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The muskrat Ondatra zibethicus is native to North America, However it has successfully dispersed into most areas of northeast China in the past decades, which may lead to potential impact on endemic eco-system. We determined and annotated the whole mtDNA genome of the muskrat O. zibethicus to better understand the evolutionary relationship of this invasive species with other Rodentia distributed in China. The complete mitogenome is 16,351 bp in length, includes 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region. We built the phylogenetic tree of muskrat and other 11 most closely related Rodentia species.

“One hundred worst” lists of alien species of the greatest concern proved useful for raising awareness of the risks and impacts of biological invasions amongst the general public, politicians and stakeholders. All lists so far have been based on expert opinion and primarily aimed at representativeness of the taxonomic and habitat diversity rather than at quantifying the harm the alien species cause. We used the generic impact scoring system (GISS) to rank 486 alien species established in Europe from a wide range of taxonomic groups to identify those with the highest environmental and socioeconomic impact. GISS assigns 12 categories of impact, each quantified on a scale from 0 (no impact detectable) to 5 (the highest impact possible). We ranked species by their total sum of scores and by the number of the highest impact scores. We also compared the listing based on GISS with other expert-based lists of the “worst” invaders. We propose a list of 149 alien species, comprising 54 plants, 49 invertebrates, 40 vertebrates and 6 fungi. Among the highest ranking species are one bird (Branta canadensis), four mammals (Rattus norvegicus, Ondatra zibethicus, Cervus nippon, Muntiacus reevesi), one crayfish (Procambarus clarkii), one mite (Varroa destructor), and four plants (Acacia dealbata, Lantana camara, Pueraria lobata, Eichhornia crassipes). In contrast to other existing expert-based “worst” lists, the GISS-based list given here highlights some alien species with high impacts that are not represented on any other list. The GISS provides an objective and transparent method to aid prioritization of alien species for management according to their impacts, applicable across taxa and habitats. Our ranking can also be used for justifying inclusion on lists such as the alien species of Union concern of the European Commission, and to fulfill Aichi target 9.

Climate change is predicted to increase the frequency of droughts and intensity of seasonal precipitation in many regions. Semiaquatic mammals should be vulnerable to this increased variability in precipitation, especially in human-modified landscapes where dispersal to suitable habitat or temporary refugia may be limited. Using six years of presence-absence data (2007-2012) spanning years of record-breaking drought and flood conditions, we evaluated regional occupancy dynamics of American mink (Neovison vison) and muskrats (Ondatra zibethicus) in a highly altered agroecosystem in Illinois, USA. We used noninvasive sign surveys and a multiseason occupancy modeling approach to estimate annual occupancy rates for both species and related these rates to summer precipitation. We also tracked radiomarked individuals to assess mortality risk for both species when moving in terrestrial areas. Annual model-averaged estimates of occupancy for mink and muskrat were correlated positively to summer precipitation. Mink and muskrats were widespread during a year (2008) with above-average precipitation. However, estimates of site occupancy declined substantially for mink (0.56) and especially muskrats (0.09) during the severe drought of 2012. Mink are generalist predators that probably use terrestrial habitat during droughts. However, mink had substantially greater risk of mortality away from streams. In comparison, muskrats are more restricted to aquatic habitats and likely suffered high mortality during the drought. Our patterns are striking, but a more mechanistic understanding is needed of how semiaquatic species in human-modified ecosystems will respond ecologically in situ to extreme weather events predicted by climate-change models.

Musk, secreted by adult male forest musk deer, is a kind of precious Chinese traditional medicine for treating cardiovascular, cerebrovascular and neurogenic diseases. However, a lack of knowledge on musk biosynthetic mechanism and limited musk deer population have seriously hindered the development of the musk industry. Fortunately, given that muskrat musk has similar constituents and pharmacological action with deer musk, muskrat is an ideal model animal for exploring musk biosynthetic mechanism. To explore the biosynthetic mechanism of muskrat musk, in the current study, transcriptomic analysis in the liver, kidney and musk glands of male muskrats between musk secreting and non-musk secreting stages was conducted. The findings indicated that the role of muskrat liver on musk biosynthesis was altering sugar, lipid and amino acid metabolism as well as producing basic resources to support musk glands. Moreover, Tigar , Slc11a2 , Gpt , Hmgcr , Slc27a4 , and Elovl1 were identified as candidate genes for musk biosynthesis via a remotely controlled process. Expression of the Tigar , Slc11a2 , and Gpt genes in the liver are downregulated to support the production of musk in muskrat musk gland. And the Hmgcr , Slc27a4 , and Elovl1 genes in the musk gland participate in muskrat musk synthesis by influencing lipid metabolism in the musk secreting period. This study provided novel insights into the musk biosynthetic pathway in muskrat by transcriptomic analysis and preliminarily suggested the remote control of metabolism from the liver to musk gland during musk biosynthesis, which was useful to further understanding the musk biosynthetic process and improve musk production in the future.

Background This study aimed to provide a systematic review on the geographical distribution of Echinococcus multilocularis in definitive and intermediate hosts in the European Union (EU) and adjacent countries (AC). The relative importance of the different host species in the life-cycle of this parasite was highlighted and gaps in our knowledge regarding these hosts were identified. Methods Six databases were searched for primary research studies published from 1900 to 2015. From a total of 2,805 identified scientific papers, 244 publications were used for meta-analyses. Results Studies in 21 countries reported the presence of E. multilocularis in red foxes, with the following pooled prevalence (PP): low (≤ 1 %; Denmark, Slovenia and Sweden); medium (> 1 % to < 10 %; Austria, Belgium, Croatia, Hungary, Italy, the Netherlands, Romania and the Ukraine); and high (> 10 %; Czech Republic, Estonia, France, Germany, Latvia, Lithuania, Poland, Slovakia, Liechtenstein and Switzerland). Studies from Finland, Ireland, the United Kingdom and Norway reported the absence of E. multilocularis in red foxes. However, E. multilocularis was detected in Arctic foxes from the Arctic Archipelago of Svalbard in Norway. Conclusions Raccoon dogs (PP 2.2 %), golden jackals (PP 4.7 %) and wolves (PP 1.4 %) showed a higher E. multilocularis PP than dogs (PP 0.3 %) and cats (PP 0.5 %). High E. multilocularis PP in raccoon dogs and golden jackals correlated with high PP in foxes. For intermediate hosts (IHs), muskrats (PP 4.2 %) and arvicolids (PP 6.0 %) showed similar E. multilocularis PP as sylvatic definitive hosts (DHs), excluding foxes. Nutrias (PP 1.0 %) and murids (PP 1.1 %) could play a role in the life-cycle of E. multilocularis in areas with medium to high PP in red foxes. In areas with low PP in foxes, no other DH was found infected with E. multilocularis . When fox E. multilocularis PP was >3 %, raccoon dogs and golden jackals could play a similar role as foxes. In areas with high E. multilocularis fox PP, the wolf emerged as a potentially important DH. Dogs and cats could be irrelevant in the life-cycle of the parasite in Europe, although dogs could be important for parasite introduction into non-endemic areas. Muskrats and arvicolids are important IHs. Swine, insectivores, murids and nutrias seem to play a minor or no role in the life-cycle of the parasite within the EU and ACs.

The muskrat, Ondatra zibethicus, is a semiaquatic rodent native to North America that has become a highly successful invader across Europe, Asia, and South America. It can inflict ecological and economic damage on wetland systems outside of its native range. Anecdotal evidence suggests that, in the early 1900s, a population of muskrats was introduced to the Isles of Shoals archipelago, located within the Gulf of Maine, for the purposes of fur harvest. However, because muskrats are native to the northeastern coast of North America, their presence on the Isles of Shoals could be interpreted as part of the native range of the species, potentially obscuring management planning and biogeographic inferences. To investigate their introduced status and identify a historic source population, muskrats from Appledore Island of the Isles of Shoals, and from the adjacent mainland of Maine and New Hampshire, were compared for mitochondrial cytochrome b sequences and allele frequencies at eight microsatellite loci. Appledore Island muskrats consistently exhibited reduced genetic diversity compared with mainland populations, and displayed signatures of a historic bottleneck. The distribution of mitochondrial haplotypes is suggestive of a New Hampshire source population. The data presented here are consistent with a human-mediated introduction that took place in the early 1900s. This scenario is further supported by the zooarchaeological record and island biogeographic patterns. This is the first genetic study of an introduced muskrat population within US borders and of any island muskrat population, and provides an important contrast with other studies of introduced muskrat populations worldwide.

Background Seasonal reproduction is critical for animals adapting to environmental changes, yet the mechanisms driving these shifts remain incompletely understood. Gut microbiota are increasingly recognized as important modulators of reproductive health, but their roles in seasonal breeding species remain unclear. Results In the muskrat ( Ondatra zibethicus ), a well-established seasonal breeder, morphological and histological analyses revealed enhanced follicular development during the breeding season (BS). Subsequent integrated ovarian transcriptomics and metabolomics identified that lipid metabolic processes were significantly enriched during the BS. This was validated by the increased expression of key lipid metabolic enzymes (e.g., DGAT1, CPT1A) and elevated triglyceride content in BS ovaries. Systemically, we found that serum vitamin D 3 (VD 3 ) and ovarian vitamin D receptor (VDR) expression were significantly elevated during BS. In contrast, analysis of upstream factors during the non-breeding season (NBS) showed a significant enrichment of gut Lactobacillus and a concurrent elevation of plasma lithocholic acid (LCA), a known VDR agonist. Correlation analyses confirmed that both Lactobacillus and LCA were inversely associated with serum VD 3 levels. Critically, in vit ro experiments demonstrated that VD 3 treatment enhanced the expression of key lipid metabolism genes in muskrat granulosa cells. Conclusions Collectively, our findings provide evidence for a gut microbiota-VD 3 -ovary axis that modulates seasonal ovarian lipid metabolism and function. This axis represents a new layer of host-microbiota interaction in reproductive physiology.

Muskrats (Ondatra zibethicus) are aptly described as \"ecosystem engineers\" for their influences associated with herbivory, house building, and movement within freshwater wetlands. Sensitivity to flow regime alteration via hydrologic regulation, however, may limit their populations and ability to facilitate wetland diversity and heterogeneity, Muskrat house surveys in coastal wetlands in tributaries (reference wetlands) subject to regional scale water level regulation were compared to treatment sites where local scale water-control structures were installed to alter the regulation effect. Data were used to develop a two-step model to predict wetland occupancy then house density to assess effects associated with proposed water level regulation plans. Field surveys indicated low house densities for cattail-dominated reference wetlands, and nearly 85% of houses located were in treatment sites. House distribution at reference sites was limited to channel edges, whereas houses at treatment sites were found throughout the floodplain. Occupancy of wetlands by muskrats was estimated by winter water depth, and fall water depth, and winter air temperature were selected as predictors of house density. Model validation indicated complete agreement for wetland occupancy, but density tended to be underestimated. Simulations provided a tool to evaluate water management plans and indicated that muskrat populations are suppressed under the current water level regulation regime.

Muskrats (Ondatra zibethicus) are native to North America and widely distributed across the continent. Recent evidence and anecdotal reports suggest that muskrat populations may be declining; however, this assumption has not been rigorously evaluated. We used 42 years of muskrat harvest data (1970–2012) from 37 states to examine trends in muskrat populations across the United States. Annual harvest data are highly correlated with annual pelt prices, which must be controlled for prior to analysis. After adjusting harvest data for the effects of current-year and 1-year-lagged pelt prices, we found strong support that muskrat populations have declined during this period. The slope of decline appeared stronger in the southeastern states and less pronounced in the midwestern states. Our results suggest that wildlife managers should consider active management programs for muskrat populations in regions where declines are observed. Along with recording annual muskrat harvest data, managers should also use rigorous surveys to identify changes in muskrat population abundances. Additionally, our study highlights the need for future research directed at revealing mechanistic explanations for synchronous muskrat declines across this large spatiotemporal scale.

The aftermath of the North American fur trade resulted in the depletion of many furbearing mammal populations in their native North American range while simultaneously creating invasive populations of these species through translocations worldwide. Here, we document the ongoing results of this mass ecological experiment by describing the natural history of a remnant fur colony of muskrats (Ondatra zibethicus) putatively introduced to the Isles of Shoals archipelago in the Gulf of Maine in the early 20th century. Through a combination of intensive surveys and camera trapping, we document how muskrats have been influenced by insular conditions under expectations of island biogeographic theory. Unlike other translocated muskrats that have produced successful wetland‐restricted populations in continental Europe and Asia, the Shoals muskrats appear to have shifted their habitat use and lodge building behavior and have encountered a new predator: gulls (Laridae). This Nature Note formalizes decades of anecdotal observations and provides important insight into the ecological flexibility of muskrats given the paradox of a species that is apparently now declining in its native range but expanding outside of it. The North American fur trade fundamentally shifted baselines of furbearing mammals worldwide. Using camera traps and visual surveys, we document unexpected ecological and behavioral characteristics of a population of muskrats (Ondatra zibethicus) that was likely introduced to the Isles of Shoals (Maine/New Hampshire, USA) in the early 1900s.