Elevational Distribution of Amphibians: Resolving Distributions, Patterns, and Species Communities in the Republic of Korea.

Species biodiversity organises along elevational trends and is generally expected to decrease with increasing elevation. This pattern is regulated by numerous factors, although principally overridden by temperature in ectotherms such as amphibians. Here, we collated elevation data (n = 55,182) collected between 1909 and 2020. We then determined elevation distribution patterns and species communities for all amphibians in the Republic of Korea. Species were found to range from sea level up to 1,393 m a.s.l. The average elevational distribution was significantly different between species but also between anura and caudata. On average, anura were found at lower elevations with a peak in species richness and abundance matching with the lowlands. In opposition, the peak in species richness and abundance for caudata matched with low hilly landscapes. The altitudinal distributions of species were strongly skewed, with all 23 species found within the 0-199 m range, and steadily decreasing with only five species within the last elevational range (1,200-1,399 m). Finally, only a few species were found below 30 m, reflecting a likely risk of salinisation in this environment. Our results help understand the altitudinal distribution of amphibians in the Republic of Korea.

Distribution Change of Invasive American Bullfrogs (Lithobates catesbeianus) by Future Climate Threaten Endangered Suweon Treefrog (Hyla suweonensis) in South Korea.

The American Bullfrog (Lithobates catesbeianus) has been imported into South Korea in earnest for food since the 1970s and introduced into nature due to release and escape. Accordingly, the influx and spread of American Bullfrogs are expected to have a direct impact on native species, but few related studies have been conducted on this. We predicted changes in the potential distribution and future distribution based on climate change scenarios to analyze how those changes affect critically endangered Suwon treefrogs. Suwon treefrog sites (63.9%, 78/122) overlapped with the distribution of Bullfrogs. According to the prediction of the future distribution of Bullfrogs, the overlapping of American Bullfrogs and Suwon treefrog will remain similar to the current level in the Representative Concentration Pathway (RCP) 4.5 scenario. On the other hand, in the RCP 8.5 scenario, the number of overlapping sites will increase to 72.1% (88/122) due to the spreading of the American Bullfrogs. The results show that climate change directly affects the distribution expansion of the American Bullfrogs but also indirectly can lead to an increased threat to Suwon treefrogs. In conclusion, our results strongly suggest why climate change should be actively addressed in terms of the spread of invasive species and the protection of endangered species.