Historic data analysis reveals ambient temperature as a source of phenotypic variation in populations of the land snailTheba pisana

Abstract

Pulmonate land snails are often polymorphic in their shell coloration pattern. To quantify the contribution of environmental parameters to the nondirectional change in phenotypic variation, we used a historic dataset on Theba pisana morph frequencies and climate data for statistical modelling. We found significant correlations of the degree of phenotypic diversity between juveniles and corresponding adult individuals within the same and the subsequent generation. Among climate parameters, the phenotypic diversity of adults correlated significantly and positively with the mean and maximum ambient temperatures in the winter and spring only. There was no correlation between high or low temperatures and the frequency of distinct morphs. Akaike's information criterion‐based model selection revealed the particular importance of only parental phenotypic diversity for next generation juvenile phenotypic diversity. By contrast, phenotypic diversity of the juveniles of the preceding year and the mean temperatures in winter and spring were important for the phenotypic diversity of adult snails. Approximately two‐thirds of the explicable variation in phenotypic diversity of adults was explained by inheritance and approximately one‐third was expained by ambient temperature. The present study shows that genetics and temperature interact to generate nondirectional changes in phenotypic variation within populations, which also can be reflected by changes in the phenotype of individuals. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 241–256.

Snails in the sun: Strategies of terrestrial gastropods to cope with hot and dry conditions

“…The banding of shells has a well‐characterized genetic background (Cowie, ; Jones et al, ; Murray, ) but suppression of pigmented bands in Cepaea nemoralis by expression of the hyalozonate gene is a long‐known phenomenon by which the phenotype of the shell can be modified (Cain, Sheppard, & King, ). In contrast to a directed selection (Johnson, , ), Köhler et al () who used a dataset of Cowie () showed high winter and spring temperatures to be associated with high variation in morph frequencies but not with the frequency of a particular morph. Also, a study on the phenotypic disequilibrium in a large dataset obtained for Cepaea nemoralis suggested that selection has favored combinations of common morphs, whichever they were (Cook, ).…”

“…This mechanism, however, cannot explain the maintenance of variation in uniformly hot habitats. Although to date there are not many studies statistically linking morph frequencies of snails to environmental parameters such as heat, three of them (Johnson, , ; Köhler et al, ) have identified moderately elevated temperatures acting on free‐living populations of Theba pisana in the middle of their lifetime as a key element for the variation in shell coloration. The studies of Johnson (, ) found hot summer conditions to increase the frequency of unbanded morphs in T heba pisana , attributing this phenomenon to climate selection.…”

“…Thus, a maintenance of shell color polymorphism in some helicoid snail populations for decades can be the result of changes in the direction of selection between different places and times (as interpreted by Cook, 2005;Johnson, 2011;Johnson, 2012) or of epigenetic nondirectional changes within phenotypic plasticity (as interpreted by Köhler et al, 2009;Köhler et al, 2013). Both selection of varying directions and phenotypic plasticity could lead, in combination with migration, to prolonged polymorphism within a population (Cook, 2005;Köhler et al, 2013). Furthermore, selection pressure by predation, drift, founder effects and differentiation in refugia leading to area effects (Cain & Currey, 1963) contribute to maintain polymorphism in populations (Carter, 1967;Cook, 2005;Cook & Pettitt, 1998;Davison & Clarke, 2000;Jones et al, 1977).…”

Hsp70 and lipid peroxide levels following heat stress in Xeropicta derbentina (Krynicki 1836) (Gastropoda, Pulmonata) with regard to different colour morphs

“…Moreover, numerous studies on Cepaea nemoralis Linnaeus 1758, one of the most polymorphic land snail species in Europe (Cain 1977;Goodhart 1987), revealed differences between shell colour morphs: this was the case for the reflectance of the shell, the internal temperature after solar radiation, and the extent of dehydration and mortality after severe heat exposure (Chang 1991;Heath 1975;Richardson 1974). Another frequently studied snail species is Theba pisana Müller 1774, which also shows a highly polymorphic shell banding (Cowie 1984;Köhler et al 2013) and is found in Southern France as well as in coastal plains of the Mediterranean Sea. The northernmost boundary of its distribution is Southern England and Wales; furthermore T. pisana can be found in Northern Africa and in Australia.…”

Interplay of temperature and light influences wild guppy (Poecilia reticulata) daily reproductive activity

“…Individuals face the challenge of maximizing their fitness when exposed to predictable and unpredictable changes in environmental conditions. Seasonal changes in day length and temperature are important for the phenology of seasonal responses, such as flowering in plants (Andres & Coupland, ), reproductive diapause in butterflies (Goehring & Oberhauser, ), shell morphology in snails (Kohler et al ., ), seasonal spawning and oviposition in fish (Pankhurst & Porter, ), migration in birds (Both, ), and decisions on energy budget requirements in mammals (e.g. Valencak, Tataruch & Ruf, ).…”