Natural Selection Undoes What It Does
A theory that can explain opposites can explain anything, therefore nothing. Darwin’s chief mechanism for evolution collapses.
Three preprints from bioRxiv indicate dissatisfaction with standard evolutionary theory taught in textbooks. Why, otherwise, would these scientists be looking to improve on it or modify it?
Natural selection reverses the exaggeration of a male sexually selected trait, which increases female fitness (bioRxiv). Natural selection theory needs some tweaking. It doesn’t accomplish what people were led to believe it does, especially when sexual selection is involved. If they can’t get these things to work in the wild, maybe they can make it work in simulations:
Theory shows how sexual selection can exaggerate male traits beyond naturally selected optima and also how natural selection can ultimately halt trait elaboration. Empirical evidence supports this theory, but to date, there have been no experimental evolution studies directly testing this logic, and little examination of possible associated effects on female fitness. Here we used experimental evolution of replicate populations of broad-horned flour-beetles to test for evolutionary effects of sex-specific predation on an exaggerated sexually selected male trait, while also testing for effects on female lifetime reproductive success. We found that populations subjected to male-specific predation evolved smaller sexually selected traits and this indirectly increased female fitness, seemingly through intersexual genetic correlations we documented. Predation solely on females had no effects. Our findings support fundamental theory, but also reveal novel outcomes when natural selection targets sex-limited sexually selected characters.
“Novel outcomes” 160 years after Darwin; do they really have his selection mechanisms figured out? What about those peacock feathers?
Evolution without variation and selection (bioRxiv). If one can get evolution without natural selection, who needs it? Actually, it adds a new kind of Stuff Happens process into the old Stuff Happens Law (natural selection). Why, it explains everything without Darwin!
A central tenet of evolutionary theory is that it requires variation upon which selection can act. We describe a means of attaining cumulative, adaptive, open-ended change that requires neither variation nor selective exclusion, and that can occur in the absence of generations (i.e., no explicit birth or death). This second evolutionary process occurs through the assimilation, restructuring, and extrusion of products into the environment by identical, interacting Reflexively Autocatalytic and Food set-generated (RAF) networks. Since there is no self-assembly code, it is more haphazard than natural selection, and there is no discarding of acquired traits (a signature characteristic of natural selection). We refer to this more primitive process evolutionary process as Self–Other Reorganisation because it involves internal self-organising and self-maintaining processes within entities, as well as interaction between entities. In the extreme, it can work with just one entity but it differs from learning because it can operate in groups of entities and produce adaptive change across generations. We suggest that this more primitive process is operative during the initial stage of an evolutionary process, and that it is responsible for both the origin and early evolution of both organic life, and human culture. In cultural evolution, this ‘evolution without variation’ process can increase homogeneity amongst members of a group and thereby foster group identity and cohesion.
Natural selection and the advantage of recombination (bioRxiv). Recombination, a process that swaps material during sexual reproduction, is often invoked as an evolutionary process. But all it does is shuffle existing genetic information – it cannot explain the origin of new genes, cells, tissues and organs.
These scientists admit to bafflement about the origin and maintenance of recombination, which natural selection should eliminate. How can these scientists rescue recombination as an evolutionary benefit? In short, they don’t. They just conclude that this problem that has “defied explanation since the time of Darwin” needs to be “viewed anew.”
Exchanging genetic material with another individual seems risky from an evolutionary stand-point, and yet living things across all scales and phyla do so quite regularly. The pervasiveness of such genetic exchange, or recombination, in nature has defied explanation since the time of Darwin. Conditions that favor recombination, however, are well-understood: recombination is advantageous when the genomes of individuals in a population contain more selectively mismatched combinations of alleles than can be explained by chance alone. Recombination remedies this imbalance by shuffling alleles across individuals. The great difficulty in explaining the ubiquity of recombination in nature lies in identifying a source of this imbalance that is comparably ubiquitous. Intuitively, it would seem that natural selection should reduce the imbalance by favoring selectively matched combinations of high-fitness alleles, thereby opposing the evolution of recombination. We show, however, that this intuition is wrong; to the contrary, we find that natural selection has an encompassing tendency to assemble selectively mismatched combinations of alleles (the products of natural selection), thereby increasing the imbalance and promoting the evolution of recombination. We further show that population dynamics that lead to the fixation of these selectively mismatched genotypes (the process of natural selection) themselves produce an average imbalance that promotes the evolution of recombination. This fact is completely independent of the distribution of allelic fitness effects and is primarily due to the additive component of those effects. Our findings provide a novel vantage point from which the enormous body of established work on the evolution of sex and recombination may be viewed anew. They further suggest that recombination evolved and is maintained more as an unavoidable byproduct of natural selection than as a catalyst.
Natural selection, that theory that is held up as a model of science, with Charles Darwin the greatest of all scientists, is still baffling.
They’ve had 160 years and it keeps throwing up problems that defy explanation. What, exactly, is the “enormous body of established work on the evolution of sex” doing to increase understanding of biology – apart from keeping scientists employed in endless puzzle-solving games? What a useless theory!