A groundbreaking study published in Nature Ecology & Evolution has uncovered a fundamental rule that governs the distribution of life across our planet. Led by scientists from Umeå University, this research reveals a stunning global pattern in how species cluster in core areas within biogeographical zones and expand outward. By exploring this rule, scientists have shed light on how biodiversity is organized and how ecosystems might respond to environmental shifts in the future.
This discovery not only reshapes our understanding of biodiversity but also offers new insights into how life on Earth is more interconnected than previously thought. The study’s findings are set to have profound implications for conservation strategies and climate change mitigation efforts worldwide.
The Core of the Earth’s Bioregions: A Surprising Pattern of Biodiversity
The study’s core revelation is that all bioregions on Earth—vast ecological zones separated by natural barriers such as mountains and oceans—share a similar structure. At the heart of each bioregion lies a core area that harbors the majority of the species, which then radiate outward into surrounding environments. “In every bioregion, there is always a core area where most species live. From that core, species expand into surrounding areas, but only a subset manages to persist. It seems these cores provide optimal conditions for species survival and diversification, acting as a source from which biodiversity radiates outward,” explains Rubén Bernardo-Madrid, lead author of the study and a researcher at Umeå University.
The consistency of this pattern across diverse species and bioregions—from amphibians and reptiles to trees and birds—was unexpected. Initially, researchers believed that species distribution would vary drastically depending on the type of organism and the particular conditions of each bioregion. However, what they discovered was a universal principle that transcends these differences. Species not only cluster around central core areas but also exhibit a clear and predictable pattern of expansion into adjacent regions, which leads to the formation of a unique ecological structure in each area.
This research offers a new way to think about biogeography, especially as it concerns the movement and survival of species in a world undergoing rapid environmental changes. By identifying this pattern, the study provides an essential framework for understanding how biodiversity has evolved and how it may continue to evolve under the pressures of global warming and other environmental stresses.
Environmental Filters: How Only the Toughest Species Survive
At the heart of this pattern lies the concept of environmental filtering. Environmental filters refer to the idea that only species that are capable of tolerating specific local conditions—such as heat, drought, or cold—are able to establish themselves in a particular region. This principle has been a foundational theory in ecology but has lacked global empirical evidence until now.
“The predictability of the pattern and its association with environmental filters can help to better understand how biodiversity may respond to global change,” says Joaquín Calatayud, co-author and researcher from Rey Juan Carlos University. This finding is particularly relevant in today’s context of rapid climate change, as it suggests that environmental conditions play a crucial role in determining which species thrive and which fail to establish new populations.
The study demonstrates that these environmental filters are responsible for shaping the very structure of biodiversity across the globe. The distribution of species within a bioregion is not random; rather, it is a result of environmental conditions that either enable or restrict certain species from expanding into new areas. This also highlights the delicate balance that species must maintain in order to survive in their native habitats, and how any shift in environmental conditions could disrupt this equilibrium, leading to a cascading effect on biodiversity.
