Chapter 55 Community Ecology Flashcards
What factors shape a community? Abiotic and biotic
Humans are part of the biotic environment and affect organisms and the energy flow and nutrient cycling throughout the environment
What is the ultimate source of energy?
The sun
Energy flows from sun to earth
A the flow of energy one way or cyclic?
- energy moves in 1 way/ direction
- moves from sun to producers to consumers, energy is not recycled
Producers
- primary producers: autotrophic, they turn light into their own food
- plants, photosynthetic prokaryotes and protists
Consumers
-get energy and nutrients (carbon) from otter organisms
-primary: herbivores who eat the producers
-secondary: carnivores who eat the herbivores
Tertiary: top predators who eat other animals
Omnivores
Consumers who eat vegetation and meat, nothing goes to waste
Detritivores and decomposes
Feed on organic matter and wastes/remains of other organisms
-the clean up crew
What is a trophic level? How much energy makes it to the next level? Why is this?
- hierarchy of feeding relationships, energy and nutrients are transferred from one level to the next.
- Only 10% reaches the next level
- energy is lost as metabolic heat which is not useable, energy becomes stored in molecules that consumers can’t break down
Are nutrients cyclic or one way
- nutrients are cycled within an ecosystem, they use a bio, chemical, geo processes
- cycles between living organism and abiotic components of ecosystems
- water cycle, phosphorus cycle, nitrogen cycle, carbon cycle
What is a food chain?
- a sequence of steps where energy is captured by primary producers and is transferred to higher tropic levels
- ex: plants all the way to quaternary consumers (top carnivores)
What is a food web?
- a set of food chains that are interconnected
- shows energy flow through a community
What is bio accumulation?
- a chemical stored in fat that is increasingly concentrated in he tissues of animals as it moves up the food chain
- ex: a rat eats poison, predators eat that rat and also get the poison, top of the food chain eats the predator and gets the poison
What is a tropic cascade?
- the interaction of a single consumer species with other species in its community
- causes progression of successive effects. Ex: a predator disappears, consumer population increases, producers have pressure from more consumers. Once you lose one species another species disappears etc
Eutrophication
- lack of phosphate limits growth in aquatic producers
- reduced o2 in water and threatens survival of other species in lake
What is the story of the gray wolf and it’s role in the Yellowstone community?
- wolves are top predators they really like elk
- people didn’t like them eating their farm cattle and hunters did not like that wolves were eating elk saw them as competition
- hunting led to their elimination
- since there were no more wolves, elk population exceeded the parks carrying capacity so now people had to shoot elk to bring population down
- willow population declined and so did beavers
- wolves were reintroduced after 70 years! This brought balance back to Yellowstone
- in conclusion: removing wolves caused the community to break down, when they came back it was balanced and healthy. Wolves aren’t scary bison/Buffalo are
What is a keystone species? How important are they to a community? Is a keystone species always a predator?
- a species that has a large affect on the community structure, they influence them number of species in community and influences the number of trophic levels
- they are very important, if they are gone then it can lead to destruction of the community
- many of them are predators but not always. Ex: elephants, beavers
What is an ecosystem engineer? Do they have an important role in a community?
- organisms that build structures for existing habitats
- they make homes for species that otherwise would not live there
- if they were removed then the species who rely on them will also disappear
- ex: elephants allow for savannas to grow and things can live there. Beavers build damns for fishes and plants to live there. Prairie dogs maintain the grasslands of North America, they loosen up soli which allows water to come in and the grass gets the water
What is species diversity? How is species diversity determined?
- communities that are similar in scale differ in species, more diversity is healthy
- it is determined by species richness and evenness
Species richness
-number of species present
Species evenness
-relative abundance of each species. How many of each species
What is ecological disturbance
Disruption in a community caused by an external force that removes species and opens up new areas for colonization
- small scale: log dislodges algae and animals attached to a rock
- large scale: hurricane, Forrest fire, tsunami, movement of a glacier, urbanization
What are pioneer species?
- colonize a disturbed are
- introduced variety and they gradually replace by a succession of others
How does primary succession differ from secondary succession? What type of disturbance preceded each? Is there life/soil left it’s the after the disturbance?
Primary: no existing soil or species. Lava or glacial retreat caused this. No life is left after. Hardy plants like lichens and mosses come in, soil develops from chemical weathering and erosion. Grass and shrubs move in, lichens and moss dies which contributes waste and decomposition build up. Tall trees and species come in. Takes a long time because you need to build soil
Secondary: natural disasters or human disturbance like forest clearing. The soil is left intact so there is life, which makes it easier for plants and species to come back.
Explain the gradient found in biodiversity, what factors affect this gradient?
- diversity decreases with increasing latitude, moving away north or south from the equator. The tropics have the most diversity because they get the most sunlight and rainfall, less seasonal variation
- depends on weather, climate with less variation, high solar energy, seasonal change, air circulation and rainfall, landforms (windward side)
Explain island biogeography
Explains the patterns of species diversity on islands. Number of species on an island represents the balance between the rate of immigration of a new species and the rate of extinction of species on the island
The area effect
Relationship between size of the island and number of species. The larger the island the more species can live there
The distance effect
Relationship between distance from mainland and number of species. The farther the island from mainland the fewer number of species
Rate of immigration and extinction
Immigration: determined by distance. More immigration to a near island
Extinction: determined by islands size. Small islands support small population sizes. There is more extinction when the island is small since there is less socave and resources
