SPERM COMPETITION IN THE SIMULTANEOUS HERMAPHRODITE FRESHWATER SNAIL BIOMPHALARIA GLABRATA (GASTROPODA: PULMONATA)

• Published in: Journal of molluscan studies Vol. 62; no. 4; pp. 451 - 457
• Main Authors: VIANEY-LIAUD, MARC, JOLY, DOMINIQUE, DUSSART, GEORGES
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01.11.1996
• Subjects: Biomphalaria glabrata; Freshwater
• ISSN: 0260-1230; 1464-3766
• DOI: 10.1093/mollus/62.4.451

An isolated heterozygous Cc Biomphalaria glabrata produces, in strict self-fertilization involving C and c oocytes and spermatozoa, an excess of pigmented progeny, when compared with the expected 3.1 Mendelian ratio. When isolated after insemination by an albino partner, an heterozygous Cc snail shows for 17 days an expected 1:1 Mendehan ratio of pigmented and albino progeny; after the 17th day, self-fertilization is progressively resumed. When fertilized by only c spermatozoa, the two kinds (C and c) of oocytes play a similar role and do not explain the excess of pigmented progeny obtained by selfing. After a similar pairing (Cc × cc), the isolated albino parent also produces, from the 2nd to 20th day, a significant excess of pigmented progeny These experimental results confirm previous observations obtained from homozygous lineages. In both homozygous strains (CC and cc), around 50% of spermatozoa are apyrene or oligopyTene. C spermatozoa are significantly longer than c spermatozoa, this difference, which is classically related to better kinetics, could explain the present results.