earticle

영어

American bullfrogs (Lithobates catesbeianus), which are native to the eastern United States, have been widely introduced to other parts of the world through food and pet trade. These include parts of North, Central, and South America, Western Europe, and parts of Asia. In many of these regions, they have become invasive by predating or outcompeting native animals. This is true in the Republic of Korea. Because of the potentially damaging impact on ecosystems where this species is not native, it is pertinent to delineate through habitat suitability models where it is most likely to find suitable habitat outside of its native range in order to effectively prevent future outbreaks. Here, we use presence points available through the Global Biodiversity Information Facility (GBIF) along with mixed method habitat suitability modelling to determine areas of highest suitability and areas most at risk of invasion. We first ran ecological niche factor analysis (ENFA) of bioclimatic factors on global and local (Korean) grids representing presence and pseudo-absence points. The original and ENFA modelled presence-pseudoabsence points were then fed separately into random forest algorithms using the same bioclimatic variables. The two results were subsequently averaged to indicate areas at greatest risk of invasion; points with a value > 0.5 were considered risk areas. The model for South Korea was then combined with habitat factors including elevation, vegetation, and landscape type to represent suitable habitat. The final global model showed that globally, the highest risk areas are located in Western North American, South America, Western Europe, parts of Africa, Japan, Southeast Asia, Western Australia, and New Zealand. Within these areas, L. catesbeianus already occurs at high levels in Western North America and moderate levels in South America, Western Europe, and Japan; the species also has limited occurrences in Southeast Asia. In South Korea, the model shows highest suitability in the western and southeastern parts of the country, with suitable habitat located at lower elevations and in areas with higher wetness indices.