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Abstract 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.

AbstractThe complete mitochondrial genome of Chrysemys dorsalis in Korea was sequenced and characterized. The mitochondrial genome is 17,258 bp in length and the GC content is 39%. It is constituted of 37 genes, 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a noncoding region. Phylogenetic analysis reveals that C. dorsalis forms a monophyletic group with C. picta turtles but is distinctly separated from them, aligning with previous findings. In Korea, C. dorsalis forms a discrete clade, separate from both native and invasive turtle species. No evidence of genetic disturbance or intermingling is observed. This is the first case of a complete mitochondrial genome from C. dorsalis and provides crucial data for understanding C. dorsalis and managing invasive species effectively, emphasizing the need for continued mitochondrial genome data accumulation.

AbstractSternotherus 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.

AbstractThe complete mitochondrial genome of Chrysemys picta bellii 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 revealed that C. p. bellii from Korea formed a cluster with C. p. bellii from China and C. picta from the USA, while showing clear separation from other turtle species within the C. picta cluster. This study presented the first complete mitochondrial genome from C. p. bellii in Korea, offering crucial information for managing invasive species and protecting the local ecosystem.

Given their pervasiveness in the environment, particularly in aquatic ecosystems, plastics are posing a growing concern worldwide. Many vertebrates and invertebrates in marine, freshwater, and terrestrial ecosystems exhibit microplastic (MP) uptake and accumulation. Some studies have indicated the fatal impacts of MPs on animals and their possible transfer through food chains. Thus, it is crucial to study MP pollution and its impacts on environment-sensitive and globally threatened animal groups, such as amphibians, which also play an important role in the energy transfer between ecosystems. Unfortunately, research in this field is lacking and sources of organized information are also scarce. Hence, we systematically reviewed published literature on MPs in amphibians to fill the existing knowledge gap. Our review revealed that most of the previous studies have focused on MP bioaccumulation in amphibians, whereas, only a few research highlighted its impacts. We found that more than 80% of the studied species exhibited MP accumulation. MPs were reported to persist in different organs for a long time and get transferred to other trophic levels. They can also exhibit cytotoxic and mutagenic effects and may have fatal impacts. Moreover, they can increase the disease susceptibility of amphibians. Our study concludes the MPs as a potential threat to amphibians and urges increasing the scope and frequency of research on MP pollution and its impacts on this vulnerable animal group. We also provide a generalized method for studying MPs in amphibians with future perspectives and research directions. Our study is significant for extending the knowledge of MPs and their impacts on amphibians and guiding prospective research.

Abstract 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.

Tidal flats provide critical habitat for migratory waterbird species; however, populations of migratory waterbirds have significantly declined due to tidal flat loss and degradation caused by human activities, particularly in Asia. Gochang getbol is one of tidal flats located on the southwest coast of South Korea and a center of clam production. Using bird monitoring data collected at five zones (zone1 to zone5) established across Gochang getbol and near coastal area, we examined distribution patterns of migratory bird diversity and conservation-related species along the coast of Gochang getbol. The intensity of human activity ‒ mudflat culture (mostly bivalve) and aquaculture was relatively high at zone2 and zone3, occupying > 30% of 2km circular area surrounding most sample points of these zones. Zone1 and particularly zone4 contained more natural/semi-natural habitats (less disturbed mudflats and wetlands) and zone5 had smallest mudflat than others. Shannon diversity, species richness, and abundance of migratory birds differed between zones (Anova test, P ≤ 0.02) except Shannon diversity in winter. In fall, all values were higher at zone4 than zone3 and zone5. In winter, zone1 showed greatest species richness and higher abundance than zone2, zone3, and zone5. In spring, while most differences were found between zone4 and zone5, abundance at zone4 was somewhat higher than zone2. The results from the fourth corner analysis indicated that abundance of species foraging at mudflat level was positively associated with zone1 (winter) but negatively with zone3 (fall). Sandpipers were positively associated with zone4. Abundance distribution maps of conservation-related species, created by inverse distance-weighted interpolation modeling, also showed high abundance of most conservation-related species at zone4 and 1. The findings of our study suggest the importance of natural/semi-natural habitat, and the possible link between human activity and distribution patterns of migratory birds in Gochang getbol. While we need further investigation on direct response of migratory birds to human activity, areas with low human activity with more natural/semi-natural habitat, e.g., zone4 and zone1 may be crucial for the conservation of migratory birds.

Calling is one of the unique amphibian characteristics that facilitates social communication and shows individuality; however, it also makes them vulnerable to predators. Researchers use amphibian call properties to study their population status, ecology, and behavior. This research scope has recently broadened to species identification and taxonomy. Dryophytes flaviventris has been separated from the endangered anuran species, D. suweonensis, based on small variations in genetic, morphometric, and temporal call properties observed in South Korea. The Chilgap Mountain (CM) was considered as the potential geographic barrier for the speciation. However, it initiated taxonomic debates as CM has been hardly used and is considered a potential barrier for other species. The calls of populations from both sides are also apparently similar. Thus, to verify the differences in call properties among populations of D. suweonensis sensu lato (s.l.; both of the species), we sampled and analyzed call data from five localities covering its distribution range, including the southern (S) and northern (N) parts of CM. We found significant differences in many call properties among populations; however, no specific pattern was observed. Some geographically close populations, such as Iksan (S), Wanju (S), and Gunsan (S), had significant differences, whereas many distant populations, such as Pyeongtaek (N) and Wanju (S), had no significant differences. Considering the goal of this study was only to observe the call properties, we cautiously conclude that the differences are at the population level rather than the species level. Our study indicates the necessity of further investigation into the specific status of D. flaviventris using robust integrated taxonomic approaches, including genetic and morphological parameters from a broader array of localities.

Invasive species are of global conservation concern. South Korea is also facing the same challenge, especially, due to the growing pet trade. Herein, we report Pelomedusa cf. olivacea (Schweigger, 1812) from the wild in South Korea, where it has been imported as a pet. This is the first record of Pelomedusa in the Asian continent. In October 2019, we found an individual of this species beside Hongje Stream in Seoul. We recommend immediate control measures and strict monitoring of the pet trade to avoid the introduction of more invasive species.

Abstract The invasive species are of global concern, and the Invasive American Bullfrog (IAB; Lithobates catesbeianus) is one of the worst invasive amphibian species worldwide. Like other countries, South Korea is also facing challenges from IAB. Although many studies indicated impacts of IAB on native anurans in Korea, the actual risk at the specific level is yet to evaluate. Considering the putative invasiveness of IAB, it is hypothesized that any species with the possibility of physical contact or habitat sharing with them, will have a potential risk. Thus, we estimated and observed their home range, preferred habitats, morphology, behavior, and ecology. Then, comparing with existing knowledge, we assessed risks to the native anurans. We found a home range of 3474.2 ± 5872.5 m2 and identified three types of habitats for IAB. The analyses showed at least 84% of native anurans (frogs and toads) were at moderate to extreme risks, which included all frogs but only 33% of toads. Finally, we recommended immediate actions to conserve the native anurans based on our results. As this study is the first initiative to assess the specific risk level from the invasiveness of L. catesbeianus, it will help the managers to set conservation priorities and strategies.

- Ban the trade of non-native species for consumption as food or derived products and for personal use (i.e., as pets).- Ban the trade of native species when they do not originate from within the nation (i.e., same genetically defined conservation unit).- Tracking of potential established alien Rana populations.- Eradication of potentially established alien Rana populations.

The complete mitochondrial genome of Pseudemys concinna in Korea was sequenced and characterized. The mitochondrial genome is constituted of 37 genes (13 protein-coding genes, 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes) and a noncoding region. Phylogenetic analysis based on the complete mitochondrial genome showed that P. concinna has closer relationship with Chrysemys picta than Trachemys scripta elegans. This is the first case for complete mitochondrial genome from P. concinna in Korea, which will provide information for biogeographical studies and management plan for invasive species.

In social animals that form flocks, individuals compete or cooperate to gain access to shared resources. In particular, group-foraging individuals frequently engage in aggressive interactions with conspecifics, including threat displays and physical attacks, in order to acquire food resources. Here, we investigated social interactions in flocks of captive tree sparrows (Passer montanus) to observe the formation of dominance hierarchies. We also examined correlations between social status and morphological traits to identify which physical traits act as indicators of dominance. To do so, we recorded aggressive behaviours (attacks and threats) of tree sparrows caught in two distinct regions in the Republic of Korea (Gwangju and Gurye). After merging the two groups, we examined dominance structures using David's scores for one month, and we recorded 1,051 aggressive interactions at a feeder in a group of 19 individuals. Using the number of aggressions and attack and threat behaviours, we tested whether morphological traits and sex influenced dominance structures. Aggressions were significantly more frequent in males than in females. However, no significant difference was observed the frequency of between- and within-sex aggression. In addition, differences in the frequency of aggression behaviours were observed between capture-site groups. Dominance structure was significantly correlated with certain morphological traits; specifically, the frequency of attacking behaviours was correlated with bill-nose length, and the frequency of threat displays was correlated with sex and badge size. These results suggest that social signals are closely related to morphological traits that are used to form dominance hierarchies in tree sparrow flocks.

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.

Tidal flats along the southwestern coast of the Republic of Korea are known as internationally important habitats for migratory shorebirds in the East Asian–Australasian Flyway (EAAF). Recent habitat destruction at stopover sites has caused declines in migratory shorebird populations, but the population sizes and habitat use patterns of these species remain poorly understood. We investigated the status of migratory shorebirds using tidal flats in the Republic of Korea. Using population sizes and species diversity, we identified internationally important stopover sites for shorebirds and compared the results of shorebird surveys conducted during the 2014–2015 and 2019–2020 migration period. On Korean tidal flats, 230,000–270,000 shorebirds were counted on their northward migration, and approximately 120,000 individuals were counted on their southward migration. All surveyed areas met internationally important stopover site criteria because they contained more than 0.25% of the shorebird population of one or more species (as opposed to 1% to allow for turnover). We estimated that approximately 20% of the EAAF populations of the Eurasian Curlew (Numenius arquata), Far Eastern Curlew (Numenius madagascariensis), Kentish Plover (Charadrius alexandrinus), and Eurasian Oystercatcher (Haematopus ostralegus) used tidal flats in the Republic of Korea. Importantly, we also confirmed that the critically endangered Spoon-billed Sandpiper (Calidris pygmaea) continued to migrate to the Republic of Korea. These results imply that Korean tidal flats still have great international importance as shorebird stopover sites. Thus, expanding the protection of internationally important stopover sites is necessary to ensure the conservation of migratory shorebirds in the EAAF.

We used three-dimensional micro-computed tomography to compare the skeletal features of two species of male tree frogs with similar morphologies: the globally prevalent Hyla japonica and critically endangered Hyla suweonensis. One of the most prominent differences between the two species was the angle of the alary processes of the premaxilla. In H. suweonensis, the alary processes were inclined posteriorly at an angle of 77.05°, whereas in H. japonica, they were deflected at an angle of 93.27° (a difference of more than 16°). This difference accounts for the more protruded shape of H. suweonensis compared with that of H. japonica. Sizes and proportions related to skeletal compartments (e.g. skull, forelimb, vertebrae, and hindlimb) also differed between the two species, which is consistent with the general exterior observation that compared with H. japonica, H. suweonensis has a more acuminate snout and a more slender body. The full skeletal configuration could provide classification keys for the two sympatric species that will be applicable to ecological field surveys and conservation activities.

Eurasian Tree Sparrow Passer montanus is widely distributed passerine bird, and one sub-species P. m. saturatus is known to inhabit North-East Asia. In this study, we decode the complete mitochondrial genome of P. m. saturatus from the Republic of Korea. Mitogenome was 16,904 bp in length, and the content of A, T, G, and C were 30.0% (5079 bp), 22.5% (3810 bp), 15.5% (2621 bp), and 31.9% (5394 bp), respectively. The circular mitogenome contained 38 genes (13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs) and a non-coding region. Phylogenetic analysis based on the complete mitogenome sequences indicated genetic distances in the species of Passeriformes, and P. m. saturatus in the Republic of Korea is included in a monophyletic group with P. montanus in China. This result provide basic information of population genetics of wide-ranging species Eurasian Tree Sparrow.

The complete mitochondrial genome of Pseudemys peninsularis in Korea was sequenced and characterized. The mitochondrial genome is constituted of 37 genes (13 protein-coding genes, 22 transfer RNA genes, and two ribosomal RNA genes) and a noncoding region. Phylogenetic analysis based on the 13 protein-coding gene sequences showed that P. peninsularis has closer relationship with Chrysemys picta than Trachemys scripta elegans. This is the first case for a complete mitochondrial genome from P. peninsularis, which will provide information for biogeographical studies and management plans for invasive species.

The complete mitochondrial (mt) genome of Trachemys scripta ssp. in Korea was sequenced and characterized. The mt genome is constituted of 37 genes (13 protein-coding genes, 22 transfer RNA genes and 2 ribosomal RNA genes) and a control region. Phylogenetic analysis based on the complete mt genome showed that the unidentified turtle had the mt genome closely related to that of T. s. elegans, though it had distinct morphology compared to T. s. elegans. This study can provide information for biogeographical studies and management plan for invasive species.

The complete mitochondrial (mt) genome of Trachemys scripta troostii was sequenced and was characterized, which comprised 37 genes (13 protein-coding genes, 22 transfer RNAs, and 2 ribosomal RNAs) and a non-coding control region. Phylogenetic analysis based on the full mt genome indicated that T. s. troostii was more closely related to T. scripta from Canada than to T. s. elegans from China or T. s. scripta fom China. This is the first complete mt genome from T. s. troostii, which provides data for further study of phylogeny in Emydidae.

Vocal individuality has been used as a monitoring tool, and two criteria are a prerequisite: high variation among individuals and low variation within individuals, and vocal consistency within and across seasons. We examined individual variation in the territorial hoot calls of the tawny owl (Strix aluco) to discriminate between males and to assess a possible conservation technique that would allow for monitoring individuals within a study area. The territorial calls were recorded from five males in the Naejang Mountain National Park in South Korea during the breeding season in 2015 and 2016 and analyzed both quantitatively and qualitatively to determine the amount of variation within and between individuals. Our results showed that the territorial calls were specific to individuals within a population and that the acoustic distances between males living in the same territory during the two years were the smallest for the four nesting sites. Our results suggest that territorial calls of the tawny owls are individually identifiable over two years and that this acoustic technique can be useful for monitoring individual site fidelity.

Despite having some limitations, the use of skeletochronology—age determination by counting lines of arrested growth (LAGs)—in amphibians is increasing. The main limitation of using skeletochronology is identifying the innermost visible line (IVL) and counting the exact number of LAGs. Thus, we tested its applicability to Kaloula borealis, a class II endangered amphibian in South Korea. We reared juveniles in the lab to investigate the process of bone formation. This confirmed the development of one LAG each year. Hence, our study validates skeletochronology for the age determination of this species and recommends it for others that show similar growth patterns. Furthermore, the comparison of threshold diameters with the IVL of wild individuals confirmed no LAG1 resorption. The average age of males and females in this population was 2.75 ± 1.05 and 3.64 ± 3 years, respectively. We estimated sexual maturity at 2 years with rapid growth up to that stage in both sexes. We found a female-dominated sexual size dimorphism. This study offers accurate information on the life history traits and age structure of K. borealis that may help to evaluate population dynamics in other areas, identify vulnerable life stages and sites, assess the causes of population decline, and set conservation priorities.

There is much controversy over the species and subspecies status of the white wagtail complex, which is further compounded by interbreeding between two subspecies, the Amur Wagtail (Motacilla alba leucopsis) and the Black-backed Wagtail (M. a. lugens). This study presents preliminary information on the breeding biology of both subspecies on Ulleung Island, Korea, over two breeding seasons (2012–2013). Mixed pairs of the two subspecies were common on this island, with almost 50% of all pairs being heterotypic or intermediate pairs; however, assortative mating was still present. Females of both subspecies were more likely to be paired with Amur wagtail males, whereas intermediate females were more likely to be paired with Black-backed Wagtail males. Clutch size, egg size and mass, and reproductive parameters (such as hatching success and nest success) did not significantly differ from each other. However, the mean values were low in intermediate pairs. Our results indicate no reproductive barrier between the two subspecies, but that some post-isolating mechanisms are still in progress.

The complete mitochondrial (mt) genome of Trachemys scripta elegans in Korea was sequenced and characterized. The mt genome is constituted of 37 genes (13 protein-coding genes, 22 transfer RNA genes and 2 ribosomal RNA genes) and a noncoding control region. Phylogenetic analysis based on the complete mt genome showed that T. s. elegans Korea has closer relationship with T. scripta Canada than T. s. elegans China. This is the first complete mt genome from T. s. elegans in Korea, which provides information for biogeographical studies and management plan for invasive species.

The complete mitochondrial genome of a treefrog (Hyla sp.) was determined. The circular mitochondrial genome is 18,288 bp long and encodes 13 proteins, 22 transfer RNAs, and 2 ribosomal RNAs. Phylogenetic analysis of its full genome sequences showed that H. sp. was closely related to H. ussuriensis and H. japonica rather than Dryophytes suweonensis, consistent with the results from each protein-coding gene and a cluster between 12S rRNA and 16S rRNA. The present study will provide essential genomic information for biogeographical distribution and evolutionary history of an endemic treefrog, H.sp.

The razor-backed musk turtle (Sternotherus carinatus) is native to the Southwestern United States and is traded as a pet. Currently, turtle species that are traded as pets have been observed in the wild with increasing frequency, and S. carinatus is among them. To effectively manage an invasive species, it is necessary to know its distribution. Therefore, in this study, we report a new observation of S. carinatus. We captured the turtle in a reservoir in Gwangju, South Korea, and confirmed it to be S. carinatus through morphological characteristics and genetic analysis. Our results show that, despite extensive efforts in the management of invasive species, species traded as pets continue to be observed in the wild. [ABSTRACT FROM AUTHOR]

Invasive species are a growing global concern. Modern transportation and the pet trade are facilitating the spread of invasive species. In particular, the global trade of freshwater turtles remains prevalent, with a significant emphasis on their utilization as pets. Aligning with other parts of the world, many recent studies reported a number of alien turtle species in the wild in Korea. However, knowledge of their local establishment and natural breeding is still very limited. In the current study, we report the first natural breeding of Mauremys sinensis in the wild in South Korea. The external features of the observed individual and egg characteristics confirmed its identification. The individual took around 70 minutes to build the nest, lay eggs, and cover up the nest with the soil that it dug from the nest. We recorded a clutch size of ten eggs. The rigid-shelled eggs had an average elongation of 1.82 mm, smaller than M. reevesii. Thus, we confirm the natural breeding and local establishment of M. sinensis in South Korea. Considering previous reports, this finding is significant for understanding both potential competition and putative hybridization with the native species, especially M. reevesii, the endangered native freshwater turtle species in Korea. [ABSTRACT FROM AUTHOR]

Calling is one of the unique amphibian characteristics that facilitates social communication and shows individuality; however, it also makes them vulnerable to predators. Researchers use amphibian call properties to study their population status, ecology, and behavior. This research scope has recently broadened to species identification and taxonomy. Dryophytes flaviventris has been separated from the endangered anuran species, D. suweonensis, based on small variations in genetic, morphometric, and temporal call properties observed in South Korea. The Chilgap Mountain (CM) was considered as the potential geographic barrier for the speciation. However, it initiated taxonomic debates as CM has been hardly used and is considered a potential barrier for other species. The calls of populations from both sides are also apparently similar. Thus, to verify the differences in call properties among populations of D. suweonensis sensu lato (s.l.; both of the species), we sampled and analyzed call data from five localities covering its distribution range, including the southern (S) and northern (N) parts of CM. We found significant differences in many call properties among populations; however, no specific pattern was observed. Some geographically close populations, such as Iksan (S), Wanju (S), and Gunsan (S), had significant differences, whereas many distant populations, such as Pyeongtaek (N) and Wanju (S), had no significant differences. Considering the goal of this study was only to observe the call properties, we cautiously conclude that the differences are at the population level rather than the species level. Our study indicates the necessity of further investigation into the specific status of D. flaviventris using robust integrated taxonomic approaches, including genetic and morphological parameters from a broader array of localities. [ABSTRACT FROM AUTHOR]