I'm confused on why mutation-selection balance is responsible for this: looking at the host-parasite co-evolution graph attached and it shows how host genotypes decline in frequency when they are common and increase when they are rare.
I'm confused on why mutation-selection balance is responsible for this: looking at the host-parasite co-evolution graph attached and it shows how host genotypes decline in frequency when they are common and increase when they are rare.
I'm confused on why mutation-selection balance is responsible for this: looking at the host-parasite co-evolution graph attached and it shows how host genotypes decline in frequency when they are common and increase when they are rare.
I'm confused on why mutation-selection balance is responsible for this: looking at the host-parasite co-evolution graph attached and it shows how host genotypes decline in frequency when they are common and increase when they are rare.
Transcribed Image Text:**Host-parasite co-evolution.** The dynamics of evolutionary change in allele frequencies over 15 generations are depicted, showing oscillations in a hypothetical host population’s genotype (black) and its corresponding parasite population’s genotype (gray).
The graph illustrates the co-evolutionary relationship between host and parasite alleles. The x-axis represents generations (1 to 15), while the y-axis shows allele frequency (ranging from 0.0 to 1.0).
- The host allele (black line) and the parasite allele (gray line) demonstrate periodic oscillations, indicating changing allele frequencies through generations.
- The oscillations suggest an ongoing evolutionary arms race, where changes in the host population’s genotype are matched by changes in the parasite population’s genotype.
- The peaks and troughs of the allele frequencies in host and parasite populations are out of phase, illustrating reciprocal adaptation.
Definition Definition Organism that lives in the body of another organism and obtains food at the expense of the host. A parasite can directly or indirect harm the host. There are two kinds of parasites: internal and external. An internal parasite lives inside another organism and is known as an endoparasite. An external parasite lives on the body surface of the host and is known as an ectoparasite. Protozoa and helminths are examples of major human parasites.
Expert Solution
Step 1: Host-parasite coevolution
Coevolution between interacting species is known as host-parasite coevolution. According to the red queen hypothesis (RQH), coevolution between hosts and parasites maintains genetic variation across time. The RQH hypothesizes that "parasites evolve to specifically infect the most prevalent host genotypes in a population." As a result, parasites exert negative frequency-dependent selection (balancing selection) on their hosts, with the most prevalent host genotypes having low fitness and declining in frequency as parasites infect them. Rare host genotypes escape infection and thus increase in frequency. The frequency of host genotypes and parasite genotypes oscillates over time as a result of this rare advantage. Thus, host-parasite coevolution is anticipated to maintain genetic diversity in host and parasite populations.
