Populations

Hierarchy

Biome

Ecosystem

Community

Population

Organism

Competition

Competition occurs when two or more organisms seek the same resource at the same time.– This limits population size

Population Size

Why would an ecologist want to know about the size of something like a deer population?

Methods of Population Measurement:– Trap-Mark-Release: they compare the number of

tagged animals to the number of untagged animals to estimate the pop. size

– Sample Counts: Estimate the population size of a large area by counting the number of an animal in a smaller area then multiplying.

Sample Count

Human Population Density Map

Limiting Factors & Carrying Capacity

Limiting Factor is anything that restricts the number of individuals in a populations.– Less rain = less seeds = less food for seed eating

mice. Carrying Capacity is the largest number of

individuals of one species that an ecosystem can support – Space, food, etc will limit carrying capacity– Have to move if they want to survive.

Changes in Populations

What effects changes in populations?– Birth Rate– Death Rate– Moving – Migration