Repeatability of energy metabolism and resistance to dehydration in the invasive slug Limax maximus

Abstract

Abstract. Standard metabolic rate (SMR) and resistance to body dehydration (BD) are important physiological traits that have an effect on water balance and the amount of energy available for activity and production, and thus could contribute to variation in life history traits expressed across a range of environments. Few studies have tested whether SMR and BD show consistent between-individual variation in molluscs. Significant repeatability of SMR and BD indicates that the traits might be heritable and therefore a possible target for natural selection, so describing the repeatability of SMR and BD is important in studies of phenotypic variability. Here, we studied energy metabolism (body mass-corrected SMR) and the change in the scaling relationship of SMR and body mass in response to time between measurements in the giant garden slug Limax maximus. Limax maximus is one of the most invasive terrestrial molluscs, with a wide geographical distribution, and is considered an important pest of horticultural and agricultural crops. Our results show that L. maximus follows the expected relationship of increasing SMR with increasing mass, but the scaling exponent varies through time and is different from that described for other gastropods. We also found significant inter-individual variation in VCO 2 Mean , VCO 2 Min , VCO 2 Max , and BD (τ=0.25, 0.29, 0.24, 0.22, p<0.05, respectively), and significant repeatability of body mass (τ=0.90). To our knowledge, this is the first comprehensive analysis of the repeatability of body mass-corrected SMR and BD in terrestrial slugs. Our results suggest that energy metabolism and water balance could potentially respond to selection.

Variation in Thermal Sensitivity and Thermal Tolerances in an Invasive Species across a Climatic Gradient: Lessons from the Land Snail Cornu aspersum

“…In this study, standard metabolic rate (SMR), the obligatory maintenance energy cost in ectotherms [52], was measured as the rate of carbon dioxide production using an open system, as described by Gaitán-Espitia et al (2012) [53]. Briefly, CO 2 production at 20°C was measured continuously with an infrared CO 2 analyzer (LI-COR 7000 Sable System®) capable of resolving differences of up to 1 part per million of CO 2 in air, connected to a computerized data-acquisition system (Expe Data software, Sable Systems), similar to one used by [54].…”

Metabolism, Growth, and the Energetic Definition of Fitness: A Quantitative Genetic Study in the Land SnailCornu aspersum

“…Terrestrial mollusks face two important challenges, dehydration and the energetic costs of locomotion (Denny 1980;Rizzatti and Romero 2001;Czarnołęski et al 2008;Gaitán-Espitia et al 2012). Previous studies of C. aspersum in Chile have shown that physiological traits at the whole-animal level are remarkably constant and repeatable across the geographical range (Artacho and Nespolo 2008;Naya et al 2011).…”

Is there metabolic cold adaptation in terrestrial ectotherms? Exploring a latitudinal compensation using a common garden experiment of the invasive snailCornu aspersum

“…To avoid any noise or erroneous recordings generated by animal manipulation, we eliminated the first 10 min of the record (600 samples) (Gaitán-Espitia et al, 2012). From each individual record, we extracted the average of each transformed record (V · CO2,mean ) which is used here as a proxy of SMR.…”

“…body dehydration), the snails were weighed at the beginning of each trial, when the animals were fully hydrated, and at the end of the test period (i.e. 45 min), recording the mean M b and also the differences between initial and final M b as a proxy for body water loss (Gaitán-Espitia et al, 2012).…”

“…6 months after eclosion) were randomly selected for metabolic analysis. In this study, SMR, the obligatory energetic cost of maintenance in ectotherms, was measured as the rate of carbon dioxide production in a computerized open-flow respirometry system, as described previously (Gaitán-Espitia et al, 2012). In brief, CO 2 production was measured continuously with an infrared CO 2 analyser (LI-COR 7000, Sable Systems), which was calibrated periodically against two kinds of gas (CO 2 -free air, and a commercial mix of 101 ppm CO 2 ).…”