posted on December 06, 2013 04:21PM GMT
Excerpt 1) “…the difference between species has more to do with which genes are expressed and when, than with the repertoire of protein-encoding genes that they possess.”
Excerpt 2) Genes controlling other genes are exactly the kind of genes I have in mind when I speak of “selfish genes” as the “immortal replicators”, the “units of natural selection”.
Excerpt 1) “Scientists are exploring how organisms can evolve elaborate structures without Darwinian selection.”
Excerpt 2) “…as random mutations arise, complexity emerges as a side effect, even without natural selection to help it along. Complexity, they say, is not purely the result of millions of years of fine-tuning through natural selection—the process that Richard Dawkins famously dubbed “the blind watchmaker.” To some extent, it just happens.”
My comment: Darwin’s entire house of cards collapses under the weight of experimental evidence that supports nutrient-dependent pheromone-controlled adaptations that enable individual differences in genomes and species diversity.
See for example: Evolution: Sex or Survival
Summary: “A classic paradox in sexual selection is how sexual traits under strong directional selection maintain underlying genetic variation. A new study has found that in Soay sheep a trade-off between reproductive success and survival maintains variation in horn size.”
My comment: A single gene for a receptor has two alleles, which could explain the gene’s frequency increase by 20%. If female Soay sheep sexually select males with larger horns, the frequency of the gene increases. The authors refute that representation of Dawkin’s selfish gene theory, when they write: “However, this rate of increase need not be the result of selection as it is not distinguishable from random fluctuations through drift .”
Thus, despite clear evidence of nutrient-dependent pheromone-controlled adaptations that enable sexual selection for phenotypic traits in all species that sexually reproduce, the vast diversity of bizarre and extravagant ornamentation and weaponry used in courtship has not been linked to any selfish gene or epigenetically effected selfish genes in these sheep.
Could a selfish gene act outside the context of Darwinian natural selection? That question again arises from a summary of a theme issue: Evolution of transcriptional enhancers and animal diversity. (with my emphasis) “Each of these papers, in one way or another, consolidates the idea that there will probably be no fixed law, like gravity, to explain at the molecular level how endless forms most beautiful and most wonderful have been, and are being evolved. It rather seems that a wide variety of peculiar molecular mechanisms perform, together, the complex task of putting the genome in action, in each cell type of each animal species, at every moment in life and under every possible physiological and environmental circumstance.”
Someone must try to tell Richard Dawkins that there is no experimental evidence that supports his concept of a selfish gene, and there never has been any. Experimental evidence supports the fact that epigenetic effects of olfactory/pheromonal input on genetically predisposed hormone-organized and hormone activated sex differences in the behavior of Soay sheep are responsible for females that select males with larger horns. The size of the horns is not fixed. It is epigenetically effected as is morphogenesis of any physical feature of phenotypic expression in any species.
Models for comparison.
1) If there were a model in which a selfish gene or combination of selfish genes enabled their own selection via phenotypic representations in physical features such as horn size, it could be supported with experimental evidence that visual input directly effects the conserved molecular mechanisms of hormone-organized and hormone-activated behavior in vertebrates, like mammals.
2)If there were a model in which mutations caused natural selection that resulted in sexual selection for physical features such as horn size, it could be supported by experimental evidence of how mutations initiate natural selection that results in sexual selection.
In either case, one of those non-existent models could then be compared to an established model of cause and effect associated with conserved molecular mechanisms that allow the epigenetic landscape to become the physical landscape of DNA in the organized genome of species from microbes to man. That model probably applies to Soay sheep, since it explains differences in sexual orientation of rams. See for example: A Comparison of LH Secretion and Brain Estradiol Receptors in Heterosexual and Homosexual Rams and Female Sheep and Nutrient-dependent/pheromone-controlled adaptive evolution: a model.