Module 9S1 Ecological Interactions
Module Summary and Assessment
Module Summary—Section 1
The ability to analyze complex ecosystems to identify the relationships between community members is a difficult task. Each organism belongs to a given trophic level and has a role to play within the community. However, organisms within the same trophic level compete with each other in interspecific competition for food (the previous trophic level), water and other scarce resources. Competition between members of the same species (intraspecific competition) happens the same way. Those with alleles that allow the individual to compete better, live to reproduce, improving the population gene pool within that environment.
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Predator/prey or producer/consumer interactions describe a community’s food chain. Predators act as selecting agents, removing those with less successful alleles and leaving those more genetically fit. Predators and prey cycle together through time as the populations of one control the numbers of the other. Prey species and producers have evolved many chemical, structural, and behavioral defences that protect them from consumption. The more effective the defense, the more likely the organism is to survive to pass on their genes.
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As an organism fills its niche (does its job) in the food chain it may have positive or negative effects on those it lives with. Mutualistic relationships benefit both parties, commensal relationships benefit one and don’t affect the other, and parasitic relationships benefit one organism at the expense of the other.
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Succession refers to the changes that occur in communities as a geographical area ages. Whether primary (from rock) or secondary (from soil), pioneer species invade a barren habitat, changing the environment so that they can no longer survive there, creating an environment for a more suitable organism to replace it, terminating in a climax species which remains indefinitely until the succession starts over. As producer species change through succession, the consumer species who rely on them change as well. The changing cast of characters in successions are part of a natural process and do not indicate a problem.
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Module Assessment—Section 1
In addition to submitting a tutorial summary for each tutorial video each student should also submit the following assignments
Bio30 4.9.1S1 online assignment