Simulated shifts in trophic niche breadth modulate range loss of alpine butterflies under climate change

Species currently track suitable abiotic and biotic conditions under ongoing climate change. Adjustments of trophic interactions may provide a mechanism for population persistence, an option that is rarely included in model projections. Here, we model the future distribution, of butterflies in the western Alps of Switzerland under climate change, simulating potential diet expansion resulting from adaptive behavior or new host opportunities. We projected the distribution of 60 butterfly and 298 plant species with species distribution models (SDMs) under three climate change scenarios. From known host plants, we allowed a potential diet expansion based on phylogenetic constraints. We assessed whether diet expansion could reduce the rate of expected regional species extinction under climate change. We found that the risk of species extinctions decreased with a concave upward decreasing shape when expanding the host plant range. A diet expansion to even a few phylogenetically closely related host plants would significantly decrease extinction rates. Yet, even when considering expansion toward all plant species available in the study area, the overall regional extinction risk would remain high. Ecological or evolutionary shifts to new host plants may attenuate extinction risk, but the severe decline of suitable abiotic conditions is still expected to drive many species to local extinction

Monitoring of the last stronghold of native pool frogs (Pelophylax lessonae) in Western Europe, with implications for their conservation

The original diversity of Pelophylax water frogs has been compromised by multiple biological invasions all over Western Europe. For the European pool frog (P. lessonae), the Joux Valley—a 30 km highland depression in northwestern Switzerland—stands as the last stronghold spared by exotic lineages. In order to manage P. lessonae in the valley, we combined traditional field surveys with environmental DNA metabarcoding and mapped the regional distribution of amphibian species. Both approaches concurred that P. lessonae persists at a single isolated site (Pontet). Continuous monitoring of this population throughout the spring and summer 2019 informed on their wintering quarters (most likely the forest litter immediately surrounding the breeding pond), as well as the timing of migration (end of April), breeding (June), and larval development (June–August). In parallel, we experimented the first use of drone technology for amphibian surveillance: 30 adults were individually counted during an aerial survey at the peak of the breeding season, confirming the small size of the population. Finally, we compared some biotic and abiotic properties among water bodies throughout the valley and flagged a few sites that were ecologically similar to Pontet. In a landscape dominated by pastoral activities where Pelophylax dispersal is virtually impossible, these could be candidates for future translocation efforts. Our study illustrates the application of next-generation monitoring techniques for the urgent management of threatened species and stresses the need for reevaluating the conservation status of P. lessonae in Western Europe, where it appears to subsist in low numbers at one last locality

Only males care about their environment: sex-biased dispersal in the asp viper (Vipera aspis)

Sex-biased dispersal is common among vertebrates and numerous studies have documented a tendency towards male-biased dispersal in mammals and female-biased dispersal in birds. A few studies have demonstrated that male-biased dispersal seems to be prevalent in reptiles. However, most of these studies considered only a single study site without taking into account possible local variability. We investigated sex-biased dispersal in Vipera aspis in four study sites in Switzerland using microsatellite markers and we predicted a higher dispersal in males than females. In two study sites, females were more spatially autocorrelated and showed a stronger isolation by distance compared with males, which suggests male-biased dispersal. In the other two study sites, the absence of sex-biased dispersal could have been the result of habitat fragmentation. Surprisingly, the dispersal ability of females was similar in the four sites, regardless of habitat fragmentation. This finding suggests a limited impact of habitat on female dispersal and the opposite for male dispersal. Our study demonstrates the importance of inferring sex-biased dispersal in different habitats, because local barriers can affect the outcome of such studies. Hence, general conclusions about patterns of sex-biased dispersal should be drawn with caution when studies are conducted at a single study site

Fungal infection in free-ranging snakes caused by opportunistic species

Emerging infectious fungal diseases such as chytridiomycosis, caused by Batrachochytrium dendrobatidis and B. salamandrivorans in amphibians, or ophidiomycosis in reptiles (Ophidiomyces ophiodiicola), are major threats that can drive species or entire populations to extinction over a short period of time. Besides these well-documented pathogens, such diseases can be caused by numerous opportunistic fungal species that can target e.g. immunocompromised individuals from various species of vertebrates. In reptiles, opportunistic species are mainly documented in captive animals kept in inadequate conditions, but data remains scarce for wild individuals. In the present study, we isolated and genetically identified fungal species responsible of skin lesions in wild-caught smooth snakes (Coronella austriaca) during a field survey targeting endangered reptile species in Switzerland. A total of 18 fungal species were isolated and genetically identified from the lesions of the two wild-caught snakes and included several species known for being opportunistic pathogens in vertebrates and infecting mainly immunocompromised individuals, such as Alternaria infectoria and Rhodotorula spp. It is not possible to establish whether the snakes had such an issue. However, the exceptional wet and cold conditions experienced in spring 2021 might have trigger the infections. Indeed, high humidity has been recorded as a predisposing factor for mycoses in captive reptiles

Atlas des amphibiens du canton de Vaud

Amphibians constitute one of the most threatened taxa in Switzerland. Half of them are on the verge of extinction, as their reproduction is dependent on aquatic environments that have been battered for more than a century. To counter this negative dynamic, conservation measures must be informed by a clear diagnosis of the distribution of the species, the location of the issues at stake and conservation measures to reverse the general trend. Following an intensive field survey campaign carried out in 2020 at 325 amphibian breeding sites, it became clear that a new assessment was needed, 45 years after the previous cantonal inventory. The past and current distribution of the 14 species of amphibians in the canton are presented, as well as the aspects of their ecology that are crucial for their conservation. Recommendations are made on a territorial basis in order to target the implementation of measures where they are most likely to have an impact