ch. 17 communities and ecosystems

Define community

“Different populations close enough to interact”

What is the difference between interspecific interactions and intraspecific interactions?

Which applies to communities and which applies to populations

Interspecific interactions: interactions between species

This applies to communities

Intraspecific interactions: interactions “within” species

This applies to populations

List and describe the three categories of community level interactions.

Competition: habitat (location, where it lives), niche (occupation role, how it lives)

Predation: “when one species (predator) eats another species (prey)”

Symbiosis: “when one species (symbiont) lives in or on another species (host)”

What is the competitive exclusion principle?

What are the ramifications of this type of conflict? How do species avoid this result? Include the words niche, habitat, and resource partitioning in your answers.

The competitive exclusion principle is when two different species share the same niche (occupation role) in the same habitat, until the more efficient one wins and drives the other species to extinction in that location.

Resource partitioning is an alternative outcome, “species that have a similar niche will subdivide resources by specializing in different aspects” (don’t share, separate territory)

How are predator and prey defined

Predators are species who eat other species. Prey is the species that gets eaten.

How are symbiont and host defined

symbiont is a species that line in or on different species. The host are species who are homes for these symbionts

What were the three types of symbiosis covered in lecture? recognize them from examples or descriptions

Parasitism: symbiont benefits, host harmed (rabies, dog)

Commensalism: symbiont benefits, host neutral (buffalo + bird takes a rest)

Mutualism: both symbiont and host benefit (clown fish + sea enemy)

Explain how a food web is a complex community network.

“Disturbances to one part of the community affects the entire community.”

Define an ecological disturbance and how it relates to the intermediate disturbance hypothesis for species diversity

Ecological disturbances, of nonbiological or biological origin, that bring mortality to organism and changes in the ecosystems they inhabit.

Intermediate disturbance hypothesis: species diversity is typically greatest where disturbances are moderate (in both severity + frequency)

If disturbances are

too severe: plant community dominated by opportunistic early colonizers (weeds)

too mild: plant community dominated by climax species (oak trees)

Recognize the different forms of ecological succession discussed in lecture. What leads to each