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Gastropods are capable of being either male or female, or hermaphrodites, and this makes their reproduction system stand out amongst many other invertebrates. Hermaphroditic gastropods possess both the egg and sperm gametes which gives them the opportunity to self-fertilize. [4] C. obtusus is a snail species of the Eastern Alps. In the ...
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 ...
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]
Obligate parthenogenesis is the process in which organisms exclusively reproduce through asexual means. [41] Many species have transitioned to obligate parthenogenesis over evolutionary time. Well documented transitions to obligate parthenogenesis have been found in numerous metazoan taxa, albeit through highly diverse mechanisms.
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 ...
The Komodo dragon, which normally reproduces sexually, has also been found able to reproduce asexually by parthenogenesis. [54] A case has been documented of a Komodo dragon reproducing via sexual reproduction after a known parthenogenetic event, [ 55 ] highlighting that these cases of parthenogenesis are reproductive accidents, rather than ...
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.