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Nancy J Thomas - One of the best experts on this subject based on the ideXlab platform.
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CANINE DISTEMPER VIRUS IN THE SEA OTTER (Enhydra lutris) POPULATION IN WASHINGTON STATE, USA.
Journal of wildlife diseases, 2020Co-Authors: Nancy J Thomas, C. Leann White, Jeremiah T. Saliki, Krysten L. Schuler, Deanna Lynch, Ole Nielsen, Jitender P. Dubey, Susan KnowlesAbstract:Before 2001, all serosurveys for morbilliviruses in sea otters (Enhydra lutris) in California, Washington, and Alaska, USA, documented a 0% seroprevalence. The first published serologic detections of morbillivirus in sea otters occurred in 2001-02 in live-captured Washington sea otters, with a documented 80% seroprevalence. We conducted a retrospective study of sea otter cases from 1989 to 2010 compiled at the US Geological Survey, National Wildlife Health Center to identify cases of morbilliviral disease in Washington sea otters and to characterize the disease using immunohistochemistry, reverse transcription (RT)-PCR, genetic sequencing, virus isolation, and serology. We identified six cases of morbilliviral disease and 12 cases of morbilliviral infection in this population of sea otters during 2000-10. Significant histologic findings included inflammation in the white and gray matter of the brain characterized by lymphoplasmacytic perivascular cuffing, neuronal necrosis, and satellitosis in gray matter and by spongiosis, myelin degeneration, spheroids, and gemistocytes in white matter. Intranuclear and intracytoplasmic viral inclusion bodies were found in neurons, Purkinje cells, and glia. Immunohistochemistry for canine distemper virus (CDV) showed positive staining in neurons, glial cells, and cell processes. A pan-morbillivirus RT-PCR with subsequent restriction endonuclease digestion or sequencing identified CDV. Virus isolation was not successful. Two sea otters with morbilliviral encephalitis showed greater antibody titers to CDV than phocine distemper virus. Histologic changes were confined to the central nervous system and resembled neurologic canine distemper in domestic dogs. Cases of sea otters with morbilliviral infection without histologic changes could represent early infections or incompletely cleared sublethal infections. We found that morbillivirus was present in the Washington sea otter population as early as 2000, and we provide a description of the pathology of canine distemper in sea otters.
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Leptospirosis in Northern Sea Otters (Enhydra lutris kenyoni) from Washington, USA.
Journal of wildlife diseases, 2019Co-Authors: Susan Knowles, Deanna Lynch, Nancy J ThomasAbstract:We diagnosed leptospirosis in six northern sea otters (Enhydra lutris kenyoni) that stranded on beaches in Washington State, US in 2002. Significant gross findings included cyanotic oral mucous membranes, renal swelling, congestion or pale streaks on the cut surface of renal lobules, hematuria, dehydration, lymphadenopathy, pulmonary congestion, and rarely adrenal hemorrhage and congestion. Histopathology showed lymphoplasmacytic tubulointerstitial nephritis with intraluminal spirochetes and immunoreactivity to leptospiral antigens in the renal tubules and interstitium. A quantitative polymerase chain reaction (qPCR) using kidney or urine for the leptospiral lipL32 gene was positive with cycle threshold values indicative of abundant or moderate amounts of nucleic acid. A microscopic agglutination test showed the highest serum antibody titer to serovar Pomona and positive titers to serovars Autumnalis, Bratislava, Hebdomadis, Grippotyphosa, Icterohaemorrhagiae, Pyrogenes, Ballum, Canicola, and Hardjo. Although antibodies to Leptospira interrogans have been previously detected in sea otters, this report describes the pathology of leptospirosis in diseased free-ranging sea otters.
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MORTALITY TRENDS IN NORTHERN SEA OTTERS (Enhydra lutris KENYONI) COLLECTED FROM THE COASTS OF WASHINGTON AND OREGON, USA (2002–15)
Journal of wildlife diseases, 2017Co-Authors: C. Leann White, Krysten L. Schuler, Deanna Lynch, Jitender P. Dubey, Susan Knowles, Emily W. Lankau, Valerie I. Shearn-bochsler, Marcos Isidoro-ayza, Nancy J ThomasAbstract:Abstract: During 2002−15 we examined the causes of mortality in a population of northern sea otters (Enhydra lutris kenyoni). Beachcast sea otters were collected primarily from the US coast of Washington. Although there are no permanent sea otter residents in Oregon, several beachcast otters were collected from the Oregon coast. Infectious diseases were the primary cause of death (56%) for otters we examined. Sarcocystosis was the leading infectious cause of death (54%) and was observed throughout the study period. Some infectious diseases, such as morbilliviral encephalitis and leptospirosis, were documented for a limited number of years and then not detected again despite continued testing for these pathogens in necropsied animals. Trauma was the second most common cause of death (14%) during the study period. The continued stable growth of the Washington population of otters suggests they are able to tolerate current mortality rates.
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pathogen exposure and blood chemistry in the washington usa population of northern sea otters Enhydra lutris kenyoni
Journal of Wildlife Diseases, 2013Co-Authors: Leann C White, Nancy J Thomas, Jeremiah T. Saliki, Krysten L. Schuler, J P Dubey, Julie L Webb, Elizabeth R FrameAbstract:Abstract Northern sea otters (Enhydra lutris kenyoni) from Washington State, United States were evaluated in 2011 to determine health status and pathogen exposure. Antibodies to Brucella spp. (10%) and influenza A virus (23%) were detected for the first time in this population in 2011. Changes in clinical pathology values (serum chemistries), exposure to pathogens, and overall health of the population over the last decade were assessed by comparing 2011 data to the data collected on this population in 2001–2002. Several serum chemistry parameters were different between study years and sexes but were not clinically significant. The odds of canine distemper virus exposure were higher for otters sampled in 2001–2002 (80%) compared to 2011 (10%); likelihood of exposure significantly increased with age. Prevalence of exposure to Sarcocystis neurona was also higher in 2001–2002 (29%) than in 2011 (0%), but because testing methods varied between study years the results were not directly comparable. Exposure to L...
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osteosarcoma of the maxilla with concurrent osteoma in a southern sea otter Enhydra lutris nereis
Journal of Comparative Pathology, 2012Co-Authors: Rodriguezramos J Fernandez, Nancy J Thomas, Richard R Dubielzig, Randi DreesAbstract:Summary Southern sea otters ( Enhydra lutris nereis ) are threatened marine mammals that belong to the family Mustelidae and are native to the coast of Central California. Neoplasia is reported infrequently in sea otters. An adult female free-ranging southern sea otter was found alive at Pebble Beach, Monterey County, California, on January 1st, 1994 and died soon after capture. The carcass was submitted to the US Geological Survey – National Wildlife Health Center for necropsy examination. Grossly, a mass with rubbery texture was firmly attached to the left maxillary region of the skull and the nasopharynx was occluded by soft neoplastic tissue. Post-mortem skull radiographs showed an oval, smoothly marginated mineralized opaque mass centered on the left maxilla, extending from the canine tooth to caudal to the molar and replacing portions of the zygomatic arch and palatine and temporal bones. The majority of the mass protruded laterally from the maxilla and was characterized by central homogeneous mineral opacity. Microscopically, the mass was characterized by fully differentiated lamellar non-osteonal bone that expanded beyond the margins of the adjacent normal osteonal bone. Sections of the nasopharyngeal mass were comprised of moderately pleomorphic cells with bony stroma. Gross, microscopical and radiological findings were compatible with maxillary osteosarcoma with concurrent osteoma.
J P Dubey - One of the best experts on this subject based on the ideXlab platform.
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pathogen exposure and blood chemistry in the washington usa population of northern sea otters Enhydra lutris kenyoni
Journal of Wildlife Diseases, 2013Co-Authors: Leann C White, Nancy J Thomas, Jeremiah T. Saliki, Krysten L. Schuler, J P Dubey, Julie L Webb, Elizabeth R FrameAbstract:Abstract Northern sea otters (Enhydra lutris kenyoni) from Washington State, United States were evaluated in 2011 to determine health status and pathogen exposure. Antibodies to Brucella spp. (10%) and influenza A virus (23%) were detected for the first time in this population in 2011. Changes in clinical pathology values (serum chemistries), exposure to pathogens, and overall health of the population over the last decade were assessed by comparing 2011 data to the data collected on this population in 2001–2002. Several serum chemistry parameters were different between study years and sexes but were not clinically significant. The odds of canine distemper virus exposure were higher for otters sampled in 2001–2002 (80%) compared to 2011 (10%); likelihood of exposure significantly increased with age. Prevalence of exposure to Sarcocystis neurona was also higher in 2001–2002 (29%) than in 2011 (0%), but because testing methods varied between study years the results were not directly comparable. Exposure to L...
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sarcocystis neurona retinochoroiditis in a sea otter Enhydra lutris kenyoni
Veterinary Parasitology, 2011Co-Authors: J P Dubey, Nancy J ThomasAbstract:Sarcocystis neurona is an important cause of fatal disease in sea otters in the USA. Encephalitis is the predominant lesion and parasites are confined to the central nervous system and muscles. Here we report retinochoroiditis in a sea otter (Enhydra lutris kenyoni) found dead on Copalis Beach, WA, USA. Salient lesions were confined to the brain and eye. Multifocal nonsuppurative meningoencephalitis was present in the cerebrum and cerebellum associated with S. neurona schizonts. The retina of one eye had a focus of inflammation that contained numerous S. neurona schizonts and merozoites. The focus extended from the retinal pigment epithelium inward through all layers of the retina, but inflammation was most concentrated at the inner surface of the tapetum and the outer retina. The inner and outer nuclear layers of the retina were disorganized and irregular at the site of inflammation. There was severe congestion and mild hemorrhage in the choroid, and mild hemorrhage into the vitreous body. Immunohistochemistry with S. neurona-specific polyclonal rabbit antibodies stained schizonts and merozoites. To our knowledge this is the first report of S. neurona-associated retinochoroiditis in any naturally infected animal.
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sarcocystis neurona infections in sea otter Enhydra lutris evidence for natural infections with sarcocysts and transmission of infection to opossums didelphis virginiana
Journal of Parasitology, 2001Co-Authors: J P Dubey, Nancy J Thomas, David S Lindsay, Alexa C Rosypal, Benjamin M. Rosenthal, J F Stanek, S M Reed, W J A SavilleAbstract:Although Sarcocystis neurona has been identified in an array of terrestrial vertebrates, recent recognition of its capacity to infect marine mammals was unexpected. Here, sarcocysts from 2 naturally infected sea otters (Enhydra lutris) were characterized biologically, ultrastructurally, and genetically. DNA was extracted from frozen muscle of the first of these sea otters and was characterized as S. neurona by polymerase chain reation (PCR) amplification followed by restriction fragment length polymorphism analysis and sequencing. Sarcocysts from sea otter no. 1 were up to 350 μm long, and the villar protrusions on the sarcocyst wall were up to 1.3 μm long and up to 0.25 μm wide. The villar protrusions were tapered towards the villar tip. Ultrastructurally, sarcocysts were similar to S. neurona sarcocysts from the muscles of cats experimentally infected with S. neurona sporocysts. Skeletal muscles from a second sea otter failed to support PCR amplification of markers considered diagnostic for S. neurona b...
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biological characterisation of sarcocystis neurona isolated from a southern sea otter Enhydra lutris nereis
International Journal for Parasitology, 2000Co-Authors: David S Lindsay, Nancy J Thomas, J P DubeyAbstract:Sarcocystis neurona was isolated from the brain of a juvenile, male southern sea otter (Enhydra lutris nereis) suffering from CNS disease. Schizonts and merozoites in tissue sections of the otter’s brain reacted with anti-S. neurona antiserum immunohistochemically. Development in cell culture was by endopolyogeny and mature schizonts were first observed at 3 days postinoculation. PCR of merozoite DNA using primer pairs JNB33/JNB54 and restriction enzyme digestion of the 1100 bp product with Dra I indicated the organism was S. neurona. Four of four interferon-γ gene knockout mice inoculated with merozoites developed S. neurona-associated encephalitis. Antibodies to S. neurona but not Sarcocystis falcatula, Toxoplasma gondii, or Neospora caninum were present in the serum of inoculated mice. This is the first isolation of S. neurona from the brain of a non-equine host.
Melissa A. Miller - One of the best experts on this subject based on the ideXlab platform.
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Mycoplasma Enhydrae sp. nov. isolated from southern sea otters (Enhydra lutris nereis).
International journal of systematic and evolutionary microbiology, 2018Co-Authors: Dmitriy V. Volokhov, Melissa A. Miller, Francesca Batac, Yamei Gao, Vladimir E. ChizhikovAbstract:Five Mycoplasma strains have been isolated from the oropharynx of southern sea otters (Enhydra lutris nereis) from the Central California Coast, USA. These strains were phenotypically and genetically characterized and compared to other established Mycoplasma species. All five strains hydrolysed arginine but not urea, but did not produce acid from glucose, and all were isolated and propagated under anaerobic and aerobic atmospheric conditions at +35–37 ˚C using either SP4 or PPLO medium supplemented with arginine. Colonies on solid medium showed a typical fried-egg appearance and transmission electron microscopy revealed a typical mycoplasma cellular morphology. Molecular characterization included assessment of the following genetic loci: 16S rRNA, 16S–23S rRNA ITS, rpoB, rpoC, polC, topIIA, tufB, arcA and smc. Complete 16S rRNA gene sequence analysis indicated that these strains were most closely related to Mycoplasma phocicerebrale , and to Mycoplasma arginini , Mycoplasma gateae and Mycoplasma canadense with nucleotide similarities of 99 and 98 %, respectively. Nucleotide analysis of other genetic loci revealed 73–91 % nucleotide similarity to the corresponding genes of the above closely related species. All five strains clustered into a distinct group on the 16S rRNA and rpoB phylogenetic trees. Serological testing via growth inhibition and metabolic inhibition tests employing antiserum to type strains of M. phocicerebrale , M. arginini , M. gateae and M. canadense failed to recognize these novel strains. Our results suggest that the strains isolated from southern sea otters represent a novel species of the genus Mycoplasma , for which the name Mycoplasma Enhydrae sp. nov. is proposed; the type strain is 6243-11T (=DSM 106704T=ATCC TSD-140T).
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first report of an adult tapeworm cestoda diphyllobothriidea in a southern sea otter Enhydra lutris nereis
Journal of Wildlife Diseases, 2017Co-Authors: Colleen Young, Melissa A. Miller, Roman Kuchta, Jan Brabec, Seth D Newsome, Murray D DaileyAbstract:We present a novel case of an intestinal cestode infection in a southern sea otter (Enhydra lutris nereis). The cestode species Diphyllobothrium tetrapterum (syn. Diplogonoporus tetrapterus) was confirmed genetically. Stable isotope analysis of whiskers collected from the sea otter did not confirm the consumption of fish as the route of exposure.
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Serologic Detection of Subtype-specific Antibodies to Influenza A Viruses in Southern Sea Otters (Enhydra lutris Nereis)
Journal of wildlife diseases, 2017Co-Authors: Alyssa M. Capuano, Melissa A. Miller, Erin Dodd, Francesca Batac, David E. Stallknecht, Megan E. Moriarty, Magdalena Plancarte, Walter M. BoyceAbstract:Abstract There are approximately 3,000 southern sea otters (Enhydra lutris nereis) in the nearshore environment along the California coast, US, and the species is classified as Threatened under the Endangered Species Act. We tested sera from 661 necropsied southern sea otters sampled from 1997 to 2015 to determine overall exposure to influenza A viruses (IAVs) and to identify subtype-specific antibody responses. Using an enzyme-linked immunosorbent assay (ELISA), antibodies to IAV nucleoproteins were detected in 160 (24.2%) otters, with seropositive animals found in every year except 2008. When the ELISA-positive samples were tested by virus microneutralization, antibody responses were detected to avian-origin hemagglutinin subtypes H1, H3, H4, H5, H6, H7, H9, and H11. Strong antibody responses to pandemic H1N1 (pdmH1N1) were also detected, indicating that epizootic transmission of pdmH1N1 occurred among the southern sea otter population after the emergence of this human-origin virus in 2009. We conclude ...
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isolation and characterization of marine brucella from a southern sea otter Enhydra lutris nereis california usa
Journal of Wildlife Diseases, 2017Co-Authors: Michael J. Murray, Melissa A. Miller, Erin Dodd, Spencer S Jang, Tristan L. Burgess, Barbara A. Byrne, Jack C Rhyan, Frances M D Gulland, Sharon ToychoutkaAbstract:Abstract We characterize Brucella infection in a wild southern sea otter (Enhydra lutris nereis) with osteolytic lesions similar to those reported in other marine mammals and humans. This otter stranded twice along the central California coast, US over a 1-yr period and was handled extensively at two wildlife rehabilitation facilities, undergoing multiple surgeries and months of postsurgical care. Ultimately the otter was euthanized due to severe, progressive neurologic disease. Necropsy and postmortem radiographs revealed chronic, severe osteoarthritis spanning the proximal interphalangeal joint of the left hind fifth digit. Numerous coccobacilli within the joint were strongly positive on Brucella immunohistochemical labelling, and Brucella sp. was isolated in pure culture from this lesion. Sparse Brucella-immunopositive bacteria were also observed in the cytoplasm of a pulmonary vascular monocyte, and multifocal granulomas were observed in the spinal cord and liver on histopathology. Findings from bioch...
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endemic infection of stranded southern sea otters Enhydra lutris nereis with novel parvovirus polyomavirus and adenovirus
Journal of Wildlife Diseases, 2017Co-Authors: Juliana D Siqueira, Melissa A. Miller, Erin Dodd, Francesca Batac, Xutao Deng, Eric DelwartAbstract:Abstract Over the past century, the southern sea otter (SSO; Enhydra lutris nereis) population has been slowly recovering from near extinction due to overharvest. The SSO is a threatened subspecies under federal law and a fully protected species under California law, US. Through a multiagency collaborative program, stranded animals are rehabilitated and released, while deceased animals are necropsied and tissues are cryopreserved to facilitate scientific study. Here, we processed archival tissues to enrich particle-associated viral nucleic acids, which we randomly amplified and deeply sequenced to identify viral genomes through sequence similarities. Anelloviruses and endogenous retroviral sequences made up over 50% of observed viral sequences. Polyomavirus, parvovirus, and adenovirus sequences made up most of the remaining reads. We characterized and phylogenetically analyzed the full genome of sea otter polyomavirus 1 and the complete coding sequence of sea otter parvovirus 1 and found that the closest ...
James L. Bodkin - One of the best experts on this subject based on the ideXlab platform.
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effects of wildfire on sea otter Enhydra lutris gene transcript profiles
Marine Mammal Science, 2015Co-Authors: Lizabeth Bowen, James L. Bodkin, Michael J. Murray, Keith A Miles, Crystal A Kolden, Justin A Saarinen, Tim M TinkerAbstract:Wildfires have been shown to impact terrestrial species over a range of temporal scales. Little is known, however, about the more subtle toxicological effects of wildfires, particularly in downstream marine or downwind locations from the wildfire perimeter. These down-current effects may be just as substantial as those effects within the perimeter. We used gene transcription technology, a sensitive indicator of immunological perturbation, to study the effects of the 2008 Basin Complex Fire on the California coast on a sentinel marine species, the sea otter (Enhydra lutris). We captured sea otters in 2008 (3 mo after the Basin Complex Fire was controlled) and 2009 (15 mo after the Basin Complex Fire was controlled) in the adjacent nearshore environment near Big Sur, California. Gene responses were distinctly different between Big Sur temporal groups, signifying detoxification of PAHs, possible associated response to potential malignant transformation, and suppression of immune function as the primary responses of sea otters to fire in 2008 compared to those captured in 2009. In general, gene transcription patterns in the 2008 sea otters were indicative of molecular reactions to organic exposure, malignant transformation, and decreased ability to respond to pathogens that seemed to consistent with short-term hydrocarbon exposure.
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Gene transcription in sea otters (Enhydra lutris); development of a diagnostic tool for sea otter and ecosystem health.
Molecular ecology resources, 2011Co-Authors: Lizabeth Bowen, B E Ballachey, James L. Bodkin, Michael J. Murray, Martin Haulena, A. Keith Miles, Judy Tuttle, William Van Bonn, Lance Adams, James A. EstesAbstract:Gene transcription analysis for diagnosing or monitoring wildlife health requires the ability to distinguish pathophysiological change from natural variation. Herein, we describe methodology for the development of quantitative real-time polymerase chain reaction (qPCR) assays to measure differential transcript levels of multiple immune function genes in the sea otter (Enhydra lutris); sea otter-specific qPCR primer sequences for the genes of interest are defined. We establish a ‘reference’ range of transcripts for each gene in a group of clinically healthy captive and free-ranging sea otters. The 10 genes of interest represent multiple physiological systems that play a role in immuno-modulation, inflammation, cell protection, tumour suppression, cellular stress response, xenobiotic metabolizing enzymes, antioxidant enzymes and cell‐cell adhesion. The cycle threshold (CT) measures for most genes were normally distributed; the complement cytolysis inhibitor was the exception. The relative enumeration of multiple gene transcripts in simple peripheral blood samples expands the diagnostic capability currently available to assess the health of sea otters in situ and provides a better understanding of the state of their environment.
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PHENOTYPIC PLASTICITY IN AGE AT FIRST REPRODUCTION OF FEMALE NORTHERN SEA OTTERS (Enhydra lutris KENYONI)
Journal of Mammalogy, 2009Co-Authors: Vanessa R. Von Biela, James L. Bodkin, Verena A Gill, Jennifer M. BurnsAbstract:Life-history theory predicts that within a species, reproduction and survival rates will differ among populations that differ in resource availability or predation rates through phenotypic plasticity. When populations are near carrying capacity (K) or when they are declining due to reduced prey resources, the average age at 1st reproduction (average AFR) is predicted to be older than in populations below K. Differences between the trajectories of northern sea otter (Enhydra lutris kenyoni) populations in Alaska provides an opportunity to examine phenotypic plasticity. Using premolar teeth or reproductive tracts, we estimated average AFR from demographically distinct populations of sea otters in Alaska. We obtained samples from 2 populations near K, Prince William Sound (PWS) and the Aleutian Archipelago (archived samples), and from 2 populations below K, the Kodiak Archipelago and Sitka. The average AFR was lower in populations below K (3.60 years 6 0.16 SD) compared to those near K (4.21 6 0.13 years, P , 0.001), and differed among all populations, with the Aleutian population possessing the oldest average AFR (4.29 6 0.09 years) followed by PWS (4.05 6 0.24 years), Sitka (3.80 6 0.21 years), and Kodiak (3.19 6 0.37 years). The difference in average AFR among populations supports life-history theory and provides evidence of phenotypic plasticity in sea otters. Our findings highlight the value of using average AFR as a tool for monitoring mammalian populations.
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microsatellite dna and mitochondrial dna variation in remnant and translocated sea otter Enhydra lutris populations
Journal of Mammalogy, 2002Co-Authors: Shawn Larson, James L. Bodkin, Ronald J. Jameson, Michelle M. Staedler, Paul BentzenAbstract:All existing sea otter (Enhydra lutris) populations have suffered at least 1, and in some cases 2, population bottlenecks. The 1st occurred during the 18th and 19th centuries as a result of commercial hunting that eliminated sea otters from much their native range and reduced surviving populations to small remnants. The 2nd bottleneck occurred when small numbers of otters were reintroduced, via translocation, to areas where the species had been eliminated. We examined genetic variation at 7 microsatellite loci and the mitochondrial DNA (mtDNA) control region in 3 remnant populations, Amchitka Island (Aleutian Islands, Alaska), central coastal California, and Prince William Sound (Alaska), and in 2 reintroduced populations, southeast Alaska and Washington, that were founded with transplants from Amchitka, and in the case of southeast Alaska, individuals from Prince William Sound as well. We found no evidence of reduced genetic diversity in translocated populations. Average expected microsatellite heterozygosities (H E) were similar in all populations (range, 0.40‐0.47), and mtDNA haplotype diversities were higher in reintroduced populations (0.51 for both Washington and southeast Alaska) than in remnant populations (X ¯ 5 0.35; range, 0.18‐0.45). The levels of genetic diversity we observed within sea otter populations were relatively low when compared with other mammals and are thought to be the result of fur trade exploitation.
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STOCK STRUCTURE OF SEA OTTERS (Enhydra lutris KENYONI) IN ALASKA
Marine Mammal Science, 2001Co-Authors: C.s. Gorbics, James L. BodkinAbstract:Sea otters in Alaska are recognized as a single subspecies (Enhydra lutris kenyoni) and currently managed as a single, interbreeding population. However, geographic and behavioral mechanisms undoubrably constrain sea otter movements on much smaller scales. This paper applies the phylogeographic method (Dizon et al. 1992) and considers distribution, population response, phenotype and genotype data to identify stocks of sea otters within Alaska. The evidence for separate stock identity is genotypic (all stocks), phenotypic (Southcentral and Southwest stocks), and geographic distribution (Southeast stock), whereas population response data are equivocal (all stocks). Differences in genotype frequencies and the presence of unique genotypes among areas indicate restricted gene flow. Genetic exchange may be limited by little or no movement across proposed stock boundaries and discontinuities in distribution at proposed stock boundaries. Skull size differences (phenotypic) between Southwest and Southcentral Alaska populations further support stock separation. Population response information was equivocal in either supporting or refuting stock identity. On the basis of this review, we suggest the following: (1) a Southeast stock extending from Dixon Entrance to Cape Yakataga; (2) a Southcentral stock extending from Cape Yakataga to Cape Douglas including Prince William Sound and Kenai peninsula coast; and (3) a Southwest stock including Alaska Peninsula coast, the Aleutians to Attu Island, Barren, Kodiak, Pribilof Islands, and Bristol Bay.
Shawn Larson - One of the best experts on this subject based on the ideXlab platform.
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Genetic Diversity and Population Parameters of Sea Otters, Enhydra lutris, before Fur Trade Extirpation from 1741–1911
2016Co-Authors: Shawn Larson, Ron Jameson, Michael Etnier, Terry Jones, Roberta HallAbstract:All existing sea otter, Enhydra lutris, populations have suffered at least one historic population bottleneck stemming from the fur trade extirpations of the eighteenth and nineteenth centuries. We examined genetic variation, gene flow, and population structure at five microsatellite loci in samples from five pre-fur trade populations throughout the sea otter’s historical range: California, Oregon, Washington, Alaska, and Russia. We then compared those values to genetic diversity and population structure found within five modern sea otter populations throughout their current range: California, Prince William Sound, Amchitka Island, Southeast Alaska and Washington. We found twice the genetic diversity in the pre-fur trade populations when compared to modern sea otters, a level of diversity that was similar to levels that are found in other mammal populations that have not experienced population bottlenecks. Even with the significant loss in genetic diversity modern sea otters have retained historical structure. There was greater gene flow before extirpation than that found among modern sea otter populations but the difference was not statistically significant. The most dramatic effect of pre fur trade population extirpation was the loss of genetic diversity. For long term conservation of these populations increasing gen
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stress related hormones and genetic diversity in sea otters Enhydra lutris
Marine Mammal Science, 2009Co-Authors: Shawn Larson, Ronald J. Jameson, Daniel H. Monson, Brenda E. Ballachey, Samuel K. WasserAbstract:Sea otters (Enhydra lutris) once ranged throughout the coastal regions of the north Pacific, but were extirpated throughout their range during the fur trade of the 18th and 19th centuries, leaving only small, widely scattered, remnant populations. All extant sea otter populations are believed to have experienced a population bottleneck and thus have lost genetic variation. Populations that undergo severe population reduction and associated inbreeding may suffer from a general reduction in fitness termed inbreeding depression. Inbreeding depression may result in decreased testosterone levels in males, and reduced ability to respond to stressful stimuli associated with an increase in the stress-related adrenal glucocorticoid hormones, cortisol and corticosterone. We investigated correlations of testosterone, cortisol, and corticosterone with genetic diversity in sea otters from five populations. We found a significant negative correlation between genetic diversity and both mean population-level (r 2 = 0.27, P < 0.001) and individual-level (r 2 = 0.54, P < 0.001) corticosterone values, as well as a negative correlation between genetic diversity and cortisol at the individual level (r 2 = 0.17, P = 0.04). No relationship was found between genetic diversity and testosterone (P = 0.57). The strength of the correlations, especially with corticosterone, suggests potential negative consequences for overall population health, particularly for populations with the lowest genetic diversity.
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Stress‐related hormones and genetic diversity in sea otters (Enhydra lutris)
Marine Mammal Science, 2009Co-Authors: Shawn Larson, Ronald J. Jameson, Daniel H. Monson, Brenda E. Ballachey, Samuel K. WasserAbstract:Sea otters (Enhydra lutris) once ranged throughout the coastal regions of the north Pacific, but were extirpated throughout their range during the fur trade of the 18th and 19th centuries, leaving only small, widely scattered, remnant populations. All extant sea otter populations are believed to have experienced a population bottleneck and thus have lost genetic variation. Populations that undergo severe population reduction and associated inbreeding may suffer from a general reduction in fitness termed inbreeding depression. Inbreeding depression may result in decreased testosterone levels in males, and reduced ability to respond to stressful stimuli associated with an increase in the stress-related adrenal glucocorticoid hormones, cortisol and corticosterone. We investigated correlations of testosterone, cortisol, and corticosterone with genetic diversity in sea otters from five populations. We found a significant negative correlation between genetic diversity and both mean population-level (r 2 = 0.27, P < 0.001) and individual-level (r 2 = 0.54, P < 0.001) corticosterone values, as well as a negative correlation between genetic diversity and cortisol at the individual level (r 2 = 0.17, P = 0.04). No relationship was found between genetic diversity and testosterone (P = 0.57). The strength of the correlations, especially with corticosterone, suggests potential negative consequences for overall population health, particularly for populations with the lowest genetic diversity.
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microsatellite dna and mitochondrial dna variation in remnant and translocated sea otter Enhydra lutris populations
Journal of Mammalogy, 2002Co-Authors: Shawn Larson, James L. Bodkin, Ronald J. Jameson, Michelle M. Staedler, Paul BentzenAbstract:All existing sea otter (Enhydra lutris) populations have suffered at least 1, and in some cases 2, population bottlenecks. The 1st occurred during the 18th and 19th centuries as a result of commercial hunting that eliminated sea otters from much their native range and reduced surviving populations to small remnants. The 2nd bottleneck occurred when small numbers of otters were reintroduced, via translocation, to areas where the species had been eliminated. We examined genetic variation at 7 microsatellite loci and the mitochondrial DNA (mtDNA) control region in 3 remnant populations, Amchitka Island (Aleutian Islands, Alaska), central coastal California, and Prince William Sound (Alaska), and in 2 reintroduced populations, southeast Alaska and Washington, that were founded with transplants from Amchitka, and in the case of southeast Alaska, individuals from Prince William Sound as well. We found no evidence of reduced genetic diversity in translocated populations. Average expected microsatellite heterozygosities (H E) were similar in all populations (range, 0.40‐0.47), and mtDNA haplotype diversities were higher in reintroduced populations (0.51 for both Washington and southeast Alaska) than in remnant populations (X ¯ 5 0.35; range, 0.18‐0.45). The levels of genetic diversity we observed within sea otter populations were relatively low when compared with other mammals and are thought to be the result of fur trade exploitation.
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Loss of genetic diversity in sea otters (Enhydra lutris) associated with the fur trade of the 18th and 19th centuries.
Molecular ecology, 2002Co-Authors: Shawn Larson, Ronald J. Jameson, Michael A. Etnier, Melissa A. Fleming, Paul BentzenAbstract:Sea otter ( Enhydra lutris ) populations experienced widespread reduction and extirpation due to the fur trade of the 18th and 19th centuries. We examined genetic variation within four microsatellite markers and the mitochondrial DNA (mtDNA) D -loop in one prefur trade population and compared it to five modern populations to determine potential losses in genetic variation. While mtDNA sequence variability was low within both modern and extinct populations, analysis of microsatellite allelic data revealed that the prefur trade population had significantly more variation than all the extant sea otter populations. Reduced genetic variation may lead to inbreeding depression and we believe sea otter populations should be closely monitored for potential associated negative effects.