Lecture 11 - Virus Ecology II Flashcards
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
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.
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
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
What is the r/K selection theory?
describes the trade-offs that organisms do between quantity and quality of offspring
What are the characteristics of r-strategists?
small opportunistic organisms, reproduce quickly, lots of progeny, short life-span
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
Which are viruses mostly classified as: r or K strategists? Why?
r-strategists
Are there any viruses that are considered to be K-strategists?
lysogenic viruses that are not considered virulent (they don’t lyse cells)
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
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)
What are rank abundance curves?
chart that illustrates relative species abundance to other species
What can the rank abundance curve give insight to?
strategies used by organisms to survive
On the rank abundance curve, what will rank as the most abundant species? (number rank)
1
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
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
What do viruses do in the ocean?
will influence the composition of marine communities, can cause disease, and help drive biochemical cycles
What is the percentage of bacteria in the ocean that are lysed every day? (estimate)
20%
What are the 4 roles of marine phages?
global biogeochemical cycles, regulate microbial diversity, cycle carbon in marine food webs, prevent bacterial population explosions
What is the viral shunt?
the production of DOM/POM and its later use by microbes | a way to cycle nutrients
How does the viral shunt work?
viruses infect and lyse marine heterotrophs and autotrophs »_space; lysed cells release nutrients »_space; DOM/POM available for uptake by other marine heterotrophs and autotrophs
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
What would be a consequence to reducing the infectivity of the viruses?
will alter the microbial population
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
