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Rodriguez-Perez H.,Research Center for the Conservation of Mediterranean Wetlands | Cayuela H.,CNRS Center of Evolutionary and Functional Ecology | Cayuela H.,French National Center for Scientific Research | Hilaire S.,Research Center for the Conservation of Mediterranean Wetlands | And 3 more authors.
Hydrobiologia | Year: 2014

The non-indigenous red swamp crayfish (Procambarus clarkii) has been shown to be a threat for amphibian conservation. Many amphibian species breed in temporary ponds to diminish predation risk as such ecosystems are free of large predators. However P. clarkii, occurring as an invasive species in the Camargue delta, can readily disperse on the ground and thus colonize isolated ponds. We studied the current impact of the exotic crayfish on the reproductive success of the Mediterranean tree frog (Hyla meridionalis). In a mesocosm experiment, we tested the effect of two crayfish densities (1 and 3 crayfish/m2) on tadpole abundance. We also tested in a field experiment, within a temporary pond, the crayfish's predation on the tree frog's eggs. Finally, we developed site occupancy models using data from 20 ponds to assess the effect of crayfish abundance on tadpole abundance. Neither the experiments, nor the site occupancy models showed a negative impact of the current crayfish abundance on the tree frog populations breeding in ponds. We found that recorded crayfish densities were lower than in other areas where crayfish has impacted amphibian populations, but we hypothesize that current crayfish abundance in the area may increase in the future, thus impacting tree frog populations. © 2013 Springer Science+Business Media Dordrecht.

Sylvestre D.,French National Institute for Agricultural Research | Jean-Marc B.,French National Institute for Agricultural Research | Jean-Claude M.,French National Institute for Agricultural Research | Christophe L.P.,CIRAD - Agricultural Research for Development | And 5 more authors.
Agricultural Systems | Year: 2016

Alternative agricultural systems, such as organic farming (OF), are promising options to sustain both agriculture productivity and environmental health. However, the adoption of OF by farmers is occurring more slowly than is advocated. A key factor limiting farmers is an inability to predict socio-economic consequences of converting to OF. To overcome this, we developed a novel method of integrated assessment of agricultural systems (IAAS) and applied it to scenarios of development of OF in the Camargue region, South of France. In collaboration with the local stakeholders, we characterized the agricultural systems at different spatial scales and defined scenario related to the future of agriculture and to OF. We then used agent-based modeling with farmers and bio-economic modeling with local stakeholders for scenario assessment. We examined the effects on the development of OF systems of key factors such as the ongoing reform in the European Common Agricultural Policy and the effects of regulations for decreased use of pesticides. The policy reform implied trends towards a diversification of crops and greater possibility for conversion to OF. Development of OF at the regional level led to improved environmental performance, but caused a decrease in profitability of the rice supply chains. In light of the observed trade-off between rice production and OF development, objectives and options towards more sustainable agricultural systems were discussed with farmers and local stakeholders. Stakeholders' assessment of the framework provided insights on the positive and specific aspects of the IAAS methodology requiring improvement. The complementarities of agent-based and bio-economic modeling provide stakeholders with a better-informed assessment of diverse scenarios, for the development of more sustainable agricultural systems. © 2015 Elsevier Ltd.

Brennan A.C.,CSIC - Doñana Biological Station | Brennan A.C.,Durham University | Woodward G.,Imperial College London | Seehausen O.,University of Bern | And 7 more authors.
Evolutionary Ecology Research | Year: 2014

Background: Due to increasing global change, the rate of hybridization appears to be increasing. Question: Is hybridization adding problems or solutions to the effects of global change on biodiversity? Methods: We divided ourselves into two independent groups. Each group listed topics it thought appropriate. We then compared and combined the lists, extracting a natural structure of the topics. We next divided ourselves into three specialized subgroups and discussed the topics in more depth. In a final plenary meeting, we brought ideas together, discussed open topics, identified consensus or differences of opinion, and prepared a preliminary report. Results: Our lists of topics were highly similar, suggesting that we missed only a few topics. We agreed that it is important to consider hybridization in both its genetic and ecological context and with explicit attention paid to phylogenetic and biogeographic history. It is also necessary to distinguish between underlying processes and resulting consequences. Knowledge of the consequences of hybridization is more developed in genetics than in ecology. We suggest that hybridization adds problems (loss of biodiversity, ecosystem degradation) as well as solutions (new adaptive variation, ecosystem robustness) to global change challenges. Which of these applies in a given case depends on its evolutionary and environmental context, and on the objectives of conservation management. We provide five groups of questions to stimulate further research. © 2014 Pim Edelaar.

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