Exam 1 Community Ecology

Ecological niche

Ecological niche

variables that define requirements for persistence

Competitive exclusion principle

two species cannont co-exist on one limited resource

Fundimental niche

Abiotic condtions where species can persist

Grinnelian niche

Determined by habitat and accompanying behavior adaptations

Eltonian niche

Functional attributes of animals and their corresponding trophic position. (who eats who)

Hutchinsonian niche

n dimensional hyper volumes that defines where a species can persist

Realized niche

Where it actually does persist, abiotic and biotic

Community

Different species that occur together in space and time

Ecology

study of how organisms interact with each other and their environment

Community Ecology

How SPECIES are interacting with each other and their environment

Commensalism

Species A benefits, Species B is unaffected

Realized niche is limited by

Partisism, predation, and competition

Realzied niche is expanded by

Mutualism and commensialism

Why can communities at times be hard to define?

Migration and immigration of species

Space and time can be hard to define (storms / changing environment)

Define the competitive exclusion principle and its consequences.

• Two species cannot coexist on one limiting factor

• Consequences: elimination of one species

How is the realized niche limited?

Predation, competition, and parasitism

What is different about temporary ecosystems than permanent?

Temporary: is a lot less stable and can be limited by the ability to leave and arrive

Permanent: More stable and long lived with the ability to support more species

What are the components of the community structure of a food web?

Species identity, complexity of the web, food chain length, trophic strategies

What aspects of ecosystem size drive playa food webs? Why?

Depth of the playa allows for more complex food webs because of the longer existence of the playa

Surface area not as important

What aspects of biodiversity drive playa food webs?  Why?

• More species richness = more complex food webs

o Later stages when producers are diminished predatorial cannibalistic behavior occurs

How do the common human impacts found in the region (Colorado) alter playa food webs?

Grazing by cows lead to increased complexity and richness

Agriculture: Corn and wheat affected the levels of N and C, Decreasing richness and complexity

How do each of the diversity indices correlate with alpha, beta, and gamma diversity?

Shan and Simp: alpha and gamma due to finding out the measures of richness and diversity of an area or region

Jaccard’s: is beta since it is the measure of one community compared to the whole

Explain the two reasons why species abundance curves look the way they do.

• Steeper: less even + diverse

• Flater: more even + diverse

How do species abundance curves look like for communities with different levels of diversity?  Evenness?

More diverse: flatter higher, lower steeper (can lead to longer graphs and more points)

Evenness: flatter higher, lower steeper

How can null models create patterns without ecological mechanisms?

Because random chance and distribution; standard distribution is a bell curve