The ecology of geographic range limits

Area of Science:

• Ecology
• Biogeography
• Climate Change Biology

Background:

• Ecological research increasingly focuses on geographic range limits due to climate change.
• Despite theoretical advances, empirical understanding of range limit causes remains limited.
• Existing syntheses show mounting support for various hypotheses but struggle to differentiate ecological processes.

Purpose of the Study:

• Recommend a shift in ecological research on range limits.
• Propose a first-principles hypothesis structuring range limit studies.
• Re-evaluate the processes that limit species' geographic distributions.

Main Methods:

• Advocate for estimating the scenopoetic niche (habitat requirements excluding biotic interactions) as a primary approach.
• Review theoretical models of geographic range limits, highlighting parameter commonalities.
• Discuss observational and empirical methods for testing range limit hypotheses, considering practical constraints.

Main Results:

• The scenopoetic niche offers a first-principles framework for understanding distributions and limits.
• Theoretical models suggest range limit causes are fewer and more redundant than often assumed.
• Antagonistic biotic interactions (predation, competition, parasitism) can similarly affect range limits.

Conclusions:

• Estimating the scenopoetic niche should precede testing other range-limiting factors.
• A unified theoretical framework can improve understanding of diverse range limit causes.
• Future research should integrate spatiotemporal variability and differentiate ecological processes for better predictions.