title: High Rates of Self-Fertilization in a Marine Ribbon Worm (Nemertea).
abstract: Organisms capable of self-fertilization ("selfing") typically exhibit two evolutionary syndromes: uniting high inbreeding depression with low levels of selfing, or low inbreeding depression with high levels of selfing. We examined the effect of inbreeding on fecundity and time to first reproduction in an apparently self-compatible, simultaneously hermaphroditic marine nemertean worm Prosorhochmus americanus. Adult and juvenile worms were raised in isolation or in pairs. Isolated worms produced significantly more offspring than paired worms (in the adult experiment), and did not exhibit inbreeding avoidance (in the juvenile experiment). The selfing rate of six natural populations was evaluated using 17 species-specific, microsatellite markers, and was consistent with preferential selfing (mean: 0.843, SD: 0.027). Our results showed that P. americanus exhibited an interesting suite of life-history traits, uniting high colonization potential through self-fertilization and high fecundity, with no dispersive larval stage, and with moderate levels of gene flow. We believe that P. americanus is an ideal model system for studies of mating system evolution, inbreeding, and sex allocation.
authors.affiliation: Center for Population Biology, Department of Evolution and Ecology, College of Biological Sciences, University of California, 1 Shields Avenue, Davis, California 95616; and sacaplins@ucdavis.edu.
authors.forename: Serena A
authors.initials: SA
authors.lastname: Caplins
authors.affiliation: Department of Biology, College of Humanities and Sciences, Virginia Commonwealth University, 1000 W. Cary Street, Richmond, Virginia 23284.
authors.forename: James M
authors.initials: JM
authors.lastname: Turbeville
mesh_terms: D000818:Animals; D005298:Fertility; D051456:Gene Flow; D057850:Hermaphroditic Organisms; D007178:Inbreeding; D007448:Invertebrates / Q000235:genetics / Q000502:physiology*; D018895:Microsatellite Repeats; D012098:Reproduction / Q000502:physiology; D057945:Self-Fertilization