Otter Species Research Articles

A comparative analysis of the complete mitochondrial genome of the Eurasian otter Lutra lutra (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.

Surgical Implantation of Intra-abdominal Radiotransmitters in Marine Otters (Lontra felina) in Central Chile

Six free-ranging marine otters (Lontra felina) were livetrapped on the central coast of Chile and implanted with specially designed radiotransmitters as part of a spatial ecology study. Marine otters frequent the rocky seashore, often squeezing their narrow bodies through cracks and crevices and grooming themselves on the rocks. They are also among the smallest of the otter species, weighing between 3.4 kg and 4.5 kg. For these reasons, the transmitter used was small, rectangular, and flat, measuring 3.5 x 3.2 x 1.0 cm. They were implanted using a ventral midline approach to minimize contact between the skin incision and sharp-edged rocks. Surgical incisions healed within 2 wk. The transmitters functioned well, but the duration varied from 62 days to 143 days instead of the 240 days predicted by the manufacturer. All six marine otters reestablished in their home ranges, and survey results suggest they survived well beyond the life of the transmitters.

Characterization of basal seminal traits and reproductive endocrine profiles in North American river otters and Asian small‐clawed otters

In this study, fecal samples were collected from 24 North American river (NARO) and 17 Asian small-clawed otters (ASCO) for 6-36 months and semen collected seasonally from NARO males (n=4/season) via electroejaculation. Our main objectives were to: (1) characterize endocrine parameters by longitudinal monitoring of fecal hormone metabolites and (2) investigate semen collection and basal seminal traits in NARO. NARO demonstrated a distinct seasonality in the spring, with females having a monoestrual estrogen elevation lasting 15.33+/-1.98 (mean+/-SEM) days and males peaking in testosterone production for 25.50+/-7.51 days. Pregnancy was characterized by 7-9 months of basal fecal progesterone, presumably corresponding to embryonic diapause, followed by a rapid increase over the final 68-73 days to term. Pseudopregnancy exhibited a similar late winter progesterone peak of 68-72 days, which could not be differentiated from pregnancy. Geographic latitude possibly influenced the timing of increased testosterone in males and increased progesterone in pregnant/pseudopregnant females. In ASCO, monitoring of fecal estrogens did not allow consistent detection of peak values associated with behavioral estrus. Both pregnancy and pseudopregnancy were characterized by a moderate rise in fecal progesterone for 14-16 days postovulation followed by a marked increase. Total gestation length was 67-77 days compared with 62-84 days for pseudopregnancy. In NARO, optimal sperm recovery and quality occurred only in the spring, corresponding with seasonal increases in testicular volume and fecal testosterone. These findings represent the first comprehensive information on normative endocrine and seminal traits in freshwater otter species.

Gene sequences for Cytochromes p450 1A1 and 1A2: The need for biomarker Development in Sea otters ( Enhydra lutris)

There has been recent public concern regarding the impacts of environmental pollution on populations of otters. Population level impacts have been seen with otter ( Lutra lutra) populations in Europe due to polychlorinated biphenyls, and with some segments of the Prince William Sound, AK, sea otter ( Enhydra lutris) population following the Exxon Valdez oil spill. Despite public interest in these animals and their ecological significance, there are few tools that allow for the study of otter's response to contaminant exposure. Cytochrome p450 1A (CYP1A) performs the first step in metabolizing many xenobiotics, including many polychlorinated biphenyls and polycyclic aromatic hydrocarbons. CYP1A induction is a frequently used biomarker of exposure to these compounds. Despite the potential importance of this gene in ecological risk assessment, the complete coding sequence has not been published for any otter species. This study's objective was to isolate the gene for CYP1A1 and CYP1A2 in sea otters using a series of PCR-based approaches. The coding sequences from CYP1A1 and CYP1A2 from sea otters were identified and published in GenBank. Both CYP1A sequences are homologous to those obtained from marine mammals and other carnivores. These sequences will be useful as tools for researchers assessing contaminant exposure in mustelid populations.

Detailed Devotion

Detailed Devotion

New middle Pleistocene Galictini (Mustelidae, Carnivora) from the Matsugae cave deposits, northern Kyushu, West Japan

ABSTRACT In the early 20th century, Tokunaga, followed by Naora, reported a Middle Pleistocene mammalian fauna from the Matsugae limestone cave deposits in northern Kyushu, West Japan. Within this fauna Naora (1968) described a new extinct species of otter (Lutra nipponica). Recently, we have identified new, well preserved dentitions of this mustelid in their original collection. We suggest that the definition of L. nipponica given by Naora should be emended, and that the specimens belong to a new genus of the tribe Galictini (Mustelidae, Carnivora), namely, Oriensictis gen. nov., according to the following characteristics: short muzzle; transversely expanded P4; and anteroposteriorly expanded M1. The extinct Chinese otter L. melina (Pei, 1934) from the Middle Pleistocene cave deposits of Choukoutien locality 1 is also included in Oriensictis based on the characteristics of M1 and a short mandible. These two occurrences of this genus are the first records of East Asian galictines, and this suggests that t...

Evaluating bridge survey ability to detect river otter Lontra canadensis presence: a comparative study

Many researchers use bridges as search sites to monitor freshwater otter species along watercourses. Bridges enable rapid and easy access to their habitat, but for most otter species little is known on whether these anthropogenic structures affect their distribution, their marking preferences, and consequently, the ability of such surveys to detect their presence. We investigated the bridge survey method using data gathered during four winters of survey along the rivers and streams of Kouchibouguac National Park and surrounding area in New Brunswick, Canada. Our results show that sign surveys using bridges as search sites can have the same capability to detect river otter Lontra canadensis occurrences as surveys using randomly distributed sites. Future surveys can be improved by increasing search distance at bridge sites. This will increase detection rates and safeguard against results underrepresenting otter occurrence in the landscape, which could prompt unnecessary conservation actions. Researchers choosing to increase search distance are advised to augment survey efforts in order to maintain large sample sizes, ensuring sufficient statistical power for tests aiming to detect trends in river otter occurrence.

Diversity of mtDNA in Southern River Otter (Lontra provocax) from Argentinean Patagonia

Lontra provocax is an endemic species from Patagonia that has been categorized as "endangered" by the International Union for Conservation of Nature. In this study, noninvasive molecular methods were used to investigate the genetic diversity and haplotype distribution of L. provocax in Argentinean Patagonia. We analyzed 150 scat samples collected from 1995 to 2006 and obtained 13 sequences of control region with 1 haplotype and 34 sequences of cytochrome b with 4 haplotypes. The population of the south of Patagonia (Tierra del Fuego and De los Estados Island) showed a relatively high haplotype diversity (h = 0.71) and was statistically different to the population of the north (analysis of molecular variance, F(ST) = 0.15, P = 0.018). We concluded that there are 2 different subpopulations of L. provocax that deserve conservation attention and that the southern population appears not to have suffered a human-induced population bottleneck of the sort typically experienced by various otter species around the world.

Establishing the foundation for an applied molecular taxonomy of otters in Southeast Asia

Four species of otters (Mustelidae, Lutrinae) occur in Southeast Asia and are considered to be of conservation concern: Aonyx cinerea (Asian small-clawed otter), Lutra lutra (Eurasian otter), Lutra sumatrana (Hairy-nosed otter), and Lutrogale perspicillata (Smooth-coated otter). Among these, L. sumatrana is endemic to the region, yet little is known about its biology, and the precise distribution of all four species in Southeast Asia is not well known. Furthermore, the taxonomy and systematics of L. sumatrana and L. perspicillata have been the subject of controversy, which has implications for the legal protection and for conservation programs of these taxa. To resolve these controversies, we used a multigene data set comprised of segments from 13 nuclear and 5 mitochondrial loci (11,180 nucleotides) to evaluate the phylogenetic relationships of Asian Old World otters. Phylogenies were also estimated using two mitochondrial loci (1,832 nucleotides) obtained from two or more individuals of the four Southeast Asian species. The results from maximum parsimony, maximum likelihood and Bayesian inference showed that L. sumatrana and L. lutra are sister taxa, whereas L. perspicillata is sister to A. cinerea. Furthermore, the results from the two-mitochondrial gene analyses indicate that L. sumatrana is reciprocally monophyletic with respect to L. lutra, supporting the specific validity of the former taxon. Signs such as tracks and feces are often used in field surveys to provide information on the distribution and abundance of otters, but the accuracy of these methods may be compromised when several closely related species occur sympatrically. Therefore, the two-gene data set was used to develop a provisional set of diagnostic nucleotides that can be potentially used to identify the four species of Southeast Asian otters from noninvasively collected biological samples, such as feces.

Genetic diversity of the Neotropical otter (Lontra longicaudis Olfers, 1818) in Southern and Southeastern Brazil

The Neotropical otter is one of the least known otter species, and it is considered to be threatened to various degrees throughout its geographic range. Little information exists on the ecological characteristics of this species, and no genetic study has been published about it until now, hampering the design of adequate conservation strategies for its populations. To contribute with genetic information to comprehensive conservation efforts on behalf of L. longicaudis, we characterized the molecular diversity of the 5 portion of the mtDNA control region in samples from this species collected in Southern and Southeastern Brazil. The sequence analysis revealed a high level of haplotype diversity (h=0.819; SE=0.0052) and nucleotide variability ranging from 0.0039 to 0.0067. One of the sampled haplotypes was the most common in both regions and, from this sequence, several other (locally occurring) haplotypes could be derived by single point mutations. No significant genetic differentiation was observed between the Southern and Southeastern regions.

Cytogenetic study of the giant otter Pteronura brasiliensis Zimmermann 1780 (Carnivora, Mustelidae, Lutrinae)

The giant otter, Pteronura brasiliensis Zimmermann 1780 (Carnivora, Mustelidae, Lutrinae), was widely distributed in South America but stable populations are now only found in the Pantanal and Amazon regions and the species is classified as endangered. There is only one recognized species of giant otter, although two subspecies of doubtful value have also been cited in the literature. We present the first karyotype of four captive P. brasiliensis specimens, all of which posses 2n = 38 chromosomes as 14M+8SM+6ST+8A and one pair of sexual chromosomes. An heteromorphic secondary constriction, associated with the nucleolar organizer region (NOR), was seen on the long arms of chromosome pair 17. The C-banding technique revealed heterochromatin in the centromeric region of all the chromosomes and the NOR was C-banding positive. The giant otter presented the same diploid number as most mustelids, although its karyotype is quite species-specific.

Giant bunodont Lutrinae from the Mio-Pliocene of Kenya and Uganda

Three new species of bunodont otters are described from the Mio-Pliocene of East Africa. They are provisionally attributed to the genus Sivaonyx Pilgrim, 1931. The species described are Sivaonyx soriae, nov. sp. and Sivaonyx senutae nov. sp. from the Latest Miocene Lukeino Formation (Kenya) and Sivaonyx kamuhangirei nov. sp. from the Pliocene of Kazinga and Warwire (Uganda). Additional material of the species Sivaonyx ekecaman (Werdelin, 2003) is described from Sagatia, Mabaget Formation (Kenya). The systematics of the new tribe Enhydriodontini are discussed and we report the presence of evolutionary tendencies in the bunodont African otters: increase in body size, modification of the carnassial teeth. In particular in the P4/ the protocone becomes well separated from the paracone, at the same time that an anterior valley develops.

Distribution and habitat of otters (Aonyx capensis and Lutra maculicollis) in southern Nigeria

We report new data on the distribution and habitat of two otter species, Aonyx capensis and Lutra maculicollis, from southern Nigeria. Although preliminary, our investigations suggest that these two species may use the available habitat differently. Lutra maculicollis appears more linked to freshwater streams and Aonyx capensis is mainly restricted to brackish water streams (with mangrove vegetation along the banks) and, more occasionally, to transitional habitats between freshwater and brackish‐water environments. The possible reasons explaining habitat partitioning are discussed.

Testing the surveys and visual and track censuses of Eurasian otters (Lutra lutra)

AbstractAt the end of the 1970s otter surveys were developed to study the distribution of the Eurasian otter Lutra lutra. The method was quickly adopted and expanded to include other species of otter. Different methods to estimate otter density were also used. There is some uncertainty, however, as to the significance and precision of the results. Otter surveys, radio‐tracking studies and otter censuses (tracks and visual) were conducted in the same areas simultaneously. Comparison of the home ranges of otters tagged with transmitters with the results from otter surveys carried out in the same areas showed very similar otter distribution. Some 71+ of those sites examined in which only one otter lived were positive, and 97+ of those sites with two or more otters. Differences were found between different watercourses. In small or average sites with waterways, one single otter was capable of marking many kilometres so that it could be detected in most of the conventional 600 m sites (here 71+ of sites). The data obtained by radio‐tracking showed that almost all otters can be seen by experienced observers, confirming the validity of visual censuses. A high correlation was found between the number of otters seen during visual censuses and the number of otters detected by means of the length of their footprints. Using new and old tracks (2‐days‐old or more) the number of otters was overestimated.

Phylogenetic relationships of otters (Carnivora: Mustelidae) based on mitochondrial cytochrome b sequences

Otters are classified in the Lutrinae and are united by a suite of semi-aquatic adaptations that distinguish them from the rest of the Mustelidae. Past systematic studies have been based primarily on overall similarity of morphological characters but have not been concordant, with regard either to relationships within the subfamily or to the relationships of the Lutrinae to other taxa in the Mustelidae. We evaluate the relationships among nine of the 13 species of otters and their position in the Mustelidae through phylogenetic analysis of the complete nucleotide sequence of the mitochondrial cytochrome b gene. Based on the sequence data presented here, our results suggest that otters are divided into three primary clades that include: (1) the North American river, neotropical and marine otters; (2) the sea, Eurasian, spotted-necked, cape clawless and small-clawed otters; and (3) the giant otter. Furthermore, our results indicate that among sampled mustelid taxa, members of the genus Mustela are most closely related to otters. The hierarchical relationships among clades are not well resolved, particularly the monophyly of otters, largely because a pattern of short internal branches combined with long terminal branches suggests a rapid evolutionary radiation. Estimates of divergence time calibrated by the fossil record suggest that the lineages leading to the North American river, neotropical and marine otters, and the giant otter diverged before the end of the Miocene, much earlier than predicted from the fossil record.

Phylogenetic relationships of otters (Carnivora: Mustelidae) based on mitochondrial cytochrome b sequences

AbstractOtters are classified in the Lutrinae and are united by a suite of semi‐aquatic adaptations that distinguish them from the rest of the Mustelidae. Past systematic studies have been based primarily on overall similarity of morphological characters but have not been concordant, with regard either to relationships within the subfamily or to the relationships of the Lutrinae to other taxa in the Mustelidae. We evaluate the relationships among nine of the 13 species of otters and their position in the Mustelidae through phylogenetic analysis of the complete nucleotide sequence of the mitochondrial cytochrome b gene. Based on the sequence data presented here, our results suggest that otters are divided into three primary clades that include: (1) the North American river, neotropical and marine otters; (2) the sea, Eurasian, spotted‐necked, cape clawless and small‐clawed otters; and (3) the giant otter. Furthermore, our results indicate that among sampled mustelid taxa, members of the genus Mustela are most closely related to otters. The hierarchical relationships among clades are not well resolved, particularly the monophyly of otters, largely because a pattern of short internal branches combined with long terminal branches suggests a rapid evolutionary radiation. Estimates of divergence time calibrated by the fossil record suggest that the lineages leading to the North American river, neotropical and marine otters, and the giant otter diverged before the end of the Miocene, much earlier than predicted from the fossil record.

Biology and conservation of the Giant Otter Pteronura brasiliensis

The Giant Otter Pteronura brasiliensis (Zimmermann, 1780) is endemic to South America, distributed throughout the Orinoco, Amazon and La Plata River basins and numerous localities in the Guyanas. This otter is the largest member of the family Mustelidae, clearly distinguished from other South American otter species by morphological and behavioural characteristics. Large‐scale pelt hunting in the 1950s and 1960s led to the classification of the species as ‘vulnerable’ by the World Conservation Union (IUCN, 1990). Habitat degradation and destruction now present the largest threat to remaining populations. The current distribution of the Giant Otter is presented, emphasizing recent information collected in the Amazon Basin. Morphology, systematics, habitat, behaviour, diet, predation, competition, reproduction, development and physiology are discussed. New data on habitat use and preference, behaviour and diet in northern Amazônia are included, and recommendations for future conservation measures are made. Because of the decimation of the Giant Otter in its southern distribution and the habitat destruction occurring in the remainder of its range, we recommend that this species be elevated to ‘endangered’ status in the IUCN Red Data Book.

Use of Habitat, Size of Prey, and Food-Niche Relationships of Two Sympatric Otters in Southernmost Chile

In Magallanes (southernmost Chile), the marine otter Lutra felina tends to use more open and wave-exposed coastal areas, whereas L. provocax is found in more protected habitats. To investigate the hypothesis that the two species segregate habitats to avoid competition for food, we surveyed the available literature on food habits and analyzed food-niche relationships of both species of otters in Magallanes. Overlap of diet between species of otters was relatively high, and L. provocax tended to have a narrower diet than L. felina . Both species consumed prey of similar size. These findings are consistent with the use of different habitats to avoid competition for food resources. However, alternate models, including habitat segregation resulting from differential abilities of the two species at catching prey in more wave-exposed habitats, deserve some attention. Our analysis also revealed that niche breadth and size of prey taken by L. felina at three sites along the Chilean coast were relatively similar. At Chiloe, however, L. felina exhibited the narrowest diet and consumed the largest prey. Although such a difference might be related to variation in abundance of prey among localities, it may also have resulted from the relatively small sample available for Chiloe.

Habitat use by <em>Aonyx capensis</em> and <em>Lutra maculicollis</em> in the Natal Drakensberg (South Africa): preliminary results

Habitat prcfercncc of two sympatric otter species (Aonyx capensis and Lutra muculicollis) was defined recording sprainting sites along the banks of three rivers. The use of the riverine habitats was similar between the otter species and stretches of river characterized by emerging rocks, either covered or uncovered by vegetation, were particularly selected. Nevertheless, the sprainting sites of both species were located where dense vegetation cover occurred in the surrounding of the site (within 2 m radius).

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.