No abstract

Human land-use results in widespread range change across taxa. Anthropogenic pressures can result in species’ realized niches expanding, shifting, or contracting. Marginalization occurs when contraction constrains species to the geographic or ecological extremes of their historic niche. Using 4,785 terrestrial mammal species, we show that range contraction results in niche space and habitat diversity loss. Additionally, ecological marginalization is a common consequence of range contraction caused by human land use change. Remnant populations become located in the climatic and topographic extremes of their historic niche that are more likely to be at the periphery of their historic niche at greater distances from historic niche centroids. This ecological marginalization is associated with poor performance and increased extinction risk independent of geographic range loss. Range loss and marginalization may create a “double whammy” in vulnerable groups, such as large-bodied species and species with small geographical range size. Our results reveal a hitherto unrecognized conservation threat that is vital to incorporate into conservation assessment and management.

One in five vertebrate species is classified by the IUCN as vulnerable, endangered, or critically endangered (Hoffmann et al., 2010). These declines and losses are largely attributed to anthropocentric changes in the environment such as land conversion, climate change, and unsustainable natural resource harvesting and extraction (Brook et al., 2008).Ultimately, range contraction and biodiversity loss are the end product of extrinsic or intrinsic challenges leading to population decline, emigration, and local extirpation. Across a species' range, populations occur