Intra-specific morphological variation of the spermatheca in the simultaneously hermaphroditic land snail Helix aperta

Abstract

Intra-specific morphological variation of the spermatheca in the simultaneously hermaphroditic land snail Helix aperta Abdelli, Meriem; Benbellil-Tafoughalt, Saida; Koene, Joris M.

Intraspecific morphological variation of the sperm storing organ in two hermaphroditic land snail species

“…Despite the consistency of the pattern the number and the lengths of the spermatheca tubules which correlate to the sperm storage capacity of the organ vary greatly in the snail species studied. The number of tubules in the spermatheca of H. lucorum (5–16 tubules) was similar to the number reported for C. aspersum (4–19 tubules [10]; 3–13 tubules [35]) but it was greater than that of A. arbustorum (2–9 tubules [9]; 1–5 tubules [36]; 2–7 tubules [22, 25]), Helix pomatia (3–5 tubules [37]), C. vindobonensis (1–8 tubules [33 and present study]) and Helix aperta (3–9 tubules [27]). Furthermore, the number of spermathecal tubules varied considerably among snails within populations and also between populations.…”

“…In A. arbustorum [9, 24], in H. lucorum , and in C. vindobonensis [33 and present study] the length of the main tubule of the spermatheca exceeds the length of the fertilization chamber in the vast majority of the snails studied. On the contrary, in C. aspersum [10] and in Helix aperta [27] the fertilization chamber appears to be the longest structure exceeding the length of the spermatheca. The structural pattern of the FPSC appears to be consistent in different populations of the species studied, characterized by different density [9, 27] or microclimatic conditions and mating propensity [10], therefore appearing unaffected by environmental factors or selective pressures.…”

“…Sperm storage capacity of the spermathecae has been considered to reflect sperm competition level, the latter being approximated in several studies by population density, or environmental characteristics favouring more frequent copulations or prolonged reproductive activity [27, 29].…”

“…The few studies that exist until now for land snails have shown contradictory results regarding the relation of spermatheca complexity to sperm competition levels. While Baminger and Haase [9], did not reveal any relationship between the degree of complexity of the spermatheca of Arianta arbustorum and sperm competition intensity, Abdelli et al [27], revealed a strong correlation of spermatheca storage capacity to population density in Helix aperta . In both studies population density was used as a proxy for sperm competition level.…”

“…Two empirical studies failed to establish a relationship between the degree of complexity of the sperm storing organ and sperm competition intensity as assessed either by population density [9] in Arianta arbustorum , or by direct observations of mating frequency in laboratory experiments in Cornu aspersum [10]. Nevertheless, a recent study on Helix aperta populations revealed a strong correlation of spermatheca storage capacity to population density [27].…”