Molecular systematics of pinniped hookworms (Nematoda: Uncinaria): species delimitation,host associations and host-induced morphometric variation |
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| Authors: | Steven A. Nadler,Eugene T. Lyons,Christopher Pagan,Derek Hyman,Edwin E. Lewis,Kimberlee Beckmen,Cameron M. Bell,Aurelie Castinel,Robert L. DeLong,Padraig J. Duignan,Cher Farinpour,Kathy Burek Huntington,Thijs Kuiken,Diana Morgades,Soraya Naem,Richard Norman,Corwin Parker,Paul Ramos,Terry R. Spraker,Bá rbara Beró n-Vera |
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| Affiliation: | 1. Department of Entomology and Nematology, University of California, One Shields Avenue, Davis, CA 95616, USA;2. Department of Veterinary Science, University of Kentucky, Gluck Equine Research Center, Lexington, KY 40546, USA;3. Alaska Department of Fish and Game, Division of Wildlife Conservation, 1300 College Road, Fairbanks, AK 99701, USA;4. Department of Environment and Primary Industries, PO Box 2500, Bendigo DC, VIC 3554, Australia;5. Cawthron Institute, Private Bag 2, Nelson 7042, New Zealand;6. National Marine Mammal Laboratory, AFSC, NNMS, 7600 Sand Point Way NE, Seattle, WA 98115, USA;g UCVM, University of Calgary, 3280 Hospital Dr. NW, Calgary, Alberta T2N 9B5, Canada;h 23834 The Clearing Dr., Eagle River, AK 99577, USA;i Viroscience Lab, Erasmus MC, PO Box 2040, 3000 CA Rotterdam, The Netherlands;j Department of Parasitology and Parasitic Diseases, Faculty of Veterinary Science, University of the Republic, Alberto Lasplaces 1550, Montevideo, Uruguay;k Department of Pathobiology, Faculty of Veterinary Medicine, Urmia University, PO Box 1177, Urmia, Iran;l School of Veterinary Science, University of Melbourne, 250 Princes Highway, Werribee, VIC 3030, Australia;m Zoos Victoria, PO Box 74, Parkville, VIC 3052, Australia;n Colorado State University Diagnostic Laboratory, College of Veterinary Medicine, Colorado State University, 300 West Drake Road, Fort Collins, CO 80526, USA;o Laboratorio de Mamíferos Marinos, Centro Nacional Patagónico, CONICET, Blvd. Brown 3600, Puerto Madryn, 9120 Chubut, Argentina |
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| Abstract: | ![]()
Hookworms of the genus Uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, Uncinaria lucasi from northern fur seals (Callorhinus ursinus) and Uncinaria hamiltoni from South American sea lions (Otaria flavescens). Hookworms were sampled from these hosts and seven additional species including Steller sea lions (Eumetopias jubatus), California sea lions (Zalophus californianus), South American fur seals (Arctocephalus australis), Australian fur seals (Arctocephalus pusillus), New Zealand sea lions (Phocarctos hookeri), southern elephant seals (Mirounga leonina), and the Mediterranean monk seal (Monachus monachus). One hundred and thirteen individual hookworms, including an outgroup species, were sequenced for four genes representing two loci (nuclear ribosomal DNA and mitochondrial DNA). Phylogenetic analyses of these sequences recovered seven independent evolutionary lineages or species, including the described species and five undescribed species. The molecular evidence shows that U. lucasi parasitises both C. ursinus and E. jubatus, whereas U. hamiltoni parasitises O. flavescens and A. australis. The five undescribed hookworm species were each associated with single host species (Z. californianus, A. pusillus, P. hookeri, M. leonina and M. monachus). For parasites of otarids, patterns of Uncinaria host-sharing and phylogenetic relationships had a strong biogeographic component with separate clades of parasites from northern versus southern hemisphere hosts. Comparison of phylogenies for these hookworms and their hosts suggests that the association of U. lucasi with northern fur seals results from a host-switch from Steller sea lions. Morphometric data for U. lucasi shows marked host-associated size differences for both sexes, with U. lucasi individuals from E. jubatus significantly larger. This result suggests that adult growth of U. lucasi is reduced within the host species representing the more recent host–parasite association. Intraspecific host-induced size differences are inconsistent with the exclusive use of morphometrics to delimit and diagnose species of Uncinaria from pinnipeds. |
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| Keywords: | Hookworm Pinniped Phylogenetics Molecular systematics Cophylogeny Species Morphometrics |
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