This article is speculating about evolution of species which is not based on changes in DNA.
Horizontal Gene Transfer
Currently, evolution is seen as DNA-based, because DNA is regarded as the only part of organisms that is inherited. DNA is the blueprint for an organism in the next generation. Richard Dawkins, in his book “The Selfish Gene” even shifted the focus of natural selection from complete genomes (species) to single genes. There is recently some unrest about Horizontal Gene Transfer (HTG, also called Lateral Gene Transfer). HTG is troubling, because it impacts our view of the tree of life. If genes are tranfered from one species to another, then the Tree of Life no longer has only branches (where species split of), but also knots (where the genome of different species are mixed to produce a new species).
Horizontal Gene Transfer is however not the only reason that the Tree of Life might have knots. There are researched cases of new species developed from hybridization of two other species, for example in the butterfly genus Heliconius and cichlids in Lake Tanganyika (fishes in East Africa).
The beneficial prion
A prion is an infectious protein. Some diseases are caused by prions, such as the Mad Cow Disease. A protein is a long chain of amino acids. Proteins can carry out their function in a cell because they have a special three-dimensional shape. Some proteins can be folded in different shapes. When such a protein has been folded differently, it will no longer be able to carry out the function it used to do. Prions are proteins that are shaped differently and also have the ability to refold other proteins into their own shape. The latter makes prions infectious. Once a single prion comes into a cell, it folds another protein. After finishing the job, there are two differently shaped proteins which each can fold another protein into their own shape. Then there are four, eight, sixteen etc of them.
It is interesting to notice that prions are self replicators. They require a very specific substrate which is only found in certain living cells.
MORE from Takaita: http://urlet.com/frequency.deport
May 3, 2008 at 11:27 am
GENETIC TRANSFER IS NOT THE ANSWER.
The following text is taken from Volume 2 of The Quest for Right.
The inherent ability of procreation to prevent successful mating and/or genetic intervention between populations whose genetic constitution (code) are vastly different (as a cow and a moose) is well documented. The highly elaborate code may be compared to a microchip in an advanced computer that stores information. The genetic code contains elaborate, immeasurable genetic instructions for every aspect of procreation, and is fixed. A fragment of genetic material may be altered or lost and a species may still be able to reproduce with a like-kind; however, the code will break down if any attempt is made to reproduce with a different species. The breakdown is not unlike a computer chip: one malfunction allows the program to continue but with errors; a dramatic malfunction will effectively shut down all operations.
Procreation has provided several isolating mechanisms to prevent the occurrence of intermediates. Foremost in importance, a lethal genetic condition usually prevails with the introduction of genes (through semen) from a totally different species, causing premature death of the carrier. Procreation also controls the introduction of any so-called active colonizing genes by B cells in the immune system, which, when activated, become plasma cells that secrete antibodies to attack the foreign material. The transfer of a few hapless genes by virus or mosquitoes would be devoured quite rapidly. Furthermore, the mixing of gene products and/or chromosomal behavior between species is incompatible; this often produces sterility in the hybrid offspring or, else, the hybrid will develop abnormalities so great in the zygotes (“cells formed by the union”) that they are rarely completed and inviability (“unable to live”) results. When two species have different gene arrangements, due to the great structural changes within and between chromosomes, the result is hybrid sterility. During meiosis when nuclear division reduces chromosomes from the paired to the unpaired, the hybrid will then be irregular. The improper pairing would prevent any future fertilization and cause reproductive isolation.
Forced breeding between closely related species results in mismatched chromosomes; any offspring is either stillborn or infertile.
If the occurrence of active gene intervention were possible, procreation has provided a variety of other barriers to prevent the successful introduction of any new species. Gene action in the hybrid often reduces the size of the male’s testes and negates the proper secondary sexual characteristics and drive, resulting in sterility. Moreover, a potent hybrid is stopped by differences in body language, color, and form: the characteristic color of scales in fishes and feathers in birds are the distinguishing factors for mating in those species. Females of the individual species are sexually stimulated only by males of the same species. All creatures, without exception, recognize their own kind and mate accordingly; if this were not so, there would be no species.
A grossly different hybrid is not accepted as a mate by females of the species. Any advances by an amorous male are usually stopped by a hostile female, showing her inherent disfavor by running, kicking, and biting. Any forced sexual advances by a hybrid male result in a lethal genetic condition bringing premature death to the female (as previously discussed). Often there is an incapability of sex organs and failure of one species to fertilize the egg of another. When any crossover does occur, the female produces an insemination rejection by the swelling of her vagina and the clumping of sperm which results in the failure of fertilization. Yet another barrier is that many species are fertile at different times and some are nocturnal and others diurnal, thus, they may never come into contact with one another.
The least compromising of these laws, and the ultimate barrier of any new species or lasting hybrids, is that all procreation, when left alone, will revert back to its original state; this is the fourth law of procreation. Numerous pedigree breeds have been established by emphasizing desired traits and characteristics by crossbreeding. A case in point is the successful breed of Leicestershire sheep bred by Robert Bakewell, an 18th Century English agriculturist. If, however, these same animals are left alone and not isolated, they will return to their former state in a very short period. Instead of sheep with distinguishing marks and form, they will revert back to a similar likeness as that of all sheep. More relative, there are a great variety of pedigree breeds of dogs which breed true to form; two poodles will produce other poodles, two shepherds will produce other shepherds, and two collies will produce other collies. If the animals are left alone and allowed to interbreed freely, each one will revert back to a similar likeness. The chance of a new species emerging and reproducing so as to create a new species is impossible due to the many genetic safeguards set by the fourth law of procreation.
Procreation is for all to see and teaches that there are set genetic constitutions that cannot be crossed. Only the male and his female of like flesh may reproduce. There is no shortcut to the “theory” of protracted graduation, as promoted by Birnstiel; the jumping gene concept is insolvent. And with the great gulf in the fossil record dispelling the myth of protracted graduation, only the historical version of prototypes has the ring of truth.
September 28, 2009 at 12:35 pm
we are not men, we are DEVo