In an effort to link quantitative morphometric information with molecular data on the population level, we have analysed 19 populations of the conchologically variable land snail Candidula unifasciata from across the species range for variation in quantitative shell traits L and at the mitochondrial16S ribosomai (r)DNA locus. In genetic analysis, including 21 additional populations, we observed two fundamental haplotype clades with an average pairwise sequence divergence of 0.209 f 0.009 between clades compared to 0.017 IT 0.012 within clades, suggesting the presence of two different evolution-y lineages. Integrating additional shell material from the Senckenberg Malacological Collection, a highly signific ant discriminant analysis on the morphological sheli traits with fundamental haplotype clades as grouping variable suggested that the less frequent haplotype corresponds to the described subspecies C. U. rugosiuscula, which we propose to regard as a distinct species.Both taxa were highly subdivided genetically (GT = 0.648 and 0.777 P < 0.001). This was contrasted by the partition of morphological variance, where only 29.6% and 21.9% of the variance were distributed among populations, respectively. In C. unifasciata, no significant association between population pairwise Fs, estimates and corresponding morphologicai fixation indices could be detected, indicating independent evolution of the two character sets. Partial least Square analysis of environmental factors against shell trait variables in C. U. unifasciata revealed significant correlations between environmentai factors and certain quantitative shell traits, whose potential adaptational values are discussed.

Summary1. Land snail dispersal abilities are considered poor; however, the current invasion of the French Mediterranean region by Xeropicta derbentina (Krynicki 1836), as well as the past invasions of this region by several other species, seems to contradict this view. 2. Using a multilevel approach, from individual experimentation to landscape analysis, the dispersal abilities and mechanisms allowing the passive dispersal of X. derbentina are studied. 3. The colonization of Provence occurred by stratified diffusion, where short-range active dispersal occurs side by side with long-range passive dispersal. 4. Active dispersal is not as limited as previously thought. In the field, the capturemark-recapture method recorded a maximum distance covered of 42 m in 6 months within a radius of 38 m from the original release point. 5. Temperature and humidity, and therefore the time of year, influence the main type of dispersal. Dispersal is active during wet periods and essentially passive in dry and hot months. 6. Heat avoidance behaviour is one of the mechanisms allowing passive dispersal. 7. Passive dispersal via human activities is the main determinant of X. derbentina distribution within the landscape. In comparison to other species, X. derbentina is found more often in the vicinity of a communication route. 8. These results show that land snails can cover large distances in a lifetime. The potential for active and passive dispersal described in this paper enables X. derbentina to be a successful invasive species and explains the rapid spread and current distribution of this species.

The aim of the study was to assess the impact of a pastoral management chosen to limit the recent expansion of woodland on a Mediterranean mountain on land snail diversity. An additional aim was to acquire quantitative data that could be used to identify pasture environments from Holocene molluscan assemblages. The work was undertaken at the Luberon mountain, Provence, south of France. We used a stratified quantitative sampling scheme according to altitude and vegetation structure. A total of 80 sites were studied. Large species were collected within a 5 × 5-m plot. Small species were extracted from litter and surface soil. A standard procedure for site description was used based on 35 environmental variables. Grazing pressure was estimated according to the impact of grazing on the herb layer. Correspondence analysis and canonical correspondence analysis were performed using canoco 4.0 software. The distribution of land snails is related to altitude and grazing intensity. Large patches of grazed grassland harbour open country and mountain snail species. Thermophilic open ground species are located in grazed grasslands at lower altitude. Shade-loving species are present in ungrazed scrublands or in small clearings on the upper slopes. The lowest species richness, diversity and equitability are associated with large patches of grazed grassland, the presence of a continuous cover of short grass reinforcing this negative impact on snail diversity. Our study is consistent with similar works on land snails or other invertebrates but discordant with vegetation studies. A homogeneous grazed herb layer significantly reduces snail diversity and abundance. Heterogeneity seems to favour snail diversity both at the local and landscape scales. However, sheep grazing contributes to the expansion of suitable habitats for rare snail species.

In the Mediterranean region, wildfires have devastating effects on animals with limited mobility. With their poor dispersal abilities, their habitats on vegetation and in litter, and their sensitivity to humidity and shade, we expected land snails to be an interesting model to assess short, medium and long-term impact of fires on fauna biodiversity and their resilience. Stratified sampling was carried out on 12 sampling sites in garrigues and forests of Provence (southeastern France), according to fire regime (number of fires, fire intervals and age of the last fire) over the past 30 years. Data were investigated using diversity indexes, Kruskal-Wallis test, dendrogram of affinities and Correspondence Analysis (CA). We found, however, that Mediterranean land snail communities are particularly resilient to fires. Although abundance is drastically reduced in the short-term, species richness and community diversity are preserved provided that the time lapse between two successive fires is longer than the time required for recovery (i.e. around 5 years). This high community resilience in the short-term may be partly due to ecological and ethological aptitudes of land snails. However, these astonishing results, which have implications for conservation biology, are mainly due to the presence, within burned areas, of cryptic refuges that allow initial land snail survival, malacofauna persistence after successive fires and consistent biogeographical patterns in the long-term.