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Author Topic:   Discussion of Phylogenetic Methods
PaulK
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Posts: 17815
Joined: 01-10-2003
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Message 169 of 288 (796048)
12-21-2016 2:01 PM
Reply to: Message 166 by caffeine
12-21-2016 12:58 PM


Re: The purpose of phylogenetics
I think that your point is a little pedantic.
To set it in context before somebody tries to make it much more than it is:
First, confused phylogenetic information is hardly the worst case for evolution, even if it were general (and if it was general I think we would have a rather different version of evolutionary theory).
Second, given that this confusion only gives one group of species it has relatively little weight compared with the overall pattern anyway.
Now if the genetic data showed a pattern inconsistent with evolution altogether then things would be very different.
As it is, I think we can say that there are things that can confuse genetic phylogenies, such as horizontal transfer, hybridisation and rapid radiations. But only the first could even conceivably pose a threat to evolution - and then only if the rate required to explain the genetic data was well above reasonable expectations (and to the best of my knowledge it is not)

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 Message 166 by caffeine, posted 12-21-2016 12:58 PM caffeine has replied

Replies to this message:
 Message 172 by caffeine, posted 12-21-2016 4:13 PM PaulK has replied

  
PaulK
Member
Posts: 17815
Joined: 01-10-2003
Member Rating: 2.1


Message 174 of 288 (796056)
12-21-2016 4:37 PM
Reply to: Message 172 by caffeine
12-21-2016 4:13 PM


Re: The purpose of phylogenetics
As I said I was setting it in context - and suggesting that someone other than you might (quite possibly wilfully) misrepresent your point as a challenge to evolution.
But it is not a challenge to evolution because it does support common ancestry, and it need not do so. We could find, for instance, that cytochrome C variations did not follow the pattern expected for evolution. If creationism were true, all the original kinds might have been created with the same cytochrome C and all differences are due to subsequent drift (which would not be very great in a YEC scenario)
I think it is something of a parody of phylogeny to say that common ancestry is simply assumed. It is certainly possble in principle for the data to be inconsistent with any likely ancestry - indeed the only reason common ancestry is assumed now is because it has already been established beyond reasonable doubt - in large part by the evidence used to establish phylogeny.

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 Message 172 by caffeine, posted 12-21-2016 4:13 PM caffeine has replied

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 Message 177 by caffeine, posted 12-21-2016 4:53 PM PaulK has replied

  
PaulK
Member
Posts: 17815
Joined: 01-10-2003
Member Rating: 2.1


Message 180 of 288 (796062)
12-21-2016 5:08 PM
Reply to: Message 177 by caffeine
12-21-2016 4:53 PM


Re: The purpose of phylogenetics
quote:
I don't see it as a parody. It seems to me you have to assume common ancestry in order to research phylogeny. All the techniques we have for building a phylogeny assume there is actually one there to discover. I don't understand how a falsification of common ancestry is supposed to differ from an unresolvable polytomy like that amongst Natatanuran families
As I said, a confused phylogeny is far from the worst case. And a phylogeny that is confused in parts is even less of a problem. We have evidence that the frogs are related, it just fails to make the distinctions we need to work out the details. There is no reason in principle why the genetic evidence could not tell us that some of the frogs were not closely related and did not belong in the Natatanuran family at all.
Seriously if you admit that the evidence says that they are related - then you are saying that there is strong evidence of common ancestry.
quote:
I understand what you mean that people may misrepresent what I say as a challenge to evolution; but it's precisely the fear of misrepresentation that makes me wary of the idea of presenting phylogenetics as evidence for evolution. This is probably because I spend a lot more time reading about the difficult bits than the easy bits. If nothing else I think it's a tactical error in arguing with am honest creationist, since the difficult bits are of course those focused on by researchers
I wouldn't want to hide the problems, but claiming that the findings of phylogenetic research is not evidence for evolution is going well beyond that. The evidence for common ancestry is the same as the evidence for any phylogeny we can work out. Additional data has caused revisions to phylogenies, but none so drastic or far reaching as to call common ancestry in doubt. This IS evidence for evolution.

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