Ecology Population Problems You will be able to determine population sizes of organisms in an ecosystem You will be able to determine the health of an ecosystem and recognize potential problems

What are populations? Population is a group of organisms of the same species living in a precise area of an ecosystem Populations are used to determine the health of ecosystems using a quantity known as POPULATION DENSITY POPULATION DENSITY = #of organisms Unit Area

4 Ways to Determine Population Size 1. Direct Observation – Counting each organism within an ecosystem. Most Accurate but most inefficient 2. Indirect Observation- counting each organism by signs they leave in environment. Foot tracks, nests, burrows, holes… 3. Sampling- Taking small area of ecosystem and converting findings to size of entire ecosystem. Most Time Efficient, but prone to errors since organism’s distribution may not be random Mark and Capture- Capture Organisms and Mark them. Return after time has passed and recapture in same area. Best Way ecologists use to estimate populations of organisms

Mark and Capture Formula Total Pop = Number Marked X Total Number Captured Number Recaptured (with Marks) MOST COMMON METHOD USED BY ECOLOGISTS

What Affects Population Sizes Birth Rate- number of Births in Population Death Rate- number of Deaths in Population Immigration Rate – number of organisms moving INTO the ecosystem Emigration Rate- number of organisms leaving ecosystem

Population Sizes If BR > DR Population is growing If IM > EM Population is growing If BR<DR Population is in decline If EM < IM Population is in decline

Population limits

Populations are limited in Size Limiting Factors- control size of an organism’s population Food- amount available to organism Space- amount of living space an organism needs Weather/Seasons- Natural Events which alter conditions in Ecosystem The maximum number of an Organism within an Ecosystem is known as the CARRYING CAPACITY of the Ecosystem or the K0 Factor

REMINDER When Estimating populations of Organisms you must ROUND whole numbers. (.anything of any organism can not exist!)