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.

Laboratory experiments to determine the maximum size of sediment transported in shallow, rain-impacted flow were conducted in a recirculating flume 4·80 m long and 0·50 m wide. Rainfall intensities were varied between 51 and 138 mm h −1 , flow was introduced from a header tank into the flume at rates ranging from 0 to 0·64 1s −1 , and experiments were conducted on gradients between 3·5 and 10°. The following equation was developed:in which M is particle mass, L is distance moved in unit time (cm min −1 ), RE is rainfall energy (J m −2 s −1 ) and FE is flow energy (J m −2 s −1 ). This equation can be used to predict sediment-transport competence of interrill overland flow. The equation is limited in its utility insofar as it has been developed using quartz grains and takes no account of variations in absorption of rain energy by natural ground surfaces.

The use of environmental DNA (eDNA) to monitor rare and elusive species has great potential for conservation biology. Traditional surveying methods can be time-consuming, labour-intensive, subject to error or can be invasive and potentially damaging to habitat. The Trinidad golden treefrog (Phytotriades auratus) is one such species that would benefit from such an approach. This species inhabits the giant bromeliad (Glomeropitcairnia erectiflora) on two peaks on the Caribbean island of Trinidad. Traditional survey methods for this species have required the destruction of the giant bromeliad, which is the only known habitat of this frog. Here we described the development of an eDNA PCR-based assay that uses water drawn from the water-filled phytotelmata of the giant bromeliad along with the use of a synthetic DNA positive control that can be easily amplified in the bacterium Escherichia coli. The assay can detect to a DNA concentration of 1.4ng. Sampling of 142 bromeliads using this method revealed 9% were positive for P. auratus DNA. These data suggest that eDNA methods also have great potential for revealing the presence of elusive species in arboreal habitats.

The sixth mass extinction is a consequence of complex interplay between multiple stressors with negative impact on biodiversity. We here examine the interaction between two globally widespread anthropogenic drivers of amphibian declines: the fungal disease chytridiomycosis and antifungal use in agriculture. Field monitoring of 26 amphibian ponds in an agricultural landscape shows widespread occurrence of triazole fungicides in the water column throughout the amphibian breeding season, together with a negative correlation between early season application of epoxiconazole and the prevalence of chytrid infections in aquatic newts. While triazole concentrations in the ponds remained below those that inhibit growth of Batrachochytrium dendrobatidis, they bioaccumulated in the newts' skin up to tenfold, resulting in cutaneous growth‐suppressing concentrations. As such, a concentration of epoxiconazole, 10 times below that needed to inhibit fungal growth, prevented chytrid infection in anuran tadpoles. The widespread presence of triazoles may thus alter chytrid dynamics in agricultural landscapes.

12Recent reviews on sexual dichromatism in frogs included Mannophryne trinitatis as the only example 13 they could find of dynamic dichromatism (males turn black when calling) within the family 14 Aromobatidae and found no example of ontogenetic dichromatism in this group. We demonstrate 15 ontogenetic dichromatism in M. trinitatis by rearing post-metamorphic froglets to near maturity: the 16 throats of all individuals started as grey coloured; at around seven weeks, the throat became pale 17 yellow in some, and more strongly yellow as development proceeded; the throats of adults are grey 18 in males and variably bright yellow in females, backed by a dark collar. We demonstrated the degree 19 of throat colour variability by analysing a large sample of females. The red: green (R:G) ratio ranged 20 from ~1.1 to 1.4, reflecting variation from yellow to yellow/orange, and there was also variation in 21 the tone and width of the dark collar, and in the extent to which the yellow colouration occurred 22 posterior to the collar. Female M. trinitatis are known to be territorial in behaviour. We show a quality. Our field observations on Tobago's M. olmonae showed variability in female throat colour 25 and confirmed that males in this species also turn black when calling. Our literature review of the 20 26 Mannophryne species so far named showed that all females have yellow throats with dark collars, 27 and that male colour change to black when calling has been reported in eight species; in the 28 remaining 12 species, descriptions of males calling are usually lacking so far. We predict that both 29 dynamic and ontogenetic sexual dichromatism are universal in this genus and provide discussion of 30 the ecological role of dichromatism in this genus of predominantly diurnal, non-toxic frogs, with 31 strong paternal care of offspring. 32 Keywords: Aromobatidae, Anurans, Mannophryne, sexual dichromatism, sexual signalling 33 36 found, a wide diversity of visual signalling (movements, colours, patterns, shapes) both in diurnal 37 and in nocturnal species is becoming established. For example, Rojas (1) reviewed the roles of 38 colours and patterns, Hodl and Amezquita (2) reviewed and classified the variety of visual signals, 39 and Starnberger et al. (3) discussed the multimodal roles of the vocal sac in signalling: not only 40 auditory, but also visual and chemical in some cases. One category of visual signals involves sexual 41 dichromatism, reviewed by Bell and Zamudio (4). They distinguished two types. First, dynamic 42 dichromatism, restricted to males, where the male develops a temporary colour signal related to 43 courtship and breeding. The review identified 31 species in nine families where this occurred. 44 Second, ontogenetic dichromatism, where either males or females develop a permanent colour 45 difference as they mature. The review found this reported from 92 species in 18 families. Bell et al. 46 (5) extended the dataset for dynamic dichromatism to 178 species in 15 families and subfamilies. Dynamic sexual dichro...