Solar radiation stress in climbing snails: behavioural and intrinsic features define the Hsp70 level in natural populations of Xeropicta derbentina (Pulmonata)

Abstract

Ectotherms from sunny and hot environments need to cope with solar radiation. Mediterranean land snails of the superfamily Helicoidea feature a behavioural strategy to escape from solar radiation-induced excessive soil heating by climbing up vertical objects. The height of climbing, and also other parameters like shell colouration pattern, shell orientation, shell size, body mass, actual internal and shell surface temperature, and the interactions between those factors may be expected to modulate proteotoxic effects in snails exposed to solar radiation and, thus, their stress response. Focussing on natural populations of Xeropicta derbentina, we conducted a 'snapshot' field study using the individual Hsp70 level as a proxy for proteotoxic stress. In addition to correlation analyses, an IT-model selection approach based on Akaike's Information Criterion was applied to evaluate a set of models with respect to their explanatory power and to assess the relevance of each of the abovementioned parameters for individual stress, by model averaging and parameter estimation. The analysis revealed particular importance of the individuals' shell size, height above ground, the shell colouration pattern and the interaction height×orientation. Our study showed that a distinct set of behavioural traits and intrinsic characters define the Hsp70 level and that environmental factors and individual features strongly interact.

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

“…As reported in other studies related to adaptations of land snails from Southern France to elevated temperatures (Di Lellis et al 2012;Dieterich et al 2012;Köhler et al 2009;Scheil et al 2011;Troschinski et al 2014), X. derbentina reacts to heat stress with a clear Hsp70 induction when being confronted with increasing temperatures. A maximum induction of Hsp70, the intensity of which depended on the identity of the population, was regularly observed between 38°and 40°C in different populations (Di Troschinski et al 2014).…”

“…Among these pale individuals lower percentages of individuals were observed which were characterized by a darkly pigmented banding of the shell and which can be categorized according to the banding pattern described in previous studies (Di Lellis et al 2012;Dieterich et al 2012;Dittbrenner et al 2009;Köhler et al 2009). …”

“…The sampling site was not used for agricultural purpose, thus, no pesticides were applied. Individual snails were sorted according to their colour category as predefined in other studies (Di Lellis et al 2012;Dieterich et al 2012;Köhler et al 2009). Colour category 1 snails were defined as snails which carry a uniformly white shell.…”

Antioxidant defense and stress protein induction following heat stress in the Mediterranean snailXeropicta derbentina[Pulmonata, Hygromiidae]

“…The pulmonate X. derbentina is well adapted to such unfavourable conditions. Thus, this snail species has become a common subject for the investigation of physiological heat stress responses in recent years Köhler et al, 2009;Scheil et al, 2011;Di Lellis et al, 2012;Dieterich et al, 2013;Troschinski et al, 2014). In contrast to the well-documented induction of Hsps in response to heat exposure, activation of the antioxidant defence system is poorly understood in this context in this terrestrial snail species.…”

Daily and seasonal changes in heat exposure and the Hsp70 level of individuals from a field population of Xeropicta derbentina (Krynicki 1836) (Pulmonata, Hygromiidae) in Southern France

“…Measurements of the ground temperature and several centimetres above show a dramatic decrease of the air temperature even a few centimetres above the ground ). Shifting the activity to the cooler and moister night hours is another common behaviour of land snails in their response to hot environments (Abdel-Rehim 1983; Di Lellis et al 2012). In the climate of Southern France with hot and dry summers, ground temperatures frequently reach 50°C and more.…”