A new global study has uncovered a universal rule that shapes how life is distributed across Earth’s varied environments. Though species might appear to be randomly scattered across landscapes and oceans, researchers found that biodiversity follows a clear and repeated spatial pattern that applies to many different types of organisms and regions. Published in Nature Ecology & Evolution, the study analyzed data from over 30,000 species, including amphibians, birds, dragonflies, non-flying mammals, rays, reptiles, and trees.
The research team, made up of scientists from Umeå University in Sweden, Rey Juan Carlos University in Spain, and several UK institutions, discovered what they call a “core-to-edge” biodiversity pattern. In every biogeographical region—from rainforests to deserts and coral reefs—they found a central core zone where most species are concentrated. These core zones act like hubs of life, providing the most suitable conditions for species to survive and diversify. As species move outward from these cores into surrounding areas, the number of species gradually decreases. These surrounding areas, known as transition zones, are harder to live in, and only certain adaptable species are able to persist there.
This finding was consistent across very different ecosystems and types of species. The researchers were surprised by how predictable the pattern was, regardless of whether the species lived on land or in water, or whether they were plants, invertebrates, or vertebrates. The pattern appears to be driven by a process known as environmental filtering—where only species suited to local conditions like temperature, rainfall, and soil can survive. Two types of filters were identified: one within core areas, where stable conditions support unique species, and one at the edges, where more variable conditions allow only generalists or neighboring species to survive.
To understand the structure, the researchers analyzed four key aspects of biodiversity: species richness (how many species are present), range size (how widely each species is spread), endemicity (whether a species is found only in that area), and biota overlap (how much species are shared with nearby regions). These indicators allowed them to divide each biogeographical region into seven distinct zones, ranging from species-rich cores to mixed outer zones.
This research carries important implications for conservation and climate resilience. Core areas, though they may represent only a small portion of a region, are crucial for sustaining biodiversity. Protecting them could have an outsized impact on preserving ecosystems. As climate change and habitat destruction continue to reshape environments, understanding where species are most vulnerable can help guide conservation efforts.
This study challenges the idea that nature is governed by random patterns. Instead, it shows that consistent, global-scale processes shape the distribution of life. Recognizing these processes offers a powerful tool for predicting how biodiversity may shift in the face of global change—and for making better decisions to protect the natural world. Whether looking at rainforest frogs or coral reef fish, life clusters in core zones and fades toward the edges, filtered by environmental pressures that shape the future of Earth’s living systems.