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These land snails have opercula, which helps identify them as "winkles gone ashore", in other words, snails within the clade Littorinimorpha and the informal group Architaenioglossa. Members of the snail family Pulmonata , which includes carboniferous land sails and some freshwater snails of the order Basommatophora , are protandrous ...
The freshwater snail Physa acuta is a self-fertile organism that can be exposed either to strong sexual selection or to self-fertilization depending on its mode of reproduction. Noel et al. [ 29 ] used Physa acuta to experimentally determine whether accumulation of deleterious mutations is avoided by inbreeding populations of the snail, as well ...
As the snails can reproduce both sexually and asexually, the snail has been used as a model organism for studying the costs and benefits of sexual reproduction. Asexual reproduction allows all members of a population to produce offspring and avoids the costs involved in finding mates. However, asexual offspring are clonal, so lack variation ...
Parthenogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. Among all the sexual vertebrates, the only examples of true parthenogenesis, in which all-female populations reproduce without the involvement of males, are found in squamate reptiles (snakes and lizards). [1]
Each of the germ balls grows and eventually contributes to the next asexual generation. The miracidium itself can differentiate into a replicative primary sporocyst as it sheds its epidermal plates within the snail intermediate host. Trematodes may have varying numbers of asexual generations and larval forms, but share a cercarial stage. [8]
Many digenean trematodes require two hosts; one (typically a snail) where asexual reproduction occurs in sporocysts, the other a vertebrate (typically a fish) where the adult form engages in sexual reproduction to produce eggs.
Trematoda is a class of flatworms known as flukes or trematodes.They are obligate internal parasites with a complex life cycle requiring at least two hosts.The intermediate host, in which asexual reproduction occurs, is usually a snail.
Further evidence for the Red Queen hypothesis was provided by observing long-term dynamics and parasite coevolution in a mixed sexual and asexual population of snails (Potamopyrgus antipodarum). The number of sexuals, the number of asexuals, and the rates of parasitic infection for both were monitored.