Lecture 11 - Virus Ecology II Flashcards Preview

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Flashcards in Lecture 11 - Virus Ecology II Deck (50)
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1

What is the "kill the winner" model?

as the number of hosts increases so will the virus = causes host number to decrease = virus number decreases = causes host number to increase = cycle starts again

2

In the "kill the winner" model, what is the host (prokaryote in this case) doing at each cycle?

constantly evolving mechanisms to help resist viral infections by becoming stronger, change surface proteins, etc.

3

If the hosts (prokaryotes in this case) are constantly evolving, why are they still getting infected by viruses?

the virus evolves with its host cell as it regenerates faster than the host cell

4

What is another name for the "kill the winner" model? Why is this name fitting?

"Red Queen" hypothesis because something is always trying to chase something else but it never catches up

5

What is the r/K selection theory?

describes the trade-offs that organisms do between quantity and quality of offspring

6

What are the characteristics of r-strategists?

small opportunistic organisms, reproduce quickly, lots of progeny, short life-span

7

What are characteristics of K-strategists?

larger organisms with longer lifespan and less progeny; invests more on their offspring = become better competitors and live longer due to this investment

8

Which are viruses mostly classified as: r or K strategists? Why?

r-strategists

9

Are there any viruses that are considered to be K-strategists?

lysogenic viruses that are not considered virulent (they don't lyse cells)

10

What are 2 ways you can classify viruses on the r/K selection theory?

based on how their host is classified OR the viral infection they cause

11

In the r/K selection theory, how can viruses be classified based on the type of viral infection they cause?

acute infections = r-strategists | chronic infection = K-strategists (HepC, HIV)

12

What are rank abundance curves?

chart that illustrates relative species abundance to other species

13

What can the rank abundance curve give insight to?

strategies used by organisms to survive

14

On the rank abundance curve, what will rank as the most abundant species? (number rank)

#1

15

On a rank abundance curve for marine prokaryotes, what type of prokaryote would you assume would be most abundant and least abundant? Based on how fast/slow they grow and their resistance to viruses.

Most abundant = slow growers and more resistant | Least abundant = fast growers and more susceptible

16

On a rank abundance curve for marine viruses, which would be most abundant and least abundant and why? Lytic vs. Lysogenic viruses.

Most abundant = lytic viruses because of higher burst output, more infection of prey | Least abundant = lysogenic viruses because they grow slower and integrate, lower burst size

17

What do viruses do in the ocean?

will influence the composition of marine communities, can cause disease, and help drive biochemical cycles

18

What is the percentage of bacteria in the ocean that are lysed every day? (estimate)

20%

19

What are the 4 roles of marine phages?

global biogeochemical cycles, regulate microbial diversity, cycle carbon in marine food webs, prevent bacterial population explosions

20

What is the viral shunt?

the production of DOM/POM and its later use by microbes | a way to cycle nutrients

21

How does the viral shunt work?

viruses infect and lyse marine heterotrophs and autotrophs >> lysed cells release nutrients >> DOM/POM available for uptake by other marine heterotrophs and autotrophs

22

What are the environmental factors that can inactivate viruses?

UV light, temperature, salt, pH, competition, pollution, grazers, inorganic/organic particles that viruses can absorb to and cause to aggregate

23

What would be a consequence to reducing the infectivity of the viruses?

will alter the microbial population

24

What are the environmental factors that will alter host dynamics?

pollution, UV, temperature, viral pool, number of hosts, infection susceptibility and morphology, and viral life strategy

25

What environmental factors influence the infectious activity of viruses? (from most to least effective)

UV, inorganic, organic particles

26

What environmental factors influence the viral contact rate to a host? (from most to least effective)

Abundance, host size, host morphology

27

What environmental factors influence viral adsorption to the host? (from most to least effective)

Temperature, salinity, host physiology

28

What environmental factors influence the life strategy viruses will undertake (lysogenic or lytic)? (from most to least effective)

Nutrient availability, UV, pollution

29

Why are algal blooms an issue?

a huge increase in algal cells that use up all of the O2 in the water

30

What do algal blooms cause and why?

dead zones which are zones of dead marine animals and microbes because the algae are taking up all of the O2