Diploid genes?

[jebus197]

Hi, I am struggling with a phrase in a text book I am reading at a section discussing gene duplication (note this is not a question for amateurs). The phrase reads "the Genomes of many jawed vertebrates appear to have four diploid sets of many major genes." I have read this phrase several times, and for what ever reason it just isn't sinking in what it means. I mean I understand that the chromosomes of almost all living things are diploid in one way or another, but what does "four diploid sets of many major genes mean in reality? Does anyone care to expand on this?

[wbla3335]

It is believed that two rounds of whole-genome duplication occurred after the divergence of the cephalochordates, so each cephalochordate gene ended up as four copies (haploid number) in the jawed vertebrates. In diploids, the total number would be eight ("four diploid sets" - not the best way to say it, though). Of course, these four copies have not remained identical and have become different genes.

That's my guess.