Domesticated animals and plants; a Domesticated animals and plants; a brief treatise upon the origin and development of domesticated races, with special reference to the methods of improvement domesticatedan00dave Year: 1910 EFFECT OF NATURAL SELECTION 93 not only to develop still further their naturally valuable qualities, but to bring about more or less radical readjustments occasioned and made necessar) by these new demands of ours. Natural selection always at work. We must not for a mo- ment suppose that our domestication and the new standards of breeding entirely do away with natural se
Domesticated animals and plants; a Domesticated animals and plants; a brief treatise upon the origin and development of domesticated races, with special reference to the methods of improvement domesticatedan00dave Year: 1910 EFFECT OF NATURAL SELECTION 93 not only to develop still further their naturally valuable qualities, but to bring about more or less radical readjustments occasioned and made necessar) by these new demands of ours. Natural selection always at work. We must not for a mo- ment suppose that our domestication and the new standards of breeding entirely do away with natural selection. In respect to tooth and claw, of course selection stops the moment we make warfare impossible, but in such fundamental matters as constitu- tional vigor, fecundity, and the vital and reproductive faculties natural selection never surren- ders its hold upon a species. Ofttimes we forget this and are brought up standing by the consequences. Sometimes our standards of selection are unwit- tingly at opposites with these fundamental matters, and then the shock and the lesson are severe. For instance, many an amateur breeder will select the fattest and smoothest pigs for breeding purposes, not knowing that these are neither the most prolific nor the hardiest. His herd soon runs out. Natural selection has been at work day and night to undermine his herd at the point of infertility. Some ver}' favorite strains of cattle or sheep are decidedly '' shy breeders.' If so, it may as well be understood that they will go down under the relentless work of natural selection, unless indeed the defect can be speedily remedied by finding prolific strains among the favorites. Power of selection to modify type. Selection can do far more than develop a single type to conform to some single Fig. 13. Rock or wild blue pigeon, Coliiviha livia, and parent of all do- mesticated strains (see pp. 94 and 95). After Lydekker
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