Shell size differences in Helix lucorum Linnaeus, 1758 (Mollusca: Gastropoda) between natural and urban environments

Helix lucorum Linnaeus, 1758 is a large helicid snail widespread in Georgia. While its occurrences are mainly associated with human activity, it is frequently impacted by strong direct pressure, which could cause local extinctions of populations. Instead, H. lucorum populations in anthropogenic landscapes are usually dense and apparently well adapted. Morphometric studies were carried out on 12 populations from both anthropogenic and more natural habitats in a wide range of altitudes and climatic regimes in Georgia to investigate the effects of human pressure. Populations in more anthropogenic habitats have smaller adult shells independently of any effects of climate, altitude, or density. H. lucorum appears to adapt to anthropogenic pressures by changes in population dynamics, ceasing growth at a smaller size.

Shell size differences in Helix lucorum Linnaeus, 1758 (Mollusca: Gastropoda) between natural and urban environments

Helix lucorum Linnaeus, 1758 is a large helicid snail widespread in Georgia. While its occurrences are mainly associated with human activity, it is frequently impacted by strong direct pressure, which could cause local extinctions of populations. Instead, H. lucorum populations in anthropogenic landscapes are usually dense and apparently well adapted. Morphometric studies were carried out on 12 populations from both anthropogenic and more natural habitats in a wide range of altitudes and climatic regimes in Georgia to investigate the effects of human pressure. Populations in more anthropogenic habitats have smaller adult shells independently of any effects of climate, altitude, or density. H. lucorum appears to adapt to anthropogenic pressures by changes in population dynamics, ceasing growth at a smaller size.

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  • Bantock, C.R. and Bayley, J.A. 1973. Visual selection for shell size in Cepaea (Held.). J. Anim. Ecol. 42: 247–261. Baur, B. 1984. Shell size and growth rate differences for alpine populations of Arianta arbustorum (L.) (Pulmonata: Helicidae). Rev. Suisse Zool. 91: 37–46.
  • Baur, B. 1988. Microgeographical variation in shell size of the land snail Chondrina clienta. Biol. J. Linn. Soc. 35: 247–259.
  • Cameron, R.A.D. and Carter, M.A. 1979. Intra- and interspecific effects of population density on growth and activity in some helicid land snails (Gastropoda: Pulmonata). J. Anim. Ecol. 48: 237–246.
  • Chiba, S. 2009. Morphological divergence as a result of common adaptation to a shared environment in land snails of the genus Hirasea. J. Mollus. Stud. 75(3): 253–259.
  • Cook, L.M. and Cain, A.J. 1980. Population dynamics, shell size and morph frequency in experimental populations of the snail Cepaea nemoralis (L.). Biol. J. Linn. Soc. 14: 259–292.
  • Goodfriend, G.A. 1986. Variation in land-snail shell form and size and its causes: a review. Syst. Biol. 35(2): 204–223.
  • Gould, S.J. 1984. Covariance sets and ordered geographic variation in Cerion from Aruba, Bonaire, and Curaçao: a way of studying nonadaptation. Syst. Zool. 33(2): 217–237.
  • Hijmans, R.J., Cameron, S.E., Parra, J.L., Jones, P.G. and Jarvis, A. 200 Very high resolution interpolated climate surfaces for global land areas. Int. J. Climatol. 25: 1965–1978.
  • Joliffe, I.T. and Morgan, B.J. 1992. Principal component analysis and exploratory factor analysis. Stat. Methods Med. Res. 1: 69–95.
  • Konuma, J. and Chiba, S. 2007. Trade-offs between force and fit: extreme morphologies associated with feeding behavior in carabid beetles. Am. Nat. 170: 90–100.
  • Lazaridou-Dimitriadou, M. and Bailey, S.E.R. 1991. Growth, reproduction and activity rhythms in 2 species of edible snails, Helix aspersa and Helix lucorum, in non 24-hour light cycles. J. Zool. 225: 381–391.
  • Lazaridou-Dimitriadou, M. and Saunders, D.S. 1985. The influence of humidity, photoperiod, and temperature on the dormancy and activity of Helix lucorum L. (Gastropoda, Pulmonata). J. Mollus. Stud. 52(3): 180–189.
  • Lejava, G. 1973. Animal World of Georgia, Tom IV. Metsniereba, Tbilisi (in Georgian).
  • Lubell, D. 2004. Prehistoric edible land snails in the circumMediterranean: the archaeological evidence. In: Petits animaux et sociétés humaines du complément alimentaire aux resources utilitaires (Eds. J.P. Brugal and J. Desse). Éditions APDCA, Antibes.
  • Osselaer, C.V. and Tursch, B. 2000. Variability of the genital system of Helix pomatia L., 1758 and H. lucorum L., 1758 (Gastropoda: Stylommatophora). J. Mollus. Stud. 66: 499–515.
  • Ożgo, M. 2008. Current problems in the research of Cepaea polymorphism. Folia Malacologica 16(2): 55–60.
  • Pollard, E. 1973. Growth classes in the adult Roman snail (Helix pomatia L.). Oecologia 12: 209–212.
  • Sokal, R.R. and Rohlf, F.J. 1995. Biometry: The Principles and Practice of Statistics in Biological Research. W. H. Freeman and Company, New York.
  • Staikou, A., Lazaridou-Dimitriadou, M. and Farmakis, N. 1987. Aspects of the life cycle, population dynamics, growth and secondary production of the edible snail Helix lucorum Linnaeus, 1758 (Gastropoda, Pulmonata) in Greece. J. Mollus. Stud. 54(2): 139–155.
  • Williamson, P., Cameron, R.A. and Carter, M.A. 1976. Population density affecting adult shell size of snail Cepaea nemoralis L. Nature 263: 496–497.