Module 4: Microbial Ecosystems (Defining and Analysis) Flashcards
Life is a…
collection of ecosystems
Abiotic vs Biotic Factors
Biotic Factors = Living organisms
Abiotic Factors = Non-living factors
What are some examples of abiotic factors in an ecosystem?
Gases, minerals, water, sunlight, etc.
Ecosystems describe the __________ and __________ of materials between __________ and _____________
Ecosystems describe the interactions and exchange of materials between organisms and surrounding environment
What is the chain reaction following environmental change in ecosystems?
1) Environmental Change
2) Organisms react to the change
3) Organisms change (adapt) in response to the change
4) The response then impacts the environment and leads back to #1
Primary Producers
Organisms that utilize energy from the sun or chemical reactions to produce organic molecules from inorganic starting materials
Photosynthetic Primary Producers
Organisms that utilize photosynthesis; harness light energy from the sun to drive carbon fixation
Chemosynthetic Primary Producers
Organisms that utilize chemosynthesis; harness energy for organic molecule synthesis from chemical reactions
(light INDEPENDENT autotrophs)
What are the two types of primary producers?
1) Photosynthetic (photoautotrophs)
2) Chemosynthetic (chemoautotrophs)
What is an example of chemosynthesis?
Chemolithoautotrophic Bacteria
–> Oxidize hydrogensulfide to produce organic molecules
Reaction equation for chemolithoautotrophic bacteria that oxidize hydrogen sulfide:
CO2 + O2 + 4H2S
Consumers
“Heterotrophs”
== Organisms that ingest the stored nutrients and energy of other organisms
–> The consumption of other organisms is their source of energy and carbon!
Decomposers
Organisms that consume/breakdown dead organic matter and release simple organic products
What is the important of decomposers?
They recycle organic molecules back into the environment!
Functional Guilds
Groups of organisms that carry out similar processes
(Play a similar role in a given ecosystem)
Members of functional guilds do not…
do not have to be genetically related!
–> Guild classification is solely based upon functions and processes BUT we will often see that genetically related organisms end up in the same guilds
What are 2 examples of microbial guilds?
1) Anoxic Phototrophic Bacteria = Shared process of harvesting light energy without producing oxygen!
2) Thermophilic methanogens = Shared process of methane production!
Niche
The specific functional role of an organism within an ecosystem which includes an organism’s direct and indirect interactions with their physical habitat and co-existing organisms
What factors help define an organism’s niche?
The 1) Type, 2) Quantity, and 3) Quality of sustaining resources (that are available)
An organism’s niche tells us about…
How a given organism interacts with its environment (both abiotic and biotic)
How does evolutionary pressure impact niche?
Selection processes and competition results in specialization of organisms for their “prime” niche
== Ensures all possible niches are “occupied”
What is a major ecological rule regarding niches?
No 2 populations of organisms can occupy the same niche and co-exist sustainably
–> One population will always outcompete the other if they have identical niches
Populations with distinct niches can…
CO-EXIST
What is an example of organisms with distinct niches co-existing?
In the human gut:
1) Methanobacter smithii (M. smithii) –> Niche = methane producer
2) Escherichia coli (E. coli) –> Niche = fermenter
–> They coexist within the human gut, one does not outcompete the other because they aren’t “fighting” for the same resources due to their different functions!
BUT this does NOT mean that they don’t interact! We often see that co-existing organisms for mutually beneficial relationships! –> here M. smithii consumes the fermentation products of E. coli which in turn helps E. coli maintain a proper gradient for fermentation