Population genomic analysis suggests strong influence of river network on spatial distribution of genetic variation in invasive saltcedar across the southwestern United States.

Understanding the complex influences of landscape and anthropogenic elements that shape the population genetic structure of invasive species provides insight into patterns of colonization and spread. The application of landscape genomics techniques to these questions may offer detailed, previously undocumented insights into factors influencing species invasions. We investigated the spatial pattern of genetic variation and the influences of landscape factors on population similarity in an invasive riparian shrub, saltcedar (Tamarix L.) by analysing 1,997 genomewide SNP markers for 259 individuals from 25 populations collected throughout the southwestern United States. Our results revealed a broad-scale spatial genetic differentiation of saltcedar populations between the Colorado and Rio Grande river basins and identified potential barriers to population similarity along both river systems. River pathways most strongly contributed to population similarity. In contrast, low temperature and dams likely served as barriers to population similarity. We hypothesize that large-scale geographic patterns in genetic diversity resulted from a combination of early introductions from distinct populations, the subsequent influence of natural selection, dispersal barriers and founder effects during range expansion.

Development of 17 polymorphic microsatellite loci from Jeju striped field mouse, Apodemus agrarius chejuensis (Rodentia: Muridae), by 454 pyrosequencing.

BACKGROUND: The striped field mouse, Apodemus agrarius, is the most common mammal in Korea. Although microsatellite loci for the species have been identified from populations in southwestern China, amplification of those markers for Korean populations have been unsuccessful. The complicated taxonomy of Korean striped field mouse including populations on Jeju Island (A. a chejuensis) necessitates identification of additional molecular markers. FINDINGS: We applied 454 pyrosequencing systems to develop a suite of microsatellite markers. Muscle tissue was harvested and sequenced from 30 Jeju striped field mouse specimens which yielded 12,165 reads with a mean length per read of 287 bp. From these reads, we identified 17 microsatellite loci for A. a. chejuensis and tested these new markers against samples of both A. a chejuensis and A. a coreae, the mainland taxon. All 17 loci were amplified successfully for both taxa. Of the total 17 loci, one locus failed to amplify for a population on Heuksan Island. The cross-species transferability was also tested with the allied taxon, A. peninsulae and confirmed successful for 12 loci. CONCLUSIONS: These newly developed markers will benefit studies of genetic structure, evolution, and resolving taxonomic problems of striped field mice and allied taxa in Korea.

The Origin and Invasion Pathway of Brown Rats Rattus norvegicus on Dok-Do Island Revealed by Genome-Wide Markers from 3-RADseq Approach.

Biological invasions are known to cause local extinctions on islands. Dok-do, a small, remote volcanic island in the East Sea of Korea in the western Pacific, has recently been invaded by rats, posing ecological problems. To infer their origin and invasion pathway, we collected rats from Dok-do and from the potential introduction source locations, Ulleung-do in the Pacific Ocean, and four east coastal ports. First, we identified that the brown rat (Rattus norvegicus) was the only rat species occurring at collecting sites based on the key morphological characteristics. To determine the population-level genetic diversity pattern, we applied the 3-RADseq approach. After a series of filtrations (minor allele frequency < 0.05, Hardy-Weinberg equilibrium p < 1 × 10-7), 4042 SNPs were retained for the final dataset from the 25,439 SNPs initially isolated. The spatial structure and genetic diversity pattern of brown rats suggested that the rat population on Dok-do was likely introduced from Ulleung-do. Our work provides practical information that will assist in the management of invasive brown rats in vulnerable island ecosystems.

African Swine Fever in wild boar: Assessing interventions in South Korea.

African Swine Fever (ASF) was detected in South Korean pig farms in September 2019. Currently, ASF occurs mostly in wild boar (Sus scrofa). We describe the ASF dynamics in wild boar in South Korea from October 2019 to October 2020 and use case studies to evidence the advantages and limitations of the control measures applied. During 2019, ASF remained confined in fenced areas of three counties. Since January 2020 however, the ASF management policy changed from fencing with limited disturbance to culling (with more disturbance), and ASF spread east and south. Until 31 October 2020, a total of 775 wild boar ASF cases have been confirmed, affecting 9 counties. Interventions for ASF control in wild boar included silent (trapping) and non-silent (shooting) population control, local and large-scale fencing, and carcass destruction. Pre-ASF wild boar densities were closed to 10 per km2 . Biosafety risks arose from the movements of people and vehicles, swill feeding of wild boar, destroying pig herds, handling wild boar during trapping and hunting, and searching for and disposing of carcasses. Despite training efforts, biosafety regulations were sometimes ignored. We observed differences between counties regarding disease control. While interventions apparently succeeded in controlling ASF in one site where geographical features and fast decision making facilitated an early and efficient fencing, and culling was performed silently, biosafety problems and habitat- and management-related delays hindered ASF control in other situations. Given that carcass, destruction faces specific limitations in South Korea, fencing and trapping (under appropriate biosafety conditions) might represent the most effective intervention option.

Complete mitochondrial genome sequencing of Lutra lutra (Linnaeus, 1758) (Carnivora: Mustelidae) and its phylogenetic status in Mustelidae.

We report the complete mitochondrial genome sequence of the endangered Eurasian otter, Lutra lutra. The complete mitochondrial genome is 16,537 bp in length and contains 13 protein-coding genes, 22 transfer RNA, two ribosomal RNA, and one control region. The mitogenome is A + T rich, with a composition of 32.2% A, 27.5% C, 14.5% G, and 25.8% T. Phylogenetic analysis based on 13 protein-coding mitochondrial genes of Mustelidae supports the conventional systematic treatment with eight subfamilies. Lutra lutra is closely related to Lutra sumatrana and the subfamily Lutrinae was closely grouped with the Ictonychinae. This study provides genetic and taxonomic information for future studies of Eurasian otters and the Mustelidae.

African swine fever in wild boar, South Korea, 2019.

South Korea is the only Asian country where African swine fever (ASF) is spreading in wild boar (Sus scrofa) populations. This rapid communication describes the situation of ASF in South Korea since its first detection on 17 September 2019 with special attention to ASF dynamics and management in wild boar. Since the first case in a wild boar was detected on 2 October 2019, a total of 86 wild boar have been confirmed as infected by PCR until 18 January 2020, and the monthly number of cases has been growing from October 2019 to January 2020. Interventions to limit ASF spread among wild boar in South Korea consist in fencing, population control and carcass search and disposal. The confirmed ASF-infected sites are immediately fenced, and a three-layer fencing system has been deployed to avoid southward spread of ASF. Hunting and trapping allowed culling 2,623 wild boar on 2,414 km2 (1.08/km2 ), and a total of 889 wild boar carcasses were detected and destroyed. Unfortunately, mine fields impose constraints to effective carcass search, impeding effective quantification of cases and carcass destruction in parts of the infected zone and generating a unique epidemiological setting.

Mammals of Korea: a review of their taxonomy, distribution and conservation status.

The Korean Peninsula and its associated Pacific islands have a distinctive, yet poorly studied mammalian fauna. Korea was a land of invasions and wars for many centuries. The loss of large mammals per unit area that has occurred in Korea may have been greater than in any other country. The peninsula has a depauperate rodent community. The forests are mostly harvested, replaced by intensive agriculture. Unfortunately, the dissemination of information about the mammals of Korea and their taxonomy has been limited because most publications were written in Japanese or Korean. We provide an updated checklist of all the species of Korean mammals, including a review of their taxonomy, distribution, and conservation status based on information extracted from international museum collections, local survey databases (Wildlife Survey and National Nature-Environmental Survey, South Korea) and a literature review. We identify 84 species of terrestrial mammals and 43 species of marine mammals that occur, or once occurred, in Korea. Due to previous, erroneous identifications, we delisted three soricids, two vespertilionids, one phocid, one sciurid and one murid. In total, we confirm the presence in Korea of 127 species of mammals distributed in eight Orders and 32 Families. We provide dichotomous keys for the identification of all the Korean species of mammals together with updated distribution maps.