Communities and Ecosystems

A series of free High School Biology Video Lessons. Here we look at the Biological Community and discuss a few inter-related key concepts such as biological competition, predation, symbiotic relationships and keystone species.

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Biological Community
In biology, a community is a group of potentially interacting species living in the same place. Members of a community may have a variety of relationships including, predator/prey, competitors, or mutualism.
An overview of the biological community.

Biological Competition
In biology, competition is an interaction between multiple organisms within a community that all depend on the same limited resource. One species generally adapts to better access that resource and the other dies off, an example of natural selection
Understanding the different types of biological competition.

Predation is the consumption of one organism by another. Predation occurs when one organism benefits from killing another. Herbivores, parasites, and parasitoids can also be considered predators.
Understanding the concept of predation and the types of predators.

Symbiotic Relationships
Symbiotic relationships are the relationships organisms in a community have with one another. Types of symbiotic relationships includes mutualism, parasitism, predation and commensalism. In mutualism both organisms benefit, in commensalism one organism benefiting parasitism one organism benefits, in predation one organism benefits while the other dies.
Understanding the relationships between organisms living in a community.

Keystone Species
A keystone species is a species which maintains the balance and diversity of its community. Often keystone species are predators which check the population of other species that might otherwise become dominant. Sometimes they are mutualists which perform a necessary function for a community. Other keystone species are engineers, changing the habitat in a way that creates food or shelter for other species.
An explanation of keystone species.

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.
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