THE FERTILIZATION PROCESS IN THE SNAIL,<i>LYMNÆA STAGNALIS APPRESSA</i>SAY

Crabb, Edward D.

doi:10.2307/1537031

Cited by 36 publications

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“…From this it is clear that, when albino and pigmented snails are paired, not only does cross-fertilization occur, but, contrary to the opinion of Crabb (1927b), it is the predominating process.…”

Section: Prevalence Of Self-fertilizationmentioning

confidence: 88%

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Studies on Cross-Fertilization and Self-Fertilization in Lymnaea Stagnalis Appressa Say

Cain¹

1956

The Biological Bulletin

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Marine Biological Laboratory is collaborating with JSTOR to digitize, preserve and extend access to Biological Bulletin.In 1817 Oken obtained fertile eggs from Lymnaea auricularis which were reared in isolation during their entire reproductive period. Baudelot (1863) reported both self-fertilization and cross-fertilization in Lymnaea. Pelseneer (1920) saw only one polar body extruded from the eggs of Lymnaea (three species), and concluded that reproduction in isolated snails was parthenogenetic. However, Colton, (1918) in L. columella and Crabb (1927a) in L. stagnalis observed two polar bodies and on the basis of their observations concluded that parthenogenesis did not occur. Colton further reported that, although self-fertilization did occur, crossfertilization was the rule; Crabb reported that cross-fertilization was mechanically impossible (1927b). Seshaiya (1927) concluded from a study of breeding habits of L. luteola that both cross-and self-fertilization occurred in this species. Lang in 1900 claimed that self-fertilization could occur without self-copulation, while Kunkel (1908) believed that self-copulation was indispensable to self-fertilization, basing his opinion in part on the observation of self-copulation in L. auricularis by Von Baer in 1835. Colton and Pennypacker (1934) reported that self-fertilization in L. columella for 93 generations did not decrease the viability of the strain. Boettger (1944), in his survey of the Basommatophora, concluded that self-and cross-fertilization were both common in this order. DeWitt (1954) found the percentage of hatching less in self-fertilized eggs of Physa gyrina than in cross-fertilized eggs.The first genetic proof that both self-and cross-fertilization occur in snails was supplied by Diver, Boycott and Garstang (1925) in a study of the inheritance of inverse symmetry in L. peregra. Further proof was obtained in the study of the inheritance of albinism in this snail (Boycott and Diver, 1927). Ikeda and Mura (1934), using shell color as a genetic marker, demonstrated that both self-and cross-fertilization occurred in the land snail, Bradybaena similaris.Bretschneider (1948a, 1948b) investigated the mechanism of insemination and oviposition in L. stagnalis. He reported that he had seen sperm balls leaving the seminal vesicle and being swept up the female tract to the hermaphroditic duct, where he assumed fertilization occurred. As additional evidence he reported seeing a complete spermatozoon inside the cytoplasm of an egg still in the duct.

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Section: Prevalence Of Self-fertilizationmentioning

confidence: 88%

“…If diploid parthenogenesis had occurred exclusively, only pigmented offspring would have been expected. Moreover, the work of Colton (1918) and Crabb (1927bCrabb ( , 1928 indicated that two polar bodies are extruded by the eggs in Lymnaea.…”

Section: Prevalence Of Self-fertilizationmentioning

confidence: 99%

Studies on Cross-Fertilization and Self-Fertilization in Lymnaea Stagnalis Appressa Say

Cain¹

1956

The Biological Bulletin

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“…In a classical work, Crabb (1 927a) concluded that there was not a precise mechanism of germ cells sorting in the carrefour in Lymnaea stagnalis, since he found spermatozoa and oocytes, respectively, in the female and male ducts. This author also considered the possibility of oocyte transfer by copulation (Crabb, 1927b). In a later work, Duncan (1958) equally describes the occasional presence of spermatozoa inside the female tract of Physa fontinalis and P.…”

Section: Discussionmentioning

confidence: 99%

The functional organization of the carrefour in the reproductive tract ofBiomphalaria tenagophila(Mollusca, Planorbidae)

Tomé

Ribeiro

1998

Invertebrate Reproduction & Development

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A detailed morphological analysis of the carrefour, corresponding to the site of bifurcation of the hermaphroditic duct of the reproductive tract of Biomphalaria tenagophila (Mollusca, Planorbidae), has been carried out by light and electron microscopy, including 3D anatomical reconstruction. The carrefour receives the tangential entrance of the ovispermiduct and secretory duct of the albumen gland in its posterior face whereas the exits to the oviduct and spermiduct are situated in its anterior face. Histologically, this bulbuous organ is very similar to the ovispermiduct and thus may be considered as a hermaphroditic structure. It is lined by highly ciliated columnar epithelium with a few mucous secretory cells. The h e structural analysis of the epithelium reveals the presence of long and abundant cilia and numerous microvilli in the apical surface of the ciliated cells, along with signs of micropinocytic activity. The observation of basal membrane infoldings with associated mitochondria indicates the existence of an apexbase motion of fluid through the carrefour epithelium. In contrast, the mucous cells show an intense secretory activity. Germ cell trafficking and sorting inside the carrefour are very complex, involving the segregation of oocytes and spermatozoa produced in the ovotestis of the animal itself and the exogenous spermatozoa acquired by copulation. Based on morphological evidence presented in this work, we concluded that the flux produced by ciliary beating of the epithelial cells along with the insertion angle and relative positioning of the openings of the ducts in the carrefour are the most important factors in the traffic and differential destiny of the germ cells inside the organ. The presence of secretion of the albumen gland in the so-called fertilization pocket should prevent the sperm entrance into the oocyte and thus the zygote formation in this specialized region of the carrefour.

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“…It primarily inhabits the littoral zone of stagnant or slow‐flowing water bodies. Lymnaea stagnalis can reproduce through both self‐fertilization and outcrossing (Crabb ), and has the ability to store allosperm for over two months (Cain ; Nakadera et al. ).…”

Section: Methodsmentioning

confidence: 99%

“…It primarily inhabits the littoral zone of stagnant or slow-flowing water bodies. Lymnaea stagnalis can reproduce through both self-fertilization and outcrossing (Crabb 1927), and has the ability to store allosperm for over two months (Cain 1956;Nakadera et al 2014). It reproduces by depositing egg clutches of variable size, containing as few as one egg to as many as 200 eggs per egg clutch.…”

Section: Study Organism and Experimental Animalsmentioning

confidence: 99%

Natural selection on immune defense: A field experiment

2017

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Predicting the evolution of phenotypic traits requires an understanding of natural selection on them. Despite its indispensability in the fight against parasites, selection on host immune defense has remained understudied. Theory predicts immune traits to be under stabilizing selection due to associated trade-offs with other fitness-related traits. Empirical studies, however, report mainly positive directional selection. This discrepancy could be caused by low phenotypic variation in the examined individuals and/or variation in host resource level that confounds trade-offs in empirical studies. In a field experiment where we maintained Lymnaea stagnalis snails individually in cages in a lake, we investigated phenotypic selection on two immune defense traits, phenoloxidase (PO)-like activity and antibacterial activity, in hemolymph. We used a diverse laboratory population and manipulated snail resource level by limiting their food supply. For six weeks, we followed immune activity, growth, and two fitness components, survival and fecundity of snails. We found that PO-like activity and growth were under stabilizing selection, while antibacterial activity was under positive directional selection. Selection on immune traits was mainly driven by variation in survival. The form of selection on immune defense apparently depends on the particular trait, possibly due to its importance for countering the present parasite community.

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THE FERTILIZATION PROCESS IN THE SNAIL,LYMNÆA STAGNALIS APPRESSASAY

Cited by 36 publications

References 0 publications

Studies on Cross-Fertilization and Self-Fertilization in Lymnaea Stagnalis Appressa Say

Studies on Cross-Fertilization and Self-Fertilization in Lymnaea Stagnalis Appressa Say

The functional organization of the carrefour in the reproductive tract ofBiomphalaria tenagophila(Mollusca, Planorbidae)

Natural selection on immune defense: A field experiment

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