A new theory reveals that biodiversity doesn’t increase uniformly from local gardens to entire continents, challenging long-held ecological assumptions and offering fresh insights into species distribution.
Key Points at a Glance
- Species richness doesn’t scale linearly with area; it follows a three-phase pattern.
- The new model explains biodiversity patterns from local to continental scales.
- Findings aid in predicting species loss due to habitat destruction.
- Research published in Nature Communications by an international team including iDiv scientists.
Biodiversity—the variety of species across the planet—is often described with a deceptively simple pattern: the larger the area, the more species you’ll find. But this long-held ecological rule is being redefined by new research that reveals the relationship is far more complex than previously thought.
A study recently published in Nature Communications, led by Dr. Luís Borda-de-Água of the CIBIO research centre in Portugal in collaboration with the German Centre for Integrative Biodiversity Research (iDiv) and Martin Luther University Halle-Wittenberg, introduces a new theory that reshapes our understanding of the species–area relationship (SAR). The key revelation? Biodiversity doesn’t increase evenly with scale—it follows a distinct three-phase pattern that fundamentally changes how we should model and protect ecosystems.
This three-phase pattern describes how species richness—the number of different species—grows as the area surveyed increases:
– Phase One (Local to Regional): A rapid rise in species numbers as more microhabitats and ecological niches are included in the sampling area.
– Phase Two (Regional to Continental): The rate of new species discovery slows down. Many widespread species are repeatedly recorded across different regions, adding less new diversity per unit area.
– Phase Three (Continental to Intercontinental): An acceleration in species accumulation resumes due to the inclusion of endemic species—those unique to certain continents or major biomes.
This dynamic, non-linear pattern provides a much-needed correction to conventional models that assume a uniform or log-linear increase in species richness with area. It helps explain discrepancies seen in biodiversity data gathered at different scales and offers a unified framework for comparing studies across ecosystems, latitudes, and continents.
Understanding this pattern is not just academically interesting—it’s vital for conservation planning. Accurately estimating how many species could be lost due to deforestation, habitat fragmentation, or urban sprawl depends on how species richness scales with area. If models overestimate or underestimate species density at certain scales, conservation strategies may fall short or misdirect critical resources.
The new model incorporates species’ geographic ranges as a key variable. Unlike traditional models that treat all species as spatially random, this approach reflects the reality that some species are widespread generalists, while others are rare and localized. By factoring in how species are distributed in space, the model provides better predictions of how diversity builds—and declines—across different landscapes.
“This is one of the most fundamental patterns in ecology,” said co-author Dr. Henrique Pereira from iDiv. “But until now, we lacked a general theory that could link the way biodiversity behaves from a backyard garden to an entire continent. Our work closes that gap.”
The implications extend into how we communicate biodiversity science to the public. The idea that biodiversity accumulates unevenly—sometimes slowly, sometimes explosively—makes it easier to visualize why losing even small patches of unique habitat can have outsized impacts on global biodiversity. A wetland lost in one region may eliminate a species found nowhere else, even if that region seems small on a map.
The model is also a powerful educational and policy tool. It can help decision-makers identify ecological “hotspots” that deserve urgent protection and anticipate where conservation efforts are likely to yield the greatest gains in species preservation. In a world where biodiversity is declining at an unprecedented rate, every bit of predictive accuracy matters.
Finally, this theory may have applications beyond ecology. The way patterns emerge, plateau, and accelerate again across spatial scales resembles dynamics in other complex systems—such as urbanization, information flow, or disease spread—hinting at broader scientific principles waiting to be explored.
By providing a more nuanced and realistic understanding of how biodiversity scales, this study offers both clarity and urgency. It reminds us that ecological patterns, like ecosystems themselves, are living systems: layered, nonlinear, and deeply dependent on scale. And in conservation, as in nature, size isn’t everything—but understanding how size relates to diversity might just be the key to saving what we still have.
Source: German Centre for Integrative Biodiversity Research (iDiv)
