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Biotic and Abiotic Population Influences within Ecosystems • Limiting factors • Tolerance • Biotic & Abiotic population influences • Symbiosis • Predator-Prey relationships • Population equation • Exponential growth

Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

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Page 1: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Biotic and Abiotic Population Influences within Ecosystems• Limiting factors• Tolerance• Biotic & Abiotic population

influences• Symbiosis• Predator-Prey relationships• Population equation• Exponential growth

Page 2: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Limiting Factor• Abiotic factors determine where a species can

live (temperature, precipitation, etc.)• Biotic factors determine the species’ success

(number of predators, available food, etc.)• A limiting factor is any factor that places an

upper limit on the size of a population.

Page 3: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Examples of limiting factors:

– Availability of water & food would affect how many, if any, organisms can live in an area

– Predators to an area would affect the number of organisms (prey) living in the area

– Temperature of the area affects which animals live there (ex., polar bears will not be in a desert because they would overheat)

Page 4: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

• Factors that limit one population in a community may also have an indirect effect on another population.

• Example: lack of water limits the growth of flowers

less flowers = less food for caterpillars less caterpillars

less caterpillars = less food for frogs less frogs

less frogs less snakes

less snakes less owls

Page 5: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Tolerance• The ability of an

organism to withstand a range of biotic and abiotic factors.

• Different species have different ranges of tolerance.

Page 6: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Tolerance

• Optimal Zone = best conditions for the organism to survive

• The further you go from the optimum zone, the lower your population

Page 7: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

• The range of tolerance are the conditions that the organism can continue to exist in.

• Outside the range of tolerance, the organism will not survive.

Page 8: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Abiotic Impacts on the Biomes of the World

Page 9: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Carrying capacity - number of organisms of one species that an environment can support indefinitely (forever).

Biotic Influences

Page 10: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Do all organisms get along with each other?

• How organisms live together in an ecosystem is called symbiosis.

• There are 3 types of symbiosis:1. Mutualism2. Parasitism3. Commensalism

Page 11: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Mutualism• Both species benefit from the relationship.• E.g. Clown fish and sea anemones. Clown fish

are protected from predators by the stinging tentacles of the sea anemones and in return, the anemone receives protection from animals that would prey upon it.

Page 12: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Parasitism• One species benefits at the expense of another species.• Parasites usually don’t kill their host (the animal they live

on). Why would they kill the thing that is providing them food and a home?

• Example – ticks on a dog– A tick is a parasite that feeds off the nutrients in the

dog’s blood. The dog doesn’t get the nutrients so it is harmed.

Page 13: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Commensalism• Occurs when one species benefits from a

partnership (gets food, protection, etc.) without benefiting or harming the other.

• E.g. Tigers and golden jackals. These jackals will attach themselves to a particular tiger, trailing it at a safe distance in order to feed on the big cat's kills.

Page 14: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Symbiosis: Mutualism, Commensalism, and Parasitism

Page 15: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Predator – Prey Relationship• Predator – a type of consumer that will seek

out and eat other organisms.• Prey – the animal that the predator eats.• Examples – cat & mouse; lion & antelope

Page 16: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Predator – Prey!!

Page 17: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Predator – Prey Relationship• In many cases they act to regulate each other. • E.g. If there are more predators, the population

of prey will decrease. If prey numbers decrease, there is less food for the predators so their population decreases.

Page 18: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Predator = Lynx, Prey = Hare

Predator = WolfPrey = Moose

Page 19: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Population Factors

• How a populations change (increase or decrease)

• Natality (Births)• Mortality (Deaths)• Immigration (Animals coming in)• Emigration (Animals leaving)

Page 20: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Population Factors

The Population equation

New Population =

Old Population + Natality + Immigration – Mortality – Emigration

Page 21: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

Exponential Growth• Rapid, uncharacteristic growth which only occurs

under certain circumstances for a short period of time

• Can be seen when an organism enters a new habitat that has a lot of resources or when predators are removed

Page 22: Biotic and Abiotic Population Influences within Ecosystems Limiting factors Tolerance Biotic & Abiotic population influences Symbiosis Predator-Prey relationships

• E.g. In South Africa, elephants became protected after many years of hunting for their tusks. This graph shows the result of the hunting ban instituted in 1960.