Assessment of American Bullfrog (Lithobates catesbeianus) spreading in the Republic of Korea using rule learning of elementary cellular automata.

The spread of American Bullfrog has a significant impact on the surrounding ecosystem. It is important to study the mechanisms of their spreading so that proper mitigation can be applied when needed. This study analyzes data from national surveys on bullfrog distribution. We divided the data into 25 regional clusters. To assess the spread within each cluster, we constructed temporal sequences of spatial distribution using the agglomerative clustering method. We employed Elementary Cellular Automata (ECA) to identify rules governing the changes in spatial patterns. Each cell in the ECA grid represents either the presence or absence of bullfrogs based on observations. For each cluster, we counted the number of presence location in the sequence to quantify spreading intensity. We used a Convolutional Neural Network (CNN) to learn the ECA rules and predict future spreading intensity by estimating the expected number of presence locations over 400 simulated generations. We incorporated environmental factors by obtaining habitat suitability maps using Maxent. We multiplied spreading intensity by habitat suitability to create an overall assessment of bullfrog invasion risk. We estimated the relative spreading assessment and classified it into four categories: rapidly spreading, slowly spreading, stable populations, and declining populations.

The first record of leucism in the Rhabdophis tigrinus (Boie, 1826) (Squamata, Colubridae) in South Korea.

Leucism, in which pigmentation is lost over part or the entire body of an animal, has a range of possible genetic causes. Here, we report leucism in an individual tiger keelback (Rhabdophis tigrinus) found on Jeung Island, Shinan-gun, Jeollanam-do, South Korea, during a survey of the distribution of reptiles in the area. The individual was observed sunbathing in the bushes next to a pond. This individual exhibited ecdysis, thus it considered that have normal feeding activity. Our report represents the first observation of leucism in R. tigrinus, and thus, further analysis is needed of this phenotype to more clearly understand its impact on the species and its natural history.

Confirmation of the local establishment of alien invasive turtle, Pseudemys peninsularis, in South Korea, using eggshell DNA.

Alien invasive species are posing conservation challenges worldwide. Pet trade, one of the many ways, is worsening the situation. Especially, pet turtles have been released into nature due to their longer life span and peoples' religious and traditional beliefs. In addition, unwanted and undesired pets are also released. While information on the successful local establishment and subsequent dispersal into new habitats is required to designate an invasive and ecosystem-disturbing species, alien freshwater turtle nests have always been hard to find and identify in nature. Because one should identify nests by the eggs, which do not always guide properly, as adults abandon the sites quickly. We thought the recent advancement in DNA technology may help improve the situation. We studied Pseudemys peninsularis, one of the most traded freshwater turtle pet species, which has already been reported from a wide range of wild areas in South Korea. Yet, it is not designated as ecosystem-disturbing species due to a lack of adequate information on their local reproduction and establishment. We conducted surveys and found two nests in Jeonpyeongje Neighborhood Park, Maewol-dong, Seo-gu, Gwangju. We developed the methodology for extracting DNA from the eggshells and successfully identified the nests by phylogenetic analysis and verified through egg characteristics and morphological features of artificially hatched juveniles. This was the first successful initiative to extract DNA from freshwater turtle eggshells. We believe it will help future researchers identify the alien invasive turtle nests and develop their control and management policies. In addition, our study also included comparative descriptions and schematic diagrams of the eggs of eight freshwater turtles, including a native and three ecosystem-disturbing species, from South Korea. We urged an immediate designation of P. peninsularis as an ecosystem-disturbing species considering its local establishment, distribution range, and potential negative impact on native ecosystems.

Complete mitochondrial genome of the razor-backed musk turtle (Sternotherus carinatus, testudines: emydidae) in Korea.

Sternotherus carinatus has been considered as a potential invasive species in Korea. However, the mitochondrial genome information of S. carinatus which can be used to control its effect on ecosystem is lacking. In this study, the complete mitochondrial genome of S. carinatus in Korea was sequenced and characterized. The mitochondrial genome consists of 37 genes (13 protein-coding genes, 22 transfer RNA genes, and 2 ribosomal RNA genes) and a noncoding region. Phylogenetic analysis based on the mitochondrial genome sequences showed that S. carinatus from Korea is separated from other turtles which are the invasive species in Korea. Sequence divergence calculations indicated near-zero divergence between S. carinatus populations in Korea, the USA, and China, suggesting limited genetic differentiation. In the context of the broader issue of invasive species disrupting ecosystems, this research contributes to the identification of mitochondrial genomes for various freshwater turtle species, emphasizing the need for extended data collection to discern genetic mixing trends between native and non-native species. This study is a significant step toward managing S. carinatus as a potential invasive species in Korea.