Lizards of the Thar Desert e Resource partitioning and community composition Ishan Agarwal * , Surendra P. Goyal, Qamar Qureshi Wildlife Institute of India, Chandrabani, Dehradun 248001, India article info Article history: Received 21 December 2012 Received in revised form 17 February 2015 Accepted 2 March 2015 Available online 10 March 2015 Keywords: Desert lizard community Visual encounter survey Spatial overlap Daily activity India abstract How similar species co-exist in nature is a fundamental question in community ecology. Resource par- titioning has been studied in desert lizard communities across four continents, but data from South Asia is lacking. We used area-constrained visual encounter surveys to study community composition and spatial and temporal resource partitioning in a lizard community during summer in the Thar Desert, western India, addressing an important biogeographic gap in knowledge. Twelve one-hectare grids divided into 25 m  25 m plots were placed across four habitats e barren dunes, stabilized dunes, grassland, and rocky hills. We recorded 1039 sightings of 12 species during 84 sampling sessions. Lizard abundance decreased in the order stabilized dunes > grassland > barren dunes > rocky hills; richness was in roughly the opposite order. Resource partitioning was examined for the seven commonest spe- cies. Overall spatial overlap was low (<0.6) between species pairs. Overlap was higher within habitats, but species showed finer separation through use of different microhabitat categories and specific spatial resources, as well as by positioning at different distances to vegetation. Diurnal species were also separated by peak time of activity. Space appears to be an important resource dimension facilitating co- existence in this desert lizard community. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction How do similar species co-exist in nature? Answering this fundamental question involves studying how species in a com- munity partition multivariate niche space (Schoener, 1974). The three major niche dimensions across which resource partitioning has been studied are space, food and time (Pianka, 1973; Schoener, 1974). Space is among the most important resource dimensions that is partitioned in lizards (Pianka, 1973, 1986; Schoener, 1974; Toft, 1985; Vitt et al., 2000; Luiselli, 2007a). Species that are broadly sympatric in a region may or may not co-occur within specific habitats; and species that do co-occur within habitats often partition microhabitat resources, restricting further overlap (Pianka, 1973, 1986; Toft, 1985). Time of activity is closely linked to the thermoregulatory and foraging behavior of a species, and ex- poses lizards to differing food resources, in addition to reducing interspecific encounters (Pianka, 1986). Though differentiation along the trophic niche has been long investigated, a recent meta- analysis using null models demonstrated that most lizard com- munities do not partition the trophic niche (Luiselli, 2007b). Thus, spatial and temporal segregation appear to be important in allowing the co-existence of sympatric lizards. Desert lizard communities have proved to be a useful natural system to answer a range of questions in community ecology, with studies spanning four continents (e.g. Pianka, 1986; Shenbrot et al., 1991; Rogovin et al., 2000). The reasons these communities have been extensively studied include that desert lizards are habitat specific, diverse, relatively abundant, and easily detectable (Pianka, 1986; Toft, 1985); resources are likely to be limiting in deserts; and that the desert provides a simple system in which to explore ecological questions and hypotheses (Pianka, 1986; Kotler and Brown, 1988). The lizard community of the Thar Desert in Western India and adjacent Pakistan is poorly studied, with previous work limited to checklists, and even basic information on community composition lacking. In order to address this biogeographic gap in knowledge, we examined spatial and temporal resource partitioning in the lizard community of the Thar Desert, Jaisalmer District, Rajasthan, India. Besides collecting data on community composition, we asked * Corresponding author. Present address: Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India. E-mail addresses: ishan.agarwal@gmail.com (I. Agarwal), goyalsp@wii.gov.in (S.P. Goyal), qnq@wii.gov.in (Q. Qureshi). Contents lists available at ScienceDirect Journal of Arid Environments journal homepage: www.elsevier.com/locate/jaridenv http://dx.doi.org/10.1016/j.jaridenv.2015.03.003 0140-1963/© 2015 Elsevier Ltd. All rights reserved. Journal of Arid Environments 118 (2015) 58e64