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Microbial Ecology (BIOL 355) > Lecture 9: Microbial Population Ecology > Flashcards

Lecture 9: Microbial Population Ecology Flashcards

1
Q

Explain the biological species concept.

A

Members of a population that interbreed & produce fertile offspring
- Based on sexual reproduction

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2
Q

Explain the ecology species concept.

A

Set of individuals that are identical in terms of ecology

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3
Q

What is the most common OTU definition used to describe microbial species?

A. 97% whole genome hybridization
B. 70% 16S rRNA sequence identity
C. 97% 16S rRNA sequence identity
D. 100% plasmid compatibility test

A

A. 97% whole genome hybridization B. 70% 16S rRNA sequence identity
C. 97% 16S rRNA sequence identity
D. 100% plasmid compatibility test

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4
Q

Define operation taxonomic unit (OTU).

A

Clusters of organisms grouped by DNA sequence similarity of a specific taxonomic marker gene

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5
Q

Explain the genetic species concept.

A

A genetic species is a group of genetically compatible organisms
- Focuses on genetic isolation (as opposed to reproductive isolation)

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6
Q

Why is it difficult to categorize bacterial species?

A

Horizontal gene transfer
- Results in the blurring of distinctions between microbial organisms

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7
Q

What does chimeric mean? What are core genomes vs. accessory genomes?

A
  • Chimeric:
  • Core genome: gene set shared by almost all clade members (conserved)
  • Accessory genome: more mobile elements of the genome (may be shared with only a few other strains)
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8
Q

Explain what happens in resource partitioning and utilization.

A
  • Through time and natural selection, the two species diverge in their use of the resource
  • A new species arrives, and further competition leads to a narrower range of resource use for all three species
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9
Q

Define niche.

A

The role an organism plays in a community
- Encompasses both physical and environmental conditions and interactions with other species

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10
Q

What is the ecological niche concept?

A

The range of conditions under which an organism can survive and reproduce

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11
Q

What are fundamental vs. realized niches?

A
  • Fundamental: full range of conditions that an organism could use
  • Realized: portion of the fundamental niche actually occupied by that species
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12
Q

Which of the following determine the “size” of a population’s niche?

A. Tolerance for abiotic conditions
B. Competition
C. Overlap in resource utilization
D. Both A & B
E. All of the above

A

A. Tolerance for abiotic conditions
B. Competition
C. Overlap in resource utilization
D. Both A & B
E. All of the above

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13
Q

Define competition.

A

Interaction between populations in which growth rates decrease for both

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14
Q

What is competitive exclusion?

A

If there is significant niche overlap and limited resources, one population will drive the other to extinction

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15
Q

Explain intraspecific competition. Why would a population level out?

A
  1. Competition within a population
    - Carrying capacity (K) = max population size the environment can sustain
    - S shaped curve
  2. As pop gets closer to K, growth slows and eventually levels out
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16
Q

How well do these populations fit the logistic growth model?

A
  • Lab populations of some small animals and microorganisms fit an S-shaped curve if resources are limited
  • Constant environment lacking predators and competitors
17
Q

What are r-selected vs. K-selected populations?

A
  • r-selected: high growth rate, poor competitors, good dispersal
  • K-selected: slow growth, good competitors
18
Q

What are the equivalent terms for growth types in soil vs. aquatic vs. overall ecology?

A
19
Q

Explain zymogenous vs. autochthonous soil bacteria.

A
  1. Zymogenous: require an easily oxidizable external sources of energy that causes the population to fluctuate with nutrients
  2. Autochthonous: doesn’t fluctuate in response to nutrient availability
    - Found in soil with limited resources
20
Q

According to the logistic model, what would happen if the 2 species were competing for the same nutrient?

A
21
Q

The Lotka-Volterra model of interspecific competition is able to generate a range of possible outcomes. What are they?

A
  1. The predictable exclusion of one species by another
  2. Exclusion dependent on initial densities
  3. Stable coexistence
22
Q

What does coexistence of 2 species occur?

A

When interspecific competition is weaker than intraspecific competition
- Even so, the final or equilibrium density of each species is lower than its carrying capacity

23
Q

Niche partitioning _____ competition (increases/decreases).

A

decreases

24
Q

Define succession.

A

Directional, continuous pattern of colonization and extinction of a site by populations

25
Q

What is primary vs. secondary succession? Give examples.

A
  1. Primary: new habitat; pioneer species
    - Ex. Newborn’s gut, lichens
  2. Secondary: catastrophe resets clock
    - Ex. Forest fire
26
Q

Why can it be hard to identify successions?

A

Because of temporal and spatial heterogeneity and variability

27
Q

Describe autotrophic succession vs. heterotrophic succession.

A
  1. Autotrophic: primary production –> respiration
    - Microbial mat formation
    - Slow
  2. Heterotrophic: breakdown of complex substrates
    - Quick
28
Q

What is facilitation?

A

Preparation of habitat by primary colonizers can lead to their being displaced by secondary colonizers

29
Q

What is the Intermediate Disturbance Hypothesis?

A

Periodic, non-disastrous disturbances create patchiness but also lead to increased diversity

30
Q

To understand community structure, we use two fundamental features. What are they?

A
  1. Species diversity
  2. Trophic diversity
31
Q

What is species diversity and what are its 2 components?

A

Measure of the number of organisms that make up the community, but it has
1. Species richness: number of species in the community
2. Species evenness: proportion of each species represents of all individuals in the community

32
Q

Define biodiversity.

A

The variability among living organisms

33
Q

What is the Shannon diversity index (H)?

A
34
Q

What are rarefaction curves?

A

Microbial Ecology (BIOL 355) (17 decks)

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