Difference Between Density Independent and Density Dependent Limiting Factors

The key difference between density independent and density dependent limiting factors is that density independent limiting factors are abiotic factors and environmental factors such as weather, natural disasters, and pollution, etc. while density dependent limiting factors are biotic factors such as predation, competition and diseases caused by parasites.

With the presence of unlimited resources, we expect a population to grow exponentially. However, achieving an indefinite exponential growth of a population is not possible in natural ecosystems. Population comes to a limit and stabilizes at a certain point since the density of a population is influenced by various factors, including both density dependent and density independent factors. Density independent limiting factors are the factors that influence the size and growth of population irrespective of the population density. In contrast, density dependent limiting factors are the biological factors that influence the size and the growth of population depending on the density of the population.

CONTENTS

1. Overview and Key Difference
2. What are Density Independent Limiting Factors
3. What are Density Dependent Limiting Factors
4. Similarities Between Density Independent and Density Dependent Limiting Factors
5. Side by Side Comparison – Density Independent vs Density Dependent Limiting Factors in Tabular Form
6. Summary

What are Density Independent Limiting Factors?

Density independent limiting factors are the abiotic factors and environmental factors that regulate the population growth rate. Generally, they are physical or chemical in nature. These factors affect the birth and death rates of a population. Some of these factors include climate extremes, natural disasters (fires, floods, earthquakes and hurricanes) and pollution. Food or nutrient limitation is another density independent limiting factor.

Regardless of the population size, individuals may die due to these density independent limiting factors – environmental factors or abiotic factors. Therefore, a large population of a species can be regulated into a normal population by density independent manner by these factors.

What are Density Dependent Limiting Factors?

Density dependent limiting factors are biological in nature. The main factors are diseases, competition, and predation. These factors positively or negatively correlate with the population size. Density dependent limiting factors influence the population growth either by affecting reproduction or survival.

Moreover, these factors affect population mortality and migration. Carrying capacity is dependent on the density dependent limiting factors. It is the maximum number of individuals that can live in an area based on the density dependent limiting factors.

What are the Similarities Between Density Independent and Density Dependent Limiting Factors?

• Both density independent and density dependent limiting factors influence the size of the population.
• They control the population growth.

What is the Difference Between Density Independent and Density Dependent Limiting Factors?

Density independent limiting factors are often abiotic factors, while density dependant limiting factors are often biotic factors. So, this is the key difference between density independent and density dependent limiting factors. That is; density independent limiting factors include nutrient limitations, natural disasters, severe weather, and pollution. Density dependent limiting factors include competition, predation, diseases and parasites and waste accumulation.

Below infographic summarizes the difference between density independent and density dependent limiting factors.

Summary – Density Independent vs Density Dependent Limiting Factors

Size and the growth of populations are affected by many factors. These factors are mainly two types as density independent limiting factors and density dependent limiting factors. Density dependant factors are often biotic factors, while density-independent factors are often abiotic factors. Density independent factors include climatic extremes, natural disasters, foods, and pollutants. Density dependent limiting factors include disease caused by parasites, competition and predation.

Reference:

1. “Population Limiting Factors | Learn Science At Scitable”. Nature.Com, 2020, Available here.
2. “Population Regulation & Density Dependent Factors | Ecology “. Khan Academy, 2020, Available here.

Image Courtesy:

1. “Fire-Forest” By Cameron Strandberg from Rocky Mountain House, Alberta, Canada – DSC_7139 (CC BY 2.0) via Commons Wikimedia
2. “Bear predation on salmon can be high in many Alaskan rivers” By Mark Wipfli, Alaska Cooperative Fish and Wildlife Research Unit. Public domain. – United States Geological Survey (Public Domain) via Commons Wikimedia