Land Mammal to Whale transition: fossils Part II

This is intended to continue the thread from:
Message 301The basic concept is to discuss two major issues:
1) Is there adequate (not a well defined term) evidence for whale evolution?
2) How many samples along the whale evolutionary path should we expect to find?

Since it seems we are throwing too many things out at once let's see if we can get on the same page for just one concept.Speciation EventAn "event" implies to me something which occurs in a localized place and time.
Let's start with a population of individuals that are under selective pressure for a number of generations let's say 1,000,000 generations. every 10,000 generations we are able to examine and test the population and we find that each time the population every 10,000 generations can not interbreed with either population -10,000 or +10,000 generations (that is the population of generation 30,000 can't interbreed with generation 20 or 40 thousand).I think you would then say we have 100 speciations, correct?But if we test the 10,000th population with the 5,000th and the 15,000ths they can still interbreed. And the 5,000th with the first and the 15,000th with the 20,000th can still interbreed. So the speciation event did not happen between the 5,000th and the 10,000th for one thing. But the 5,000th can interbreed with the first so it there was no speciation between those. So where was this localized "event"?The real case may, of course, be more complex than this if the population split into multiple separated populations but even it the "tests" were conducted with populations that are before and after a split the results will still be the same. I won't go in to the extra complexity here since it is not important.The spectrum of light is analogous to this. That is it is an aid to understanding the concept. Which you have yet to give a reason to think that you have gotten yet. The frequency spread of light is analogous to the time span of the populations. The color of the light is analogous to the species of the populations. Yellow is one species , red another an so on. There is in the spectrum no "event" where red turns to yellow. That is all the analogy is trying to point out nothing fancier.Now why would you have or not have "missing links"? What is the difference in your picture from the picture I have painted above and why does it produce "missing links" (please define what they are) and the above scenario not produce these things.Since this is off topic for the fossilization process I am replying here. Please refer to: Message 56Please explain "new" and "prior" group. About the only way I can see this being different from the above simplified scenario is if the new group and prior are just one generation apart. This is in no way what is suggested for most evolution and particularly the evolution of whales. We have fossil samples spread over several 10's of millions of years. They would 10,000's to 100,000's of generations apart if were in a direct ancestral line to each other. At each point they have some differences to the points earlier and later. The differences are just what would be expected if there were a continuous series of changes between them. The size of the "leaps" are not particularly large over the time spans involved.So one possible explanation for the pattern is that these represent samples in the continuous evolution of whale ancestral forms. The data in entirely consistent with that idea.What other explanation do you have? This is simply mumbo-jumbo and if you use it as an excuse for anything again you will be suspended.

Please define a "speciation event". You have yet to do that and your use of it in this paragraph doesn't help.The GDs and Chichihuaus would be (within this discussion) different species no one would call them speciation events. If, for the discussin, we define GDs and chichihuaus as different species then how many speciation events have occured between them? We are precisely quibbling over the difficulties. We can't count separated transitional forms if we don't have an operation definition (google that) of what a 'transitional form' is.If a small population is under significant selective pressure (and having an open niche available that is very different from the one before is about as significant a pressure as you can get) then the populations may undergo changes in very perhaps 100's of generations giving us 10,000's of 'transitional forms' in the first couple of 10's of millions of years of whale evolution and some 1,000's thereafter (when the niche is less open and the populations are larger).The above scenario combined with a low chance of a fossil forming and being found produces the case where every single fossil find will be a 'transitional' as they are all different.In fact the approximately 160,000 year history of the development of H. sapiens which is treated as all one species shows 'transitions' in that time. Archaic H. sap. is not exactly like us. But more recently we find much more homogeneity.

Randman is as confused on this as he is on pretty well every single issue discussed.The molecular clock is a way of dating genetic changes by comparing stretchs of genomes of, say chimps and humans and using that to determine when they last were one population.The clock makes a basic assumption that the rate of mutations of the chosen stretchs is constant. This is partially set by using fossils where possible.The stretchs used are specifically not those that randman is talking about since they have to be NOT subject to selection so he is way off track (again).

This series of 3 lines leaves me just going "huh?". I was going to reply to the following lines of yours with:
It seems that my ability to write english isn't good enough to be able to convey the concept that I am trying to help you with. I've done about all I can so I think I'll let others with a better command of the language try to help.Now, having read the above lines it seems my ability to comprehend the language is even more impaired than my ability to write it since I have no idea why you would put those two lines of yours after my "constant mutations" line.

One difficulty is determining mutation rates is that for much of what we are talking about we are not measuring the mutation rates directly. I think, based on other parts of your post, you understand that.That is even if mutations were utterly random and of a constant rate the selection process would mask this. That is, mutations that interrupt the development of a fetus may not show up even if we are studying a living population because they may well abort at the intial few cell stage. This leaves some parts of the genome relatively constant not because they don't get mutations but because any change is a disaster.This comment of yours suggest you understand that: Randman said nothing about the column he was referring to long periods of time. You misread what he said. I am very sure that they way he characterizes it is inaccurate . Randman is mixing up the parts of the genome necessary to produce the phenotypical changes necessary for selection and, eventually, speciation with the parts used for the "clock". Since any part of the genome subject to selection could have it's apparent rate of mutation skewed all to hell (even appear to be effectively zero of very long times as noted above) they are not used.

Since you asked for a reply I'll give you my best understanding (as a non-professional) for you to consider until you can post again. Other than you don't like the term vestigial why would they be "most likely ... necessary for mating"? There are lots of creatures (snakes, blue whales) that manage to mate without them. In addition, even if they had a use for basilosaurus they are nicely intermediate between the earlier forms and later legless whales. You are arriving at a conclusion based on what you want without any other support. This has been explained to you several times. To demonstrate that you do have some understanding of the topic perhaps you can offer some reasoning as to why we would have a harder time finding this. I see nothing particularly interesting about that. Perhaps you can explain in more detail. The basilosaurus is about a million generations after the first ancestors of cetaceans started to explore the sea. It shows characteristics of cetaceans and of earlier mammals from long before. It represents a stage of the transition even if it is only a cousin of the actual ancestors to modern whales.Remember: it was hypothosized based on evolutionary theory and the characteristics of modern whales that there would be an evolutionary series of creatures that had as one looks back into the past fewer and fewer of the features of modern whales and more features of the land living ancestors.All the fossils we do have support this hypothosis. You think there should be more fossils. That seems to be the only argument that you have. When there are more fossils you will remain just as unconvinced so why bother?This message has been edited by Admin, 08-12-2005 07:17 AM

I know that the coelacanth is not the same species (or even genus) and has changed quiet a bit from the last found fossils.I'm less sure of others but suspect that none of them are the same species however much they are generally similar to modern forms.In any case, the point is that they are not modern forms. So if you are trying to say there are modern species mixed in I think there is no support for that.

Ok, but you'd better quantify the "millions" -- single digits I think is no problem.Beyond that the organisms are not the same or we can't tell AFAIK.If you have anything that supports the actual same species back beyond 10 Myrs I would be interested in it.This message has been edited by NosyNed, 08-12-2005 04:00 PM

You noted, of course, that I said it was simplified and later stated that the real situation was more complex including splits.However, I also said that the extra complexity is not important to this point. Why do you think it is? It is not important to this specific point because the continuity without any break in the interbreeding crosses the splits in populations. That is why, for the most part, geographic barriers must hold for long enough to give time for full speciation to occur.Do you agree that an event is localized and specfic or not?What about the rest of the post you are replying to?

A very good point. Your lottery analogy is also useful here.It is rare for an individual organisim to fossilize. This point has been made, very indirectly before. This has been shown through taphonomic tests some of which have been refered to for you. Have you refered to any such tests? Even one? Have you suppied any quantification that you haven't just made up?So, as has been noted to you before, to determine if a fossil might be found one of the things you need to estimate is the overall population size and geographic breadth of the population.Thus a large population may have enough individuals in it that some will win the lottery. However, this is just the sort of population that will surpress the fixation of new genes and thus be more resistant to speciation other than very gradually over time under ongoing selective pressures. Thus the mathematics of gene flow supports the fact that rapid change will tend to happen more often in small populations.

As has been noted before you have not yet shown why we should expect any particular number of speciation events. You have still not been clearn on what such an 'event' is.You seem to think that each individual small change equals a 'speciation event'. Why is that? It has been pointed out that multiple changes could (and there is every reason to think that they would) happen at the same time in a population. Why does it appear that you have ignored that?

You have not yet, in 100's of post demonstrated just how you calculate what we should see. I think you should do that before you keep harping on this.

Will we are discussing fossils the fact that there is strong morphological evidence and genetic evidence supporting the evolution of whales from particular land animals is certainly something that can not be totally disregarded. They do NOT, in any way indicate the opposite of anything. There are transitionals! All we are discussing is how many there are and how many there "should" be.You have yet to offer any significant support for your estimates of how many there should be. In fact, the only quantification I can recall is your 90% number which you have yet to support or retract.Have you abandoned that number or not? What other numbers do you have?You have been given references that suggest that fossilization is rare and that we should expect gaps in the detailed record.What record of fossils that we do have fits in perfectly well with ALL the other data supporting the idea that whales are the descendants of land animals. It simply isn't as detailed as we might like it is not opposite anything.Evolutionary models say something rather different from what you are saying. This has, in bits and pieces been pointed out to you several times. You seem to be having trouble putting together all the details that are presented to you.

Then do the analysis. It has been pointed out to you that your suggestions do not seem to be based on any understanding of evolutionary theory.Why, by the way, do you think it is more appropriate to use families since that is a change, IIRC, from your intial claims.ABEBut have you supplied some suggested objective criteria to pick the "changes"? How many occur in one population in parallel? How much genetic change produces just how much morphological change?( I can answer that last one in a rough way -- it is possible to have rather a lot of change with limited genetic change. This is determinable by comparing extant species.)This message has been edited by NosyNed, 08-13-2005 02:00 AM