1. Characteristics of Populations
Spring 2018

2. Characteristics of Populations
A group of organisms of the same species that live in the same area.
Population density
The number of individuals per unit area.

3. Characteristics of Populations
To grow exponentially, a population
Has to have abundant space and food
Is well protected from predators and disease

4. Characteristics of Populations
Exponential growth-
Occurs when individuals of population reproduce at a constant rate
J-shaped curve

5. Characteristics of Populations
Logistic growth
As resources become less available, the population growth rate slows or stops
Carrying capacity
The number of organisms of one species that can be supported in an environment
S- shaped curve

6. Density-Dependent Limiting Factors
Factors that are related to the density of a population:
Competition
Organisms compete for food, water, space, sunlight, and other essentials
Predation
Population control caused by predator-prey relationships
Parasitism and disease
Robs organisms of nourishment

7. Density-Independent Limiting Factors
Effects of a population no matter what the size is.
Unusual weather
Drought
Seasonal cycles
El Nino
Natural Disasters
Volcanic eruptions, fires, floods
Human activities
Clear-cutting forests, damming rivers