Method of identifying genes which promote hybrid vigour and hybrid debility and uses thereof

Disclosed is a method for identifying candidate genes capable of producing hybrid vigour in an animal or plant, comprising the steps of: (i) comparing the nucleotide sequence of alleles of candidate genes isolated from an animal or plant which exhibits hybrid vigour with the nucleotide sequences from the corresponding alleles isolated from the parents of said animal or plant; (ii) identifying nucleotide sequence differences in the alleles from said animal or plant which exhibits hybrid vigour which codes for amino acid sequence variation; and (iii) identifying that the amino acid sequence variation between alleles of the candidate gene in said animal or plant is encoded by nucleotide sequences which are located within two or more different exons within the candidate gene.