Gosavi, N. | bioRxiv Science

bioRxiv2025

Effects of tree plantations on population and roosting ecology of an endemic agamid lizard in Western Ghats Biodiversity Hotspot

Low-elevation wet tropical forests support herpetofaunal diversity but are increasingly replaced by monoculture tree plantations and have poor Protected Area coverage, leaving herpetofauna vulnerable. Research on how monoculture plantations affect reptile populations remains inconclusive, and the ecology of endemic species in these changing landscapes is poorly understood. We compared densities and roosting ecology of Monilesaurus rouxii, an endemic agamid lizard, across low- and high-elevation forests and cashew and rubber plantations in the Western Ghats Biodiversity Hotspot using nocturnal transects. We found that low-elevation forests, despite poor Protected Area coverage, had significantly higher densities of Monilesaurus rouxii than high-elevation forests and cashew plantations. Roost site use did not differ significantly across the different land-use, indicating roost fidelity. However, Monilesaurus rouxii exhibited ontogenetic shifts in roosting substrate and height. Our findings highlight the conservation importance of unprotected low-elevation forests, which are rapidly being converted to monoculture tree plantations. We show that plantation types may differ in their impacts on reptile populations. We also show the utility of nocturnal transects for population estimation of diurnal lizards.

ecology↗

bioRxiv2024

Effects of land use change and elevation on endemic shrub frogs in a biodiversity hotspot

Agroforestry, often promoted as a sustainable agriculture practice, is rapidly expanding, often at the cost of primary tropical forests. While agroforestry impacts amphibian diversity negatively, its effects on population demography, microhabitat use and body condition are relatively understudied. This information is crucial for determining and promoting amphibian-friendly land use practices. We compared habitats, population densities, microhabitat use, and body condition of two endemic species of shrub frogs (Pseudophilautus amboli and Raorchestes bombayensis) across 1) elevations (low- and high-elevation forests) and 2) land use categories (cashew, rubber, and low-elevation forests) in the northern part of the Western Ghats Biodiversity Hotspot. Using distance sampling, we demonstrated that abundances of the two shrub frog species differed across elevation categories, with Pseudophilautus more common in low-elevation forests and Raorchestes more prevalent in high-elevation forests. Both species of frogs exhibited extremely skewed, male-biased sex ratios, with three females for 100 males. Pseudophilautus had lower densities and poor recruitment and exhibited altered microhabitat use in cashew plantations compared to low-elevation forests. Although adult male Pseudophilautus densities in rubber were similar to those in low-elevation forests, they exhibited altered microhabitat use and smaller body sizes than in forests, indicating poor body condition. We demonstrate differential impacts of agroforestry types on shrub frogs. We also demonstrate that distance sampling can be a useful tool for population monitoring of shrub frogs, which comprise almost 25% of the anuran diversity in the Western Ghats. Additionally, there is a need to identify the drivers of extremely skewed sex ratios, which make these species vulnerable to population crashes. Considering the recent downlisting of the two focal species to Least Concern, we advocate for their uplisting to at least Near Threatened status in light of their patchy distribution, negative impacts of rapidly expanding agroforestry plantations and extremely skewed sex ratios.

ecology↗