. The elements of genetics. Genetics. CORRELATED RESPONSE price of linkage is therefore that, apart from the primary character, the immediate overall response to selection is poorer. Time is At Bi A2 ba Ol bl 02 B2 CROSSING-OVER A, bl 02 Bz 1 1 1. Az b; Ai bl 02 bz 01 Bl A2 B2 Ai bl A2 bz Ol Bl 02 B2 Fig. 75.—The mechanism of correlated response to selection. The two A-a genes represent members of one polygenic system and the two B-b genes of another all carried on the same chromosome. Both systems are balanced in the sense that each of the original chromosomes carry genes of opposing tendenci
. The elements of genetics. Genetics. CORRELATED RESPONSE price of linkage is therefore that, apart from the primary character, the immediate overall response to selection is poorer. Time is At Bi A2 ba Ol bl 02 B2 CROSSING-OVER A, bl 02 Bz 1 1 1. Az b; Ai bl 02 bz 01 Bl A2 B2 Ai bl A2 bz Ol Bl 02 B2 Fig. 75.—The mechanism of correlated response to selection. The two A-a genes represent members of one polygenic system and the two B-b genes of another all carried on the same chromosome. Both systems are balanced in the sense that each of the original chromosomes carry genes of opposing tendencies, as indicated by capital and small letters. Selection will pick out the chromosomes which have lost this balance by recombination bringing together two genes of reinforcing tendency either in the direction indicated by capitals or that by small letters. According to the position of the crossing-over, upon which recombination depends, (i) the A system may be unbalanced, the B sys- tem remains balanced (left); (ii) the B system may be unbalanced, the A system remaining balanced (right), or (iii) both systems may be unbalanced (centre). Then in (i) selection c^n be effectively practised for the character controlled by the A sys- tem without that controlled by B changing, or (ii) selection can be effective for the B character without the A character changing. But in (iii) effective selection for either character must also result in change in the other, solely by virtue of the linkage of the genes. This is correlated response, and it may be in either direction for the subor- dinate character, again according to the precise linkage arrangement. luccded for recombination to permit the attainment of a full new adjustment in the primary character without deleterious effects on 299. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble th
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Keywords: ., bookcentury1900, bookpublishernewyorkmacmil, booksubjectgenetics
