Ch. 36 Communities and Ecosystems Flashcards
Community
An assemblage of all the organisms living together and potentially interacting in a particular area
Diversity
The variety of different kinds of organisms that make up a community (Species richness and abundance of each species)
Stability
Community’s ability to resist change and return to its original species composition after being disturbed
- depends on type of community/distrubance
Trophic Structure
The feeding relationship in an ecosystem
- determines the route of energy flow and the pattern of chemical cycling in an ecosystem
What are the forces that tie populations together into communities?
1) Competition
2) Predation
3) Symbiosis
Example of Competition
1) Interspecific Competition
2) Competitive Exclusion Principle
a contest between individuals of two populations that require a limited resource (helps structure communities)
Interspecific Competition
Concept that populations of two species cannot coexist in a community if their niches are nearly identical
- using resources more efficiently and having a reproductive advantage, one will outcompete the other
Competitive Exclusion Principle
Niche
A population’s role in its community
- the sum total of a population’s use of the biotic and abiotic resources of its habitat
An interaction between species in which the predator eats the prey
Predation
Evolutionary change, in which adaptations in one species acts as a selective force on a second species, inducing adaptations that in turn act as a selective force on the first species
- mutual influence on the evolution of two different interacting species
- evolves thru natural selection
Coevolution
Example of predation
Plants using chemical toxins and antipredator thorns
Bright colors, camouflage, mimicry
Batesian Mimicry
A species that a predator eats looks like a different dangerous species.
Mullerian Mimicry
A mutual mimicry by 2 species, both harmful to the predator
Why is it difficult to assess predation in natural communities?
Predators never drive species to extinction. With so many species, predators are prey too so their numbers are limited. Due to this, it is hard to assess when so many organisms are linked and continue to be linked.
Keystone Predator
A predator species that reduces the density of the strongest competitors in a community therefore maintain diversity
Symbiotic Relationship
3 types
An interaction between 2+ species in which one species lives in/on another
1) Parasitism 2) Commensalism 3) Mutualism
Parasitism
A parasite (predator) lives in/on the surface of a host, from which it derives its food
Commensalism
One partner benefits without significantly affecting the other
Mutualism
Both partners benefit
A force that changes a biological community and usually removes organisms from it
- small ones tend to have positive effect
Disturbance
Process of biological community change resulting from disturbance
Ecological succession
Primary succession
Biological community arises in an area without soil
Secondary Succession
Occurs where a disturbance has destroyed an existing biological community but left the soil intact
How are disturbances a characteristic of many communities?
Fires (major one) and floods are examples.
In deciduous forest, decomposition occurs fast so no fire fuel. Grassland prairies depend on fire to avoid tree growth.
All the organisms in a given area along with the ABIOTIC factors with which they interact
Ecosystem
Passage of energy through components
- continuous new energy from sun
Energy Flow
Light -> Chemical -> Heat -> Chemical Cycling
Circular moment of materials within the ecosystem. Involved abiotic and biotic.
Chemical cycling
Food Chain
sequence of food transfer between trophic levels
Quaternary Consumers
An organism that eats tertiary consumers
Tertiary consumers
An organism that eats secondary consumers
Secondary Consumer
An organism that eats primary consumers
Primary Consumer
An organism that only eats autotrophs
Producers
An organism that makes organic food molecules from inorganic raw material
Detritivores
An organism that derives its energy from organic waste
Detritus
Nonliving matter
Decomposition
Breakdown of organic material to inorganic
Food Web
A network of interconnecting food chains
- animals can be multiple consumers
Biomass
Amount (mass) of organic material in an ecosystem
Primary Productivity
Rate at which an ecosystem’s producers convert solar energy to chemical energy
Part of an ecosystem where a chemical, such as carbon or nitrogen, accumulates or is stockpiled outside of living organisms
Abiotic Reservoir
An increase in productivity of an aquatic ecosystem
- balance of freshwater is easily upset by this increased
- reduces species diversity if accelerated
Eutrophication
An extensive region of land that includes one or more areas that are undisturbed by humans; surrounded by altered lands
Zoned Reserves
What are the dominant pathways of water, carbon, nitrogen, and phosphorous cyclic movements?
Water is driven by solar heat and the ocean.
Carbon is ran by plants but increased excessively by fossil fuel burning.
Nitrogen is from the atmosphere as main reservoir and driven by plants/soil bacteria though there can be excess by humans.
Phosphorous has a reservoir of rock in which it relies on weathering.
