Homogenous Population Genetic Structure of the Non-Native Raccoon Dog (Nyctereutes procyonoides) in Europe as a Result of Rapid Population Expansion

Dietary change influences the composition of the fecal microbiota in two rescued wild raccoon dogs (Nyctereutes procyonoides)

The gut microbiota of wild animals, influenced by various factors including diet, nutrition, gender, and age, plays a critical role in their health and disease status. This study focuses on raccoon dogs (Nyctereutes procyonoides), a commonly found wild animal, and its gut microbiota composition in response to dietary shifts. The study aimed to compare the fecal bacterial communities and diversity of rescued raccoon dogs fed three different diet types (fish and amphibians, mixed protein with maize, and solely maize) using high-throughput sequencing. Results indicated that the dietary composition significantly influenced the gut microbiota, with notable differences in the abundance of several key phyla and genera. The study identified Firmicutes as the dominant phylum in all diet groups, with notable variations in the relative abundances of Bacteroidota, Proteobacteria, and Verrucomicrobiota. Notably, the group solely fed maize exhibited a significant increase in Proteobacteria, potentially linked to dietary fiber and lignin degradation. The genus-level analysis highlighted significant differences, with Lactobacillus and Bifidobacterium responding to dietary shifts. The genus Akkermansia in Verrucomicrobiota can be identified as a marker for assessing the health of the gut and deserves further investigation. Gender-specific differences in the gut microbiota were observed, highlighting the influence of individual variation. Furthermore, the analysis of bacterial functions suggested a connection between diet and host metabolism, emphasizing the need for further research to understand the complex mechanisms underlying the relationship between dietary composition and gut microbiota in wild animals. These findings provide crucial insights into conservation and rescue efforts for wild animals.

Effect of Soil Type on Native Pterocypsela laciniata Performance under Single Invasion and Co-Invasion

Native and invasive plant competition is usually controlled by the soil properties and the soil type underlying interspecific interactions. However, many uncertainties exist regarding the impact of soil type on native plant growth under single invasion and co-invasion despite the significant number of previous studies that focused on plant invasion. This study aims to elucidate the effects of soil type on the response of the native plant Pterocypsela laciniata under single invasion and co-invasion. Three different soils were used: natural soil, nutrient soil, and nutrient sterilized soil. The native P. laciniata was grown in monoculture and under single invasion and co-invasion with Solidago canadensis and Aster subulatus Michx. The results show that the native plant height and total biomass were 75% and 93.33% higher, respectively, in nutrient sterilized soil in monoculture than in natural and nutrient soil. In contrast, the native P. laciniata presents its best competitive ability in nutrient sterilized soil, being about 100% higher than in natural and nutrient soil under single invasion and co-invasion. However, no significant increase was observed in its growth parameters under co-invasion compared to single invasion. Conclusively, this study shows that nutrient soil sterilization positively affects native plant growth in monoculture and under single invasion, contrasting co-invasion in which more pronounced negative effects were observed on the native plant response.

A genetic analysis of grey squirrel (Sciurus carolinensis) populations in Ireland

The grey squirrel (Sciurus carolinensis) is an invasive rodent in Ireland that has had detrimental impacts on the native Irish red squirrel (S. vulgaris) as well as on silviculture. This invasive species spread rapidly throughout Ireland, but in recent years appears to be declining in certain areas of the country. This study analysed the genetic profile of grey squirrel populations in Ireland to gain insight into their introduction, evolutionary history in Ireland, and vulnerability to management strategies. The genetic diversity and population structure of eight grey squirrel populations in Ireland was assessed using 11 species-specific microsatellite loci, and was compared to a small population from Tennessee, U.S.A., part of the native range of the grey squirrel. This is the first time these microsatellite markers developed specifically for grey squirrels have been used to study the species in Ireland. We found low to moderate genetic diversity overall across Irish populations as well as the presence of inbreeding. One population in particular, (in Co. Kildare), was differentiated from all other populations, which could indicate genetic isolation between Irish populations or a secondary introduction of S. carolinensis to Ireland.

Genetic diversity and structure of Saussurea polylepis (Asteraceae) on continental islands of Korea: Implications for conservation strategies and management

Saussurea polylepis Nakai is an herbaceous perennial endemic to Korea and is highly restricted to several continental islands in the southwestern part of the Korean Peninsula. Given its very narrow geographical distribution, it is more vulnerable to anthropogenic activities and global climate changes than more widely distributed species. Despite the need for comprehensive genetic information for conservation and management, no such population genetic studies of S. polylepis have been conducted. In this study, genetic diversity and population structure were evaluated for 97 individuals from 5 populations (Gwanmaedo, Gageodo, Hongdo, Heusando, and Uido) using 19 polymorphic microsatellites. The populations were separated by a distance of 20–90 km. We found moderate levels of genetic diversity in S. polylepis (Ho = 0.42, He = 0.43). This may be due to long lifespans, outcrossing, and gene flow, despite its narrow range. High levels of gene flow (Nm = 1.76, mean Fst = 0.09), especially from wind-dispersed seeds, would contribute to low levels of genetic differentiation among populations. However, the small population size and reduced number of individuals in the reproductive phase of S. polylepis can be a major threat leading to inbreeding depression and genetic diversity loss. Bayesian cluster analysis revealed three significant structures at K = 3, consistent with DAPC and UPGMA. It is thought that sea level rise after the last glacial maximum may have acted as a geographical barrier, limiting the gene flow that would lead to distinct population structures. We proposed the Heuksando population, which is the largest island inhabited by S. polylepis, as a source population because of its large population size and high genetic diversity. Four management units (Gwanmaedo, Gageodo, Hongdo-Heuksando, and Uido) were suggested for conservation considering population size, genetic diversity, population structure, unique alleles, and geographical location (e.g., proximity).

Dynamic range expansion leads to establishment of a new, genetically distinct wolf population in Central Europe

Local extinction and recolonization events can shape genetic structure of subdivided animal populations. The gray wolf (Canis lupus) was extirpated from most of Europe, but recently recolonized big part of its historical range. An exceptionally dynamic expansion of wolf population is observed in the western part of the Great European Plain. Nonetheless, genetic consequences of this process have not yet been fully understood. We aimed to assess genetic diversity of this recently established wolf population in Western Poland (WPL), determine its origin and provide novel data regarding the population genetic structure of the grey wolf in Central Europe. We utilized both spatially explicit and non-explicit Bayesian clustering approaches, as well as a model-independent, multivariate method DAPC, to infer genetic structure in large dataset (881 identified individuals) of wolf microsatellite genotypes. To put the patterns observed in studied population into a broader biogeographic context we also analyzed a mtDNA control region fragment widely used in previous studies. In comparison to a source population, we found slightly reduced allelic richness and heterozygosity in the newly recolonized areas west of the Vistula river. We discovered relatively strong west-east structuring in lowland wolves, probably reflecting founder-flush and allele surfing during range expansion, resulting in clear distinction of WPL, eastern lowland and Carpathian genetic groups. Interestingly, wolves from recently recolonized mountainous areas (Sudetes Mts, SW Poland) clustered together with lowland, but not Carpathian wolf populations. We also identified an area in Central Poland that seems to be a melting pot of western, lowland eastern and Carpathian wolves. We conclude that the process of dynamic recolonization of Central European lowlands lead to the formation of a new, genetically distinct wolf population. Together with the settlement and establishment of packs in mountains by lowland wolves and vice versa, it suggests that demographic dynamics and possibly anthropogenic barriers rather than ecological factors (e.g. natal habitat-biased dispersal patterns) shape the current wolf genetic structure in Central Europe.

Molecular evolution of MHC class II DRB exon 2 in Japanese and Russian raccoon dogs, Nyctereutes procyonoides (Carnivora: Canidae)

Raccoon dogs, Nyctereutes procyonoides, are native to East Asia, but have been introduced into western Russia and eastern Europe. To determine allelic diversity and elucidate the evolution of major histocompatibility complex (MHC) class II genes in the raccoon dog, we analysed a 237-bp region of DRB exon 2 from 36 individuals of native and introduced populations from Japan and Russia. We detected 23 DRB alleles (Nypr-DRBs), 22 of which were novel. Some alleles were found across the species’ range, while others were geographically restricted. For both native and introduced populations, the ratio of non-synonymous to synonymous substitution rates for codons at predicted antigen-binding sites was significantly greater than 2, indicating that Nypr-DRBs have evolved under positive selection. Mixed effect model evolution analysis and an algorithm to detect recombination showed five positively selected codons and one recombination breakpoint, respectively. Overall, our results suggest that the diversity of MHC class II DRB in N. procyonoides was influenced and maintained by recombination, pathogen-driven positive selection, geographical barriers and the founder effect. A Bayesian phylogenetic tree revealed no evidence of trans-species polymorphism (TSP), but instead showed monophyly for the Nypr-DRB alleles within a larger clade of canid sequences. The lack of TSP may have been due to long-term divergence of raccoon dogs from other canids, or to their having encountered different sets of pathogens due to occupying a different ecological niche.

Genetic Diversity and Population Structure of East Asian Raccoon Dog (Nyctereutes procyonoides): Genetic Features in Central and Marginal Populations

The raccoon dog (Nyctereutes procyonoides) is endemic to East Asia but has been introduced in Europe. Its high adaptability enabled its rapid colonization of European countries, where population growth has been raising concerns regarding ecosystem disturbance and the spread of zoonotic diseases. The genetic diversity and structure of endemic, source, and introduced populations from seven locations across South Korea, China, Russian Far East, Finland (spread to Finland after introduction to European part of Russia from Russian Far East), Vietnam, and Japan (Honshu and Hokkaido) were examined based on 16 microsatellite loci. Two major and significantly different (F_ST = 0.236) genetic clusters were found: continental (South Korean, Chinese, Russian, Finnish, and Vietnamese) and island (Japanese) populations. The continental raccoon dog population comprises three subpopulations (Chinese_Russian_Finnish, South Korean, and Vietnamese) and the Japanese population consists of Honshu and Hokkaido subpopulations. The genetic diversity and geographic structure of raccoon dogs in East Asia has been influenced by natural barriers to gene flow and reveals a typical central-marginal trend in genetic diversity (continental vs. island, and central vs. marginal or source vs. introduced within continental populations). The detected differences between continental and island populations agree with those reported in previous studies that considered these populations as different species.

Population structure of the raccoon dog (Nyctereutes procyonoides) using microsatellite loci analysis in South Korea: Implications for disease management

The prevention and control of infectious diseases transmitted by wildlife are gaining importance. To establish effective management strategies, it is essential to understand the population structure of animals. Raccoon dogs (Nyctereutes procyonoides) in South Korea play a key role in the maintenance of food web stability and possess genetic compositions that are unique compared to those in other areas. However, wild raccoon dogs play another role as the main host of various infectious diseases. To establish long-term strategies for disease management, we investigated the genetic structure and possible geographic barriers that influence the raccoon dog population in South Korea by analyzing 16 microsatellite loci. The present study showed that mountains were the major factors responsible for genetic structuring, along with distance. We proposed potential management units (MUs) for raccoon dogs based on the genetic structuring and gene-flow barrier data obtained in this study. Four MUs were suggested for the Korean raccoon dog population (Northern, Central, Southwestern, and Southeastern). The Korean raccoon dog population structure determined in this study and the proposed MUs will be helpful to establish pragmatic strategies for managing Korean raccoon dog population and for preventing the transmission of infectious diseases.

Severe impact of sarcoptic mange on the movements and space use for one of its most important vector species, the raccoon dog

Sarcoptic mange is a highly contagious zoonotic skin disease that can have severe effect on population dynamics of many wild mammals. However, very little is known about its effect on the activity and space use of infected animals. In this study we equipped two raccoon dogs (Nyctereutes procyonoides) in a mange outbreak area with radio-collars and observed the spatial and temporal effects of sarcoptic mange to these individuals. Initially, the raccoon dogs had no external symptoms of mange infection, but developed these during the study period. One of the raccoon dogs died just 32 and the other 52days after collaring. During a relatively short period before their death, there was an abrupt and drastic decline in their home range size. For one of the animals it started about 1 month before its death and the home range size reduced >1000×, whereas for the other raccoon dog it took place within the last week, decreasing >200×. The daily covered distances also declined considerably. These results indicate that at the later stage sarcoptic mange affected the physiological state of the diseased animals so forcefully that made them almost immobile. Our results show for the first time how rapid and severe could the impact of sarcoptic mange be for one of its most important reservoir and vector species.

Ovulation, fertilization and preimplantation embryonic development in raccoon dogs (Nyctereutes procyonoides)

A study involving 32 sexual mature females was conducted to characterize ovulation, fertilization and early embryonic development in vivo in raccoon dogs. Oocytes and embryos were collected from the oviducts and uteri, evaluated by stereomicroscopy. Ovulation occurred 25-32h after a female first accepted mounting, regardless of copulation, when the females were paired with a male in the same cage. Ovulated oocytes were at the primary stage. The number of ovulated eggs in females with or without mating was 9.96±2.65 and 9.00±1.92, respectively. Embryos at 2-4 cell, 8-16 cell, morula, blastocyst, and hatched blastocyst stage were observed at 29-73, 48-100, 98-126, 169-198 and 217-268h after first mating, respectively. Embryos were located in the oviduct prior to 4-cell stage and moved into the uterus after 16-cell stage. Embryos at different stages were often obtained from the same female. During the zygote underwent a series of cleavage divisions, the diameter of the embryo cell mass continuously increased through the 2-cell and 4-cell stage, then started to decrease and was the minimum size at the morula stage. At the blastocyst stage, embryos increased in volume, and finally developed into a hatching blastocyst with a thinner zona pellucida. This is the first full report of preimplantation embryonic development in the raccoon dog, which will facilitate the application of advanced assisted reproductive technology in canine species.