The measurement of linkage in heredity / by K. Mather.

  • Mather, Kenneth, 1911-1990.
Date:
[1938]
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The measurement of linkage in heredity / by K. Mather. Source: Wellcome Collection.

    55/152 (page 41)
    THE DETECTION OF LINKAGE 41 The orthogonality is tested as before and we find S(mkk) = T V (9 - 9 + 27 - 27) = 0 S(mk'k) = T V (9 + 27 - 9 - 27) = 0 Thus the analysis of % 2 in an F 2 family is conducted by calculating the quantities X 2 = + a 2 — 3a 3 — 3a 4 ) 2 X 2 = 3^(«i — 3a 2 + a z — 3a 4 ) 2 X 2 — — 3a 2 — 3a 3 + 9<x 4 ) 2 The functions chosen for the calculation of the first two £ 2 are the same as those developed in the previous chapter from the detection of deviations from single factor ratios. The third function, detect ing linkage, then follows from the above considera tions. Other sets of three orthogonal functions could be chosen but would not have the same meaning for the analysis as do those adopted above. The three functions chosen for the analysis of the backcross data in Ex. 5 can be derived in the same way as the functions for the F 2 . Similarly it can be shown that in the case of two factors one of which is a member of two segregating duplicate genes, giving four classes with the expected ratios 45 : 15 : 3 : 1, the three components of ^ 2 are calculated from the formulae X 2 a = ¿(«i — 3a 2 + a 3 — 3a 4 ) 2 X 2 B = + «2 — 15,3 — 15a 4 ) 2 X 2 b = — 3a 2 — 15a 3 + 45a 4 ) 2 The derivation of these functions, and the demon stration of their orthogonality, is left as an exercise.