A group of individuals of the same species living in a particular area Populations A group of individuals of the same species living in a particular area
Characteristics of Populations Size Density Dispersion
Population Density Number of individuals per unit area (land) or volume (water)
Population Dispersion The relative distribution or arrangement of its individuals within a given amount of space Clumped resources Social congregation Mating Territorial Solitary lifestyle
) Growth Rate ( ( ) = + - + Births Deaths Growth Rate Emigration Immigration Deaths Emigration = + - +
Exponential Growth Constant growth of a population J shaped curve Birth rate exceeds the death rate J shaped curve
Conditions for Exponential Growth Unlimited resources Abundant space Abundant food Shelter Decrease in predators Decrease in disease Reproduction
Human Population Link in pic
Reasons for Human Population Growth Agriculture Industry Improved sanitation Medicine
Future Human Growth Current Human population 2025 2050 7.8 Billion
Logistic Growth Growth of a population slows or stops as resources become less available S curve
Carrying Capacity The largest number of individuals that a given environment can support at a given time
Stable Population Carrying Capacity (K) Expontential Rapid Growth Slow Growth
Factors that cause population growth to decrease Limiting Factor Factors that cause population growth to decrease
Density-Dependent Factors A limiting factor that depends on population size Factors: Predation Competition Parasitism Disease
Density Independent Factors Affect all populations regardless of size Examples Weather Natural disasters Human activities
Species that have a critical role and effect on an ecosystem Keystone Species Species that have a critical role and effect on an ecosystem Examples: Wolves Sharks
Human Impacts on Populations