chapter 5 interactions in the ecosystem 1. section 3.3 - the ecosystem 2
TRANSCRIPT
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CHAPTER 5
Interactions in the Ecosystem
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SECTION 3.3 - THE ECOSYSTEM
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SECTION 3.3 - THE ECOSYSTEMLevels of Organization
• Individual – one organism from a species.
• Species – a group of organisms so similar to one another that they can breed and produce fertile offspring.
• Since they all have the same needs they compete with one another for food, shelter, space, mates, etc.
• Populations – All the members of a species that live in the same geographic area, a group of the same species.
• Communities – are made up of different populations of organisms that interact in the same area at the same time.
• Ecosystems – are large places where all the biotic factors and abiotic factors interact with one another.
• Abiotic factors generally cause environmental differences.
• Biome – made up of ecosystems: grasslands, savannah, desert.
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SECTION 5.1 – HABITATS AND NICHES
• Habitat – the specific environment in which a particular species lives.
• Within their habitat individual organisms find the appropriate food, shelter, temperature and other factors needed to survive.
• Niche – the role or actions of an organism in an ecosystem; what the organism does in its habitat.
• An organisms niche is defined by all the biotic and abiotic factors in the environment.
• Competition occurs between species when they try to share the same niche.
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SECTION 5.1 – HABITATS AND NICHES
• Competitive Exclusion – the extinction of a population due to direct competition with another species for a resource in the same area.
• Not the extinction of the whole species!
• The presence of one species might limit the niche of another.
• Fundamental niche – a theoretical niche of an organism.
• The realized niche of an organism is an organisms actual niche.
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SECTION 5.1 – HABITATS AND NICHES
Predator vs. Prey
• Predator – an organism that actively hunts other organisms.
• Prey – the organism that is hunted.
• Predator vs. prey relationships help keep environments stable.
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SECTION 5.1 – HABITATS AND NICHES
• Keystone predator – a predator that promotes a great niche diversity in its habitat.
• It increases the biodiversity in a habitat.
• If they are removed from an environment; it often decreases the overall diversity of organisms because a chain reaction of events will occur.
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SECTION 5.2 – EVOLUTION AND ADAPTATION
Ecosystems change over time
• Change in an environment will affect the niches of organisms.
• Changes in the environment affect the evolution of populations
• Evolution – a change in the characteristics of a population of organisms over time.
• Evolution happens when some individuals have genetic variations that allow them to produce more offspring with a certain trait or gene that is more advantageous for survival.
• “Survival of the Fittest”
TIME
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SECTION 5.2 – EVOLUTION AND ADAPTATION
Evolving in a niche
• Specialized species – an organism with a small niche.
• Koala and eucalyptus trees.
• Pandas and bamboo.
• Vulnerable to extinction.
• Are less able to tolerate habitat disturbance, so would thrive in an area with outside human activity.
• Living on an island without human involvement.
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SECTION 5.2 – EVOLUTION AND ADAPTATION
Convergent Evolution
• If niches in two ecosystems are similar, the organisms that evolve there may also look alike.
• It is the independent development of similar adaptations (traits) in two species with similar niches.
• Wings of birds and wings of bats (mammals) because both their niches require flight.
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SECTION 5.2 – EVOLUTION AND ADAPTATIONCoevolution
• Organisms that live closely together and interact may have evolutionary responses to one another.
• Coevolution – species that interact closely may become adapted to one another through this process.
• Clown fish and sea anemone.
• Acacia (uh-kay-sha) tree and stinging ants.
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SECTION 5.3 - POPULATIONSPopulation Growth
• Populations can quickly grow past the environment’s ability to support it.
• As a result of growing populations, organisms experience increased competition for resources.
• So populations can continually grow exponentially unless prevented by limited resources.
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SECTION 5.3 - POPULATIONSCarrying Capacity
• As a population grows it takes move from its habitat and resources become scarce.
• The death rate rises because those who cannot compete die and the birth rate starts decreasing.
• The growth of the population slows down.
• The population will stop growing altogether because the number of births equal the number of deaths.
• Carrying capacity – the number of individuals of a species that can be supported by an ecosystem for a species.
• The carrying capacity for a species is usually determined by the ecosystem’s resources.
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SECTION 5.3 - POPULATIONSCarrying Capacity
• The S-shaped curve represents the change in the size of a new population over time.
• The population starts out small and then increases rapidly.
• As the size of the population approaches carrying capacity, the growth rate slows down.
• The population stops growing when it reaches the carrying capacity and levels off.
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SECTION 5.3 - POPULATIONSLimiting Factors
• Limiting factors – the force that slow the growth of a population.
Population Size
Climate
Human Disturbanc
eNatural Disaster
s
Predation
Water Availability
Disease
Parasitism Food
Competition
Living Space
Density- dependent
Density Independent
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SECTION 5.3 - POPULATIONSLimiting Factors
• 2 Kinds
1. Density-dependent limiting factors – limiting factors that are dependent on population size.
- Examples include: food supply, predation, and disease.
- Are related to competition and other interactions between organisms.
- Usually when one population declines, another population also declines.
2. Density-independent limiting factors – a limiting factor that affects the same percentage of a population regardless of its size.
- Examples include: Natural disasters, climate and human disturbance.