Stage- and weather-dependent dispersal in the brown garden snail Cornu aspersum

International audienceDispersal decisions are often condition-dependent, influenced by the interaction of individual phenotype and environmental conditions. Terrestrial Gastropods are simultaneous hermaphrodites, a reproductive system rarely studied in the context of dispersal. Moreover, the energetic cost of their movement is one of the highest among animals. Despite these features, which make them valuable models to understand the trade-offs between dispersal and other life-history traits, their dispersal strategies have been barely explored. We studied the movements of subadults and adults of the brown garden snail Cornu aspersum in a semi-natural 4-patch network, for 2 months in 2011 (a dry year) and 1 month in 2012 (a wet year). We assessed the effects of life-history stage (subadult/adult) and weather conditions on dispersal propensity and dispersal speed. Snails were more mobile under humid and warm weather, but nearly all individuals left patches when the relative humidity was close to 100 % in 2012. Because such humidity levels are potentially lethal to C. aspersum, we argue these extreme emigration rates might be an emergency escape response to harmful conditions. Despite a theoretically higher cost of movement, we found that subadults emigrated more, and dispersed faster and further, than adults. Thus, and contrary to what was expected, direct costs of movement do not play the main role in shaping dispersal in C. aspersum. Observed differences between subadults and adults in dispersal behaviour are discussed in the context of intraspecific competition, inbreeding avoidance and relative costs of male and female reproduction

Brachylaima spp. (Trematoda) parasitizing Cornu aspersum (Gastropoda) in France with potential risk of human consumption

The edible land snail Cornu aspersum, native to the Mediterranean coastlines of North Africa, is widely distributed on most continents and often invasive in areas where introduction is recent. This species could contribute to the geographic spread of parasites as demonstrated for Brachylaima spp. These cosmopolitan trematodes may represent a threat to human health, like in Australia where Brachylaima cribbi infects humans. In this study, we demonstrate for the first time the occurrence of Brachylaima spp. in two French populations of C. aspersum, Thorigné-Fouillard (Ille-et-Vilaine), and Arçais (Deux-Sèvres), with an overall prevalence of 10.4% (Thorigné-Fouillard) and 73.3% (Arçais), respectively and a metacercarial intensity on average three times higher in Thorigné-Fouillard (37) than in Arçais (11). Cornu aspersum may act as a first and second intermediate host, as demonstrated in Arçais. The morphometrics of metacercariae, particularly the great body length about 2 mm, discriminate our Brachylaima species from those already described in C. aspersum (B. cribbi in Australia, and B. aspersae, B. llobregatensis and B. mascomai in Europe). Molecular analysis, based on 28S and COI, suggests the occurrence of two species in our study, one of which is probably Brachylaima mesostoma, an intestinal parasite of passeriform birds described in Central Europe. We underline the need for further research to identify species of Brachylaima in France and measure the health hazard of consuming field-collected snails

Comparison between ultrathin films of YSZ deposited at the solid oxide fuel cell cathode/electrolyte interface by atomic layer deposition, dip-coating or sputtering

The effect of an 80 nm YSZ interfacial layer, deposited onto a YSZ pellet by different techniques (dip-coating, sputtering and atomic layer deposition) at the SOFC cathode/electrolyte interface to allow a maximum adhesion of the thick cathode layer, was thoroughly analysed. The LSM cathode was deposited on the solid electrolyte by painting and sintered in air at 1200°C for 2 h. The morphological and structural analyses of the samples were performed by scanning electron microscopy and X-ray diffraction; their electrical properties were examined between 390 and 700°C by electrochemical impedance spectroscopy. The impedance responses showed three different contributions. The highfrequency arc is attributed to the YSZ electrolyte. The electrode processes associated with the medium- and low frequency arcs were discussed. The electrochemical performance was influenced by the microstructure at the electrode/electrolyte interface

Dispersal syndromes in challenging environments: A cross‐species experiment

Dispersal is a central biological process tightly integrated into life-histories, morphology, physiology and behaviour. Such associations, or syndromes, are anticipated to impact the eco-evolutionary dynamics of spatially structured populations, and cascade into ecosystem processes. As for dispersal on its own, these syndromes are likely neither fixed nor random, but conditional on the experienced environment. We experimentally studied how dispersal propensity varies with individuals' phenotype and local environmental harshness using 15 species ranging from protists to vertebrates. We reveal a general phenotypic dispersal syndrome across studied species, with dispersers being larger, more active and having a marked locomotion-oriented morphology and a strengthening of the link between dispersal and some phenotypic traits with environmental harshness. Our proof-of-concept metacommunity model further reveals cascading effects of context-dependent syndromes on the local and regional organisation of functional diversity. Our study opens new avenues to advance our understanding of the functioning of spatially structured populations, communities and ecosystems. Keywords: context-dependent dispersal; dispersal strategy; distributed experiment; predation risk; resource limitatio

Terrestrial gastropods: why they should provoke the interest of cryobiologists

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Conservation at a slow pace: Terrestrial gastropods facing fost changing climate

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Terrestrial gastropods: why they should provoke the interest of cryobiologists

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Hibernation et résistance au froid chez l'escargot petit-gris Helix aspera Müller (Gastéropode, pulmoné)

En Bretagne, l'escargot terrestre Helix aspersa Müller (Gastéropode, Pulmoné) entre en hibernation en octobre. Possédant une faible capacité de surfusion et une survie limitée à la congélation de ses tissus, H. aspersa peut être considéré comme " partiellement tolérant à la congélation ". Pendant l'hiver, sa survie aux températures négatives est améliorée principalement par l'occupation de loges d'hibernation et l'extension modérée de sa capacité de surfusion, provoquée par un ensemble de caractéristiques propres à l'animal et à la dormance : (1) la diminution de la masse d'eau, (2) la formation d'un épiphragme, (3) le jeûne. La taille relativement importante de cette espèce, sa forme et la présence de la coquille, lui confèrent une certaine aptitude à supporter le gel de ses tissus. Cette capacité peut s'avérer essentielle pour des animaux soumis à un environnement plus froid. Le statut intermédiaire d'H. aspersa en terme de stratégie de résistance au froid, par rapport aux modèles d'Insectes et de Vertébrés, est discuté, en considération de ses implications dans l'évolution des escargots terrestres vers des milieux au climat plus froid.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Conservation at a slow pace: Terrestrial gastropods facing fost changing climate

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Relationship between supercooling ability and fresh mass in terrestrial shelled gastropods: A phylogenetic comparative approach

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