HINT 21A: Follow a method similar to that of Box 17.1; note the similarity to the effect of selection.

HINT 21B: Assume that change is continuous in time, and use the results in Box 28.2.

HINT 21C: In flowering plants, mitochondria are inherited through the female gamete, in the same way as in most animals.

HINT 21D: For the population to be maintained, each individual must produce a minimum of one surviving pollinated seed.

HINT 21E: Assume that there is some density-dependent regulation of population size, so that each plant produces on average two surviving offspring, one via pollen and one via ovule.

HINT 21F: A qualitative answer is sufficient.

HINT 21G: Assume random mating.

HINT 21H: Write down an expression for *p*_{t} in terms of *p*_{t – 1}, and iterate this over time.

HINT 21I: Begin by calculating the *change* in frequency of *p*, and plot this against the frequency of *p*.

HINT 21J: Plot the number of *n*_{CP} viruses in the next generation against the number in the current generation.

HINT 21K: Use the same approach as in i).

HINT 21L: Think about the number of copies passed on by females and the number via males.

HINT 21M: If the population contains +, *t*, and *t*, then there will be five viable genotypes. Work out the outcomes (i.e., genotypes) of all possible matings and use this information to calculate the new frequencies. It will be simplest to think about what happens as each allele invades from low frequency.

HINT 21N: Assume that the population is steady and outbred and that the new allele is present in a single copy in a heterozygote.

HINT 21O: Think about the way an X chromosome is inherited and consider the copies passed to sons and daughters in turn.

HINT 21P: Calculate the net copies gained (i.e., passed on both directly and indirectly).

HINT 21Q: Think about the inheritance of both maternal and paternal genes (i.e., genes inherited from the mother and genes inherited from the father).

HINT 21R: At equilibrium sex ratio, net fitness for a female must be equal whether sons or daughters are produced.

HINT 21S: Assume all foundresses produce an equal number of sons and calculate the chance that a daughter mates with a brother.

HINT 21T: Males mate within the fig, and so the number of fertilizations that they can achieve is strictly limited. Thus, if a female produces an extra son that reproduces successfully, this must be at the expense of some other male.

HINT 21U: These should correspond to Figure 21.22.

HINT 21V: Think about the fitness gained by shifting a small amount of resource or plot total fitness against *z*.

HINT 21W: The only consideration in this case would be to maximize its own fitness.

HINT 21X: An allele inherited from the mother has a 50% chance of being found in a sibling.

HINT 21Y: Use the same method as that for iii).

HINT 21Z: Use a method similar to that in iii).

HINT 21AA: Recall Problem 16.7.

HINT 21BB: Follow the proportions of demes fixed for the two alleles, *p*, *q*, across one generation; see Box 17.1.

HINT 21CC: Work out the influence of each of the two competing processes—extinction and spread of the allele.

HINT 21DD: Give a qualitative answer.