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).
