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Among ten adult specimens of the Madeiran endemic land snail Leptaxis simia (Férussac, 1832) (Gastropoda: Hygromiidae), harvested from their natural environment, kept in the laboratory, a single clutch of 110 eggs was reared, and the mortality, growth and reproductive capacity of hatchlings over a 1240-day period were monitored. Of 70 hatchlings, 34 survived to complete shell growth at around 640 days. Growth was rapid, and mortality high in the early stages; growth slowed, and mortality was very low as the full size was approached. Snails kept singly failed to lay any eggs. Among those with potential mates, only three clutches were produced, one of which yielded no hatchlings. Clutches were produced at least five months after shell growth was complete. Mortality increased sharply after the onset of sexual maturity, and the oldest snail survived for three and a half years. The apparently very strictly semelparous mode of reproduction, delayed sexual maturity and a relatively long period of juvenile growth are discussed in relation to other species and to the practical problems of rearing potentially endangered species in captivity. [ABSTRACT FROM AUTHOR]

A countrywide data set of 1048 samples of the European land snail Cepaea nemoralis (L.) from Poland was assembled from both published and unpublished sources. Analyses of shell colour and banding polymorphism revealed distinctive patterns of variation. While the frequency of brown shells showed a clear geographical pattern related to climate, other morphs showed no such clear trends. Variation among populations was great, but little of this could be accounted for by variation among regions. Spatial autocorrelation was generally restricted to very short distances, of the order of 20 km or less. Variation with habitat was found in the form of an excess of brown shells in shaded habitats and an excess of yellow and yellow effectively unbanded shells in open habitats, although this was not universal. The data suggest that cases of long-distance, passive dispersal followed by more local spread account for much of the variation, and that strong selection related to habitat may be obscured by different sources of populations within a few kilometres of each other. The data are now available to track changes over time. [ABSTRACT FROM AUTHOR]

Aim: Morphological and taxonomic diversity are intuitive measures of biological diversity. Previous studies have shown discordance between these measures at large spatial and temporal scales, but the implications of this pattern for the underlying processes are not understood. Using oceanic archipelagos as spatial units, we examine potential links between the morphological and taxonomic diversity of their land snail faunas in a biogeographical framework. Location: Eleven major oceanic archipelagos. Methods: For each archipelago, we assembled lists of indigenous land snail species, classified by family and genus, with shell height and width for each species (1723 species in total). We used biogeographic and climatic variables as potential predictors of diversity patterns. We employed regression analyses to evaluate (1) whether morphological diversity scales with taxonomic diversity at the species, genus or family level, and (2) whether morphological and taxonomic diversity correlate similarly with biogeographic/climatic factors. We also assessed which taxonomic level contributes most to morphological variation within archipelagos. Results: Morphological diversity across archipelagos was strongly related to genus but not species richness. Within archipelagos, morphological variation reflected differences among genera and families but not species. Species richness was best explained by archipelago area, but morphological diversity was not significantly related to any of the physical features of archipelagos. Main conclusions: Across archipelagos, species richness and morphological diversity of land snail faunas are decoupled. The relationship between species richness and the available ecological space (captured mainly by area) indicates the prevalence of niche-based processes while, for morphological diversity, the strong conservatism of morphology at the genus level suggests the presence of diversification-based limits. Assuming genera effectively reflect diversification, our findings indicate that morphological space on oceanic archipelagos depends primarily on the number of evolutionary units that have colonized and/or diversified through time. [ABSTRACT FROM AUTHOR]

The shell colour and banding polymorphisms in urban populations of Cepaea snails were studied in Sheffield (England) and Wrocław (Poland), which are two cities of similar size. Both Cepaea nemoralis and Cepaea hortensis were found in Sheffield, but only C. nemoralis was found in Wrocław. In neither city was variation with habitat apparent, nor was there evidence of large-scale geographical patterns. Spatial autocorrelation analyses revealed only vaguely defined local clusters. There was a greater degree of among-population variation in Sheffield, and more cases of extreme frequencies and low levels of polymorphism. Wrocław populations were more uniform and highly polymorphic. These differences can be related to the history of these snails in each city. Sheffield has been colonized mainly in the last 20 years, and some parts of the city with apparently suitable habitat remain unoccupied. Leptokurtic dispersal of small propagules followed by local spread appears likely. Values of FST resemble those seen in districts elsewhere with ‘Area Effects’. Although there are ancient woodlands within the city, they have been colonized too recently for selection to achieve a new balance. Wrocław has held Cepaea populations for at least 100 years, and they are denser and more continuous. Shaded habitats are recent and temporary; the overall pattern of variation matches that seen in open habitats in districts elsewhere in which variation with habitat is apparent, and values of FST also correspond. Population history and the character of dispersal clearly affect the patterns of variation observed. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 27–39. [ABSTRACT FROM AUTHOR]