THE TREE OF LIFE
The tree of life, as currently accepted by main-stream science, has an unaccounted for error. It is no secret to you if you have read all my posts, but the molecular phylogeny of major phyla has major errors for lack of understanding long-branch attraction. Or as I have shown from numerous citations elsewhere, abundant evidence that direct measurement of DNA differences of species is almost certain to produce an erroneous tree-of-life for phyla if it is calculated from those differences.
LONG BRANCH ATTRACTION
Molecular phylogenies are sometimes plagued with the pogonophorans or some other group appearing in some central position in a phylogeny when the researcher is quite certain it should not be there. They may note that it doesn't seem to belong there, or, I suspect, sometimes they leave it out because they think it is a long-branch attraction appropriate to ignore. Maybe they just remember not to use the group for an out-group [a group inserted that is reasonably presumed to be outside the cluster being investigated]. The correct solution is to figure out why it happened - something they cannot do without introducing a major variable of molecular clocks all ignore. I have discussed elsewhere how the nematodes may also have a slower rate of change in their genome and thus produce an example of long branch attraction.
THE POGONOPHORA
The Pogonophora are specialized descendants of polychaete annelids of which the ancient ones are ancestral to all vertebrates via hemichordates and cephalochordates as indicated in Our Evolutionary Lineage (Post 79). [ http://evolutioninsights.blogspot.com/2014/12/our-evolutionary-lineage.html ]
That post also lists approximate times of origins of groups in that lineage. From that we can see that the pogonophorans evolved about a billion years ago. Some are little changed to this day, if they stayed in the abyss, from perhaps 600 million years ago when the hemichordate line branched off from some of the pogonophorans moving into shallower waters. From hemichordates the cephalochordates branched off, perhaps 500 million years ago.
THE CAMBRIAN
About 500 million years ago the Cambrian began. Most major phyla had representatives in the Cambrian. Trilobites were arthropods whose fossils are only found in rocks through the Cambrian to the end of the Palaeozoic. Arthropods are obvious annelids descendants that have an origin from polychaetes, as do pogonophorans. Mollusks had a comparable origin from polychaetes.
The stability of conditions in the Cambrian enabled pogonophorans ancestors to migrate to shallower seas and survive following the end of major asteroid bombardment episodes. As they established themselves in shallow seas, the reduced pressure enabled physiological processes involving diffusion to speed up to a 1,000 times greater speed. A better food supply also contributed to the process. The recovery of gut development by the hemichordate descendants accompanied other developments as the worms moved out of their tubes and took on a more active life getting particulate food, mostly by filtration instead of the diffusion on which the pogonophorans had become dependent.
Parallel lines from the polychaete-pogonophora line gave rise to echinoderms and probably some of the lophophorate phyla that also made their appearance in the Cambrian.
CALCULATING THE LONG BRANCH ATTRACTION
We can ignore the fact that pogonophoran tube analysis (in earlier blogs) indicates the individuals can live from 10,000 to a million or more years. Just taking the pressure differential effect on physiology indicates evolutionary selection is likely to be 1,000 times more rapid in shallow seas than in abyssal ones.
The ancestor that remained and reproduced in the abyss over the past billion years would be expected to have one million nucleotide substitutions in their DNA while a descendant that had been near the surface has 500 million nucleotide substitutions in the past half-billion years. Another descendant branching off at the same time would also have 500 million nucleotide substitutions in the past half-billion years.
Others branching from the new lines, say one from each line 400 million years ago, each would have 400 million nucleotide substitutions in each of their lines as differences.
THE SURPRISE
Now, the four groups would all have more in common with the pogonophoran that now has half a million changes from the point of common ancestry with the other four groups that each has 500 million changes.
The branching of the new groups would be correctly interpreted from the differences as *800.0 million changes from their nearest relative and *1,000.0 million from each of their more distant pair of relatives, but only *500.5 million changes from the pogonophoran. The pogonophoran now looks closest to all by the long branch attraction, an artifact of different rates of evolution whether by physiological speed or long generation time, or by both as I think it is.
The closer the groups studied, in a phylogenetic study of relationships, the more likely it is that pogonophorans will not show up as a close relative within a group. Thus species, genus, and families in an order are unlikely to appear related to pogonophorans unless the study is of pogonophorans.
If you look at the estimated times of origins you can see that terrestrial vertebrate classes had their origins over three hundred million years ago. but most modern orders were likely beginning almost two hundred million years ago. Nearly the same thing could be said about the insects. Whereas echinoderms are a more ancient group with classes going back to the Cambrian; they even have several extinct classes.
Until the molecular phylogeneticists calculate a major tree of life taking the above into consideration they will continue to be wrong about their view of relationships of phyla. They have a lot to contribute if they stop making that error.
*The numbers used in the examples above are not precise and are only used for a simplified example of the principles involved and are calculated by summing the changes of both ancestral lines from their point of branching.
Joseph G. Engemann Kalamazoo, Michigan February 2, 2015
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