Batrachochytrium dendrobatidis (Bd), the causative agent of the amphibian disease chytridiomycosi... more Batrachochytrium dendrobatidis (Bd), the causative agent of the amphibian disease chytridiomycosis, is an important factor in the global decline of amphibians. Within Europe, animals that exhibit clinical signs of the disease have only been reported in Spain despite the pathogen's wide, but patchy, distribution on the continent. Recently, another occurrence of chytridiomycosis was reported in Euproctus platycephalus, the Sardinian brook newt, on the Mediterranean island of Sardinia, but without any evidence of fatal disease. We report further evidence of the emergence of Bd on Sardinia and the first evidence of lethal chytridiomycosis outside of Spain. Unusual mortalities of the Tyrrhenian painted frog (Discoglossus sardus) were found at three sites in the Limbara mountains of northern Sardinia. Molecular and histological screens of corpses, frogs, and tadpoles from these sites revealed infection with Bd. Infection and mortality occurred at locations that are unusual in terms of the published habitat requirements of the pathogen. Given the endemicity, the IUCN Red
Aim In a highly endemic, threatened amphibian assemblage, we measure and describe the geographic ... more Aim In a highly endemic, threatened amphibian assemblage, we measure and describe the geographic and taxonomic distribution of the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), with a view to identifying those sites and species most at risk of infection and its negative consequences. Additionally, we aimed to determine the potential for direct transmission events between two known carriers of Bd infection.
Introduction Batrachochytrium dendrobatidis (from here onwards Bd) is largely implicated in globa... more Introduction Batrachochytrium dendrobatidis (from here onwards Bd) is largely implicated in global amphibians declines (Berger et al., 1998). After the first report of chytridiomycosis infection in amphibian wild populations, dating back to the late nineties (Berger et al., 1998; ...
Sexual size dimorphism (SSD) is widespread among amphibians, and it is attributed to fecundity se... more Sexual size dimorphism (SSD) is widespread among amphibians, and it is attributed to fecundity selection, invoked for female-biased-SSD species, sexual selection, usually invoked for male-biased-SSD species, or other forms of natural selection. Further, SSD interplays with body size variability at population level. By using a male-biased-SSD newt (Euproctus platycephalus) as model species, we investigated body size and SSD variability across the whole species' range, the island of Sardinia, looking for the main evolutionary force behind SSD. We found geographic variation of body size and SSD: newts from northern populations were generally larger than those from southern ones, with a larger degree of male biased dimorphism in the former. The mean age of newts varied among populations, but it did not follow any geographical pattern, and it did not differ between sexes. Southern populations reached sexual maturity earlier than northern ones, and maturity was positively correlated with temperature. Growth curves show that northern populations achieved male-biased SSD before reaching sexual maturity, whilst in the south males become larger than females after 6 years in age, following a non-asymptotic growth curve. The geographical pattern of the adult body size variation is attributable to delayed maturation of the larger newts in more northerly populations, and earlier sexual maturation Electronic supplementary material The online version of this article (due to warmer temperature in southern populations, which leads to smaller body size. SSD varies consistently with body size: it is evident in the north, where sexual bimaturation caused larger males, but it is weak in the south, where warmer temperature caused an earlier maturation of both sexes.
Batrachochytrium dendrobatidis (Bd), the causative agent of the amphibian disease chytridiomycosi... more Batrachochytrium dendrobatidis (Bd), the causative agent of the amphibian disease chytridiomycosis, is an important factor in the global decline of amphibians. Within Europe, animals that exhibit clinical signs of the disease have only been reported in Spain despite the pathogen's wide, but patchy, distribution on the continent. Recently, another occurrence of chytridiomycosis was reported in Euproctus platycephalus, the Sardinian brook newt, on the Mediterranean island of Sardinia, but without any evidence of fatal disease. We report further evidence of the emergence of Bd on Sardinia and the first evidence of lethal chytridiomycosis outside of Spain. Unusual mortalities of the Tyrrhenian painted frog (Discoglossus sardus) were found at three sites in the Limbara mountains of northern Sardinia. Molecular and histological screens of corpses, frogs, and tadpoles from these sites revealed infection with Bd. Infection and mortality occurred at locations that are unusual in terms of the published habitat requirements of the pathogen. Given the endemicity, the IUCN Red
Aim In a highly endemic, threatened amphibian assemblage, we measure and describe the geographic ... more Aim In a highly endemic, threatened amphibian assemblage, we measure and describe the geographic and taxonomic distribution of the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), with a view to identifying those sites and species most at risk of infection and its negative consequences. Additionally, we aimed to determine the potential for direct transmission events between two known carriers of Bd infection.
Introduction Batrachochytrium dendrobatidis (from here onwards Bd) is largely implicated in globa... more Introduction Batrachochytrium dendrobatidis (from here onwards Bd) is largely implicated in global amphibians declines (Berger et al., 1998). After the first report of chytridiomycosis infection in amphibian wild populations, dating back to the late nineties (Berger et al., 1998; ...
Sexual size dimorphism (SSD) is widespread among amphibians, and it is attributed to fecundity se... more Sexual size dimorphism (SSD) is widespread among amphibians, and it is attributed to fecundity selection, invoked for female-biased-SSD species, sexual selection, usually invoked for male-biased-SSD species, or other forms of natural selection. Further, SSD interplays with body size variability at population level. By using a male-biased-SSD newt (Euproctus platycephalus) as model species, we investigated body size and SSD variability across the whole species' range, the island of Sardinia, looking for the main evolutionary force behind SSD. We found geographic variation of body size and SSD: newts from northern populations were generally larger than those from southern ones, with a larger degree of male biased dimorphism in the former. The mean age of newts varied among populations, but it did not follow any geographical pattern, and it did not differ between sexes. Southern populations reached sexual maturity earlier than northern ones, and maturity was positively correlated with temperature. Growth curves show that northern populations achieved male-biased SSD before reaching sexual maturity, whilst in the south males become larger than females after 6 years in age, following a non-asymptotic growth curve. The geographical pattern of the adult body size variation is attributable to delayed maturation of the larger newts in more northerly populations, and earlier sexual maturation Electronic supplementary material The online version of this article (due to warmer temperature in southern populations, which leads to smaller body size. SSD varies consistently with body size: it is evident in the north, where sexual bimaturation caused larger males, but it is weak in the south, where warmer temperature caused an earlier maturation of both sexes.
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