Salient features of Multiple alleles.
1. They occupy the same gene locus on the chromosome
2. In diploid organisms, as there are only two homologus chromosomes, there will be only two allelic states of the multiple series.
3. In haploid gametes multiple allelic series is represented by a single allelic state.
4. No crossing over in known to occur between multiple alleles as they occupy the same level of the homologus chromosomes. In a cross between two alleles, the F2 generation reveles the e combination of alleles.
5. A single multiple allelelic series affects only one trait-eye colour, shape, skin colour etc.
6. Suppose there is a series of five genes in the multiple allelic series starting with the wild A, Ab, Ac, Ad, Ae etc., the last one representing the last mutation (Ae) on the gene series, the wild gene (A) is dominant over all others and the last mutation (Ae) is recessive to all others.
In the series starting with A, all genes are recessive to their previous allele while dominant over the subsequent allele (A, Ab, Ac, Ad, Ae). The fact that A is wild can be proved because it is dominant over all others and fact that Ae is the last mutant can be proved by its being recessive to all others.
In a cross between two representatives of the allelic series, that which is dominant is old and that which is recessive is recent (from the point of view of mutation)