Study area
South Asia covers an area of approximately 3.75 million sq km, and
comprises the countries of Afghanistan, Bangladesh, Bhutan, India, the
Maldives, Nepal, Pakistan, and Sri Lanka (Figure 1). The region consists
of four broad climate zones (Oliver, 2005): dry subtropical in the far
North, equatorial in the far South, alpine in the mountainous regions,
and tropical (with regional variations) in most of the rest of the
subcontinent. According to the Koppen-Geiger climate classification
system (Peel et al., 2007), the region comprises 15 different climatic
subtypes, dominated by subtropical climates (humid summer, dry winter)
in the north and the Indo-Gangetic plain, and tropical savanna climates
(wet and dry) in the central, eastern, and peninsular regions. Most of
the west and north-west of South Asia consists of arid and desert
climates. Due to the large topographical variation in this region, the
variety of elevations, soil types, and biomes in South Asia is very
complex (Ramankutty et al., 2018). To avoid biases based on political
boundaries, the focal area for the analysis was defined by a rectangular
extent around the borders of South Asia (Figure 1). Due to the Himalayas
and trans-Himalayan regions forming a barrier to bat movement and
presence (Ruedi et al., 2008; Thapa et al., 2021), the regions of China
that fell under this extent were removed, thus creating a dispersal
boundary on the northern border of Nepal, which coincides with the
Himalayas. Additionally, due to distance and isolation from most of the
study area, a small region of Indonesia (Sumatra) within the study
extent was removed (Figure 1). Three of the world’s major biodiversity
hotspots (Myers et al., 2000): Himalayas, Indo-Burma, and the Western
Ghats and Sri Lanka, are located within the focal area for analysis.