Linkage in Drosophila was first discovered by

When a cluster of genes shows linkage behaviour,they:

The frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes was explained by

$A$ genetic map is one that........

The map distance between genes $A$ and $B$ is $3$ units,between $B$ and $C$ $10$ units,and between $C$ and $A$ $7$ units. The order of the genes in a linkage map constructed on the above data would be:

Genetic variation is observed in sexually reproducing species.