Jérôme Pellet’s research while affiliated with University of Lausanne and other places

Most biological survey programs rely on multi-species inventories (e.g. birds, amphibians, butterflies, dragonflies). These programs usually rely on multiple visits during pre-defined time windows. The implicit goal of this popular approach is to maximize the observed species richness. Here, we present a novel method to optimize the timing of survey windows using a framework maximizing the detectable species pool. We present a proof of concept using 20 years of entomological records in Switzerland using butterflies, dragonflies, and grasshoppers. The general framework presented can potentially be applied to a wide range of biological survey schemes. It offers a new practical tool for adaptive entomological monitoring under climate change.

Abstract The impacts of landscape anthropization on mosquito abundance and diversity are already well studied, but the underlying ecological factors behind these effects are still poorly understood. One such underlying ecological factor may be related to the loss of amphibians in human‐modified landscapes, providing ideal habitats for several mosquito species. In this study, we conducted a mosquito and amphibian larvae survey in 77 ponds along a gradient of landscape anthropization in western Switzerland. We used structural equation models to investigate the direct and indirect effects of building footprints and several local pond parameters on mosquito abundance and composition through amphibian abundance. We highlighted that landscape anthropization increases the presence probability of mosquito larvae and the proportion of Culex pipiens in mosquito communities. Our results also suggested that one of the ecological mechanisms underlying these effects is a reduction in amphibian abundance, limiting competition and predation experienced by mosquitoes in human‐modified landscapes. In addition, we showed that several local pond characteristics prevent the presence and abundance of mosquito larvae. Indeed, deep ponds, which promote amphibian abundance, limit the probability of larval mosquito presence, and large and old ponds have a lower larval mosquito abundance. Amphibians appear to be effective control agents of natural mosquito populations. Therefore, the development of measures to protect amphibians in human‐modified landscapes could help to reduce both mosquito‐related nuisances and the risk of emergence of vector‐borne diseases in humans and wildlife.

The protection of wetlands is a cornerstone in the conservation of pond-breeding amphibians. Because protected wetlands are rarely natural areas, but are often man-made, at least in Europe, it is important that they are well managed to fulfill their intended function. Appropriate management requires knowledge of the ecology of the species, particularly habitat requirements. Here, we combine species monitoring data and habitat mapping data in an analysis where our goal was to describe the factors that determine the occupancy of amphibian species in federally protected amphibian breeding sites. As expected, every species had its own habitat requirements, often a combination of both a terrestrial and aquatic habitat (i.e., landscape complementation). In most species, occupancy was strongly positively affected with the amount of aquatic habitat, but predicted occupancy probabilities were low because the amount of aquatic habitat was low in most sites. The area or proportion of ruderal vegetation also had positive effects on multiple species, while other types of terrestrial habitat (e.g., meadows) led to low occupancy probabilities. The total area of the protected breeding sites was never included in a final model and connectivity was important only for one species (Triturus cristatus). The latter finding implies that the quality of the landscape between breeding sizes is more important than distance per se, while the former implies that the area of some specific habitats within breeding sites is crucial for high occupancies. Thus, increasing the amount of aquatic habitats and likewise terrestrial habitats within protected areas would make them more likely to achieve their conservation objectives. Our study is an example of how the joint analysis of monitoring data and habitat data (based on mapping in the field) can lead to evidence-based suggestions on how to improve conservation practice.

River restoration projects are often accompanied by major land consolidation operations, notably the reallocation of adjacent farmland, which offers the opportunity to create an extensively-managed buffer zone outside the levees where specific habitat features are installed for endangered terrestrial and semi-aquatic biodiversity. Modern, enrivonmentally-friendly land consolidation operations might thus not only contribute to better integrate the newly restored river into the adjacent landscape, but also to reinstate the longitudinal ecological connectivity that crudely lacks along channelized rivers. Based on a theoretical reallocation of agricultural land via land consolidation, we simulated the creation of a longitudinal biodiversity-friendly grassland buffer along a stretch of the Rhône River (SW Switzerland) where a major revitalisation project is under development. We selected a series of focal species depending on a palette of complementary habitat features, and combinations thereof, to be created for reaching these biodiversity targets. Estimations of species-specific habitat patch size requirements as well as dispersal abilities were used to analyse what would be an optimal spatial connectivity for these habitat features. Since such a buffer zone will necessarily stretch along the riverbed, which implies different spatial contraints and consequential planning strategies, we tested two scenarios via a metapopulation model: (i) arranging key habitat features longitudinally or (ii) positioning them in an isotropic context. Simulations showed that differences in metapopulation connectivity between scenarios were negligible at the foreseen scale. We conclude that land consolidation via targeted farmland reallocation could be instrumental to restoring ecological connectivity in major river revitalisation projects. We also provide concrete quantitative values for restoring an optimal ecological buffer along the Rhône that will promote locally endangered biodiversity.

1. To be effective, the next generation of conservation practitioners and managers need to be critical thinkers with a deep understanding of how to make evidence-based decisions and of the value of evidence synthesis. 2. If, as educators, we do not make these priorities a core part of what we teach, we are failing to prepare our students to make an effective contribution to conservation practice. 3. To help overcome this problem we have created open access online teaching materials in multiple languages that are stored in Applied Ecology Resources. So far, 117 educators from 23 countries have acknowledged the importance of this and are already teaching or about to teach skills in appraising or using evidence in conservation decision-making. This includes 145 undergraduate, postgraduate or professional development courses. 4. We call for wider teaching of the tools and skills that facilitate evidence-based conservation and also suggest that providing online teaching materials in multiple languages could be beneficial for improving global understanding of other subject areas.

1. To be effective, the next generation of conservation practitioners and managers need to be critical thinkers with a deep understanding of how to make evidence‐based decisions and of the value of evidence synthesis. 2. If, as educators, we do not make these priorities a core part of what we teach, we are failing to prepare our students to make an effective contribution to conservation practice. 3. To help overcome this problem we have created open access online teaching materials in multiple languages that are stored in Applied Ecology Resources. So far, 117 educators from 23 countries have acknowledged the importance of this and are already teaching or about to teach skills in appraising or using evidence in conservation decision‐making. This includes 145 undergraduate, postgraduate or professional development courses. 4. We call for wider teaching of the tools and skills that facilitate evidence‐based conservation and also suggest that providing online teaching materials in multiple languages could be beneficial for improving global understanding of other subject areas.

«Retour à la nature!» C’est ce que souhaiteraient Jean-Jacques Rousseau et de nombreuses personnes, en particulier parmi celles qui sont actives dans la protection de la nature. Une «remarque personnelle» dans le dernier NP Inside nous l’a rappelé: «Arrêt intéressant dans l’optique des nombreux aménagements artificiels, chers, pas intégrés dans le paysage et peu durables, même s’ils visent a priori un but de conservation de la biodiversité (p. ex. étangs à fond bâché).» Nous décrivons ici les raisons pour lesquelles nous considérons que les étangs bâchés sont toujours pertinents.

Genetic pollution through introgressive hybridization of local species by exotic relatives is a major, yet neglected aspect of biological invasions, particularly in amphibians where human introductions are frequent. In Western Switzerland, crested newts make an interesting case: the Italian species Triturus carnifex was introduced at least a century ago within the range of the native and threatened T. cristatus. To understand the genetic consequences of this introduction and inform wildlife management authorities, we conducted a genetic survey on the remaining northern crested newt populations known in the area, using newly-developed species-diagnostic nuclear (microsatellites) and mitochondrial (control region) DNA markers. We documented massive nuclear introgression by the T. carnifex genome, which has completely replaced T. cristatus in most populations, especially in the Geneva area where the introduction was originally reported. However, many of these individuals retained the ancestral T. cristatus mtDNA, which could be explained by asymmetric introgression between the two species, stemming from demographic and/or selective processes. Analyses of genetic diversity support multiple events of T. carnifex releases, most-likely of proximate North Italian origin. We pinpointed the last indigenous populations in the region and recommend to prioritize their protection. Our study demonstrates the invasive potential of introduced taxa through introgressive hybridization, alerts about the underestimated rate of illegal amphibian translocations, and emphasizes the need for genetic analyses to monitor such invasions.