Question

Which one of the following concepts describes a co-evolutionary arms race between a pathogen and its host?

• A. Red Queen hypothesis
• B. Green Beard model
• C. Sympatric speciation
• D. Reinforcement

Hint:

Look for the concept named after a character who must keep running just to stay in place; that image stands for organisms that must keep evolving just to hold their current fitness against a coevolving enemy.

Answer 1

The Correct Option is A

The question describes a pathogen and its host locked in a constant tug of war, each one evolving new tricks to beat the other. You need to match that picture to the right named idea among four options.

1. Red Queen hypothesis: this is built exactly for such a race. A host evolves a new defence, the pathogen evolves a way around it, the host answers again, and so on forever, with neither side pulling permanently ahead. The name comes from having to run just to stay in the same place, which fits an arms race perfectly.
2. Green Beard model: this is about a gene that lets its carriers spot each other through a shared marker and act kindly toward one another. It explains a kind of cooperation, not a host-pathogen fight.
3. Sympatric speciation: this describes one population splitting into two new species while still living in the same place, usually driven by disruptive selection. It is a speciation story, with no pathogen involved.
4. Reinforcement: this is about two populations evolving stronger barriers against mating with each other because their hybrids do poorly. It also belongs to speciation, not to an infection arms race.

Only the Red Queen hypothesis is built around an ongoing coevolutionary struggle where the host and the pathogen keep adapting against each other, so it is the correct match.

Let's summarize:

• Red Queen hypothesis, constant mutual adaptation between host and pathogen (or predator and prey).
• Green Beard, sympatric speciation and reinforcement all describe different processes, cooperation or speciation, not an infection arms race.

So the correct concept here is the Red Queen hypothesis.