Thermal advantage of pale coloured morphs of the snail Arianta arbustorum (Helicidae, Pulmonata) in alpine habitats

Abstract

In alpine grasslands pale colour morphs of the snail Arianta arbustorum are more frequent than dark ones As pale morphs absorb less solar radiation, they may forage for longer in sunlight and/or have a lower mortality risk from overheating This hypothesis was tested Equal numbers of pale and dark morphs were kept in enclosures in an alpine meadow During the day, more pale morphs were seen than dark ones, the latter obviously remaining hidden The difference was not significant in enclosures set up in a nearby forest, confirming that the inequality in behaviour depends on the amount of sunlight Dark snails are on average warmer than pale ones Experiments were also conducted in grassland on a mountain slope at altitudes between 1200 and 2000 m Snails were marked with a paint which fades in light, and released When recaptured several days later, the marks were more faded in pale morphs than in dark, suggesting that they had been more exposed to sunlight, supporting our hypothesis The difference in fading was more pronounced at high than at low altitude

Rapid evolution in unstable habitats: a success story of the polymorphic land snail Cepaea nemoralis (Gastropoda: Pulmonata)

“…However, it is expected to be important primarily among organisms with high mobility relative to spatial variation in their environments (Edelaar et al ., 2008), whereas, in gastropods, as a result of their extremely high cost of locomotion, the distance over which it is profitable to crawl in search of suitable habitat is very limited (Denny, 1980). Although differences in microhabitat use between different coloured snails have been shown (Jones, 1982; Burla & Gosteli, 1993), this was at much smaller spatial scales than was analyzed in the present study. In Theba pisana , habitat choice partly maintains genetic change across the boundary between open and acacia habitats (Johnson, 1981; Hazel & Johnson, 1990).…”

Maintenance of clinal variation for shell colour phenotype in the flat periwinkle Littorina obtusata

“…During exposure to moderate conditions, the effects of shell colour on fitness may be strongly influenced by snail behaviour, resulting in more subtle effects on growth and reproduction. Shell colour has been found to affect activity levels, foraging behaviour and microhabitat use in other snails (Abdel‐Rehim, 1983; Chang, 1991; Burla & Gosteli, 1993; Staikou, 1999). Changes in behaviour as a result of variation in thermal stress may also act indirectly on fitness by influencing interactions with other abiotic or biotic components of the community.…”

Shell morphology, growth pattern and population dynamics of the land snail Xerolenta obvia (Menke, 1828) in two areas of different climatic conditions within a temperate climate region

“…These may affect fitness under different climatic conditions as pale shells reflect more solar radiation (Jones et al 1977, Lazaridou & Chatziioannou 2005, Ożgo 2005). Differences in thermal balance influence many behavioural and life cycle traits (Abdel-Rehim 1983, 1988, Cowie & Jones 1985, Burla & Costelli 1993, Staikou 1999, Pruitt et al 2011, Goulet et al 2017. In many species, including X. obvia from the Mediterranean region, pale or unbanded snails are more frequent in hotter and more exposed sites (Lazaridou & Chatziioannou 2005, Johnson 2011).…”