title: [Ratio of r- and K-forms of selection in life cycles of trematodes (Plathelminthes, Trematoda).
abstract: The situation is considered in a continuum of r-K-selection of hermaphroditic and parthenogenetic populations of trematodes (fish parasites) of three species: Bunodera luciopercae, Sphaerostomum bramae, and Phyllodistomum elongatum. Maritae of B. luciopercae and S. bramae are characterized by a low fertility, single-type reproduction, and long prereproductive period, and are involved in interspecific competition. On the contrary, maritae of Ph. elongatum rapidly mature, are highly fertile, repeatedly reproduce, and occur in a "competitive vacuum". Pathenitae of these trematodes combine the features of both forms of selection, which is accounted for by adaptations to the parasitic mode of life. A reproductive tactic of parthenitae has been proposed, based on the redioid or sporocystoid types. According to the community of features, B luciopercae as a species is a "K-strategiest", S. bramae equally combines the features of both forms of selection, and Ph. elongatum is an "r-strategist".
authors.affiliation: Papanin Institute of Biology of Inland Waters, Russian Academy of Sciences, Yaroslavl oblast, Russia.
authors.forename: A E
authors.initials: AE
authors.lastname: Zhokhov
mesh_terms: D000818:Animals; D005399:Fishes / Q000469:parasitology; D008018:Life Cycle Stages; D012098:Reproduction; D012641:Selection, Genetic; D014200:Trematoda / Q000254:growth & development / Q000502:physiology*