La naïveté, définie comme l’absence de reconnaissance d’un nouvel « ennemi » ou de réponses appropriées en raison d’un manque d’expérience, à été longtemps considérée comme une des caractéristiques des espèces insulaires natives, et comme un des principaux facteurs de leur sensibilité face à l’arrivée de prédateurs ou compétiteurs introduits, particulièrement en milieux insulaires. A travers l’analyse des réponses comportementales aux odeurs d’espèces invasives, nous avons étudié la naïveté de différents modèles biologiques d’espèces natives (squamates, oiseaux, mammifères), au niveau insulaire (Nouvelle-Calédonie) et continental (Mali). Ces expérimentations ont concerné différents types d’interactions (prédateurs invasifs vs proies natives, compétiteurs ou agresseurs invasifs vs compétiteurs natifs), avec une gamme d’espèces introduites depuis plusieurs dizaines, centaines, voire milliers d’années, ou face à des espèces non-encore introduites mais avec une forte probabilité d’introduction. La naïveté apparait comme un facteur complexe, présent chez des espèces natives insulaires et continentales, dépendant du couple d’espèces introduite/native considéré, et pouvant être perdu sous l’influence de différents facteurs liés à l’histoire de l’invasion et à l’intensité de l’impact de l’espèce introduite. Etudier les conséquences de la perte de naïveté, permet de mieux comprendre le rôle de la naïveté dans les processus de persistance, de déclin ou d’extinction d’espèces natives suite à l’arrivée de nouveaux « ennemis », et d’éclairer les stratégies de gestion destinées à limiter l’impact des espèces introduites et l’érosion mondiale de la biodiversité. / The introduction of alien predators are causing rapid extinctions or declines in many native prey species, and these impacts are generally attributed to prey naïveté, i.e. their failure to recognize a novel enemy and respond appropriately, due to a lack of experience, particularly on island ecosystems. Here, we tested behavioral responses of different native species towards invasive species odors for several biological models of native species (squamates, mammals, birds), on island (New Caledonia) and mainland (Mali) ecosystems. We tested different types of species interactions (invasive predators vs native prey, invasive competitors/aggressors vs native competitors), for species introduced since decades, centuries, millennium, or not yet introduced but with a high risk of introduction. Naïveté is a complex phenomenon, that occurs both for mainland and island native species, that varies among species probably as a consequence of time since introduction and of the intensity of the threat posed by invasive species. Studying the consequences of the loss of naïveté improve our understanding of the factors underpinning the persistence, declines or extinctions of native species after alien species introduction and provide insights for developing accurate management strategies of invasive species impacts and limiting the current biodiversity loss.

The aim of this thesis was to study determinants of a readiness for pro-environmental travel behavior in households. Four empirical studies were conducted examining reduction in car use (Study I), acceptability of transport policy measures (Study II and III), and behavioral adaptations in response to travel demand management (TDM) measures (Study IV). In Study I, the aim was to interrupt habitual car use by means of a deliberation intervention and to examine the importance of moral motivation (i.e., personal norm) for car use reduction. Results showed that, as a result of the intervention, car use was mainly reduced among car users with a strong car use habit and a strong moral motivation to reduce car use. The aim of Study II was to examine factors important for the acceptability of three TDM measures: raised tax on fossil fuel, improved public transport, and an information campaign. The results demonstrated the importance of general environmental beliefs (i.e., pro-environmental orientation, problem awareness, personal norm, and willingness to reduce car use) and policy specific beliefs (i.e., perceived impact on freedom to choose travel mode and own car use, perceived effectiveness, and perceived fairness) for the acceptability of the measures. Furthermore, personal norm was found to be particularly important for the acceptability of raised tax and the information campaign, whereas problem awareness was more important for the acceptability of improved public transport. Following up on Study II, the purpose of Study III was to examine the acceptability of single and combined transport policy measures, more specifically, raised tax on fossil fuel, improved public transport, subsidies of renewable fuel, a package of raised tax on fossil fuel and improved public transport, and a package of raised tax on fossil fuel and subsidies of renewable fuel. General environmental beliefs (i.e., pro-environmental orientation, problem awareness, personal norm, and willingness to act) and policy specific beliefs (i.e., perceived effectiveness and perceived fairness) were found to be important for the acceptability of the measures. Moreover, personal norm was particularly important for the acceptability of raised tax on fossil fuel and the packages, while problem awareness was more important for the acceptability of improved public transport and subsidies of renewable fuel. The aim of Study IV was to examine the behavioral adaptations, more specifically, the expected car use reduction, in response to three hypothetical TDM measures: raised tax on fossil fuel, improved public transport, and a package of raised tax on fossil fuel and improved public transport. Furthermore, factors important for the expected car use reduction were analyzed. Results showed that a combination of the measures was expected to lead to a larger car use reduction compared to the single measures, and the most commonly chosen reduction strategies were more efficient car use and changing travel mode. Moreover, internal motivational factors, such as personal norm, and the perceived personal impact of the measures were important for expected car use reduction in response to the measures.