“Evolution” of two sexes?
Topics included (among others):
CORRELATION BETWEEN ANIMAL DEVELOPMENT AND MITOCHONDRIAL EVOLUTION
THE MODEL: SIMULATION, MATHS TOO COMPLICATED TO SOLVE
Mt VARIATION BETWEEN GAMETES MAKES SOMATIC GAMETOGENESIS ADVANTAGEOUS IN BASAL ANIMALS
ONLY INCREASING MT MUTATION RATE DRIVES THE EVOLUTION OF GERMLINE
CAMBRIAN EXPLOSION: A LINK TO THE EVOLUTION OF GERMLINE
SEX CAN EVOLVE ONLY AFTER COMPETITION IS SUPPRESSED
The claim is made that “Sex had to arise at some point before the LECA [last eukaryotic common ancestor].”
That claim is followed by this question: “Was the archaeal host cell initially capable of cell-cell fusion or was it a later innovation?”
My comment: Mitochondrial quality is nutrient-dependent and pheromone-contolled at the advent of sexual reproduction in yeasts via the biophysically constrained chemistry of protein folding. Mitochondrial quality links RNA-mediated events from the light-induced de novo creation of amino acids to the amino acid substitutions that differentiate all cell types of all individuals of all genera.
Any claims that attempt to link the LECA to sexually differentiated cell types should first address the claim that no experimental evidence of biologically-based RNA-mediated cause and effect can be linked to a last universal common ancestor (LUCA).
We cannot conceive of a global external factor that could cause, during this time, parallel evolution of amino acid compositions of proteins in 15 diverse taxa that represent all three domains of life and span a wide range of lifestyles and environments. Thus, currently, the most plausible hypothesis is that we are observing a universal, intrinsic trend that emerged before the last universal common ancestor of all extant organisms.
For comparison, there are obvious nutrient-dependent links from the epigenetic landscape to the physical landscape of DNA in all genera. The links are RNA-directed via DNA methylation and include RNA-mediated amino acid substitutions that clearly differentiate the cell types that contribute to species-specific morphological phenotypes and behavioral phenotypes. In species from microbes to humans, the phenotypes are nutrient-dependent and pheromone-controlled.
Selection for mitochondrial quality is not exemplified in the context of evolution. Instead, ecological variation leads to nutrient-dependent RNA-mediated cell type differentiation and fixation of amino acid substitutions in the context of the physiology of reproduction. If fixation of amino acid substitutions does not happen in the context of the biophysically constrained chemistry of nutrient-dependent protein folding, organisms do not evolve two sexes. Instead, species become extinct.
Claims that two sexes “evolved” can be placed into the context of pseudoscientific nonsense and compared to the equally ridiculous claims that sexually differentiated cell types “evolved” and that sexual orientation “evolved.”
But see for comparison: From Fertilization to Adult Sexual Behavior
Parenthetically it is interesting to note even the yeast Saccharomyces cerevisiae has a gene-based equivalent of sexual orientation (i.e., a-factor and alpha-factor physiologies). These differences arise from different epigenetic modifications of an otherwise identical MAT locus (Runge and Zakian, 1996; Wu and Haber, 1995).
My comment: Attempts to explain the evolution of sexually differentiated cell types fail to consider what is currently known about physics, chemistry, and the conserved molecular epigenetics of RNA-mediated events. Not only do the failed attempts to explain the evolution of two sexes ignore biologically-based cause and effect, they also make it appear that sexual orientation evolved to include homosexual orientiation. If homosexual orientation “evolved,” an explanation for it must be considered outside the context of any explanation based on population genetics or the mitochondrial quality that ensures the survival of species that sexually reproduce.
See, for comparison: The Mind’s Eyes: Human pheromones, neuroscience, and male sexual preferences