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Author Topic:   Transitional fossils not proof of evolution?
Lithodid-Man
Member (Idle past 3043 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 79 of 223 (316428)
05-30-2006 10:54 PM
Reply to: Message 78 by Hyroglyphx
05-30-2006 9:49 PM


Again, please look at the primary literature
quote:
As I've shared, my main objection to phyletic gradualism, is the 'gradualism,' not so much the pace at which they suppose it has occured. As well, with PE, my concern with PE isn't that they use burst of rapidity in the theorum, but rather, that its being used as a n excuse not to present evidence, or at least, give us reasons why shouldn't expect to see any
I becomming certain that you really don't understand phyletic gradualism or punctuated equilibrium. You keep making references that make me think you are getting these definitions from sources other than the original Eldredge & Gould paper (Eldredge N and Gould SJ (1972) Punctuated equilibria: an alternative to phyletic gradualism. In T. J. M. Schopf, editor, Models in Paleobiology, pages 82--115). I believe that you think you have a handle on them, but you don't.
Phyletic gradualism is not the idea that species change slowly. It is not uniformitarianism from geology applied to biology. I think even biologists make this error. Phyletic gradualism is the idea that any genetic change in a population must necessarily spread through the entire population or go extinct. These population-wide changes gradually accumulate. Speciation could be the transformation of an entire species OR divergence into species of different populations of the same species. Essentially, under a phyletic gradualism model sympatric speciation cannot exist. Because sympatric speciation is observed we know that phyletic gradualism is not the only way in which evolution progresses. Darwin was not tied to strict gradual evolution but was tied to phyletic gradualism. A non-selection form of phyletic gradualism that is probably important (and if Douglas Futuyma is right, critically important) is genetic drift.
Punctuated equilibrium is that idea that species (groups of populations) remain relatively constant over time. Genetic changes are absorbed and usually lost through dilution. However, in small populations or subpopulations (these is key) unique traits can become fixed more easily. When we see species change in the fossil record it appears rapid because the subpopulation rapidly replaces the dominant population under selection pressure.
What is import is that both of these concepts are about species change or what you would call microevolution. Since you have no problem with this I am not sure why it keeps coming up. My suspicion is that you are under the impression that evolutionists are trying to hide the lack of transisitionals between major taxa. We have those (at least most). What is apparently rare are changes between species. They are not nonexistant, but rare. PE applies what we know about population genetics (a la Sewell Wright) to the paleontological record. Gould's original research was with a genus of landsnails with a good fossil record, Cerion. In that genus shell types remain constant then rapidly change.

This message is a reply to:
 Message 78 by Hyroglyphx, posted 05-30-2006 9:49 PM Hyroglyphx has not replied

Replies to this message:
 Message 80 by Percy, posted 05-30-2006 11:18 PM Lithodid-Man has replied

  
Lithodid-Man
Member (Idle past 3043 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 83 of 223 (316468)
05-31-2006 1:23 AM
Reply to: Message 80 by Percy
05-30-2006 11:18 PM


Re: Again, please look at the primary literature
Phyletic gradualism is the idea that any genetic change in a population must necessarily spread through the entire population or go extinct.
I'm interpreting this as meaning that every individual in a population must possess every allele, which doesn't make sense, so I must be reading this the wrong way.
I should have chosen my words better (that's what I get for writing in a hurry). I am not referring to every single allele. Just that changes in a population would be relatively homogenous throughout the population. Species could remain morphologically stable or change, but whichever occured would take place throughout the population. A novel phenotype can arise but would most often be swamped out. If it persisted it would spread gradually throughout the entire population. This is in contrast to Sewell Wright's shifting balance which states that combinations of traits would cluster around fitness peaks within the population and those traits could lead to speciation. These fitness peaks would be one source of the daughter species Eldredge & Gould propose that would "suddenly" replace the parent species. This is the reason phyletic gradualism excludes sympatric speciation in most situations.
The wiki definition is okay. I did some searches through my library and I do find phyletic gradualism synonymized with general gradualism fairly frequently. The difference as I was taught is that all evolutionary change (ok, not all, but nearly all) evolutionary change is gradual. Even those forms that rapidly dominate and replace the parent population gradually changed somewhere (the rate of gradual change varies, of course). Phyletic gradualism is the idea that the apparent evolution of a species would be gradual as changes would slowly accumulate as parent species produced daughetr species. If I have time over the next week I will search through my notes and papers for more info and refs on this. I did take exception with this from the definition:
Wikipedia writes:
It holds that the species is not a fixed type, and that the population, not the individual, evolves
The individual is the unit of selection and the population evolves. This hasn't changed since Darwin!

Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"

This message is a reply to:
 Message 80 by Percy, posted 05-30-2006 11:18 PM Percy has not replied

  
Lithodid-Man
Member (Idle past 3043 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 106 of 223 (316876)
06-01-2006 4:24 PM
Reply to: Message 95 by Chiroptera
05-31-2006 11:05 PM


Here is another example...
The following is a photo series or morphological intermediates between the decapod crustacean families Paguridae (hermit crabs) and Lithodidae (king crabs). Later are considered to be directly descended from the former and probably nest within the Paguridae (in which case there will be some reorganization of the pagurid clades!). In the Guld of Alaska we have about 20 species each in both families and it is believed that the king crabs originated here. We are also lucky enough to have living representatives of the morphological intermediates.
The first three (A-C) are true hermit crabs. The trend in this group has been a reduction in the size of the abdomen ("tail") and a hardening of the carapace. "C" represents a genus (Labidochirus) probably very close to the ancestor of king crabs. The trend in the primitive king crabs (D, E, and F) has been the fusion of the carapace into a solid structure and an increase in the number of plates on the abdomen, the flattening of the abdomen, and a loss of the ancestral hight handed coiling of the abdomen (most hermit crabs live in snail shells and the abdomen coils to fit the shell). The last two (G & H) are true king crabs. In these the abdomen is composed of fused plates (in varying degrees) and is held permanently undre the body. The right hand coiling in these can be seen in females only as a slight asymmetry. There are even more derived (advanced) king crabs that have further specialized into a (true ) crab-like mode of life. The trend in the abdomen and carapace is also seen in the walking legs, mouthparts, pleopods, etc. The relationship (ancestor to descendant) is supported by morphology, sperm microstructure, and genetics.
Edited by Lithodid-Man, : Attempting to fix picture
Edited by AdminJar, : No reason given.

Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"

This message is a reply to:
 Message 95 by Chiroptera, posted 05-31-2006 11:05 PM Chiroptera has not replied

Replies to this message:
 Message 107 by Percy, posted 06-01-2006 4:58 PM Lithodid-Man has not replied

  
Lithodid-Man
Member (Idle past 3043 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 215 of 223 (341628)
08-20-2006 12:22 AM
Reply to: Message 212 by Chuteleach
08-19-2006 10:09 PM


Xiphosurans
Chuteleach,
I am going to assume from your choice of source that you are one of those unfortunate victims of AiG deceit.
The modern species of horsecrab are not identical to any fossil species. In fact, none of the paleozoic species are in the same family and a good number of those in a different ORDER than the modern species. Pictures of fossils like those on AiG make convincing (but wrong) arguments to people with no background in invertebrate zoology. The fact is that many invertebrate taxa look similar to laymen but have profound and important differences. In horseshoe crabs the shapes of the appendages and degree of fusion of segments are very important (but not the only ones) and separate out taxa with greater differences than seen in the order Primata (lemurs, monkeys, apes).
On the link you provided there is also a plant, Comptonia peregrina shown next to a fossil:
AiG writes:
The same species of Comptonia found as a fossil, supposedly millions of years older. No evolution has taken place.
This is simply untrue. There are fossil Comptonia, but not C. peregrina.
AiG writes:
Fossil Limulus from Solnhofen limestone”Upper Jurassic (supposedly about 140 million years old).
The genus is Mesolimulus and not in the same subfamily as is Limulus. With such errors (fabrications?) on their site you need to really ask yourself how much faith you can put into anything they say.
I strongly encourage you to look up claims you read on AiG (or anywhere for that matter, creo or evo). At the very least type in some good keywords in Google and see what you get.

Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"

This message is a reply to:
 Message 212 by Chuteleach, posted 08-19-2006 10:09 PM Chuteleach has replied

Replies to this message:
 Message 217 by Chuteleach, posted 08-20-2006 9:38 PM Lithodid-Man has replied

  
Lithodid-Man
Member (Idle past 3043 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 218 of 223 (341813)
08-20-2006 10:17 PM
Reply to: Message 217 by Chuteleach
08-20-2006 9:38 PM


Re: Xiphosurans
Chuteleach writes:
no, the genus is Limulus. I double checked.
Better triple check, it isn't. Limulus polyphemos is one of the four living species, the others are in the genus Tachypleus (I believe, don't have my ref handy). The fossil from the Solnhofen limestones is Mesolimulus. Even the caption says the fossil is Jurassic, the oldest known limulin (Member of the subfamily Limulinae) are Miocene in age and IIRC that one is some dispute.
I would highly recommend doing a bit more research before making such bold statements.

Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"

This message is a reply to:
 Message 217 by Chuteleach, posted 08-20-2006 9:38 PM Chuteleach has not replied

  
Lithodid-Man
Member (Idle past 3043 days)
Posts: 504
From: Juneau, Alaska, USA
Joined: 03-22-2004


Message 222 of 223 (341833)
08-20-2006 11:15 PM
Reply to: Message 221 by Belfry
08-20-2006 10:46 PM


Re: Xiphosurans
Belfry,
Thanks for the excellent Xiphosuran link. The genus Limulus was named in 1885 by Stormer. Mesolimulus was first erected as a genus in 1952. Between 1885 and 1952 the genus Limulus was used to include many xiphosurans. The species Limulus polyphemus was first described in 1778 by Linnaeus as Cancer polyphemus.

Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"
Elim Garak: "My dear Doctor, they're all true"
Doctor Bashir: "Even the lies?"
Elim Garak: "Especially the lies"

This message is a reply to:
 Message 221 by Belfry, posted 08-20-2006 10:46 PM Belfry has not replied

  
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