Population growth rate and its determinants: an overview

Area of Science:

• Ecology
• Population Dynamics
• Environmental Science

Background:

• Population growth rate is a fundamental yet underutilized metric in ecology.
• Existing research often overlooks the unifying role of population growth rate across various ecological concepts.
• Key ecological concepts like environmental stress and ecological niche lack consistent definitions.

Purpose of the Study:

• To establish population growth rate as the unifying variable in population ecology.
• To redefine environmental stress and ecological niche based on population growth rate.
• To analyze population regulation, density dependence, and competition through the lens of population growth rate.

Main Methods:

• Literature review of studies plotting population growth rate against population density.
• Analysis of demographic and mechanistic approaches to population growth rate.
• Experimental illustration using a marine copepod (Tisbe battagliae) to distinguish competition types.

Main Results:

• Population growth rate is central to forecasting population trends and understanding environmental stress.
• Environmental stressors reduce population growth rate; the ecological niche is where growth rate is positive.
• Analysis revealed limited empirical studies (25) plotting population growth rate against density, with mostly linear or concave relationships.

Conclusions:

• Population regulation, density dependence, competition, environmental stress, and ecological niche are best defined and analyzed using population growth rate.
• This unifying variable has broad applications in conservation biology, ecotoxicology, and human demography.
• Future research should prioritize analyzing ecological phenomena through the framework of population growth rate.