HINT 22A: Think about this from the point of view of the rare allele.

HINT 22B: Ignore the possibility that a lineage crosses and then crosses back.

HINT 22C: It is simplest to plot the chance that there has been no coalescence by time *t*; this declines smoothly from 1 to 0. A rough sketch will do.

HINT 22D: This depends on the expected length of the corresponding branch.

HINT 22E: Only incompatibilities that involve two dominant alleles can be expressed in the F_{1}.

HINT 22F: Males have one X chromosome, and so any recessive incompatibility allele will be expressed if it is on this chromosome. Incompatibilities might be between genes on the autosomes, or between X and autosome, or between two genes on the X.

HINT 22G: Use a log scale on the vertical axis, as in Figure 22.22.)

HINT 22H: What is the chance that the chromosome arrangement found in one particular deme will eventually spread through a population of *D* demes? See page 425.

HINT 22I: You can find the maximum most easily using a graph; otherwise, you can differentiate and set the slope to zero.

HINT 22J: Recall Box 17.1. You can assume that allele *B*^{P} is very rare, because it is incompatible with *A*^{P}. Thus, assume that *s* and *p*_{B} are small and ignore terms such as (1 + *s*), *s* × *p*_{B}, etc.

HINT 22K: You can assume that changes are slow, so that the effects of gene flow and selection can be added together. It is most convenient to write down a pair of differential equations for *dp*_{A}/*dt*, *dp*_{B}/*dt* (Box 28.2), but you can avoid calculus by working with the changes across discrete generations, Δ*p*_{A}, Δ*p*_{B}, if you prefer.

HINT 22L: There may be several possible equilibria.