MOLECULAR AND MORPHOMETRIC EVIDENCE FOR SEPARATE SPECIES OFUNCINARIA(NEMATODA: ANCYLOSTOMATIDAE) IN CALIFORNIA SEA LIONS AND NORTHERN FUR SEALS: HYPOTHESIS TESTING SUPPLANTS VERIFICATION

AbstractPractitioners of nematode taxonomy have rarely been explicit about what species represent or how data are being used to delimit species prior to their description. This lack of explicitness reflects the broader species problem common to all biology: there is no universally accepted idea of what species are and, as a consequence, scientists disagree on how to go about finding species in nature. However, like other biologists, nematologists seem to agree that species are real and discrete units in nature, and that they result from descent with modification. This evolutionary perspective provides a conceptual framework for nematologists to view species as independent evolutionary lineages, and provides approaches for their delimitation. Specifically, species may be delimited scientifically by methods that can test the hypothesis of lineage independence. For sequence data, such hypothesis testing should be based on sampling many individual organisms for multiple loci to avoid mistaking tokogeny and gene trees as evidence of species. Evolutionary approaches to analysing data and delimiting species avoid the inherent pitfalls in approaches that use all observed sequence differences to define species through calculation of a genetic distance. To illustrate evolutionary species delimitation, molecular data are used to test the hypothesis that hookworms parasitic in northern fur seals and in California sea lions represent separate species. The advantages and potential caveats of employing nucleotide sequence data for species delimitation are discussed, and the merits of evolutionary approaches are contrasted to inherent problems in similarity-based methods.

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Parasitological examination of northern elephant seal (Mirounga angustirostris) pups for presence of hookworms (Uncinaria spp.) on San Miguel Island, California

Helminthologia ◽

10.1515/helmin-2016-0009 ◽

2016 ◽

Vol 53 (2) ◽

pp. 191-194

Author(s):

E. T. Lyons ◽

T. A. Kuzmina ◽

T. R. Spraker ◽

R. L. Delong

Keyword(s):

Elephant Seal ◽

Mirounga Angustirostris ◽

California Sea Lions ◽

Northern Elephant Seal ◽

Parasitological Examination ◽

Sea Lions ◽

Fur Seals ◽

Third Stage ◽

Northern Fur Seals ◽

San Miguel Island

SummaryNecropsy and extensive parasitological examination of dead northern elephant seal (NES) pups was done on San Miguel Island, California, in February, 2015. The main interest in the current study was to determine if hookworms were present in NESs on San Miguel Island where two hookworm species of the genus Uncinaria are known to be present - Uncinaria lyonsi in California sea lions and Uncinaria lucasi in northern fur seals. Hookworms were not detected in any of the NESs examined: stomachs or intestines of 16 pups, blubber of 13 pups and blubber of one bull. The results obtained in the present study of NESs on San Miguel Island plus similar finding on Año Nuevo State Reserve and The Marine Mammal Center provide strong indication that NES are not appropriate hosts for Uncinaria spp. Hookworm free-living third stage larvae, developed from eggs of California sea lions and northern fur seals, were recovered from sand. It seems that at this time, further search for hookworms in NESs would be nonproductive.

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Foraging characteristics of female northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus)

Canadian Journal of Zoology ◽

10.1139/z90-022 ◽

1990 ◽

Vol 68 (1) ◽

pp. 150-158 ◽

Cited By ~ 32

Author(s):

George A. Antonelis ◽

Brent S. Stewart ◽

Wayne F. Perryman

Keyword(s):

Water Depth ◽

Zalophus Californianus ◽

Callorhinus Ursinus ◽

California Sea Lions ◽

Merluccius Productus ◽

Sea Lions ◽

Fur Seals ◽

Northern Fur Seals ◽

San Miguel Island ◽

Northern Anchovy

The foraging characteristics of northern fur seals (Callorhinus ursinus) and California sea lions (Zalophus californianus) from San Miguel Island, California, were studied during the 1985 summer breeding season. A radio transmitter was attached to 25 postpartum females of each species and used to determine their locations at sea and the frequency and duration of their feeding trips. Northern fur seals usually foraged in the oceanic zone where the mean water depth was 933 m (n = 12). California sea lions principally were found in the neritic zone, where water depth averaged 323 m (n = 9). Most fur seals (92%) were found northwest of San Miguel Island, whereas the sea lions were commonly found to the northwest (55%) or in areas south (22%) of the island. Although both species evidently foraged at similar distances from the island, foraging trips of fur seals [Formula: see text] were over twice as long as those of sea lions [Formula: see text]. Fur seals were ashore less time [Formula: see text] than were sea lions [Formula: see text] between foraging trips. Analysis of scats revealed that fur seals and sea lions ate similar prey (northern anchovy, Engraulis mordax; Pacific whiting, Merluccius productus; juvenile rockfish, Sebastes spp.; market squid, Loligo opalescens; and nail squid, Onychoteuthis borealijaponicas), although the relative proportions of these prey differed. Factors influencing the observed foraging characteristics probably were availability of prey and phylogenetic constraints associated with life-history traits of northern fur seals and California sea lions.

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Stress-related and reproductive hormones in hair from three north Pacific otariid species: Steller sea lions, California sea lions and northern fur seals

Conservation Physiology ◽

10.1093/conphys/coaa069 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Mandy J Keogh ◽

Angela Gastaldi ◽

Patrick Charapata ◽

Sharon Melin ◽

Brian S Fadely

Keyword(s):

Physiological Stress ◽

In Utero ◽

Reproductive Hormones ◽

Steller Sea Lions ◽

Sea Lion ◽

California Sea Lions ◽

Sea Lions ◽

Fur Seals ◽

Hair Samples ◽

Northern Fur Seals

Abstract Assessing the physiological impact of stressors in pinnipeds is logistically challenging, and many hormones are altered by capture and handling, limiting the utility of metabolically active tissues. Hair is increasingly being used to investigate stress-related and reproductive hormones in wildlife populations due to less-invasive collection methods, being metabolically inert once grown and containing multiple biomarkers of ecological interest. We validated enzyme immunoassays for measuring aldosterone, cortisol, corticosterone, and testosterone in lanugo (natal hair grown in utero) samples collected from Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), and northern fur seals (Callorhinus ursinus). We applied laboratory validation methods including recovery of added mass, parallelism and dilution linearity. We found no effects due to differences in alcohol- versus detergent-based cleaning methods. Further, there were no significant differences in hormone concentrations in hair samples collected immediately after the molt and the subsequent samples collected over 1 year, indicating steroid hormones are stable once deposited into pinniped hair. We found no sex differences in any hormone concentrations, likely due to the lanugo being grown in utero and influenced by maternal hormone concentrations. For Steller sea lion and California sea lion pups, we found hormone concentrations significantly differed between rookeries, which warrants future research. Hair provides a novel tissue to explore the intrinsic or extrinsic drivers behind hormone measurements in otariids, which can be paired with multiple health-related metrics to further investigate possible drivers of physiological stress.

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