Micro-habitat distribution drives patch quality for sub-tropical rocky plateau amphibians in the northern Western Ghats, India

Abstract

The importance of patch quality for amphibians is frequently overlooked in distribution models. Here we demonstrate that it is highly important for the persistence of endemic and endangered amphibians found in the threatened and fragile ecosystems that are the rocky plateaus in Western Maharashtra, India. These plateaus are ferricretes of laterite and characterise the northern section of the Western Ghats/Sri Lanka Biodiversity Hotspot, the eighth most important global hotspot and one of the three most threatened by population growth. We present statistically supported habitat associations for endangered and data-deficient Indian amphibians, demonstrating significant relationships between individual species and their microhabitats. Data were collected during early monsoon across two seasons. Twenty-one amphibian taxa were identified from 14 lateritic plateaus between 67 and 1179m above sea level. Twelve of the study taxa had significant associations with microhabitats using a stepwise analysis of the AICc subroutine (distLM, Primer-e, v7). Generalist taxa were associated with increased numbers of microhabitat types. Non-significant associations are reported for the remaining 9 taxa. Microhabitat distribution was spatially structured and driven by climate and human activity. Woody plants were associated with 44% of high-elevation taxa. Of the 8 low-elevation taxa 63% related to water bodies and 60% of those were associated with pools. Rock size and abundance were important for 33% of high elevation specialists. Three of the 4 caecilians were associated with rocks in addition to soil and stream presence. We conclude the plateaus are individualistic patches whose habitat quality is defined by their microhabitats within climatic zones.

Climate structuring ofBatrachochytrium dendrobatidisinfection in the threatened amphibians of the northern Western Ghats, India

“…Regional differences in habitat and micro-habitat availability may also help explain the pattern in Bd distribution, through behavioural mitigation where amphibians move to, or persist on, plateaus with micro-habitats that are refugia from Bd [ 55 , 57 , 67 ]. Conversely, stream micro-habitats offer one possible transmission route in the Low Region, where streams are more frequent [ 55 ]. Sub-tropical stream-breeders are more susceptible to Bd and may be disease vectors with the pathogen spreading from streams into the terrestrial realm [ 67 , 68 ].…”

“…This idea possibly supported by the results for the four species of caecilian in the study which have similar prevalence to non-fossorial taxa ( table 1 ; electronic supplementary material, tables S4 and S5). They are frequently found under loose rocks where temperatures are tolerable for Bd and are close to streams which may be used by stream-breeding anuran vectors [ 55 , 67 ].…”

“…In addition to proximity of human habitation, changes in land-use influences amphibian distribution, and possibly their susceptibility and exposure to disease [ 55 , 73 , 74 ]. Sites near human habitation are likely to have anthropogenic land-uses.…”

“…Optimum rainfall for Bd is reported to be between 1500 and 2500 mm a year. Only the low lying plateaus fall within this range, the plateaus along the top of the escarpment receiving between 4000 and 9000 mm, with the exception of Masai which is east of the ridge and may be drier [ 10 , 55 ].…”

When to be a male? Role of resource-limitation and pollinators in determining floral sex in an andromonoecious spiderwort

“…Here, we show that the M. simplex population on Kaas plateau has a higher density of male flowers and a slight reduction in the number of male flowers and an increase in hermaphrodite flowers were observed only among the individuals present along the stream. We consider the stream population of M. simplex to be growing in better resource conditions than the plateau population because of the presence of water, possible higher nutrient availability due to dissolved/associated nutrients in the water, and deeper soil substrate for the plants (Thorpe et al 2018). This suggests that although the general tendency of M. simplex is to produce more male flowers over hermaphrodites, water and waterdissolved minerals may be major limiting resources and in the absence of resource constraints the plants can produce not only more flowers but also higher number of hermaphrodite flowers.…”