Population variability across geographical ranges: perspectives and challenges.

Area of Science:

• Ecology
• Population Dynamics
• Biogeography

Background:

• Understanding population variability across geographical space is crucial in population ecology.
• Species' geographical range edges are often assumed to exhibit higher population variability due to environmental unsuitability.
• However, empirical evidence frequently contradicts this assumption, indicating no clear relationship between variability and range position.

Purpose of the Study:

• To investigate geographical patterns of population variability.
• To propose and utilize performance curves to better understand these patterns.
• To identify populations vulnerable to environmental changes.

Main Methods:

• Analyzing population variability in relation to geographical range position.
• Employing species performance curves, which link population growth rates to environmental conditions.
• Comparing geographical range edges with environmental edges.

Main Results:

• Population variability is not consistently higher at geographical range edges.
• Performance curves demonstrate that population fluctuations are more pronounced in areas with lower population growth rates due to environmental factors.
• Geographical and environmental edges do not always align.

Conclusions:

• Population variability patterns are better explained by species' performance curves than by simple geographical range limits.
• This approach helps identify populations at higher risk from future environmental changes.
• Considering performance curves offers a more nuanced understanding of population dynamics across landscapes.