Analytical formulae for computing dominance from species-abundance distributions

Area of Science:

• Ecology
• Biodiversity Science
• Theoretical Ecology

Background:

• Community evenness influences ecosystem structure, function, and stability.
• Uneven communities feature rare species and dominant species affecting ecosystem properties.
• Even communities exhibit lower dominance, potentially involving numerous species in key ecological roles.

Purpose of the Study:

• To establish general rules for ecological community dominance.
• To mathematically link community dominance to parameters of common species-abundance distributions (SADs).

Main Methods:

• Mathematical modeling linking dominance to SAD parameters.
• Analysis of log-series, lognormal, exponential, and gamma SADs.
• Application of formulae to a mechanistic community model.

Main Results:

• Log-series and lognormal SADs indicate high dominance (few species comprise most individuals).
• Exponential SADs show typically high dominance.
• Gamma SADs exhibit high dominance only below a specific average species abundance threshold.
• Dominance is scale-dependent and shows non-linear trends with average species abundance.
• Environmental variance can increase dominance in mechanistic models.

Conclusions:

• Provides a theoretical framework for understanding ecological dominance dynamics.
• Highlights the influence of SAD type and scale on community dominance.
• Demonstrates how environmental factors can modulate dominance.