Unit 2 – Ecosystems and Population Change3.1 – Individuals, Populations, and Communities in Ecosystems

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Learning Objectives• What is an ecosystem?

• What are populations and communities?– How do these fit into ecosystems?

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The Parts of an Ecosystem

• An ecosystem is made up of many parts.– Ecosystems can take up many hectares of land or can be

small, such as a tide pool or a rotting log.– Abiotic factors include air, water, soil, nutrients, and light.– Biotic factors include plants, animals, and micro-organisms.– A habitat is where an organism lives.

(c) McGraw Hill Ryerson 2007

The habitat of the red fox often includes the edges of forests or marshlands.

Ecotones• Ecotones

– A transition area between ecosystems

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Abiotic Interactions in Ecosystems

• The abiotic components are what allow the biotic components to survive in an ecosystem.

• Abiotic factors include:oxygen, water, nutrientslight and soil.

Abiotic factors: Oxygen• Oxygen is produced by the green plants and

certain micro-organisms and is used by animals and most other micro-organisms.

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Abiotic factors: Water• Water is necessary for all life.

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Abiotic factors: Nutrients• Nutrients often enter the food chain with

plants and are very important for growth.

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Abiotic factors: Light• Light is required for photosynthesis, which is the

process in plants that converts and stores the Sun’s energy in the form of starches and carbohydrates.

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Abiotic factors: Soil• Soil not only contains water and nutrients but also

is home to many plants and animals.

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Earthwormsin soil

Individual Organisms• How does the

environment affect – Behavior? – Physical features (Morphology)?

• Helps to explain why some organisms are only present in certain areas Mr. Standring

Populations• Species

– Organisms that can breed with each other and produce fertile offspring

• Population– A group of individuals

of the same species living in a specific area at the same time

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Communities• Community

– All individuals in all of the interacting populations in a given area

• Interactions affecting communities:– Competition– Predator/prey relationships– Symbiotic Relationships– Abiotic factors

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Symbiotic relationships• Symbiotic relationships are the interactions

between members of two different species that live together in a close association.

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Commensalism

• Commensalism – one species benefits, one is not affected

• Example: Clownfish living in a sea anemone

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Parasitism• Parasitism – one species benefits, the other is

harmed– Example: hookworm living in dogs– A mosquito drinking human blood– A lamprey eel living off a fish

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Mutualism• Mutualism – both species benefit

– Example: a bee gathering nectar from a flower– Birds eating parasites off a rhino.

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Niches and Competition• A niche refers to the role an organism has within an

ecosystem, physically, chemically and biologically.

• Competition occurs when aresource is needed by two ormore individuals.

– Competition usually meansresources are limited.– This limits the size and health of that

individual and perhaps that population.

Coyotes compete over habitat or food sources.

Predation• Predation is the relationship between the

“eaters” and the “eaten”.– Predators have adaptations to help them catch their

prey.– Prey have adaptations to help avoid predators.

• Examples of adaptations include spines and shells, camouflage and mimicry.

– The numbers of predatorsand prey influence each other.

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Biodiversity in Ecosystems

• Biodiversity refers to the variety and number of different individuals and species in an ecosystem.– Healthy ecosystems generallyhave high biodiversity.– Most biodiversity losses occur

from the loss of habitat.

Wetlands provide habitats.

The impact of Humans on Ecosystems

• Humans often have a negative impact on biodiversity.

– Many efforts are now made to lessen this impact in order to maintain biodiversity.

– Ecological management programs try to balance human progress with maintaining biodiversity.

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Environments Change Over Time

• Abiotic factors• Biotic Factors

– Populations/Communities• Succession

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Primary Succession

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Earth’s Biosphere• Biosphere

– All of the ecosystems and their interactions

– Atmosphere, Lithosphere, Hydrosphere

• Each species has its own niche in the biosphere– They live in specific places

and are well suited to survive in these areas

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The Big Picture

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