Biology subjects

Melotto, A.

Publications and source records attributed to Melotto, A..

2 recordsLinked to original sources

bioRxiv2025

First report of overwintering tadpoles in the endemic Italian agile frog Rana latastei

Climate change is affecting organism seasonality patterns, and this can drive phenological shifts for key traits, including breeding activity. Here we report a first record of overwintering tadpoles of the Italian agile frog (Rana latastei), a threatened endemic species of Northern Italy. This species usually breeds between late January and April, with tadpoles reaching metamorphosis by early summer. In February 2025, together with the first freshly-laid egg-clutches of the season, several large-sized tadpoles were found in one reproductive site of R. latastei in Como province. A few days after hatching, six individuals from newly hatched tadpole cohorts and six individuals from large-sized cohorts were captured, photographed and measured. Concurrently, a newly metamorphosed froglet was found. Results from morphological inspections revealed that individuals showed typical traits of R. latastei. Moreover, while newly hatched tadpoles were at development Gosners stages 25-26, large cohort individuals were visibly bigger and at late development stage, which was not compatible with the classical late winter breeding timing of this species. Our study shows for the first time a case of overwintering in R. latastei, suggesting shifts in this frog development trajectory (prolonged larval time) or breeding habits (autumnal reproduction) may be occurring. While mechanisms behind this unusual observation have to be ascertained, such a phenological shift might have been favoured by variation in climatic regime.

zoology↗

bioRxiv2023

Impacts of invasive fishes on ghost frog tadpoles

Global amphibian populations are declining, and invasive fish are known to impact many threatened species. South Africa has both a biodiverse amphibian fauna and a rich history of invasive fish introductions with high establishment success. Studies have identified some preliminary evidence for negative impacts of invasive salmonids on two ghost frog species (Anura: Heleophrynidae). This study aims to investigate whether these negative impacts previously reported are reflected across a broader scale. Tadpoles of two species, Heleophryne regis and H. purcelli were sampled in the presence and absence of invasive fish at 112 sites across 26 streams in the Western Cape province of South Africa. A generalised linear mixed model showed invasive fish to have the most significant negative effect explaining tadpole abundance. Mean tadpole abundance decreases by 18 times in the presence of invasive fish. Environmental variables with significant effects on tadpole abundance include pH, oxygen saturation, temperature, stream depth and non-native riparian vegetation type. We can define an environmental niche of ghost frog tadpoles which does not differ between species. We conclude that invasive fish have significant negative impacts on ghost frog tadpole abundance, but the effect of the environment should not be overlooked in amphibian conservation planning and invasive species management decisions. This study supports the removal of invasive fish and alien vegetation to improve the conservation of ghost frogs.

ecology↗