Q5.6. The graph on the right shows the proportion of snails from different clonal strains infected by a parasite. The first four bars are from four distinct and relatively common clonal strains. The fifth bar is an average infection rate for 40 rarer strains. Imagine one of the rare snail strains with a low infection rate actually reproduces sexually. What would you expect to happen over time? The sexual population will stay rare or go extinct because the asexually reproducing snails can reproduce more quickly. The sexual population will first grow, while it is relatively rare, but then shrink and likely go extinct after it becomes common, because once it is common it will be attacked by parasites more frequently. The sexual population will grow until it is more common than all the clonal populations, because it can more quickly evolve new. protection from parasites. Q5.7. Now say you repeated the experiment but added a drug that killed all the parasites. What would you expect to happen over time? The sexual population will stay rare or go extinct because the asexually reproducing snails can reproduce more quickly. The sexual population will first grow, while it is relatively rare, but then shrink and likely go extinct after it becomes common, because once it is common it will be attacked by parasites more frequently. The sexual population will grow unti it is more common than all the clonal populations, because it can more quickly evolve new protection from parasites.Prevalence of experimental trematode (Microphallus sp.) infections in a New Zealand snail (Potamopyrgus antipodarum). Infection rate for the four most recent common clones are shown in the 4 gray bars on left, while the average infection rate for 40 rare clones is shown in the brown bar on right. From Dybdahl and Lively 1998..

1. Q5.6. The graph on the right shows the proportion of snails from different clonal strains infected by
a parasite. The first four bars are from four distinct and relatively common clonal strains. The fifth
bar is an average infection rate for 40 rarer strains. Imagine one of the rare snail strains with a low
infection rate actually reproduces sexually. What would you expect to happen over time? The
sexual population will stay rare or go extinct because the asexually reproducing snails can
reproduce more quickly. The sexual population will first grow, while it is relatively rare, but then
shrink and likely go extinct after it becomes common, because once it is common it will be
attacked by parasites more frequently. The sexual population will grow until it is more common
than all the clonal populations, because it can more quickly evolve new. protection from parasites.
Q5.7. Now say you repeated the experiment but added a drug that killed all the parasites. What
would you expect to happen over time? The sexual population will stay rare or go extinct because
the asexually reproducing snails can reproduce more quickly. The sexual population will first grow,
while it is relatively rare, but then shrink and likely go extinct after it becomes common, because
once it is common it will be attacked by parasites more frequently. The sexual population will grow
unti it is more common than all the clonal populations, because it can more quickly evolve new
protection from parasites.Prevalence of experimental trematode (Microphallus sp.) infections in a
New Zealand snail (Potamopyrgus antipodarum). Infection rate for the four most recent common
clones are shown in the 4 gray bars on left, while the average infection rate for 40 rare clones is
shown in the brown bar on right. From Dybdahl and Lively 1998.