Artículo de revista
Foundational errors in the Neutral and Nearly-Neutral theories of evolution in relation to the Synthetic Theory. Is a new evolutionary paradigm necessary?
Fecha
2013-03-11Autor
Valenzuela, Carlos Y.
Institución
Resumen
The Neutral Theory of Evolution (NTE) proposes mutation and random genetic drift as the most important evolutionary factors. The
most conspicuous feature of evolution is the genomic stability during paleontological eras and lack of variation among taxa; 98% or more
of nucleotide sites are monomorphic within a species. NTE explains this homology by random fi xation of neutral bases and negative
selection (purifying selection) that does not contribute either to evolution or polymorphisms. Purifying selection is insuffi cient to account
for this evolutionary feature and the Nearly-Neutral Theory of Evolution (N-NTE) included negative selection with coeffi cients as low
as mutation rate. These NTE and N-NTE propositions are thermodynamically (tendency to random distributions, second law), biotically
(recurrent mutation), logically and mathematically (resilient equilibria instead of fi xation by drift) untenable. Recurrent forward and
backward mutation and random fl uctuations of base frequencies alone in a site make life organization and fi xations impossible. Drift is not
a directional evolutionary factor, but a directional tendency of matter-energy processes (second law) which threatens the biotic organization.
Drift cannot drive evolution. In a site, the mutation rates among bases and selection coeffi cients determine the resilient equilibrium
frequency of bases that genetic drift cannot change. The expected neutral random interaction among nucleotides is zero; however, huge
interactions and periodicities were found between bases of dinucleotides separated by 1, 2… and more than 1,000 sites. Every base is coadapted
with the whole genome. Neutralists found that neutral evolution is independent of population size (N); thus neutral evolution
should be independent of drift, because drift eff ect is dependent upon N. Also, chromosome size and shape as well as protein size are far
from random.