>>WW wrote:
>>"Your claim is based on your inability to discrimiante between similarity (purely phenetic) and phylogeny."
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>>You cannot construct a phylogeny with convergences. The evolution of the eye shows us that independently evolved eye components can have similarities that suggest monophyly but in the end the phylogeny was rejected because of the differences in the ontogeny and comparative anatomy of the eyes. Your phylogeny of snake venom evolution is based on chemical similarities, but the fact that some colubrid lineages (e.g. Old and New World ratsnakes and the Lampropeltines) show absolutely no sign of a venomous ancestry disproves your claim that venom evolved once.
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>>"So you are saying that three-finger toxins were recruited mutliple times by the elapids?"
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>>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.
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>>"However, we did not score venom as present or absent, we looked at the phylogeny of the venom proteins."
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>>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.
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>>"Again, try to get into your tiny, overstretched mind that similarity is not the same as phylogenetic relatedness. "
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>>That is what I have been trying to get you to understand. Similarity does not equal homology.
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>>"PLA2s, which are universally represented ins nake venoms (and have, erroneously, been inferred to be among the original venom proteins, show a clear phylogenetic pattern denoting recent ancestry, i.e., elapid PLA2 form a separate clade from viperid PLA2, and these two clades are separated from each other by a number of non-venom PLA2s. Convergence does not confuse a phylogenetic analysis."
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>>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.
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>>"Note that I am getting into this argument not because I want to win it against you (you would argue that the Earth is flat if that was the only way of getting some attention), but for the benefit of others who may be following the argument and getting confused by your red herrings."
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>>It looks like you already realize that venom can evolve independently in different snakes. What you do not realize is that it has occurred far more often than you thought. If you think that snakes evolved venom only once, then you cannot win, because your hypothesis requires such nonparsimonious scenarios as the ratsnakes losing an adaptive feature like venom from a venomous ancestor, and reacquiring another adaptive feature (constriction) they had previously lost. The presence of constricting behavior in natricines such as Regina and Thamnophis (and even some elapids) shows that this behavior was never lost in the colubroid ancestor. The ratsnakes similarly show no trace of a venomous ancestry. Therefore both of the ad hoc hypotheses that your venom evolved once hypotheses require are unsupported by scientific data. And the evolution of the eye shows us that remarkably similar chemicals can end up in convergently evolved organs because of biochemical homoplasy. Until you learn that lesson, you will go around misleading others into thinking that venom evolved once.
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