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.