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Desiccation-tolerant vascular (DT) plants are predominant occupants of rock outcrops in tropical regions. Though rock outcrops are common landscapes in the Western Ghats (WG), a biodiversity hotspot in India, knowledge of DT plants in the region is poor. This study provides an overview of Indian DT vascular plants, emphasizing the WG, and includes an inventory of species with their habitat preferences. Outcrop species were scrutinized for their DT properties by seasonal field observations, followed by relative water content estimation protocols. The inventory revealed 62 DT species, many more than the earlier known nine species. Nine genera of DT plants are reported as new also in a global perspective, and Tripogon capillatus represent the first record of an epiphytic DT angiosperm. We also provide the first field observation-based proof of DT properties of the gesneriad Corallodiscus lanuginosus. Of the 62 species, 16 are Indian endemic, and 12 are exclusive to Western Ghat outcrops, highlighting WG's importance as a global DT hotspot. In addition to rock outcrops, partially shaded sites in forests are crucial habitats for DT species. This pioneering inventory addresses India's need for more knowledge on DT plants and opens new research avenues. [ABSTRACT FROM AUTHOR]

Rock outcrops support specialist plant communities that are often adapted to highly seasonal climates and heterogeneous soil cover. However, the relationship between environmental parameters and plant functional types remains unexplored in many regions of the world, including the Northern Western Ghats (NWG) in India. In the present work, we characterised the vegetation of high and low elevation rock outcrops in the NWG, and investigate the relationship between plant functional types and environmental variables. Vegetation surveys were conducted on 16 high elevation and 14 low elevation sites using a transect and quadrat method. Floristic data were used to calculate plant diversity and plant functional type abundance. The relationship between vegetation and climatic (temperature, precipitation) and soil (soil carbon and nitrogen) variables was explored using cluster and ordination analysis. Rock outcrop sites were grouped into two clusters based on elevation, distance from the sea and mean diurnal range. Plant functional type abundance was related to macro-environmental variables such as temperature, precipitation and soil nutrients such as carbon and nitrogen. We inferred that the distribution and dominance of different plant functional types in the NWG are related to primarily by elevation (a proxy for temperature) and distance from the sea. [ABSTRACT FROM AUTHOR]

When the habitat occupied by a specialist species is patchily distributed, limited gene flow between the fragmented populations may allow population differentiation and eventual speciation. 'Sky islands'—montane habitats that form terrestrial islands—have been shown to promote diversification in many taxa through this mechanism. We investigate floral variation in Impatiens lawii, a plant specialized on laterite rich rocky plateaus that form sky islands in the northern Western Ghats mountains of India. We focus on three plateaus separated from each other by ca. 7 to 17 km, and show that floral traits have diverged strongly between these populations. In contrast, floral traits have not diverged in the congeneric I. oppositifolia, which co-occurs with I. lawii in the plateaus, but is a habitat generalist that is also found in the intervening valleys. We conducted common garden experiments to test whether the differences in I. lawii are due to genetic differentiation or phenotypic plasticity. There were strong differences in floral morphology between experimental plants sourced from the three populations, and the relative divergences between population pairs mirrored that seen in the wild, indicating that the populations are genetically differentiated. Common garden experiments confirmed that there was no differentiation in I. oppositifolia. Field floral visitation surveys indicated that the observed differences in floral traits have consequences for I. lawii populations, by reducing the number of visitors and changing the relative abundance of different floral visitor groups. Our results highlight the role of habitat specialization in diversification, and corroborates the importance of sky islands as centres of diversification. [ABSTRACT FROM AUTHOR]