted to riverine corridors and adjacent uplands in the arid southwesternUnited States. As with numerous amphibians worldwide, populations are declining and face various known or suspectedthreats, from disease to habitat modification resulting from climate change. The Arizona Toad has been petitioned to belisted under the U.S. Endangered Species Act and was considered “warranted but precluded” citing the need for additionalinformation – particularly regarding natural history (e.g., connectivity and dispersal ability). The objectives of this studywere to characterize population structure and genetic diversity across the species’ range. We used reduced-representationgenomic sequencing to genotype 3,601 single nucleotide polymorphisms in 99 Arizona Toads from ten drainages across itsrange. Multiple analytical methods revealed two distinct genetic groups bisected by the Colorado River; one in the northwesternportion of the range in southwestern Utah and eastern Nevada and the other in the southeastern portion of the range incentral and eastern Arizona and New Mexico. We also found subtle substructure within both groups, particularly in centralArizona where toads at lower elevations were less connected than those at higher elevations. The northern and southernparts of the Arizona Toad range are not well connected genetically and could be managed as separate units. Further, thesedata could be used to identify source populations for assisted migration or translocations to support small or potentiallydeclining populations.