1. Community Ecology
Chapter 47
Mader: Biology 8th Ed.

2. Diversity and Composition Models Habitat and Ecological Niche
Outline
Diversity and Composition Models
Habitat and Ecological Niche
Competition Between Populations
Predator-Prey Interactions
Symbiotic Relationships
Community Development
Community Diversity
Mader: Biology 8th Ed.

3. Composition is a listing of various species in the community.
Community Concept
A community is an assemblage of populations interacting with one another within the same environment.
Composition is a listing of various species in the community.
Diversity includes both species richness and species diversity.
Mader: Biology 8th Ed.

4. Diversity and Composition Models
Gleason - Individualistic Model
Each population in community is there because its own particular abiotic requirements are met by a particular habitat.
Clements - Interactive Model
Community is the highest level of organization.
Dependent on biotic interactions.
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5. Community Structure
Competition for limited resources between two species has a negative effect on the abundance of both species.
Predation and parasitism are expected to increase the abundance of the predator and parasite at the expense of the abundance of the prey and its host.
Mader: Biology 8th Ed.

6. Habitat and Ecological Niche
Habitat is the area an organism lives and reproduces in.
Ecological niche is the role an organism plays in its community, including its habitat and its interactions with other organisms.
Fundamental niche - All conditions under which the organism can survive.
Realized niche - Set of conditions under which it exists in nature.
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7. Feeding Niches for Wading Birds
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8. Competition Between Populations
Interspecific competition occurs when members of different species try to utilize a resource in limited supply.
Competitive Exclusion Principle - No two species can occupy the same niche at the same time.
Resource Partitioning decreases competition.
Can lead to character displacement.
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9. Competition Between Barnacle Species
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10. Predator-Prey Interactions
Predation occurs when one living organism, the predator, feeds on another, the prey.
Presence of predators can decrease prey densities, and vice-versa.
Mader: Biology 8th Ed.

11. Lynx-Snowshoe Hare Interactions
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12. Prey Defenses
Prey defenses are mechanisms that thwart the possibility of being eaten by a predator.
Spines
Tough Epidermis
Poisonous Chemicals
Camouflage
Bright Coloration
Flocking Behavior
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13. Camouflage in the Anglerfish
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14. Batesian - Mimic lacks defense of the organism it resembles.
Mimicry
Mimicry occurs when one species resembles another that possesses an overt antipredator defense.
Batesian - Mimic lacks defense of the organism it resembles.
Müllerian - Mimic shares same protective defense.
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15. Symbiotic Relationships
Symbiosis refers to interactions in which there is a close relationship between members of two populations.
Parasitism
Parasite derives nourishment from a host, and may use host as habitat and mode of transmission.
Endoparasites
Ectoparasites
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16. Many examples may turn out to be mutualism or parasitism.
Commensalism
Commensalism is a symbiotic relationship in which one species is benefited and the other is neither benefited nor harmed.
Remoras and Sharks
Many examples may turn out to be mutualism or parasitism.
Amount of harm or benefit two species do to one another is partially determined by the investigator.
Mader: Biology 8th Ed.

17. Often help organisms obtain food or avoid predation.
Mutualism
Mutualism is a symbiotic relationship in which both members of the association benefit.
Often help organisms obtain food or avoid predation.
Bacteria in human intestinal tact.
Need not be equally beneficial to both species.
Cleaning Symbiosis
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18. Mutualism Between Bullhorn Acacia and Ants
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19. Cleaning Symbiosis
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20. Community Development
Ecological Succession
A change involving a series of species replacements in a community following a disturbance.
Primary Succession occurs in areas where there is no soil formation.
Secondary Succession begins in areas where soil is present.
Pioneer Species
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21. Secondary Succession in a Forest
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22. Succession Models Facilitation Model
Succession in a particular area will always lead to the same type of community.
Climax Community
Each stage facilitates invasion and replacement by organisms of the next stage.
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23. Different types of plants can colonize an area at the same time.
Succession Models
Inhibition Model
Colonists hold onto their space and inhibit growth of other plants until the colonists are damaged or die.
Tolerance Model
Different types of plants can colonize an area at the same time.
Chance determine which seeds arrive first.
Mader: Biology 8th Ed.

24. Community stability can be recognized in three ways.
Community Diversity
Community stability can be recognized in three ways.
Persistence through time.
Resistance to change.
Recovery once a disturbance has occurred.
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25. Intermediate Disturbance Hypothesis
Moderate amounts of disturbances at moderate frequency are required for a high degree of community diversity.
If widespread disturbances occur frequently, diversity will be limited.
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26. Intermediate Disturbance Hypothesis
Mader: Biology 8th Ed.

27. Predation, Competition, and Biodiversity
In certain communities, predation by a particular species reduces competition and increases diversity.
Predators that regulate competition and maintain community diversity are referred to as keystone predators.
Introduction of exotic species into a new area may lead to unbridled competition and resultant reduction in biodiversity.
Mader: Biology 8th Ed.

28. Diversity and Composition Models Habitat and Ecological Niche
Review
Diversity and Composition Models
Habitat and Ecological Niche
Competition Between Populations
Predator-Prey Interactions
Symbiotic Relationships
Community Development
Community Diversity
Mader: Biology 8th Ed.

29. Mader: Biology 8th Ed.