Population Biology

1
Population Biology
2
Characteristics of Populations

• Three important characteristics of a population
• Geographic distribution
• Density
• Growth Rate

3
Characteristics of Populations

• Three factors affect population size
• 1. of births
• 2. of deaths
• 3. Individuals entering or leaving
• Emigration and Immigration

4
Population Growth

• Exponential Growth Curve
• J-Shape
• Reproduce at constant rate
• Ideal conditions with unlimited resources
• Ex. Bacteria

5
Population Growth

• Is population growth unlimited?
• What can limit growth?
• Food availability
• Disease
• Predators
• Lack of shelter
• These are limited resources!

6
Population Growth

• Logistic Growth Curve
• As resources become less available

7
Carrying Capacity

• Since growth is limited, any given area can only
  support a certain number of individuals.
• Carrying capacity the number of organisms of
  one species that an environment can support

8
Carrying Capacity
9
Limiting Factors

• Density-Dependent
• Competition
• Predation
• Parasitism
• Disease

Young Bangladesh Girl with Small Pox
10
Predator-Prey Relationships
Snow Shoe Rabbit and Canada Lynx
11
Density-Independent Factors

• Unusual weather
• Natural Disasters
• Seasonal Cycles
• Some Human Activities

Tsunami in Thailand 2004
12
Human Demographics