Adaptation and Natural Selection

Intermediate Generalizations

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Williams mentions an interesting analogy between Mechanics and Evolutionary Biology.

The study of adaptation seems to show the opposite mode of development. It has already had its Newtonian sysnthesis, but its Galileo and Kepler have not yet appeared. The "Newtonian synthesis" is the genetical theory of natural selection, a logical unification of Mendelism and Darwinism ... The inherent strengthy of the theory is restricted by the paucity of generalizations, analogous to Kepler's laws, that can serve on the one hand as summaries of large masses of observations and, on the other hand, as logical deductions from the theory. ... The kind of generalization i have in mind is well illustrated by Lack's conclusion on the selection of fecundity in animals that feed their young ... and Fisher's conclusion on population sex ratios ...(pp. 20-1).

Thus you've got to read the explanation of Lack's and Fisher's works in advance.

(1) Fecundity (161-2): For example, take birds. If a couple of birds are to produce as many offsprings as possible, how many eggs should they produce at one time (for the mating season) ? The problem is that they have to raise their children, as well as producing eggs! There seems to be some strategy which optimizes the average number of offsprings.

(2) Sex Ratio (146-156): Suppose a sexual population; what is the best ratio of male and female (for reproductive success) in this population? Of course we need more assumptions in order to answer this; but why, in many species, is the ratio very close to one?

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