ABSTRACT
Elevational patterns in species distributions and diversity represent promising sources of evidence for the ecological effects of climate change. Elevational patterns in diversity are sometimes argued to be a consequence of climatic limits to individual species distributions, and considerable empirical data have been collected to inform this debate (Rahbek 1995; Lomolino 2001; McCain 2005). Apart from this wealth of theory and baseline evidence, there are also strong arguments why species should be expected to shift their distributions more quickly across elevational rather than latitudinal gradients as the climate warms. First, temperature and other climate variables change over much shorter geographical distances with elevation than with latitude, and indeed in the Tropics there are only weak latitudinal climate gradients (Colwell et al. 2008), so that species do not need to shift elevations as far as latitudes to remain in suitable climate space. Second, human impact is generally less pronounced in mountain environments than at lower elevations (Ellis and Ramankutty 2008; Nogués-Bravo et al. 2008). As a result, species should be able to
Background ............................................................................................................ 107 Reported Elevational Shifts in Species Distributions ............................................ 109 Identi¡cation of Uphill Range Shifts ..................................................................... 115 Attribution of Range Shifts to Effects of Climate Change .................................... 116 Mechanisms behind Uphill Range Shifts ............................................................... 119 Modeling Effects of Uphill Range Shifts on Biodiversity ..................................... 121 Synthesis, Future Directions, and Conservation .................................................... 123 Acknowledgments .................................................................................................. 125 Summary ................................................................................................................ 126 References .............................................................................................................. 126
track the distribution of suitable climates more readily by colonizing natural habitats in mountains rather than by moving across lowlands dominated by intensive human land use, where the distributions of many species are failing to keep up with climate change (Warren et al. 2001; Menéndez et al. 2006).
