Chapter 4.1, Problem 7MI

Summary Introduction

To classify:

The limiting factors as either density-independent or density-dependent.

Introduction:

Population density is one of the important characteristics of the population. It is defined as the number of organisms in a unit area. All species have limiting factors. Limiting factors keep a population from continuing to increase indefinitely. Decreasing limiting factors, such as the available food supply, the number of individuals changes. It means an increase in food results in a larger population might result and decrease in food supply results in a smaller population.

Answer to Problem 7MI

The table below representseach limiting factor as either density-independentor density-dependent. It is shown by placing an X in the appropriate column.

Factor	Density- independent	Density-dependent
Lava flow	X
Number of predators		X
Spread of disease		X
Especially cold winter	X
Toxic chemical spill into a stream	X
Another species competing forthe same resources		X
Diverting a river for irrigation	X
A fungus that attacks elm trees		X

Explanation of Solution

Density-independent factors and density-dependent are the two categories of limiting factors. The density-independent factor is a factor in the environment that does not depend on the number ofmembers in a population per unit area. These factors usually are abiotic and include natural phenomena such as weather events. Weather events that limit populations include drought or flooding, lava flow, extreme heat or cold, toxic chemical spill.

The density-dependent factor is a factor in the environment that depends on the number of members in a population per unit area. Density-dependent factors are often biotic factors such as predation, disease, parasites, and competition.