From all sorts of books including standard books (like those by Tamarin, Griffith etc) as well as internet; I could not clear-up many things about "Repulsion" and "Coupling". Such as:-
Is "Coupling" an exact synonym of "Linkage" ? and is "repulsion" an exact synonym of "recombinant"? No-where I could yet found mention of it.
What are they telling as coupling-"phase" and repulsion-"phase"? Are there 2 different "step"s or "time-frames" or "generations"?
Coupling and repulsion- are they indicating to a "phenomenon"? or the Genotypic "state"?
Now let us consider what may be learned by repeating the crossing experiments but changing the combinations of alleles contributed as gametes by the homozygous parents in the first cross. In this cross, each parent was homozygous for one dominant allele and for one recessive allele. Again F1 females were testcrossed:
The following progeny were obtained from the testcross:
Again, these results are not even close to a 1:1:1:1 Mendelian ratio. Now, however, the largest classes are those that have one dominant allele or the other rather than, as before, two dominant alleles or two recessives. But notice that once again the allelic combinations that were originally contributed to the F1 by the parental flies provide the most frequent classes in the testcross progeny. In the early work on coupling, Bateson and Punnett coined the term repulsion to describe this situation, because it seemed to them that, in this case, the nonallelic dominant alleles “repelled” each other—the opposite of the situation in coupling, where the dominant alleles seemed to “stick together.”
From this paragraph; it strongly seems to me; repulsion is not opposite word of coupling; rather it is synonym of coupling; where we started the breeding experiment with such parents those contained Dominant allele on one locus and recessive allele in the other locus for all the chromosomes. As a result; parental combination Pr+ and vg trended to stay together "coupled" (965 progenies at testcross output) and similarly parental combination pr and Vg+ stayed "coupled". Have I understood it correctly? or I'm missing certain significance of the concept of repulsion?