Does intraspecific competition promote variation? A test via synthesis

Area of Science:

• Evolutionary biology
• Ecology

Background:

• Competitive diversification, where intraspecific competition drives niche expansion, is central to adaptive diversification.
• Empirical evidence for this process is limited and lacks objective synthesis.

Purpose of the Study:

• To synthesize existing literature and assess competition as a diversifying force.
• To test if competition promotes or inhibits dietary diversification based on resource depletion.

Main Methods:

• Literature review and data collection on competition and diet breadth.
• Analysis of the relationship between intraspecific competition, diet breadth, and resource depletion.

Main Results:

• Increasing intraspecific competition did not consistently increase population diet breadth or individual specialization.
• Competition restricted diet breadth as often as it diversified it, with effects related to resource depletion.

Conclusions:

• Challenges the assumption that competition is always diversifying in evolutionary models.
• Supports theories that resource depletion limits the diversifying effects of competition, especially for species with large ecological impacts.