Standardized diversity estimation uncovers global distribution patterns and drivers of stream insects

Area of Science:

• Ecology
• Biodiversity Science
• Conservation Biology

Background:

• Freshwater insect biodiversity faces global threats from human activities.
• The specific roles of natural versus anthropogenic drivers are not well understood.
• Sampling biases can obscure true diversity patterns.

Purpose of the Study:

• To map global freshwater insect diversity for four key orders: Ephemeroptera, Plecoptera, Trichoptera, and Odonata (EPTO).
• To investigate the influence of sampling bias, natural factors, and anthropogenic stressors on EPTO diversity.
• To provide accurate insights for effective stream conservation and management.

Main Methods:

• Analysis of data from 783 river basins worldwide.
• Application of standardized diversity metrics (Shannon, Simpson) to account for sampling bias.
• Assessment of landscape, climatic, and anthropogenic factors influencing taxonomic and functional diversity.

Main Results:

• Over 60% of studied basins were under-sampled, particularly in the Global South.
• Standardized diversity metrics revealed two latitudinal peaks in EPTO diversity (~equator and ~40°N).
• Landscape factors were the primary drivers of taxonomic diversity, while climate and landscape factors drove functional diversity.

Conclusions:

• Accurate assessment of freshwater insect diversity requires controlling for sampling biases.
• Landscape and climatic factors are critical determinants of freshwater insect biodiversity patterns.
• Findings inform targeted conservation strategies for freshwater ecosystems globally.