But in this topic we are discussing if features in the genome indicates realtionshipos between species, so possible effects of a pre-flood environment don't apply.
Consider that genes code for proteins, and every three bases of a genes sequence represents one amino acid of a protein. This is the codon (I realise you probably know this already). However, most amino acids are represented in the genome by more than one codon, in fact there can be anywhere up to six different codons. Therefore there can be a great deal of variation in a genes sequence that will produce the same protein â€˜designâ€™. This allows for mutations to accrue without changing the protein. Now we can look at this sequence variation in genes that maintain basic cell function in all organisms, such as cytochromes B or C, and map the variation in gene sequences between species. Now within a kind as it diversifies into different species youâ€™d expect this variation to show relationships as mutations are inherited, just as in a familial relationship. But you wouldnâ€™t expect to fit species of different kinds into a familial relationship of variation, since the kinds were created separately and mutations are random. However that is not what we see, and the variation that is present in all species is consistent with them all being related. So for example the variation of cytochrome B between humans and Chimpanzees is less than the variation between Chimpanzees and Gorillas so itâ€™s possible to build up a pattern of relationship between these apes.
This is only addressing the question of relationships between species. The question of how changes in the genomes can result in the variety of phenotypes we see I will leave to another post. Also I note that Iâ€™ve used the terms kind and species and I know in the past this has created arguments over definitions, but itâ€™s not really relevant to what Iâ€™m trying to discuss.
What I was trying to show was that you can get variation even in the absence of microevolution, the two are not necessarily linked. So the genes I mentioned would likely have the same sequences in all the original created kinds since they perform the same function. But as the parent populations (the original kinds) they would accumulate errors during replication which will be neutral as they do not change the proteins (neutral mutations) and as the parent population split into subsequent daughter populations they would carry these neutral mutations with them like a parent to a child (which is what I meant with familial relationship of variation).
If all the original kinds were created separately then each would be experiencing itâ€™s own set of neutral mutations, so for example you wouldnâ€™t expect humans and chimps to have less variation than chimps and gorillas. But of course that is exactly what we do see, which allows us to put humans, chimps, gorillas and other apes into the same family tree.
None of this deals with evolution itself, but Iâ€™ll try to tackle that in a follow up post. Will wait to see your reply to this post first.
But where does that variation come from? Mutations are just a name for errors during cell replication. And at the moment I've talked about cytochrome genes which are involved in aerobic respiration in the cell, so serve same purpose in all eukaryotes; and mutations which don't change the proteins they produce, so are not affected by selection as they don't alter the design.