Lecture 6 - test 2 Flashcards
What are the levels of ecological organization?
- Individual
- Population
- Community
- Ecosystem
- Biome
- Biosphere
What is an ecological community?
It consists of all the populations of all the different species that live together in a particular area.
What do ecological communities vary in?
the types and numbers of species they contain.
What is community structure?
The composition of a community including the number of species in that community and their relative numbers.
What five factors shape community structure?
- Climate Patterns
- Geography
- Heterogeneity (patchiness) of an environment
- Frequency of disturbances or disruptive events
- Interactions between organisms
What are foundation species?
Species that play a unique and essential role in creating and defining community.
How do foundations species effect the environment and create community?
By modifying the environment.
What are examples of foundation species?
- Coral - foundation supports entire coral reefs and provides shelter for other animals
- Giant kelp - provides shelter for otters
- Beaver - effect the shape and size of rivers and streams
- Elephants - have a large effect on ecosystems by knocking over trees, eating massive amounts of food, and traveling in groups
What are keystone species?
A species that has a disproportionately large effect on community structure relative to its biomass.
What trophic level are keystone species more likely to belong to?
Higher trophic levels.
What are examples of keystone species?
- Wolves in Yellowstone - Over hunting of wolves increased the elk and effected the whole ecosystem
- grizzly bears - They distribute nutrients in the soil by dragging fish across soil and digging up bulbs mixing up nutrients
- Otters - eat sea urchins
How is community structure measured?
By species richness and species diversity.
What is species richness?
The number of different species in a particular community.
Where is more species richness found and why?
Near the equator because there is more solar energy, warm temperatures, large amounts of rainfall, and little seasonal change.
where is the least species richness found and why?
Near the poles because there is less solar energy, colder, dried, and less amenable to life.
What are 4 other hypothesis for why there is more species richness near the equator?
- More land and ocean
- The tropics are less effected by climate change
- stable environments allow for narrow niches, which allows multiple species to coexist
- Speciation occurs faster and/or extinction is less likely
What is species diversity?
A measure of community complexity.
What is species diversity measured in?
- Species richness
- Species evenness
what is species evenness?
The relative abundances of each species.
Practice Simson diversity index equation
Ds = 1 - (the sum of) (n/N)^2
(n = number of individuals of each species)
(N = total number of individuals)j
What is an ecosystem?
A community of living organisms existing in conjunction with nonliving components of their environment, interacting as a system.