Extinction

• BrainPOP movie: http://www.brainpop.com/science/ourfragileenvironment/extinction/quiz/

Extinction (write)

• when a species of an organism no longer exists

• Main causes:Over huntingPredatorLack of resourcesHabitat destructionNatural disasterdeforestation

Population growth BrainPOP video

• http://www.brainpop.com/science/ourfragileenvironment/populationgrowth/

Population Density (write)

Population density is the number of individuals in a specific area.

Population Density = # of Individuals

Unit area

5 meters

3 meters

Pop. Density = 16 butterflies

5 m x 3 m

Pop. Density = 16/15 m2

Pop. Density = 1.667 per sq. meter

Population density (write)

• Number of individuals divided by the size of the area

• Ex. 16 spiders in an area that measures 2 meters x 2 meters

• Area = length x width

• 16 spiders / 4 meters ²

• Simplify: 4 spiders / meter ²

Population Density

• Ecologists determine population density (DEN suh tee) by comparing the size of a population with its area.

• For instance, if 100 dandelions are growing in a field that is one square kilometer in size, then the population density is 100 dandelions per square kilometer.

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Carrying capacity (write)

• Maximum number of organisms that are able to live in a certain area

• An area can only support so many organisms

Populations can change in size when new members enter the population or when members leave the population.

Immigration means moving into a population.

Emigration means leaving a population.

Birth and Deaths

• Birth Rate is the number of births in a certain time period.

• Death Rate is the number of deaths in a population in a certain amount of time.

Population Equation

• If birth rate > death rate, population size increases.

• If death rate > birth rate, population size decreases

Characteristics of Populations

• Ecologists ask questions to describe populations.

• They want to know the size of the population, where it members live, and how it is able to stay alive.

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Studying Populations

• To study migrating monarchs, a "monarch watcher"—often a school student like yourself—carefully catches a monarch and attaches a tag to one of its wings.

• Later, someone else who catches the same butterfly can use the tag to figure out how far the butterfly has flown.

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