Universal Rule of Biodiversity Patterns Discovered Globally
Recent research has revealed a universal pattern in how biodiversity arranges itself within the world’s major biogeographical regions. This discovery challenges earlier assumptions that species distribution inside each region would be unique and unrelated to others. The study analysed over 30,000 species from various taxa across the globe. It found a clear, repeating layered structure in biodiversity that transcends continents, climate zones, and organism types.
Biogeographical Regions
The Earth is divided into large biogeographical regions, each hosting distinct species shaped by history, climate, and geographical barriers. Traditionally, scientists believed that biodiversity patterns inside these regions were idiosyncratic. Tropical zones are known for high species richness, while polar regions have fewer species. However, the new study sought to find if a universal internal pattern exists within these regions.
Methodology and Data Analysis
Researchers used global databases such as the IUCN Red List and BirdLife International to gather species range data. The Earth’s surface was divided into thousands of equal-area cells of about 111 square kilometres. Each cell’s species were recorded and grouped using a network analysis tool called Infomap. This grouped cells into biogeographical clusters based on species co-occurrence. Species were classified as either characteristic (core to a region) or non-characteristic (spillover from neighbouring regions).
Key Biodiversity Metrics
Four metrics were analysed for each cell – species richness (number of characteristic species), biota overlap (proportion of non-characteristic species), occupancy (range size of characteristic species), and endemicity (proportion of species range confined to the region). These metrics helped define the internal structure of biodiversity within each region.
Discovery of a Layered Biodiversity Pattern
The study identified seven recurring biogeographical sectors within every major region and taxonomic group. These sectors form a layered “onion-like” structure. The core layers are species-rich, highly endemic, and contain few foreign species. Moving outward, layers show decreasing richness and increasing presence of widespread generalist species. Transition zones at the edges are species-poor and dominated by generalist species shared across regions.
Environmental Influence on Biodiversity Layers
Temperature and rainfall models predicted the placement of cells within these layers in 98% of cases. This indicates environmental filters strongly influence which species survive in each layer. Outer layers mainly consist of subsets of species from inner layers rather than completely different specialists.
Implications for Conservation and Ecology
Studying this universal pattern helps in identifying biodiversity hotspots and transition zones. It guides conservation efforts to focus on core layers for maximum protection impact. The study marks the importance of environmental factors like climate and elevation in shaping species distributions. In regions like the Himalayas, this knowledge can inform strategies to protect biodiversity amid climate change.
Limitations and Future Research
The study noted gaps in data for some taxa and regions, such as dragonflies in Eurasia and trees in North America. Certain biodiversity-rich tropical areas remain underrepresented. More region-specific research is needed to complement these global findings and strengthen conservation planning.
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