The latitudinal gradient in niche breadth: concepts and evidence

Area of Science:

• Ecology
• Biogeography
• Evolutionary Biology

Background:

• Robert MacArthur's influential latitude-niche breadth hypothesis posits a positive correlation between niche breadth and latitude.
• This long-standing ecological concept has not been rigorously tested for its generality or underlying assumptions.

Purpose of the Study:

• To evaluate the empirical support for MacArthur's latitude-niche breadth hypothesis.
• To investigate the theoretical arguments and assumptions linking niche breadth and latitude.
• To propose an alternative hypothesis for the relationship between latitude and niche breadth.

Main Methods:

• Review of theoretical arguments supporting the latitude-niche breadth hypothesis.
• Empirical evaluation of the assumptions and predictions of MacArthur's hypothesis using available data.
• Development of a novel conceptual framework based on species interactions.

Main Results:

• Empirical evidence does not support the assumptions of MacArthur's latitude-niche breadth hypothesis.
• Data analysis revealed that neither the core assumptions nor the predictions of the hypothesis are substantiated.
• Existing theoretical frameworks often rely on equilibrium assumptions, which may not reflect ecological reality.

Conclusions:

• MacArthur's latitude-niche breadth hypothesis is not supported by current data.
• An alternative hypothesis is proposed, offering a new perspective on latitude-niche breadth relationships.
• The new framework avoids equilibrial assumptions and incorporates recent findings on species interactions.