>>That is possible, although the elapids are quite homogeneous as a group, and the common ancestor of the elapids is more likely than not venomous.

In your view of taxonomy, what is the common ancestor of the elapids and how does this relate to the various lineages of colubrids. Also, how do you reconcile all 3FTx (elapid and colubrid) forming a monophyletic group relative to the abundant three-finger peptides in the body? If they were evolved independtly, wouldn't they form separate monophyletic groups (as is the case with the PLA2 toxins).


>>As I said, chemical similarity can be the result of convergence. The independent recruitment of crystallin into lenses result in chemically similar crystallin in the lenses of different animal groups, misleading us into thinking that crystallin is an eye specific protein when it is in reality not. Therefore independent recruitment of the same venom precursors in different snakes and snake lineages can have the same misleading result. It misleads those who are not cautious into believing that chemical similarity is the same as homology.

So does this mean that Drosophila evolved actin and myosin separately from humans?

>>

>>That is what I have been trying to get you to understand. Similarity does not equal homology.
>>

But monophyletic groups is evidence of homology. This is the gold standard test.


>>
>>See? This is evidence that venom has, and will, continue to be independently recruited from body chemicals in different lineages. Because of that fact, you cannot simply say that because two lineages share the same venom, they must have acquired it from their common ancestor. If the same non-venomous chemical precursor is present in two lineages, then the two different lineages may end up with very similar looking venom even if they independently evolved this venom.

Which is why we test this through phylogenetic analysis and the PLA2 toxins are a very useful control in this regard. If the 3FTx had been independtly recruited then they would have formed two separate groups like the PLA2s but they form one tight monophyletic group, hence the colubrid and elapid venoms share a history and venom evolved one time. This is not to say that new toxin types have not been added independently, like the independent addition of PLA2s, but this is because venom is a moveable feast. Changes in venom does not change the single origin.

Please explain to me how you reconcile venomous and non-venomous colubrids with their common ancestor and what is the relationship of this ancestor with the elapids and vipers. Please also explain to me how two sea snake lineages independently evolving towards a non-venomous state is different than a lineage of colubrid evolving into a non-venomous state?

Ciao
B
-----
Dr. Bryan Grieg Fry
Deputy Director
Australian Venom Research Unit
University of Melbourne

www.venomdoc.com

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