Does a facultative precocious life cycle predispose the marine trematode Proctoeces cf. lintoni to inbreeding and genetic differentiation among host species?
Intraspecific variability in parasite life cycle complexity (number of hosts and species of hosts in the life cycle) may have an impact how parasite genetic variation is partitioned among individual parasites, host individuals or host species within a given area. Among digenean trematodes, a three-host life cycle is common. However, a few species are precocious and may reach sexual maturity in what is typically regarded as the second intermediate host. The objective of this study was to determine whether a precocious life cycle predisposes digeneans to possible inbreeding or genetic subdivision among host species. As a study system, we used the digenean Proctoeces cf. lintoni whose metacercariae precociously mature (facultative) without a cyst wall in the gonads of multiple sympatric species of keyhole limpets (Fissurella spp.), typically regarded as the second intermediate hosts. Genotyped parasites were collected from four species of limpets and the clingfish Sicyases sanguineus, the third and final host where sexual maturity occurs. We found very high microsatellite diversity, Hardy-Weinberg equilibrium over all genotyped individuals, and little to no genetic structuring among parasites collected from the different host species. The fact that metacercariae do not encyst in the keyhole limpets, coupled with the high mixing potential of an aquatic environment, likely promote panmixia in local populations of P. cf. lintoni.
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Isla Teja, Valdivia, Chile; Programa de Doctorado en Ciencias Aplicadas, Mención en Sistemas Marinos Costeros, Universidad de Antofagasta, Antofagasta, Chile. Electronic address: isabelvaldivia@uantof.cl.
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Valdivia
Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX 77843, USA.
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Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Casilla 567, Isla Teja, Valdivia, Chile.
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Cárdenas
Instituto de Ciencias Naturales "Alexander Von Humboldt", Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Av. Angamos 601, P.O. Box 170, Antofagasta, Chile.
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Instituto de Ciencias Naturales "Alexander Von Humboldt", Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Av. Angamos 601, P.O. Box 170, Antofagasta, Chile.
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D000818:Animals; D018509:DNA, Helminth / Q000235:genetics; D005399:Fishes / Q000469:parasitology; D014644:Genetic Variation; D006790:Host-Parasite Interactions / Q000235:genetics; D007178:Inbreeding; D008018:Life Cycle Stages / Q000235:genetics; D018895:Microsatellite Repeats; D008974:Mollusca / Q000469:parasitology; D013045:Species Specificity; D014200:Trematoda / Q000235:genetics* / Q000254:growth & development*; D014201:Trematode Infections / Q000469:parasitology
D018509:DNA, Helminth
Host race; Local scale; Population genetics; Precocious life cycle; Progenetic; Trematode