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Environmental Science Ch. 4.1-4.3 AND 5.1-5.3:

Living Things In Ecosystems

Ch. 4-1: Ecosystems: Everything Is Connected

Key Terms• Species

• Organism

• Population

• Community

• Ecosystem

• Habitat

• Niche

Ch. 2 Section 1:Why Do I Need To Know This?

1. Because we are all part of an ecosystem.

2. Because humans are having profound effects upon many ecosystems, leading to massive extinction.

3. Because the actions we do to one part of an ecosystem often has profound effects on other parts of the ecosystem.

Key Sections Ch. 2-1

• Ecosystems: Everything is Connected

• What Is An Ecosystem

• Organisms and Species

• Populations

• Communities

• Niche and Habitat

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Ecosystems: Everything Is Connected

• Everything in an

ecosystem is connected.

• What affects one part of an ecosystem often affects many other

parts of the ecosystem as well.

What Is An Ecosystem• An ecosystem includes all the different organisms in a

certain area, along with their physical environment.

– Ecosystems are divided into 2 distinct factors:1. Biotic Factors

• These are the living parts of the ecosystem and include plants, animals and microorganisms.

• Living things in an ecosystem are organized from smallest to largest units: organism, population, community, ecosystem, and biosphere.

2. Abiotic Factors

• These are the non-living parts of the ecosystem that affect life and include temperature, sunlight, humidity, water supply, soil type, and mineral nutrients.

• Although scientists often refer to ecosystems as individual units, ecosystems usually do not have clear boundaries and often flow into one another.

Biosphere

http://cde.nwc.edu/SCI2108/course_documents/earth_moon/earth/earth_science/biosphere/biosphere.htm

The Biosphere is ALL parts of the earth that host life. This includes the

environments AND the organisms

Organisms and Species

• An organism is a single living thing.

• A species is a group of organisms that can produce fertile offspringwith the same characteristics.

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•Species that have

strong and/or wide-reaching effects on a community

•Removal of a keystone species can significantly

alter the structure of a community.

Keystone Species Ecology

• Ernst Haeckel defined ecology in 1866 as

“the body of knowledge concerning the economy of nature—the total relations of the animal to both its inorganic and organic environment.”

• In other words: the total interaction of organisms to the world around it (both

living and non-living)

Populations• A population is a group of organisms

from the same species living in the same place.

• There may be thousands of populationsfor any particular species.

• Population size = # of individuals

Population Density

• This is a measure of how crowded it is in

a given area

blog.bn.eehttp://www.ehow.com/how_8349133_calculate-animal-population-density.html

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Population Distribution• How organisms are arranged within an area:

• Random distribution:Organisms arranged in

no particular pattern

• Uniform distribution:Organisms evenly spaced

• Clumped distribution:Organisms grouped near resources; most common distribution in nature

Age Structure

• Relative number of organisms of each age group within population

• Can be used to predict future population growth of a population

zoology.muohio.edu

Sex Ratio = the number of Males to Females

Birth and Death Rates• A population’s relative birth and death rates (mortality and

natality) affect how it grows.

• Survivorship curves show how the likelihood of death varies with age.

http://www.bioinquiry.vt.edu/bioinquiry/cheetah/cheetahpaid/cheetahhtmls/

popsurvivor.html

Immigration and Emigration• In addition to births and deaths, population growth is

affected by immigration and emigration— individuals moving into and out of a population.

• Migration, seasonal movement into and out of an area, can temporarily affect population size.

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Communities

• A community is a group of populations

from different species that interact with each other living in the same area.

Organism To Biosphere

Niche and Habitat

• The place an

organism lives is called its habitat.

• All of an organism’s combined relationships with the living and non-

living parts of its ecosystem is called its niche.

Resource

• ANYTHING an

organism needs;

– Nutrition

– Shelter

– Breeding sites

– Mates

blog.epicenter.net