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Member (Idle past 1430 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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Author | Topic: Dogs will be Dogs will be ??? | |||||||||||||||||||||||||||||||||||||||
Chuck77 Inactive Member |
Taq writes: Cladistics is based on shared and derived features. Ok, but to what extent?
The root of a clade is the synapomorphy which is the list of shared characteristics. Each branch from that node is defined by their derived characteristics, features that are not shared with the rest of the clade. So for example hoofs, wings, feet, webbed feet etc? Genetics too or no?
It is an elegant system at its most basic. However, shared and derived features can be hard to determine at times due to convergent evolution and loss of ancestral traits. Convergent evolution and ancestral traits? For sake of argument here, could each clade have their own common ancestor? This may seem like a stupid question but what I mean is, could there be a Canine ancestor, felidae ancestor etc etc?
You will also find that designed things do not easily fall into a nested hierarchy when using cladistics. I don't understand what nested hierarchy is.
We could use playing cards as an example. What are the shared features in playing cards? First off, all of the cards share the same rectangular shape, so the synapomorphy of the entire playing card clade is the rectangular shape (the characteristics shared by the entire clade). We have two colors so we have a red clade and a black clade which are derived traits. In the red clade we have two suits, and also two suits in the black clade. The synapomorphy in the red clade is the red color of the suit. The derived traits are diamonds and hearts. In the black clade, black is the synapomorphy while spades and clubs are the derived traits. How do we divide each clade further? The only thing left is the rank of the cards. This is where we hit a problem. Yeah, the cards can't really be broken down anymore...what's left? I might say ask the person who made the cards to find out what they were thinking. Tho, the cards should say something themselves, but seems all the cards are the same, with slight to more modification. Where does that leave us...
We find the same rank (i.e. Kings, Aces) at the ends of SOME of the clades. At this point, the nested hierarchy fails. There are features shared by some cards in the diamond clade and the club clade that are not shared by all of the cards in the heart and spade clades. I wonder why it's so difficult. There should be something that either seperates the species or brings them together...why is the line so blurred? Or is it not blurred at all and they are very similiar yer very different?
Does this help in understanding how cladistics works? Do you understand how a nested hierarchy is falsifiable? A little yes, but I don't know how a nested hierarchy is falsifiable. After I understand what it is maybe then i'll see.
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Chuck77 Inactive Member |
From EvoWiki:
"Nested hierarchy" refers to the way taxonomic groups fit neatly and completely inside other taxonomic groups. For instance, all bats (order Chiroptera) are mammals. All mammals are vertebrates. Likewise, all whales (order Cetacea) are also mammals, and thus also vertebrates. While it might seem that this arrangement is obvious and unavoidable, it is not. Taxonomic groups are defined by traits and it should be possible to mix traits from multiple defined groups. An example from classical mythology is the Pegasus, a creature with features defined as both mammal (produces milk like a horse) and bird (has feathers). Mammals and birds are both orders, so, if Pegasus existed, it would be a violation of the nested hierarchy, a creature that belonged to two separate groups. Likewise for satyrs (human torso, goats legs), jackalopes (rabbit body with an antelope head) and crocoducks (crocodile head, body of a duck). It is not always possible to define a nested hierarchy for any arbitrarily selected set of items, though many creationists have used this as an outCamp, Ashby (2001) A Critique of Douglas Theobald’s "29 Evidences for Macroevolution", Part 1: “One True Phylogenetic Tree” [1]. For instance, motor vehicles do not show conservation of traits to single taxonomic groups, no matter how you choose to define your taxonomy. Whether a car has air-conditioning is completely independent of whether it has power-steering, for example. Life, however, shows a clear nested hierarchy, at least with regards to multicellular organisms. An animal that produces milk (Mammals), will also have hair, have four limbs, be endothermic (warmblooded) plus possess many other characteristics. Why should this be? Why do no other animals or plants produce milk? Why do no mammals have four limbs plus a pair of wings, like the Pegasus or angels? This fits easily with the idea of common descent, but is not what would be expected from special creation (although it isn't completely at odds with creation either, as the creator(s) could create life in any configuration imaginable). Page not found - Evolution Wiki Geez, i'm not confused at all (sarcasm). Ok, so this seems like what you are saying. If a horse had wheels as legs, this hierarchy would be falsified - so to speak. What's the big deal? Why is this at odds with special creation? What would special creation predict, wheels? I think I understand that similiar features are put in similiar groups but they are all still one group...broken down the best possible way to explain life in catagories. What I don't understand is when it's said "why would God try to trick us?" What does this mean? What is it about the common ancestor that shows if it's not a common ancestor God is tricking us? Is there something that is so distinct that it does show common decent? If so what is it The genetic code? A sort of universal genectic code? I think genetics is a big subject in all of this. Maybe if i'm trying to find a workable definition of "kinds" that would fit in a scientific theory it's best to look at the differences in a species rather than similarities. Edited by Chuck77, : No reason given. Edited by Chuck77, : No reason given. Edited by Chuck77, : No reason given.
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Chuck77 Inactive Member |
From EvoWiki:
ConclusionsCladistics is a robust method for deciphering phylogeny, and like any such method, it has its strengths, and weaknesses. Opponents of cladistics, who categorically dismiss this procedure, are as wrong as those who elevate cladistics to the level of phylogenetic panaceareality lies somewhere in the middle. In an imperfect science, attempting to piece together a riddle wrapped inside an enigma, cladistics will continue to serve us well. Page not found - Evolution Wiki Reality lies somewhere in the middle. Do we know where the middle is?
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Chuck77 Inactive Member |
It also shows that if a designer was involved, then he made his design look like it happened via a process of evolution - not by design as a human designer would do it. (A human designer might well put wings on a horse or wheels on a pig - he'd take the best designs he had for say, an eye, and use that in every animal needing an eye - he wouldn't use sub-optimised parts if he had a better model; which is what we find in nature.) I still dont understand this. What do you mean "sub-optimsed" parts? You mean something like "generic" parts? How is it made to lool like via the process of evolution and not design? I'm not trying to get at anything here, I really just don't know. What do you mean "best designs"? Are you saying things are designed badly? I really still dont understand the argument for common decent. Are all features evolved sub-par? And a designer would do what different? Edited by Chuck77, : No reason given.
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Chuck77 Inactive Member |
chuck77 writes: Can we call the family Canidae a "kind"?RAZD writes: We could, but that could be interpreted as claiming that "kind" is defined by "family" taxon, and I would rather not be side-tracked by that issue. We can instead call it the Canidae clade, and avoid that issue. Sorry RAZD, it's been a while. What exactly is a clade compared to a family again? Down below where would clade go? Kingdom: AnimaliaPhylum: Chordata Class: Mammalia Order: Carnivora Suborder: Feliformia Family: Felidae I forgot how we got the where we are. Lots of information. I'm not sure I understand cladistics like i thought I was learning it to be. What is a clade compared to a family?
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Chuck77 Inactive Member
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I found out what I was doing wrong: Message 24
I think I got it now.
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Chuck77 Inactive Member |
Thanks a lot Caffeine. That's a lot of good information there.
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Chuck77 Inactive Member |
I'm either giving the wrong impression here or you're just up to your regular insults by actually suggesting I read "The blind watchmaker" by Richard Dawkins. How bout I grab "the god delusion" while we're at it? NO THANKS.
Edited by Chuck77, : No reason given.
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Chuck77 Inactive Member
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Sorry RAZD, it does seem that way.
I think I am a little interested in cladistics and Taxonomy at the moment. I think I should start there before getting into what species evolve into what species, if that even makes sense. Edited by Chuck77, : No reason given.
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