Contour 7.5 depicts the results out-of spot-preferential crossing over to the relationship between linkage and you may real maps. Within example, 2,one hundred thousand children out-of an effective backcross have been assessed to own recombination incidents between this new fictitious A and F loci. These loci try split up of the an actual physical point of just one,500 kb and, within our analogy, 17 crossover situations (indicated by brief straight traces into linkage chart) was in fact noticed one of many 2,100 girls and boys. A recombination frequency regarding 17/2,one hundred thousand translates into a great linkage point from 0.85 cM. This linkage distance is extremely around the 0.75 cM forecast about empirically computed equality away from 2,000 kb to one cM. But not, when you to definitely appears further at the loci between Good and you may F, the difficulty transform substantially. The newest B and you will C loci are just 20 kb except that per on physical map but are 0.cuatro cM aside from each other into the linkage chart due to the fact a spot takes place in the spot between them. That have haphazard web sites away from crossing-over, the latest linkage worth of 0.cuatro cM might have predicted an actual physical point out of 800 kb. The latest reciprocal problem occurs with the loci D and you can Age and this is actually split up of the an actual physical length from 400 kb however, which inform you zero recombination for the 2000 girls and boys. In cases like this, random crossing-over will have predict an actual range regarding less than simply one hundred kb.
The fresh new lifestyle and you may consequences out of recombinational hotspots can be looked at inside example on the quantized characteristics regarding number.