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BackgroundClimate change in the Himalayas, a biodiversity hotspot, home of many sacred landscapes, and the source of eight largest rivers of Asia, is likely to impact the well-being of ∼20% of humanity. However, despite the extraordinary environmental, cultural, and socio-economic importance of the Himalayas, and despite their rapidly increasing ecological degradation, not much is known about actual changes in the two most critical climatic variables: temperature and rainfall. Nor do we know how changes in these parameters might impact the ecosystems including vegetation phenology.Methodology/Principal FindingsBy analyzing temperature and rainfall data, and NDVI (Normalized Difference Vegetation Index) values from remotely sensed imagery, we report significant changes in temperature, rainfall, and vegetation phenology across the Himalayas between 1982 and 2006. The average annual mean temperature during the 25 year period has increased by 1.5°C with an average increase of 0.06°C yr−1. The average annual precipitation has increased by 163 mm or 6.52 mmyr−1. Since changes in temperature and precipitation are immediately manifested as changes in phenology of local ecosystems, we examined phenological changes in all major ecoregions. The average start of the growing season (SOS) seems to have advanced by 4.7 days or 0.19 days yr−1 and the length of growing season (LOS) appears to have advanced by 4.7 days or 0.19 days yr−1, but there has been no change in the end of the growing season (EOS). There is considerable spatial and seasonal variation in changes in climate and phenological parameters.Conclusions/SignificanceThis is the first time that large scale climatic and phenological changes at the landscape level have been documented for the Himalayas. The rate of warming in the Himalayas is greater than the global average, confirming that the Himalayas are among the regions most vulnerable to climate change.

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The diversity of sexual systems in plants has been generally attributed to selection for an optimal amount of genetic recombination. However, sexual systems such as hermaphroditism (including heterostyly), monoecism, andromonoecism, gynomonoecism, dioecism, androdioecism, and gynodioecism may also be viewed as different patterns of relative resource allocation to paternal and maternal functions to optimize paternal and maternal reproductive success in different ways. These different patterns may arise in large part in response to reproductive competition resulting from sexual selection. But the efficacy of sexual selection in zoophilous species is mainly determined by pollinator behavior. It follows then that the evolution of a particular sexual system must be influenced by the dynamics of the pollination system. The role of pollinators in the evolution of sexual systems is examined by considering several types of interactions between flowers and pollinators. The role of cost-sharing between paternal and maternal functions in pollinator attraction is stressed in the evolution of hermaphroditism. Andromonoecism is considered in terms of loss of pistils in that part of the flower crop which is produced merely to attract pollinators and/or to fulfill male function. In the evolution of andromonoecism to monoecism, the role of stamens of hermaphroditic flowers in the functional integrity of the pollination system is evaluated. The importance of long mouth parts of pollinators to promote compatible pollinations in the evolution of heterostyly is pointed out. The evolution of protogyny is considered in relation to long inhabitation of pollinators in flowers and inflorescences. The evolution of dioecism is examined in relation to the ability of pollinators to respond to minor changes in floral resources thereby altering the patterns of pollen donation and pollen receipt. Finally, the importance of stamens in hermaphroditic plants in attracting pollen collecting bees is emphasized in the maintenance of androdioecism. The development of a general hypothesis to explain the diversity of sexual systems will require not only a comprehensive knowledge of pollination ecology but also a revision of the sexual system classification that will take into account functional gender rather than intrinsic gender estimates based solely on morphology.The flowering plants display a wide variety of sexual systems ranging from obligate selfing in association with self-compatibility to obligate outcrossing in conjunction with self-incompatibility (