Jason G. Goldman: Extinction Happens on the Margins


Keil and his team noted that habitats can be lost in different spatial or geometrical patterns. Is extinction more likely if habitats are lost from the edge of a landscape toward the center or if they’re lost starting from the center? What if habitat loss is not quite so orderly, but more random? To find out, the researchers created four theoretical models that combined the geometry of habitat loss with species extinction, then compared them to bird, mammal, and amphibian distributions in nine real world regions to see which was most useful at predicting the impacts of habitat loss...

Of greater importance to those who aren’t just biogeography theory wonks, the researchers also discovered that extinctions are more likely to occur when landscapes are destroyed from the outside edge towards the center (such as in sea level rise) than if habitats are lost in the reverse direction (such as in urban sprawl). And the geometrical direction of habitat loss actually played a stronger role in determining the loss of species richness than the overall area lost. In other words, a little habitat loss on the edge of a region was worse for biodiversity than more habitat loss towards the center.