Recent accelerated diversification in rosids occurred outside the tropics.

Area of Science:

• Ecology
• Evolutionary Biology
• Botany

Background:

• Diversification rates and temperature show conflicting relationships across different life forms.
• Understanding these patterns is crucial for predicting biodiversity responses to climate change.

Purpose of the Study:

• To investigate global diversification patterns in rosids (flowering plants).
• To determine the association between diversification rates and climatic factors, particularly temperature.
• To analyze the influence of tropical versus non-tropical niche occupancy on diversification.

Main Methods:

• Utilized a supermatrix of nearly 20,000 rosid species.
• Incorporated historical global temperature data.
• Assessed species' temperature niches and tropical/non-tropical niche occupancy.

Main Results:

• Most rosid subclades showed increased diversification rates in the last 15 million years, coinciding with global cooling and temperate habitat expansion.
• Negative association between climatic niche (tropical vs. non-tropical) and diversification rates.
• Tropical rosids exhibited ~2-fold lower speciation rates than those in cooler climates, forming older communities.

Conclusions:

• Long-term global cooling significantly impacted non-tropical diversification rates, fostering dynamic, younger communities.
• Tropical regions harbor older, slower-evolving, yet species-rich plant communities due to relative climatic stability.
• Temperature and niche occupancy are key drivers of angiosperm diversification patterns.