Conserving biodiversity under climate change: the rear edge matters

TLDR

Climate change drives poleward shifts of many taxa, yet rear-edge populations—understudied low‑latitude limits—serve as key reservoirs of genetic diversity and speciation, and their unique dynamics mean conventional conservation practices may be ineffective or harmful. The review demonstrates that rear-edge populations are disproportionately critical for biota survival and evolution. The authors synthesize fossil, phylogeographic, and ecological evidence to assess the importance of rear-edge populations.

Abstract

Abstract Modern climate change is producing poleward range shifts of numerous taxa, communities and ecosystems worldwide. The response of species to changing environments is likely to be determined largely by population responses at range margins. In contrast to the expanding edge, the low‐latitude limit (rear edge) of species ranges remains understudied, and the critical importance of rear edge populations as long‐term stores of species’ genetic diversity and foci of speciation has been little acknowledged. We review recent findings from the fossil record, phylogeography and ecology to illustrate that rear edge populations are often disproportionately important for the survival and evolution of biota. Their ecological features, dynamics and conservation requirements differ from those of populations in other parts of the range, and some commonly recommended conservation practices might therefore be of little use or even counterproductive for rear edge populations.