Ecological marginalization is widespread and increases extinction risk in mammals

What is it about?

Habitat loss has led to widespread range contraction and population declines across taxa. The impact of range contraction on niche occupancy is rarely, if ever, incorporated into conservation assessments. We evaluate range loss in 4,785 terrestrial mammals and changes in niche parameters of range-contracted species. Range contraction results in more homogenous ranges and reduced niche sizes. Some species become restricted to ecologically extreme habitats at the periphery of their historic niche. This ecological marginalization increases extinction risk. Marginalization can result in a “double whammy” where poor performance in marginalized relict populations exacerbates population declines. This phenomenon is an underappreciated global conservation threat that may partially explain the failure of protected areas to buffer species from further decline.

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Photo by Matt Palmer on Unsplash

Photo by Matt Palmer on Unsplash

Why is it important?

Our results reveal an underappreciate conservation threat for mammals globally. Our findings suggest non-random human transformation has pushed species into ecologically extreme environments where they are unlikely to perform well. Our findings have implications for protected area placement and may explain why some protected areas preform well while others do not.