Hamilton's rule states that an altruistic allele could spread in a population if Br C, where B represents the fitness benefit to the recipient, r is the coefficient of relatedness between altruist and recipient, and C represents the fitness cost to the altruist. If r = 0.5 between the altruist and the recipient, what would the ratio of costs to benefits have to be for the altruistic allele to spread?
a. C/ B 0.5
b. C/ B 0
c. C/ B

Question

Hamilton's rule states that an altruistic allele could spread in a population if Br > C, where B represents the fitness benefit to the recipient, r is the coefficient of relatedness between altruist and recipient, and C represents the fitness cost to the altruist. If r = 0.5 between the altruist and the recipient, what would the ratio of costs to benefits have to be for the altruistic allele to spread?
a. C/ B > 0.5
b. C/ B > 0
c. C/ B < 0.5
d. C/ B < 0

a. C/ B > 0.5

b. C/ B > 0

c. C/ B < 0.5

d. C/ B < 0

Accepted Answer

Hi everyone. Let's look at our next problem. It says in Hamilton's rule, what does the coefficient of relatedness are mean? Well, Hamilton's rule has to do with when you have situations where in organisms help to raise offspring that are not their own of related individuals. And Hamilton's rule is a way to calculate whether this trait would be favored by natural selection. This trait of raising uh offspring that are not one's own but the offspring of related relatives. And it states that the trait this trait will be favored by natural selection if the benefit to others times the coefficient of relatedness which is our exceeds the cost to self. So my C. Which is the cost of self is greater than zero. In this case the coefficient of relatedness reflects the number of shared genes between the individuals. So r equals the average number of shared genes between individuals. The organism having the offspring and the organism helping to raise the offspring. Now, the trouble here, as you can imagine is how do you determine these values? How do you calculate what the benefit is the recipient? How do you calculate what the cost is to the self? So it's kind of more of a theoretical idea than an actual equation you would plug numbers into. So when we look at our answer choices, we see that choice D. Does say the average number of shared genes between the individuals. So that's our answer will just look through the other answer choices. Choice A. Says the cost to the actor. Well that see here. So the cost to the organism that's helping to raise the offspring in not having its own offspring. So that's not an answer because that's a different value. Choice B. Says the benefit to the recipient. Well, that's this letter B. Here. So the benefit to the recipient of the help, the actual parent of the offspring. But that is not the coefficient of relatedness. So not our answer. And finally, choice. See the energy loss. Um Well that's not what the coefficient of relatedness is. So that's not our answer either. So again in Hamilton's rule, the coefficient of relatedness means choice D the average number of shared genes between the individuals. Hope to see you in the next video.

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Key Concepts

Hamilton's Rule

Coefficient of Relatedness (r)

Cost-Benefit Ratio in Altruism