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Trochulus striolatus is a land snail showing great morphometric variation in its shell, which is the basis for recognition of its subspecies. However, this variability can result from an influence of environment. To verify the possible effect of bioclimatic and spatial variables on the shell size and shape, we studied many samples collected from four biotic zones (lowland, submontane, montane and subalpine). Many of its shell features appeared significantly negatively correlated with a precipitation parameter and altitude, whereas positively correlated with temperature parameters. The shells were smaller at higher altitudes and in colder environment with greater precipitation. The reduced growth period can be an adaptive response to the shorter growing season in mountainous regions compared to lowland areas, where the longer season permits a longer growth resulting in larger mean adult body size. This conforms to the converse Bergmann's cline. The synergetic interactions between seasonality, temperature and moisture best explain the size variation in T. striolatus resulting from the influence of local environmental and/or climate factors. Therefore, there is no sufficient justification for subspecies recognition and the subspecific epithets for T. striolatus should be discarded.
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Shell variation in Bulgarica cana

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Laboratory and field observations on Vertigo angustior Jeffreys, V. antivertigo (Draparnaud), V. moulinsiana (Dupuy), V. pusilla O. F. Müller, V. pygmaea (Draparnaud), V. ronnebyensis (Westerlund), V. substriata (Jeffreys), Truncatellina cylindrica (Férussac), Columella aspera Waldén and C. edentula (Draparnaud) provided new information on their life cycle. Genus Vertigo: the life span is 1–3 years, with most snails dying in the next year after hatching. The reproductive season lasts from half of May till the beginning of September; depending on the life span eggs are laid during 1–3 seasons. The number of eggs per lifetime varies widely, the maximum numbers are 55–79 in V. moulinsiana, pygmaea and ronnebyensis, 102–120 in V. angustior, pusilla and substriata and 218 in V. antivertigo. Most eggs are laid at the stage of one cell (even oocyte II), but in some the advancement of development indicates retention of 1–3 days. Hatching usually starts in the second half of June and lasts till the second half of September. Only some of the snails reach maturity in the year of hatching, usually after the reproductive season. Genus Truncatellina: in the wild the life span of most individuals is about one year, some live till the age of about two years. Eggs are laid from half of June till the end of August (in laboratory maximum 11 eggs); hatching takes place from July till the end of September. Genus Columella: in the laboratory C. aspera lays eggs from half of May till the beginning of September (maximum 5 eggs); hatching starts at half of June and continues till the end of September. C. edentula in the laboratory lays eggs at half of April, and juveniles hatch at the end of May and beginning of June.
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