Download Characteristics of Populations

Characteristics of
Populations
Spring 2017
Characteristics of Populations
• Population
•A group of organisms of the same
species that live in the same area.
• Population density
•The number of individuals per unit area.
Characteristics of Populations
• To grow
exponentially, a
population
1. Has to have
abundant space and
food
2. Is well protected from
predators and
disease
Characteristics of Populations
• Exponential
growth•Occurs when
individuals of
population
reproduce at a
constant rate
•J-shaped curve
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
Density-Dependent Limiting Factors
• Factors that are related to the density of a
population:
1. Competition
•Organisms compete for food, water, space,
sunlight, and other essentials
2. Predation
•Population control caused by predator-prey
relationships
3. Parasitism and disease
•Robs organisms of nourishment
Density-Independent Limiting Factors
• Effects of a population no matter what the
size is.
1. Unusual weather
• Drought
2. Seasonal cycles
• El Nino
3. Natural Disasters
• Volcanic eruptions, fires, floods
4. Human activities
• Clear-cutting forests, damming rivers