Continental-Scale Biodiversity Predictions Are Influenced by Climatic Variability and Extreme Weather

Area of Science:

• Ecology
• Climate Change Biology
• Biodiversity Science

Background:

• Organisms face physiological limits due to increasingly variable and extreme weather.
• Species distributions and biodiversity patterns are affected by these climatic challenges, especially at range edges.
• The precise influence of climatic variability and extreme weather on continental-scale distributions remains unclear.

Purpose of the Study:

• To investigate how climatic variability and extreme weather shape species distributions and biodiversity patterns across North America.
• To compare the predictive performance of species distribution models incorporating climatic variability and extreme weather versus those using only climatic means.

Main Methods:

• Linked citizen science bird observations (2004-2024) with high-resolution climatic variability and extreme weather risk data.
• Developed 2901 individual species distribution models for 535 North American species.
• Assessed model performance across 220 well-surveyed sites.

Main Results:

• Models including climatic variability and extreme weather risk outperformed others in predicting species richness and presence.
• Species' geographic ranges were predicted to be narrower, truncated by 6% (summer) and 10% (winter), particularly at range edges.
• Richness estimates decreased significantly (up to 35 species) in regions prone to extreme weather, like the US Southwest and Central Plains.

Conclusions:

• Climatic variability and extreme weather are critical factors defining species distributions and biodiversity patterns.
• Accounting for these factors leads to more accurate and mechanistically informed biodiversity predictions.
• Future biodiversity assessments must integrate climatic variability and extreme weather to reliably predict species' future distributions.