Populations and Life Strategies Flashcards
What is a typical population
Defined as groups of interbreeding individuals, but this doesn’t apply to most organisms
What is the ecological population
Group of like organisms living in a defined area (same place) in a specific time (same time). This is usually defined by the investigator.
What is the density of size of a population
Number of individuals per unit area. It is a fundamental parameter that is affected by births, deaths, immigrations, and emigration
What is natality
Births including binary fission
What is fecundity
Measure of potential reproductive output
What is mortality
Measure of the death of organism
What are the secondary characteristics of a population
Age distribution, genetic composition or any other that carries out their effects on the population based on the primary characteristics
What happens when the r is greater than 1
The population will increase steadily
What happens when the r is less than 1
The population decreases steadily until we reach a zero of no population present after a period of time
What happens when r is equal to 1
We aren’t growing or shrinking so the population is constant over time. Things are coming in and things are going out at the same rate.
Why can’t exponential populations persist
Not infinite supply of food, not enough space, and wastes become toxic
What is the carrying capacity
Maximum number of individuals an environment can support
What is the r-selected organisms plan
Grow fast, high growth rate and high carrying capacity
What is the K-selected organisms plan
Grow slow, low growth rate, and low carrying capacity
Where do r-selected organisms win
They win in environment with high substrate availability (“generalists”)
Where do K-selected organisms win
Win in environment with low substrate availability (“specialists”)
What is the longevity of a growth phase of a r-strategists
Short
What is the longevity of growth phase of K-strategists
Long
What is rate of growth (uncrowded) for r-strategists
High
What is the rate of growth (uncrowded) for K-strategists
Low
What is the relative food allocation during uncrowded to crowded conditions in r-strategists
Shift from growth and maintenance to reproduction
What is the relative food allocation during uncrowded to crowded conditions of K-strategists
Growth and maintenance
What is the population density dynamics (crowded) in r-strategists
High population density of resting biomass
What is the population density dynamics (crowded) in K-strategists
High equilibrium population density of competitive growing biomass.
What is the response to enrichment to r-strategists
Fast growth after variable lag
What is response to enrichment for K-strategists
Slow growth after variable lag
What is mortality of r-strategists
Often catastrophic
What is mortality of K-strategists
Variable
What is migratory tendency of r-strategists
High
What is the migratory tendency of K-strategists
Variable.
What is “Top Down” Control
Dominant regulator of population density is predation - it doesn’t have to be a large predator but it can be a disease or anything else that can kill you
What is “Bottom Up” Control
Dominant regulator of population density is nutrient availability
What happens when grazing pressure exceeds bacterial productivity
If grazing pressure exceeds bacterial productivity, we will find ourselves in a top-down control attempt to get a stable community - defense specialists will dominate
What happens when bacterial productivity exceeds grazing pressure
If bacterial productivity exceeds grazing pressure, we will find ourselves in a bottom-up control to attempt to get a stable community - competition specialists will dominate.
What is the Leibig’s Law of the Minimum
Total biomass of any organism determined by the nutrient present in lowest concentration relative to the requirements of that organism.
What is Shelford’s Law of Tolerance
There are bounds for environmental factors above and below which microorganisms cannot grow
What is source of phosphorus in water
Source of phosphorus is erosion from rocks - there is no biological mechanism to pull phosphorus out of the atmosphere
What is the source of nitrogen in water
Source of nitrogen is nitrogen fixation - nitrogen-fixing bacteria/lightning we can’t incorporate it into it has been fixed into ammonia or nitrite
What is the source of carbon in water
Source of carbon is atmosphere - CO2 is being fixed by plankton/algae into carbon
What is the Iron Hypothesis
If we were to add free iron to high nitrate area in the ocean can lead to fertilization. Fertilization with iron would lead to large blooms, which would then sink, removing carbon dioxide from the atmosphere.
Why is the Iron Hypothesis not possible
Complex trophic interactions prevent this - many studies show no carbon sequestration. Initially there was positive results, but within a few days all that biomass was returned to the atmosphere.
What is the predator-prey cycle
- Prey and Predator are both increasing in populations
- Predator increasing it leads to prey decreasing
- Prey decreasing leads to predator decreasing
- Predator decreasing leads to prey increasing
This continues in a cycle
How do bacteria live
They are free-living like plankton or surface attached like biofilm. Most bacteria that live in the environment are surface attached. Most lab studies focus on planktonic bacteria.
How do we isolate bacteria
To isolate bacteria, we enrich (liquid), select colony (surface), and then do genetics and physiology with a combination of liquid and surface techniques. Liquid only isolation techniques have been used to isolate abundant, but previously uncharacterized, planktonic bacteria
What are plankton
Planktonic cells are in a more homogenous environment. Common in aquatic systems like lakes and oceans. This includes zooplankton, phytoplankton, bacterioplankton, and virioplankton. Even in the water column, most bacteria lived attached to particles.
What are biofilms
Biofilm cells produce their heterogeneous environment with many micro-niches. Biofilms are collections of microorganisms surrounded by the slime (extracellular polymeric substances, EPS), they secrete, attached to an inert or living surface. Bacteria in the environment predominantly live in biofilms.
How are biofilms developed
- Reversible adsorption of bacteria - occurs in seconds
- Irreversible attachment of bacteria - occurs in seconds to minutes
- Growth and division of bacteria - occurs in hours to days
- Exopolymer production and biofilm formation - occurs in hours to days
- Attachment of other organisms to biofilm - occurs in days to months
What are bacterial adhesins
Cell Membrane Cell Wall Structures Intracellular Materials Flagellum Extracellular Polymetric Material
Why would they form a biofilm
- Nutrients (macromolecules) collect at surfaces - source of food
- Protection from environment
- Physical proximity - allows easy exchange of products and assists with syntrophy and other forms of co-degradation
- Genetic exchange (horizontal gene transfer)
How do biofilms impact swimming pools
Health risks and cosmetic degradation
How do biofilms impact drinking water pipes
Health risks and corrosion
How do biofilms impact food processing
Contamination
How do biofilms impact dental plaque
Caries and gingivitis
How do biofilms impact ships
Increased drag and corrosion
How do biofilms impact household drains
Slowing draining sinks
How do biofilms impact implants
Chronic infections
How do biofilms wastewater treatment
Pass through biofilter to degrade matter
How can microbe impact corrosion
Microbes are taking electrons from the surface of the material to the outside of the biofilm and dumping them on oxygen which causes a pit to form in the metal. Biocorrosion caused by bacteria results in pitting, crevice corrosion cracking. Fix with electroplating new metal onto the cracks.
What are microbial mats
Thick biofilms that are some of the earliest microbial fossils. Mainly found in extreme environments
What is vibrio cholerae
The causative agent for human intestinal disease cholera. It is a burden to mainly underdeveloped countries which cannot afford to establish or to maintain necessary hygienic and medical facilities. Can be isolated and estuarine and aquatic environments. Survival in the relatively harsh environment is believed to be due to its ability to form a biofilm with zooplankton or egg masses.
During microbial strategies, what are life history strategies
Life history strategies represent a set of traits that tend to correlate due to physiological or evolutionary trade-offs, with different strategies favoured under different environmental conditions.
During microbial strategies, what is the C-S-R triangle
Grime’s C-S-R triangle is an alternative framework that enumerates three major plant life history strategies: competitors (C) excel at maximising resource capture in productive and undisturbed systems, stress tolerators (S) prevail at continuously low-resource and stressful conditions, and ruderals (R) occupy recently disturbed but less stressful habitats
During microbial strategies, what is the High Yield (Y) Strategy
High yield strategists maximise the fraction of resource uptake that is allocated to biosynthetic processes by investing in central metabolism and associated assimilatory pathways such as amino acid, nucleotide, and fatty acid synthesis to build cellular components using these precursor components. The absence of resource limitation and stress are expected to favour the high yield strategy.
During microbial strategies, what is resource acquisition (A) strategy
Resource acquistion by heterotrophic microbes depends on uptake of depolymerized substrates using various membrane transporters. It is probably that investment in resource acquisition traits is higher in resource abundant environments like the rhizosphere, we propose that this strategy will prevail in low-resource conditions where microbes would be under selection to increase resource capture at the expense of growth yield
During microbial strategies, what is the Stress Tolerator (S) Strategy
Certain global patterns in phenotypic expression are common, including factors or molecular chaperons aimed to minimise or mitigate biomolecular damage. Thus, microbes exposed to suboptimal conditions would posses traits linked to stress tolerance at the expense of other traits.
During microbial strategies, how do they measure yield
Yield is often measured as the proportion of carbon substrate invested into biomass relative to that lost through respiration
During microbial strategies, how do they measure resource acquisition
Resource acquisition traits have been estimated with omics and biochemical techniques at both the population and the community levels
During microbial strategies, how do they measure stress
Stress tolerance taits in the form of factors, molecular chaperons, or specific physiological adaptations can be extracted from widely used omics tools.
During microbial strategies, how do Y-strategists work with carbon cycling
Y-strategists with increased investment into growth and biomass production would contribute to microbial residue formation that can be stabilized through organo-mineral interactions or aggregation
During microbial strategies, how do A-Strategists work with carbon cycling
A-strategists should contribute more to decomposition and carbon loss through investment in extracellular enzyme production. Selection for A-strategists could also occur under a lower organic matter environment that stimulates enzyme production to mine resources.
During microbial strategies, how do S-strategists work with carbon cycling
S-strategists might depend on the type of stress compounds produced, by diverting investment away from growth, S-strategists could also reduce soil carbon accumulation.
