Can’t see the wood for the trees? Canopy physiognomy influences the distribution of peninsular Indian flying lizards

Abstract

Aim In the absence of topographic barriers to dispersal, spatial boundaries of species are largely governed by the environmental regimes they occupy. Flying lizards (Agamidae: Draco) from peninsular India have surmounted prominent geographic barriers, but their northern distribution abruptly ends at the ‘Goa gap’, a latitudinal boundary separating the wet and dry regions of the Western Ghats. Given their exclusively arboreal habits, we posit that canopy physiognomy determines Draco distribution in regions of climatic suitability. Location Peninsular India. Taxa Draco dussumieri, Monilesaurus rouxii. Methods We analysed occurrence data collated from multiple sources against a suite of climatic and canopy‐specific predictors to model the occurrence of Draco. We used an information theoretic approach to binary logistic regression that incorporates presence/absence data, along with a maximum entropy‐based algorithm that models ecological niches in space using presence‐only data. Climatic data were obtained from CHELSA and WorldClim. We compared models for Draco dussumieri with the only other largely sympatric, arboreal agamid, Monilesaurus rouxii, which spans the Goa gap. Finally, we statistically tested how regions Draco inhabits differ in canopy physiognomy from the regions in the Western Ghats where it does not occur. Results Canopy height was the most influential predictor of Draco presence in regions of climatic suitability under both the logistic regression and maximum entropy models. While climatically suitable regions occur north of the Goa gap, these regions harbour significantly lower canopies with lesser coverage. Despite a narrower range of climatic suitability, Monilesaurus has spanned the Goa gap, presumably because it is less dependent on canopy traits. Main conclusions Lower canopies with lesser coverage act as a biogeographic barrier for the dispersal of Draco into regions of climatic suitability. In addition to being a climatic boundary, the Goa gap serves as a vegetational barrier that demarcates regions with significantly dissimilar canopy physiognomies. Our study highlights the importance of quantifying environmental regimes that organisms occupy to better understand distribution patterns. Our results implicitly predict the effects of deforestation on Draco distribution in the peninsula and therefore, influence its conservation strategy.

Modelling 21st century refugia and impact of climate change on Amazonia's largest primates

“…In light of these forewarning scenarios and recognizing the large potential for lagged primate responses to climate change (Sales et al 2020c), the identification of 21st century refugia that contain critical habitat features is a crucial step towards effective conservation and management of these strictly arboreal taxa. Suitable habitat physiognomy in terms of vegetation and soil conditions needs to remain coupled with suitable climatic conditions to guarantee the continued existence of colonizable habitats (Chaitanya and Meiri 2021). In addition, our results suggest a potentially extensive and significant mismatch between the climatic and the edaphic/vegetation niche dimensions of the ateline habitat in the near future.…”

“…Landsat satellites are equipped with multispectral sensors that can capture images of the Earth's surface in multiple wavelength bands that carry essential information and environmental process that underlie the geographic distributions of species (e.g. vegetation phenology: Bobrowski et al 2018, edaphic properties: Van doninck et al 2020, canopy physiognomy: Chaitanya and Meiri 2021, land use change: Ma et al 2021). A Landsat TM/ETM+ image composite, encompassing the entire Amazon biome, has been instrumental in identifying relatively stable habitat features in the region and enhancing the performance of SDMs (Van doninck and Tuomisto 2018, Tuomisto et al 2019, Van doninck et al 2020).…”

Their fates intertwined: diversification patterns of the Asian gliding vertebrates may have been forged by dipterocarp trees

“…However, it may be argued that climate change during the Pliocene-Pleistocene could have exclusively and independently affected the diversification of the gliding vertebrates. Chaitanya & Meiri [29] quantitatively showed that the Indian gliding lizard Draco dussumieri is unable to disperse into regions devoid of dipterocarps, despite climatic suitability. This suggests most gliding vertebrates may require the presence of dipterocarps even in regions where climate is suitable for their persistence.…”

“…Asian gliding vertebrate clades are largely restricted to regions dominated by Dipterocarpoideae (figure 1). Chaitanya & Meiri [29] show that gliding vertebrates such as the peninsular Indian Draco dussumieri seem unable to disperse into regions that are devoid of tall trees like dipterocarps, despite climatic suitability [29] (but see flying squirrels; figure 1 d ). Globally, gliding vertebrates are most speciose in Southeast Asia that harbours the greatest diversity of dipterocarps.…”