Originally Posted by budgiezforall
This is all very interesting, but what`s an allele?
An allele isn't something specific to budgerigar genetics it's part of all genetics.
An allele is like a different version of a gene. Genes code for traits, like height or colour, while alleles are the specific forms of those traits, like short/tall or blue/green. There are two alleles per gene, sometimes they're the same allele (like what double factor budgies have), sometimes they're different alleles (like what single factor budgies have)!
I hope this makes sense!
Also, the wild type allele in a population (like a green Australian budgie with no unusual markings or colours) is usually represented with a '+' superscript. The wild type allele isn't always dominant, it's just the allele most commonly found in the population.
Note: the slash I used didn't mean "split for" in this example, I was just using it in the conventional way to mean "or".