Global Study Reveals Universal “Core-to-Edge” Pattern in Species Distribution

Despite the Earth's diverse environments, a new international study led by Umeå University in Sweden has uncovered a striking global pattern in biodiversity: all terrestrial and marine bioregions share a similar “core-to-edge” species distribution structure. In each region, a central core area hosts the majority of species, while fewer species manage to survive and spread toward the periphery.

Published in Nature Ecology & Evolution, the research examined species distributions across amphibians, birds, dragonflies, mammals, marine rays, reptiles, and trees. Remarkably, the same core-area pattern was consistent across all groups, suggesting that these central zones act as crucial sources of biodiversity.

The team analyzed bioregions separated by natural barriers like oceans and mountains, which limit species migration and foster independent evolutionary processes. While researchers initially expected substantial variation due to differences in species’ mobility (e.g., flying vs. swimming), environmental conditions, and historical contexts, they were surprised to find a consistent distribution model globally.

The study also identified the driving mechanism behind this pattern: only species capable of adapting to local conditions—such as extreme heat or drought—can survive and expand into new territories. Though this concept has long been a central theory in ecology, this study provides the first large-scale empirical validation across multiple life forms and geographic scales.

Importantly, the findings highlight that relatively small areas can play an outsized ecological role in sustaining biodiversity across entire regions, underscoring their high conservation value.