This can be resolved by using a backcrossing programme. Backcrossing or recurrent hybridization is also used. Through backcrossing some hybrids become almost indistinguishable from pure green peafowl. Of course, this incremental rise in f carries-over into the f of the backcrossing. With each successive generation of backcrossing, the odds of a fertile hybrid female increases. Backcrossing and introgression do however occur as shown by mitochondrial DNA analysis. This may result in introgression between the two parental populations because of backcrossing. A derivative strain called sighted FVB was developed from this strain via backcrossing. This means that backcrossing would be a common mode of self-perpetuation. Backcrossing with gooseberry and blackcurrant parents was also involved, creating a new F2 generation. Backcrossing involves crossing a hybrid and subsequent generations with a recurrent parent.