WK - Ecological Principles I Flashcards
Why do i need to understand ecology? (2)
- It explains the relationships of organisms to each other and their physical surroundings (environment).
- It aids in data interpretation.
What are the growth/reproductive strategies of r-strategists (Copiotroph)? (3)
- Fast growth at high nutrient availability.
- Poor resource use efficiency
- High copy number of 16S rRNA gene.
What are the growth/reproductive strategies of k-strategists (oligotroph)? (3)
- Slower growth at various conditions.
- Good resource use efficiency
- Low copy number of 16S rRNA gene.
What are the correlations between microbial groups and carbon mineralization rates? (2)
- β-Proteobacteria and Bacteroidetes are positively correlated with carbon mineralization rates.
- Acidobacteria shows a negative correlation with carbon mineralization rates.
What is niche space and the difference between fundamental and realized niches? (3)
Niche Space: Refers to all a species’ habitat requirements, including light, temperature, pH, salinity, oxygen, and electron acceptors.
- Fundamental Niche: The entire space an organism can grow in without limitations.
- Realized Niche: The actual space an organism occupies, influenced by other factors and entities.
What is the competitive exclusion principle? (2)
- Two species competing for the same resources cannot coexist.
- The species with the larger population and/or higher reproduction rate typically wins
What are the 3 main types of partitioning?
- Resource Partitioning: Organisms divide resources to minimize competition by utilizing different types or parts of them.
- Spatial Partitioning: Organisms occupy different physical areas within the same habitat to reduce competition
- Temporal Partitioning: Organisms utilize the same resources or spaces at different times to avoid direct competition.
How do organisms split resources in their environment? (2)
- Organisms can have different affinities for various sugars.
For example, Lactobacillus 100-23 has a high affinity for maltose under low glucose conditions.
What is biological bet hedging? (2)
- Biological bet hedging involves spreading the risk among a population.
- For example, in denitrification with Paracoccus denitrificans, only 11% of cells express NIR and NOR under aerobic conditions.
What happens if we remove a competitor or constraint in an ecosystem?
Ecological Release: When competitors or constraints are removed, microbes can expand their niche space.
What are priority effects in microbial communities? (3)
- Early colonizers shape the environment for latecomers based on the order of species arrival.
- These effects can be either positive or negative for late arrivals
- An example of a positive effect is facilitation by nitrogen-fixing cyanobacteria
What are the different types of competition among organisms? (3)
Exploitative Competition: Indirect competition where organisms vie for shared resources.
- Scramble Competition: Race to exploit resources quickly and efficiently.
- Cheaters: Exploit shared resources without contributing to their production.
Interference Competition: Direct competition involving antagonistic interactions.
- Contest Competition: Direct confrontations or monopolization of resources.
- Bacterial Warfare: Use of toxins, secretion systems, or other aggressive tactics to inhibit competitors.
Apparent Competition: Indirect competition mediated by shared predators or natural enemies.
- Example: Bacteriophages targeting two bacteria, where the more resistant species outcompetes the other.
What are key concepts of cooperation among organisms? (3)
Cooperation: A form of mutualism where organisms work together for mutual benefit, such as sharing resources or signals.
- Syntrophy: Mutualistic cross-feeding where one species uses the metabolic byproduct of another.
- Cross-feeding: The exchange of nutrients or metabolites between different organisms.
- Quorum Sensing: Communication through chemical signals to coordinate group behaviors like biofilm formation or resource sharing.
What are the types of cross-feeding in microbial interactions? (2)
Contact-dependent: Nutrient or metabolite exchange requires direct physical contact between organisms, such as:
- Vesicle chain
- Nanotube
- Flagella-like structure
- Cell-cell surface contact
Contact-independent: Nutrient or metabolite exchange occurs via the surrounding environment without direct contact, including:
- Passive diffusion
- Active transport
- Outer-inner membrane vesicles
- Outer membrane vesicles
What are corrinoids and their significance in microbial metabolism? (2)
Corrinoids (Cobalamin / Vitamin B12): Important cofactors for metabolism.
- “More than 80% of gut microbes require exogenous B12, while less than 25% synthesize it themselves” (Degnan 2014).
What are the types of syntrophy in microbial interactions? (2)
- Classic Syntrophy: A mutualistic relationship where two species are required to jointly metabolize a substrate (e.g., an electron donor) that neither can degrade alone.
- Non-classic Syntrophy: An obligate mutualistic interaction where both species depend on each other for metabolic processes, but their dependency is not strictly on a single substrate or electron donor.
What are examples of syntrophy in microbial interactions? (2)
Sulfur Syntrophy:
- Chlorobium oxidizes sulfide to elemental sulfur.
- Elemental sulfur serves as an electron acceptor for Desulfuromonas during acetate oxidation.
- Produces sulfide in return, illustrating reciprocal exchange of sulfur compounds.
Chlorochromatium aggregatum (Phototrophic Consortia):
- A syntrophic association where Chlorobium chlorochromatii encloses a central Comamonadaceae bacterium.
- The central bacterium relies on the syntrophic relationship for survival and metabolic functions due to significant gene loss, making it unculturable on its own.
What are 2 types of Quorum Sensing?
Density-Dependent Signaling
- Regulates gene expression in response to cell population density.
- Notable in processes like biofilm formation and bioluminescence.
Bioluminescence
- Production of light by living organisms via a chemical reaction involving luciferin and luciferase.
- Functions in communication, camouflage, and predation, primarily in marine species.
What is ecological suicide in microbes? (3)
Microbes engage in self-destructive behavior to benefit the population.
- Controls microbial density and prevents resource depletion.
- Releases nutrients back into the environment.
Outcome: Supports the growth of surviving organisms and enhances ecosystem productivity.
What are the characteristics of dormant seeds? (3)
- Remain viable for extended periods.
- Allow for delayed germination in favourable conditions.
- Support population persistence.
What are seed banks and their significance?
Serve as a genetic reservoir.
- Maintain diversity and enable recovery after disturbances or environmental changes.
Represent a reversible state of reduced metabolic activity.
Examples include:
- AMF (Arbuscular Mycorrhizal Fungi) spores
- Cyanobacteria akinetes
- Mixed species biofilms with active and non-active cells
- Bacterial spores
What is dispersal in ecological contexts? (3)
- Enables species to colonize new habitats.
- Reduces competition and spreads genetic diversity.
- Note: Dispersal is challenging to study.
