Presence of low virulence chytrid fungi could protect European amphibians from more deadly strains

Wildlife diseases are contributing to the current Earth’s sixth mass extinction; one disease, chytridiomycosis, has caused mass amphibian die-offs. While global spread of a hypervirulent lineage of the fungus Batrachochytrium dendrobatidis (BdGPL) causes unprecedented loss of vertebrate diversity by decimating amphibian populations, its impact on amphibian communities is highly variable across regions. Here, we combine field data with in vitro and in vivo trials that demonstrate the presence of a markedly diverse variety of low virulence isolates of BdGPL in northern European amphibian communities. Pre-exposure to some of these low virulence isolates protects against disease following subsequent exposure to highly virulent BdGPL in midwife toads (Alytes obstetricans) and alters infection dynamics of its sister species B. salamandrivorans in newts (Triturus marmoratus), but not in salamanders (Salamandra salamandra). The key role of pathogen virulence in the complex host-pathogen-environment interaction supports efforts to limit pathogen pollution in a globalized world.

A genomic footprint of a moving hybrid zone in marbled newts

We developed a panel of 44 nuclear genetic markers and applied this to two species of marbled newts in the north (Triturus marmoratus) and the south (T. pygmaeus) of the Iberian Peninsula, to document pattern and process of interspecific gene flow. The northernmost occurrence of T. pygmaeus genetic material was in a T. marmoratus population north of the Vouga river estuary. This suggested the past presence of a hybrid zone, possibly coinciding with a natural river outlet at ca. 1200 A.D. Since 1808, the species contact has moved back south to a by then completed, man-made Vouga channel. We also found evidence for a T. marmoratus genomic footprint in T. pygmaeus from the Serra de Sintra, near Lisbon. In combination with a previously reported southern, relic occurrence of T. marmoratus in between both areas, the data point to the superseding with hybridization of T. marmoratus by T. pygmaeus. We estimate that the species hybrid zone has moved over a distance of ca. 215 km.

Influence of substrate types and morphological traits on movement behavior in a toad and newt species

Background Inter-patch movements may lead to genetic mixing, decreasing both inbreeding and population extinction risks, and is hence a crucial aspect of amphibian meta-population dynamics. Traveling through heterogeneous landscapes might be particularly risky for amphibians. Understanding how these species perceive their environment and how they move in heterogeneous habitats is an essential step in explaining metapopulation dynamics and can be important for predicting species’ responses to climate change and for conservation policy and management. Methods Using an experimental approach, the present study focused on the movement behavior (crossing speed and number of stops) on different substrates mimicking landscape components (human-made and natural substrates) in two amphibian species contrasting in locomotion mode: the common toad (Bufo bufo), a hopping and burrowing anuran and the marbled newt (Triturus marmoratus), a walking salamander. We tested the hypothesis that species reaction to substrate is dependent on specific ecological requirements or locomotion modes because of morphological and behavioral differences. Results In both species, substrate type influenced individual crossing speed, with individuals moving faster on soil than on concrete substrate. We also demonstrated that long-legged individuals moved faster than individuals with short legs. In both species, the number of stops was higher in females than in males. In common toads, the number of stops did not vary between substrates tested, whereas in marbled newts the number of stops was higher on concrete than on soil substrate. Discussion We highlighted that concrete substrate (mimicking roads) negatively affect the crossing speed of both studied species, with an effect potentially higher in marbled newts. Our findings corroborate negative effects of such heterogeneous landscapes on movement behavior of two amphibian species, which may have implications for the dynamics of metapopulations.

Distribution of herpetofauna in caves of Portuguese karst massifs

Amphibians are frequently found exploring subterranean environments. Even though in Europe there are already some reports of amphibians present in subterranean habitats, in Portugal there is a major lack of knowledge of these ecosystems, namely in the karst region. Considering the relevance of amphibians and their current conservational status, it is important to assess their presence in every potential habitat. In order to provide further knowledge over this subject a preliminary survey was carried out in two Portuguese karst massifs, Estremenho and Sicó. A total of 24 caves were surveyed and as result three species (Tarentola mauritanica; Salamandra salamandra and Pleorodeles waltl) were found in Estremenho karst massif, and two species (Triturus marmoratus and Bufo bufo) were observed in Sicó karst massif. Furthermore, evidences were found that P. waltl uses caves for reproduction, which had only been reported once in Spain. This allowed perceiving that herpetofauna species occupy caves of Portuguese karst massifs and are also using them as reproduction sites.