Scientists have discovered a simple rule that controls how life organizes itself in the most diverse ecosystems of the planet. From rainforests to deep oceans, over 30,000 follow the same spatial patterns, whether they are flying, swimming, crawling or rooted in the right place.
The new study, published in Nature Ecology and Evolution, shows that biodiversity radiates outward from dense cores to sparse transition zones in predictable stratigraphic arrangements, a pattern that is real everywhere in Amazon amphibians to the Pacific.
This discovery challenges people expect different forms of life to be organized differently in various landscapes on Earth. Instead, researchers discovered what they called a “core to transition” organization that appears to be the fundamental principle for managing life on our planet.
Universal model across forms of life
“In every bioregion, there is always a core area inhabited by most species. From this core, species expand into surrounding areas, but only one subset can persist. It seems that these cores provide the best conditions for species survival and diversity, and it is the source of extroverted emanation of biodiversity,” Rubun Bernardo-Madrid explained, “Rubun Bernardo-Madrid explained.
The international team examined seven distinct biota: amphibians, birds, dragonflies, mammals, marine rays, reptiles and trees. These creatures adopted very different survival strategies—some were warm-blooded, some were cold-blooded. Some are moving, some are still; some live in water, some are on land.
What is striking about this discovery is that despite these fundamental differences in biology and habitat, each group organizes itself according to the same spatial rules of the planet’s major biogeographical areas.
Environmental filters shape the distribution of life
This study identifies environmental filtering as the mechanism that drives this common model. Only species that tolerate specific local conditions such as extreme heat, cold or drought can survive when they venture from their optimal core habitat into more challenging environments.
The team used advanced computer algorithms to analyze species distribution data and divided the world into seven different types of regions, each representing different combinations of species richness, geographical scope, and endemic levels. These regions form an ordered layer that always appear in different biogeographic regions.
The core areas usually contain the largest number of species and the highest concentrations of endemic species that are nowhere to be found. As distances from these cores increase, the number of species decreases, while the rest tend to have a larger geographical range, suggesting that they have greater environmental tolerance.
Small area, huge impact
One of the most striking findings of the study is the disproportionate importance of core areas. These biodiversity hotspots account for about 30% of each biogeographic region, but account for 90% of its species, with concentrations much higher than random accidental concentrations.
This discovery has a profound impact on conservation efforts. Research shows that conserving these relatively small core areas can preserve the vast majority of species throughout the biogeographic region, making them a valuable target of international conservation programs.
“The predictability of patterns and their association with environmental filters can help better understand how biodiversity responds to global change,” said Joaquín Calatayud, co-author of Rey Juan Carlos University.
Test Theory
To test its environmental filtering hypothesis, the researchers examined whether different biogeographic departments occupied areas with different environmental conditions. Using temperature and precipitation data for terrestrial species and temperature and salinity data for marine species, they found that 97.7% of cases showed obvious environmental differences between different sectors.
The team also analyzed whether the changes in species composition were caused by species alternatives (turns) or from an area containing another species seed subset (necking). In 77% of all study populations, the differences were mainly due to nesting, which demonstrated that species spread out from the core to the core, but the most adaptable species survived in peripheral areas.
Evolutionary Insights and Climate History
The core-to-transition approach seems to be related to deep evolution and climate history. The core area may represent ancient centers of species diversity or climate refuges from the past, in which case organisms survived the Ice Age (such as the Ice Age). These areas then serve as sources of species with better dispersion capacity and environmental tolerance, spreading to the surrounding areas.
Other analyses suggest that climate change since the last glacier maximum is also associated with observed patterns, suggesting that historical climate events help shape the current organization of life on Earth.
Global impact on species richness
This study solves a fundamental question in ecology: What determines the abundance of local species around the world? The study found that regional environmental filtering (the basic process of core to transitional organization) may be as important as traditional factors, such as species and extinction rates, in explaining why some places have more species than others.
Through mathematical modeling, researchers demonstrate that classification of species within biogeographic regions explains a large part of the global change in local species richness. This challenges traditional approaches that focus primarily on regional species pool sizes and highlights the importance of understanding the environmental filtration process.
Conservation and climate change
The universal nature of the organization’s principles provides new tools for predicting how ecosystems respond to environmental changes. As climate change changes global temperature and precipitation patterns, understanding these core to transitional dynamics can help scientists predict which species and regions face the greatest risks.
The findings also suggest that conservation strategies should prioritize identification and conservation of core areas that are biodiversity reservoirs throughout the region. Not only do these areas have the largest number of species, but they may be the source of habitat for recolonial habitats.
Methods and Verification
The researchers used complex network analysis techniques to view species and geographical location as interconnected nodes in complex systems. They used the information algorithm to identify biogeographic regions and their characteristic species, and then applied machine learning clustering methods to reveal seven types of biodiversity areas.
To ensure that their findings are not artifacts for their analytical methods, the team conducted extensive sensitivity analyses using different numbers of clusters and various geographic scales. The core conversion patterns remained consistent across all tests, thus increasing confidence in the results.
The study represents one of the most comprehensive analyses of global biodiversity organizations ever, covering multiple continents, life forms and habitat types while maintaining methodological consistency across all analyses.
This study provides a new lens for understanding life on Earth, showing that the overwhelming biodiversity under Earth lies in a very simple, universal organizational principle that goes beyond the boundaries between land and oceans, animals and plants.
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