Turn homework into the basket Pick up handouts
• Turn homework into the basket. • Pick up handouts. • Accountability sheet will be due next class session.
Populations
Properties of Populations • Three properties – Population size – Population density – Dispersion • Clumped • Even • Random
Population Dynamics • What does dynamic mean? • They change in size and composition over time. • In order to understand dynamics we need to look at certain measurements. – Birth rate – Death rate (also mortality rate) – Life expectancy
Populations • Carrying Capacity – The number of organisms an environment can support. • Why don’t populations continue to display exponential growth? – Food supply is low – Nesting sites become unavailable – Competition with other organisms. • Factors that inhibit population growth are called limiting factors.
Limiting Factors • Density dependent factors are a result of the population density. – Examples: resource limitations, food shortage, nesting sites, no mates, parasitism, disease, predation • Density independent factors affect the growth of a population regardless of its population size. – Examples: floods, fires, tornado, pollution
Population Regulation • All populations fluctuate in size. • Some fluctuations are linked to environmental changes. • Fluctuations may also go in cycles. • Small populations are more vulnerable to extinction.
Predator Prey Curve • Fluctuations are predictable and maintain stability. • As the prey population increases, the predator population increases. • As the predator population increases, the prey population decreases.
- Slides: 9