4-2 What Shapes an Ecosystem?

Ecosystems are shaped by Biotic (living) & Abiotic (nonliving) factors.

Biotic factor=living organisms in the ecosystem Abiotic factors= physical (nonliving) components of the

ecosystem & how the organism uses these components.Area where an organism lives=habitat

Biotic Factors

ECOSYSTEM

Abiotic FactorsAbiotic and Biotic Factors

The NicheNiche-the combined physical and biological

conditions in which organisms live & how the organism uses these conditions.

A Niche includes:– The food type, method to obtain it and competition for the

food.– Temperature and water content.– Reproductive time and location

Community Interaction:

Competition- a conflict for the same resource in a habitat at the same time.

Resource- any necessity for life.

Predation occurs when one species (predator) captures & feeds on another species (prey).

Symbiosis: two organisms living close together. There are three types.

1) Mutualism2) Commensalism3) Parasitism

Symbiosis:

Mutualism: both species benefit.

Crocodiles and plover birdsWater buffalo and cowbird

Symbiosis: Commensalism: One member benefits & one is

neither helped nor harmed.

Barnacles on a whale

Flatworm on horseshoe crab

Symbiosis: Parasitism: One organism (parasite) lives on or in

another organism (host) and harms it.

Type of relationship

Species harmed

Species benefits

Species neutral

Commensalism

Parasitism

Mutualism

= 1 species

Symbiosis:

http://www.cstephenmurray.com/onlinequizes/biology/Ecology/typesofinteractionsexamples.htm

Ecological SuccessionEcosystems &

communities are ALWAYS changing!

Ecological Succession= a series of predictable changes in a community.1) Primary succession

2) Secondary succession

Primary succession: occurs in areas with no soil.

Example= Volcanic eruptions, glacial melts.

Ecological Succession

Ecological SuccessionSecondary succession: succession following a disturbance that

destroys a community without destroying the soil.Ex: destructed through fire, natural disasters, or clearing of land

Chapter 5-1: How Populations Grow

Populations have 3 characteristics:-- Geographic distribution-- Population Density -- Growth rate.

Characteristics of a Population

Geographic Distribution (range) is the area a population inhabits. (Where it lives.)

Population Density is the number of individuals in a given area.

Characteristics of a Population

Growth rate is the rate at which members are added or removed from the population.

Characteristics of a Population

Population GrowthThree factors affect population size: birth rate, death rate, and migration.Growing population= a higher birth rate than death rate.Shrinking populations= a higher death rate than birth rateStable populations have equal birth & death rates

Individual organisms reproduce at a constant rate

Population’s growth slows down or stops

Carrying Capacity: the largest number of individuals a given

environment can hold

Population GrowthImmigration = movement into a populationEmigration = movement out of a population

5-2 Limits to GrowthA Limiting Factor causes a population to decrease.Example: Panda & Bamboo

Density Dependent Factor

A limiting factor that depends on the population size= Density Dependent Limiting Factor.

Types of Density Dependent Factors:--Competition--Predation--Parasitism & Disease

Density Dependent Factor

1) COMPETITION:Competition is when organisms use the same resources

Density Dependent Factor

2) PREDATION: Predation creates the predator-prey relationship.

60

50

40

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0

19551960 1965 1970 1975 1980 1985 1990 1995

2000

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1200

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0

2400

Moose Wolves

Density Dependent Factor

3) PARASITISM & DISEASEParasitism & Disease harms the host

6-3 BiodiversityVariety= Diversity Biodiversity- the sum total of the variety of

organisms in the biosphere. Human activity can reduce biodiversity by

altering habitats: 1) Hunting species to extinction 2) Introducing toxic chemicals into food webs

Pollution

DDT= one of the first widely used pesticides.

GOOD BAD

CheapRemains active for a long timeKills many different insects Controls agricultural pests.

-Non biodegradable-Organisms can NOT remove it from their bodies.-DDT gets stored in organisms (producers & consumers bodies)

How DDT gets into the Environment

Pollution As you move up trophic levels in a food chain the

amount of DDT consumed increases GREATLY! Biological Magnification- concentrations of a

harmful substance increases at higher trophic levels.

Plants pick up DDT from water& store it

Herbivores eatplants and storesome DDT

Carnivores eatherbivores and store more DDT

→ →

DDT

Fish-Eating Birds10,000,000

100,000

10,000

1,000,000

1

1000

LargeFish

Small Fish

Zooplankton

Producers

Water