Influence de l'expérience antérieure de tétards de grenouille rousse, Rana temporaria et de crapaud commun, Bufo bufo, sur la relation chimiosensorielle prédateur-proie. Etude des réponses antiprédatrices morphologiques et comportementales

Diplôme : DEAil s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATIONInfluence de l'expérience antérieure de tétards de grenouille rousse, Rana temporaria et de crapaud commun, Bufo bufo, sur la relation chimiosensorielle prédateur-proie. Etude des réponses antiprédatrices morphologiques et comportementale

Prior exposure to conspecific chemical cues affects predator recognition in larval common toad (Bufo bufo)

In a laboratory experiment, we investigated the role played by conspecific chemical cues in the acquisition of chemical recognition of an unfamiliar predator by common toad tadpoles, Bufo bufo. During a ten-day period, we assigned one group of tadpoles to a control (unexposed) and five other groups to different conditioning treatments involving exposure to either an allopatric predatory crayfish (Astacus leptodactylus), or a sympatric harmless gastropod (Lymnaea stagnalis). We kept the caged crayfish under three conditions: i) starved, ii) starved in combination with cues from crushed tadpoles, or iii) fed with toad tadpoles. In the same way, we kept the caged pond snails either alone or paired with cues from crushed tadpoles. After exposure, we carried out behaviour measurements to assess the effects of conditioning treatments on the behavioural responses to chemical cues from starved crayfish, pond snails and crushed conspecifics. Test solutions from starved crayfish and snails produced a significant decrease in the percentage of moving tadpoles, a known antipredator response, but only in the two groups of tadpoles previously exposed to these organisms in combination with cues from crushed conspecifics. These results indicate that Bufo bufo tadpoles can learn to recognize an organism as representing a predation risk based on a prior association between the chemical stimuli from that organism and the chemical cues from damaged conspecifics

Embryonic experience to predation risk affects tadpoles of the common frog (Rana temporaria)

 Amphibians are known to exhibit phenotypic plasticity in response to variations in predation pressure. Data also indicate that developmental changes can be induced by embryonic exposures to predator non-contact cues. However, the possible consequences of such exposures on larval behavioural activity and sensitivity to chemical cues from predators have remained unexplored. These laboratory experiments examine the effects of predation cues experienced during embryonic development on some morphological and behavioural traits in hatchlings and tadpoles of the common frog (Rana temporaria). Eggs were raised until hatching in the nonlethal presence of either a sympatric predator (larval spotted salamander, Salamandra salamandra), or an allopatric predator (juvenile Turkish crayfish, Astacus leptodactylus), or crushed conspecific tadpoles. Predators were kept either starved, or fed with R. temporaria tadpoles. Embryonic treatments had significant consequences on weight and total length of hatchlings, as well as on the general activity of tadpoles. Olfactometric tests showed that the behavioural responses of tadpoles to chemical cues from the two predators tested were not significantly affected by embryonic treatments. In contrast, embryonic experience showed a significant influence on the behavioural response of tadpoles to chemical cues from crushed conspecifics. These results indicate that the morphology of hatchlings depends on the species and diet of the predators present during embryonic development and demonstrate for the first time that the subsequent activity and chemically mediated antipredator behaviour of tadpoles can be influenced by embryonic experience of the predation risk

Effets de substances indicatrices d un risque de prédation sur le comportement, la morphologie et les traits d histoire de vie de la grenouille rousse (Rana temporaria) et du crapaud commun (modulation par un herbicide, l amitrole)

Chez les larves d amphibiens, l estimation du risque de prédation et la mise en place de réponses anti-prédatrices adaptatives dépendent étroitement de la détection des signaux chimiques libérés par les prédateurs et (ou) les congénères blessés. Toutefois, de tels processus à support olfactif peuvent être particulièrement vulnérables à la présence de contaminants chimiques en milieu aquatique. La thèse vise donc à évaluer les effets d expositions embryo-larvaires simples et combinées à un herbicide triazole (amitrole) et à différents types de signaux chimiques indicateurs d un risque de prédation sur le comportement, la morphologie et les traits d histoire de vie de la grenouille rousse (Rana temporaria) et du crapaud commun (Bufo bufo). Cette approche expérimentale a donné lieu à une série d articles scientifiques, et à la suggestion de nouvelles pistes de recherche et mesures relatives à la conservation des amphibiens.In larval amphibians, predation risk assessment and adaptive anti-predator responses are tightly dependent on the detection of chemical signals released from predators and (or) injured conspecifics. However, such olfactory-mediated processes can be particularly vulnerable to the presence of waterborne chemical contaminants. Thus, the thesis aims to evaluate the behavioural, morphological and life-historical effects of single and combined embryo-larval exposures to a triazole herbicide (amitrole) and to different types of chemical signals indicative of a predation risk in the common frog (Rana temporaria) and the common toad (Bufo bufo). This experimental approach has resulted in a series of scientific articles, and the suggestion of some new research prospectives and measures relative to amphibians conservation.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF