| In order to make it clear how, as I believe, natural selection acts, I must beg permission to give one or two imaginary illustrations. Let us take the case of a wolf, which preys on various animals, securing some by
some by strength, and some by fleetness; and let us suppose that the fleetest prey, a deer for instance, had from any change in the country increased in numbers, or that other prey had decreased in numbers, during that season of the year when the wolf
hardest pressed for food.
such circumstances
→OMIT
the swiftest and slimmest wolves would have the best chance of surviving, and so be preserved or selected,— provided always that they retained strength to master their prey at this or
some other period of the year, when they
compelled to prey on other animals. I can see no more reason to doubt
→this, than
that man
→can
improve the fleetness of his
by careful and methodical selection, or by
→unconscious
selection which
from each man trying to keep the best dogs without any thought of modifying the breed. I may add, that, according to Mr. Pierce, there are two varieties of the wolf inhabiting the Catskill Mountains in the United States, one with a light greyhound-like form, which pursues deer, and the other more bulky, with shorter legs, which more frequently attacks the shepherd's flocks. |
