What is the taxonomic status of East Asian otter species based on molecular evidence?: focus on the position of the Japanese otter holotype specimen from museum

The Japanese otter (Lutra nippon), once inhabited in most islands of Japan, is now considered as an extinct species. Although the Japanese otter is regarded as a distinct species from the Eurasian otter (L. lutra), its phylogeny and taxonomic status are based on limited information on morphological and genetic data, and thus further clarification is required. Here, we assessed the phylogenetic relationship among the genus Lutra and taxonomic status of L. nippon by using the complete sequences of cytochrome b gene of its holotype. The present phylogenic trees supported that the genus Lutra specimens largely formed monophyletic group, with L. sumatrana as a basal to other Lutra species. Within Lutra species, L. nippon was distantly related with L. lutra. The European otter population of L. l. lutra were clustered together with its subspecies, L. l. chinensis rather than the same subspecies, Korean otter population. The discrepancy between the genetic data and traditional taxonomy justifies the necessity of reexamination of the current subspecific classification system of Eurasian otters. Level of genetic divergence between the holotype of L. nippon and L. lutra was two to three-fold lower than those among the other sister species of the Lutrinae. Based on the level of divergence between the L. nippon and L. lutra, and insufficient evidence of morphological difference between them, it is suggested that designation of Japanese otter as a separate species from L. lutra will be reconsidered.     

A review of otters (Carnivora: Mustelidae: Lutrinae) in Malaysia and Singapore

Four species of otters have been recorded from Malaysia and Singapore in the past: Lutra lutra (Common or Eurasian Otter), Lutra sumatrana (Hairy-nosed Otter), Lutrogale perspicillata (Smooth Otter) and Amblonyx cinereus (Oriental Small-clawed Otter). All four are listed in the Threatened Species Categories of the IUCN Red List of Threatened Animals: L. lutra is designated Vulnerable and the status of the other three Asian species are Insufficiently Known due to lack of information. From a review of the available literature and collation of museum records from Malaysia and Singapore, the past status of the four species are examined. Presently, only L. perspicillata and A. cinereus are common in Peninsular Malaysia where they are widely distributed, but both are rare in Singapore. L. sumatrana is rare but apparently still found in East Malaysia. It is possible that L. lutra did not range in Malaysia this century. Information about the habitat types, group size, range, diet and behaviour for all the species is poorly known. The available information allows a discussion of the Smooth and Small-clawed Otters only. This dearth of knowledge has hampered maintenance and breeding efforts of zoos and conservation activity.     

A comparative analysis of the complete mitochondrial genome of the Eurasian otter <Emphasis Type="Italic">Lutra lutra</Emphasis> (Carnivora; Mustelidae)

Otter populations are declining throughout the world and most otter species are considered endangered. Molecular methods are suitable tools for population genetic research on endangered species. In the present study, we analyzed the complete mitochondrial genome (mitogenome) sequence of the Eurasian otter Lutra lutra. The mitochondrial DNA sequence of the Eurasian otter is 16,505 bp in length and consists of 13 protein-coding genes, 22 tRNAs, 2 rRNAs, and a control region (CR). The CR sequence of otters from Europe and Asia showed nearly identical numbers and nucleotide sequences of minisatellites. Phylogenetic analysis of Mustelidae mitogenomes, including individual genes, revealed that Lutrinae and Mustelinae form a clade, and that L. lutra and Enhydra lutris are sister taxa within the Lutrinae. Phylogenetic analyses revealed that of the 13 mitochondrial protein-coding genes, ND5 is the most reliable marker for analysis of phylogenetic relationships within the Mustelidae.     

Eurasian otter (<Emphasis Type="Italic">Lutra lutra</Emphasis>) diet and prey selection in Mediterranean streams invaded by centrarchid fishes

The diet of the Iberian otter (Lutra lutra) was determined by analysing 547 spraints collected at 28 sites within a wide area invaded by centrarchid fishes (pumpkinseed sunfish, Lepomis gibbosus and largemouth bass, Micropterus salmoides): the middle Guadiana basin (South-west Iberian Peninsula). Fish was the otters’ main prey, representing more than 60% of total individuals and more than 80% of total biomass. Otters preyed on most of the fish species captured in the field; however, the consumption of centrarchids was low compared to their abundance in the streams, and Jacobs’ index of preference showed a clear rejection of both species by the otter. Consumption of native fish genera (Squalius, Barbus and Chondrostoma) by otters increased in relation to their increase in the environment. In contrast, increasing numbers of L. gibbosus in the field was not reflected in otter consumption. The general decline of native freshwater fishes in Iberian rivers, the preferred prey of otters, together with the spread of exotic fish species (centrarchids and others) could put otter populations at risk.     

Isolation and characterization of tetramicrosatellite DNA markers in the Eurasian otter (Lutra lutra)

Eight new tetramicrosatellite loci for Eurasian otter (Lutra lutra) were designed. Polymorphism of these eight loci in 29 otter individuals was tested. The results indicated that the allele numbers of each of loci ranged from three to five and the observed heterozygosity from 0.483 to 0.828. These new loci can be useful for population genetic research on otters and help improve the resolution of individual identification using noninvasive method.     

Commensal association of the common kingfisher with foraging Eurasian otters

Positive interactions between birds and mammals are a fascinating aspect of animal behaviour. Feeding associations may consist of local enhancement or facilitation, and in the latter case, of commensalism or mutualism depending on the benefits received by the facilitator. We report here on a previously undescribed feeding association between piscivorous birds and Eurasian otters Lutra lutra. In Spain, common kingfisher Alcedo atthis and grey heron Ardea cinerea were observed closely following foraging otters and benefited from feeding opportunities provided by these. Behavioural observations of otters in central Spain (28.4 hr; 19 days) revealed that an association with kingfishers occurred in 33% of otter foraging events (n = 92). Simultaneous observations in northern Spain (14.2 hr; 16 days) showed an association between otters and kingfishers or grey herons in 41.6% and 11.7% of otter foraging events (n = 77), respectively. The association probability between kingfishers and otters increased significantly when otters foraged closer to the shore and on small fish rather than other prey (crayfish or large fish). Birds fed on prey remain left by the feeding otters, on small fish captured by otters when these were satiated and playing, or on prey displaced by otters. Our observations are consistent with facilitation and commensalism: piscivorous birds gained feeding opportunities provided by the otters, with no apparent costs or benefits to the latter. Similar feeding associations have been described between other species of otters and piscivorous birds (kingfishers, herons, egrets, storks) in Asia, South America and Southern Africa, but had not yet been described in Europe. The occurrence of piscivorous bird–otter associations in different species and regions suggests that this commensalism may be often overlooked but widespread. We have shown that the association can be frequent and is context‐dependent, with benefits for associating birds depending on otters´ behaviour and targeted prey.     

Mitochondrial genetic diversity and structure of the European otter (Lutra lutra) in Britain

The European otter (Lutra lutra) is a focus for conservation efforts throughout Europe due to a population decline in recent decades and because of its importance as a biological indicator of the health of rivers and waterways. The aim of this study was to aid the conservation of this species by adding genetic information from samples originating in the United Kingdom (UK), to help build up a picture of the phylogeographic structure of the European otter throughout Europe. This was done by a comparison of 299 base pairs of the mitochondrial DNA control region. Four haplotypes were identified in the UK, one of which has not been found outside the west of the UK in the wild, and one of which was unique. Populations in the UK, and in particular the west were shown to have a higher haplotype diversity than previously found for the European otter in Europe (h = 0.7338 for the 58 UK otters sampled in this study) and an overall nucleotide diversity of π = 0.003. The western UK population was shown to have a high level of genetic distinctiveness. We discuss possible contributory population processes, the importance of the western UK population for the future conservation of the species and comment on future conservation strategies.     

Individual identification and sex determination of Eurasian otters (Lutra lutra) in Daegu city based on genetic analysis of otter spraint

The Eurasian otter, Lutra lutra, is a well known endangered species in South Korea that experienced rapid population decreases through poaching and industrialization until the 1980’s. To evaluate the genetic diversity and the existing number of otters recently found in Daegu City, 81 fecal samples collected from the Gumho River and Shincheon stream were subjected to DNA extraction for sex determination and genetic analysis using nuclear genetic markers. Individual identification and relatedness between individuals were detemined by genotypic data using twelve microsatellite loci, and sex identification was also determined based on sequence variation of the zinc finger protein gene on sex chromosomes. Our results showed that at least seven otter individuals were identified and the kinship relationships of seven individual pairs were determined. It was concluded that otters distributed widely in Daegu City have moderate levels of genetic diversity, and close monitoring of the small-sized otter population is necessary to promote successful settlement of the otters in the area.     

Genetic evaluation of an otter translocation program

The translocation of individuals from onepopulation to another is a common technique inwildlife conservation. However, the outcome oftranslocation programs is not always properlyevaluated and the relative contribution ofreleased individuals to the resident populationoften remains unknown. We used mitochondrialDNA and autosomal genetic markers to evaluatethe success of a translocation program ofEurasian otters (Lutra lutra) in Sweden.The program is regarded as successful becauseof subsequent population growths. Norwegianotters used for the restocking program could begenetically differentiated from Swedish otters.The releases took place at two sites. In anarea south of the first site, where 47 otterswere released, no genetic contribution of theintroduced animals to the population could beobserved and the genetic diversity was lowerthan before the releases. At the second site,the release of seven otters led to a change ingenetic composition of the resident population.The results of this study suggest that thegrowth of the otter population after therestocking may not be as dependent on thereleases as initially suspected. The geneticeffects of the translocations appear to berestricted to areas in the immediate vicinityof the release sites.     

Body size changes among otters, Lutra lutra, in Norway: the possible effects of food availability and global warming

Using museum data of adult specimens whose sex, age, and locality are known, we studied temporal and geographical body size trends among the otter, Lutra lutra, in Norway. We found that body size of the otters increased during the last quarter of the twentieth century, and suggest that this trend is related to increased food availability from fish farming and possibly also to energy saving due to elevated sea temperatures. Birth year and death year explained 38.8 and 43.5%, respectively, of the variation in body size. Body size of otters was positively related to latitude, thus conforming to Bergmann’s rule.     

Molecular sexing of pine marten (Martes martes): how many replicates?

We used primers developed for the SRY gene in otters (Lutra lutra) to determine sex in pine marten (Martes martes). The otter SRY primers worked accurately for pine marten and assigned sex correctly in most replicates. These primers can be used on tissue and noninvasively collected hair samples for the identification of the animal's sex. We found that, based on five sets of replicates, DNA extracted from leg muscle and hair gave significantly better results than DNA extracted from ear tissue. Finally, results indicate the optimum number of PCR replicates to accurately assign sex using this technique.     

Eurasian otters modify their trophic niche after the introduction of non-native prey in Mediterranean fresh waters

Biological invasions are a major driver behind disturbances in freshwater community structure. We investigated how the foraging strategy of the Eurasian otter Lutra lutra (L.) has responded to this change in a Mediterranean catchment of the Iberian Peninsula, over a 30-year time span (1980 vs. 2010). We found that, despite continuing to feed on a considerable amount of native fish, this carnivore has adapted its trophic niche to accommodate non-native species. Prior to the massive introductions of these new food items (1980), otters diversified their diet during the limiting season (i.e. summer drought). However, otters had largely incorporated non-native prey into their diet in 2010, with red-swamp crayfish being their main food resource, especially in the summer. This increased crayfish consumption reflects a narrowing of trophic niche during the summer drought in 2010. We discuss how this heavy specialisation may compromise the conservation of otters and their endemic fish prey.     

Decline and recovery in otter Lutra lutra populations in Italy

• 1 Changes in otter Lutra lutra distribution in Italy were examined by analysing geographical, historical and survey data.
• 2 As in other European countries, otters declined sharply in Italy during the late 1970s and throughout the 1980s. Between 1985 and 2004 the species became extinct, except for some reintroductions, in northern and most of central Italy while the species appears to have substantially recovered in its southern range. This recovery of the otter population is apparently not due to increased research effort, but reflects a real expansion of range.
• 3 Differences in the degree of range reduction during the second half of the 20th century and in the availability of suitable habitats are probably the major factors that have determined the two opposite trends shown by otter populations in the last 20 years.
• 4 Better knowledge of otter status and distribution is needed for effective conservation management. We suggest that a national survey of the Italian otter population that employs genetic approaches should represent a first step of the national action plan for otter conservation.

     

Patterns of otter Lutra lutra road mortality in a landscape abundant in lakes

In order to reduce otter (Lutra lutra) road mortality and to predict accident sites, we assessed the localities of traffic accidents involving otters in the Uckermark County, Brandenburg, Northeast Germany. Eighty-eight otter accident sites from the years 1990 to 2003—as recorded by the Naturschutzstation Zippelsförde des Landesumweltamtes Brandenburg (Brandenburg State Office for Environment)—were categorised according to traffic and road patterns, otter habitat suitability, as well as presence and type of watercourse crossings. From these numerical data, we compiled a list of characteristics to identify other potentially dangerous sites where otter road traffic accidents are likely to occur using a geographic information system. With a principal component analysis, we categorised three groups of accident sites. Firstly, most otter road accidents were located close to either one or two lakes. Secondly, otters were frequently killed at places where no body of water occurred within a distance of 200 m to the road. Thirdly, and in contrast to other locations, in the Uckermark County, fewest accidents happened where a road crossed a watercourse. Mitigation measures were suggested and discussed for the recorded and potential accident sites.

     

Sex identification of Eurasian otter (<Emphasis Type="Italic">Lutra lutra</Emphasis>) non-invasive DNA samples using ZFX/ZFY sequences

We developed a new PCR/RFLP system targeted to amplify and cut a segment of the ZFX/ZFY gene in non-invasive otter (Lutra lutra) samples. This assay produced one sex-specific fragment in females (XX genotypes) and two fragments in males (XY genotypes), and is intrinsically more reliable than alternative systems (e.g., SRY genes) that are based on the amplification of a single Y-linked fragment. The new primer pair correctly identified the sex of 23 DNA extracted from sexed otter tissues. This procedure was used to sex unknown DNA extracted from otter scats. A multi-tube approach led to identify the sex of 72/91 (79%) samples, using a minimum of two PCR replicates. This procedure is currently used in non-invasive genetic monitoring of Italian otter populations.     

Potential of restored gravel pits to provide suitable habitats for Eurasian otters in anthropogenic landscapes

In anthropogenic landscapes, which are usually characterized by the existence of highly heterogeneous patchworks of habitats with different conservation status, restored gravel pits have the potential to play a conservation role for semiaquatic species such as Eurasian otters (Lutra lutra). Here, we report an otter habitat suitability analysis on a complex fluvial system in an anthropogenic landscape to understand the role of different artificial water bodies (i.e. irrigation channels and ditches) and natural water bodies (i.e. rivers) related to a restored gravel pit lagoon system as providers of suitable habitats for otters. We implemented seven sampling campaigns during 2016 and 2017 consisting of 19 transects across all existing types of water bodies. We integrated 34 environmental variables with otter habitat use, measured by three spraint marking intensity indicators. We found that otter use of water bodies was not related to the natural or artificial origin of the water. Three key factors influenced habitat suitability: riparian vegetation tree cover, forestland use (either natural or planted) within 100 m from the banks, and the level of human disturbance. Our results suggest that otters' tolerance of human activities might be lower in key areas of their territory compared to areas they pass through or explore. We argue that restored gravel pit lagoon systems can potentially play a role in providing suitable habitats for otters in anthropogenic landscapes.     

Amphibians in Eurasian otter Lutra lutra diet: osteological identification unveils hidden prey richness and male‐biased predation on anurans

相似文献   

Prevalence of embedded shotgun pellets in protected and in legally hunted medium-sized carnivores in Denmark

Illegal killings of protected species may significantly affect their population status or lower recovery rates after protection. Poaching is difficult to monitor directly, hence indirect methods are required to document poaching incidences and levels. The use of shotguns inevitably results in wounding some animals that are not killed. Inefficient hunting methods may result in high annual infliction rates in game species. To reduce wounding of game species, an action plan was implemented in Denmark. Using X-ray analysis, we monitor trends in prevalence of embedded shotgun pellets in the legally hunted red fox (Vulpes vulpes) after the implementation of the action plan, and assess poaching levels of two protected species, the otter (Lutra lutra) and the badger (Meles meles) in Denmark. Overall, 13.8% of the red foxes and 6.9% of the otters carried embedded shotgun pellets, while none were recorded in badgers. The prevalence of embedded shotgun pellets in red foxes declined from 24.9% to 8.5% from the late 1990s to the late 2000s, while no change was recorded in otters. Prevalence of embedded shotgun pellets was similar in otters and red foxes collected in the late 2000s. The decline in wounded red foxes suggests that the hunting methods have changed after the action plan was implemented in Denmark. The high proportion of otters carrying embedded shotgun pellets shows that there is a significant poaching of this protected species in Denmark, possibly by hunters and fish farmers that cannot distinguish between otter and non-native American mink (Neovison vison).     

Trophic flexibility of the otter (Lutra lutra) in southern Italy

Diet composition of otters (Lutra lutra) was investigated in 2001 by spraints analysis (N=1323) on five rivers of southern Italy, with the aim of assessing the influence of fish availability, elevation and discharge on the consumption of food resources alternative to fish. Data were expressed as per cent frequency of occurrence (%FO) and per cent volume (%V). The study confirmed the great feeding adaptability of the otter that, in rivers partially interconnected and flowing on a small area, showed a strong fish eating habit in some rivers (Sinni and Mercure-Lao) and a diet mainly constituted by alternative resources in other ones (amphibians in the rivers Cogliandrino and Frido, crustaceans in the River Battendiero). Fish consumption for the five rivers was significantly correlated with fish biomass and with mean summer discharge, while it was inversely correlated with the mean altitude of the five rivers. The lack of a clear seasonality in the consumption of food sources alternative to fish together with the correlation between fish use and fish biomass for each river indicated fish availability as the main factor affecting otter relying to non-fish preys. Otter diet seemed influenced by the characteristics of river habitats (altitude, discharge and consequently fish biomass) more than by summer drought, typical of Mediterranean regions. The %FO and the %V allowed to drawn a similar picture of otter diet. Nonetheless the %V was useful for better illustrating diet variation among the different rivers and we argue that it could be useful in habitats where the otter feeds on preys with different proportions of indigestible remains.