Latitudinal gradients in climatic-niche evolution accelerate trait evolution at high latitudes

Area of Science:

• Evolutionary Biology
• Climate Change Research
• Ornithology

Background:

• Divergent selection drives evolutionary speed but its latitudinal prevalence is unknown.
• High latitudes experience intense paleoclimate change, while tropics have high species richness.

Purpose of the Study:

• To investigate if climatic-niche evolution rates vary with latitude.
• To determine if climatic niche divergence correlates with ecological and reproductive trait evolution.

Main Methods:

• Analyzed climatic-niche evolution rates in 111 bird species pairs.
• Utilized Brownian motion and Ornstein-Uhlenbeck models for evolutionary rate estimation.
• Examined associations between climatic divergence and body mass/song evolution.

Main Results:

• Evolutionary rates along temperature and seasonality axes were faster at higher latitudes.
• Climatic niche divergence was linked to accelerated evolution of body mass.
• Climatic niche divergence was also associated with faster song evolution, indicating reproductive isolation.

Conclusions:

• Climate-mediated divergent selection is a significant driver of evolutionary divergence at high latitudes.
• Faster evolutionary rates at high latitudes may be influenced by intense past climate fluctuations.
• Divergent selection on climate-related niches promotes both ecological differentiation and reproductive isolation.