Elastic, not plastic species: Frozen plasticity theory and the origin of adaptive evolution in sexually reproducing organisms

Abstract

BackgroundDarwin's evolutionary theory could easily explain the evolution of adaptive traits (organs and behavioral patterns) in asexual but not in sexual organisms. Two models, the selfish gene theory and frozen plasticity theory were suggested to explain evolution of adaptive traits in sexual organisms in past 30 years.ResultsThe frozen plasticity theory suggests that sexual species can evolve new adaptations only when their members are genetically uniform, i.e. only after a portion of the population of the original species had split off, balanced on the edge of extinction for several generations, and then undergone rapid expansion. After a short period of time, estimated on the basis of paleontological data to correspond to 1-2% of the duration of the species, polymorphism accumulates in the gene pool due to frequency-dependent selection; and thus, in each generation, new mutations occur in the presence of different alleles and therefore change their selection coefficients from generation to generation. The species ceases to behave in an evolutionarily plastic manner and becomes evolutionarily elastic on a microevolutionary time-scale and evolutionarily frozen on a macroevolutionary time-scale. It then exists in this state until such changes accumulate in the environment that the species becomes extinct.ConclusionFrozen plasticity theory, which includes the Darwinian model of evolution as a special case - the evolution of species in a plastic state, not only offers plenty of new predictions to be tested, but also provides explanations for a much broader spectrum of known biological phenomena than classic evolutionary theories.ReviewersThis article was reviewed by Rob Knight, Fyodor Kondrashov and Massimo Di Giulio (nominated by David H. Ardell).

General environmental heterogeneity as the explanation of sexuality? Comparative study shows that ancient asexual taxa are associated with both biotically and abiotically homogeneous environments

“…Thus, the results of the comparative analysis clearly indicate that either the AA groups tend to be associated with overall (both biotically and abiotically) homogeneous environments or that these two types of heterogeneity are so strongly correlated that it is impossible to decide in favor of theories of sexual reproduction that stress the key role of biotic or abiotic heterogeneity. In general, our results obtained on AAs support, but of course do not prove, the hypotheses that consider both biotic and abiotic heterogeneities acting as one factor in their effect on organisms (Flegr, 2010, 2013; Roughgarden, 1991; Scheu & Drossel, 2007; Song et al., 2011; Williams, 1975 pp. 145–146, 149–154, 169).…”

“…This result was significant in two of three statistical tests we conducted, and only the most conservative approach did not come to a statistically significant result. This outcome consequently supported the theoretical concepts that postulate the essential advantage of sexual species in heterogeneous environments and consider the (biotic and abiotic, temporal and spatial) heterogeneity of the environment affecting the organisms to be one factor that can exhibit itself in many ways (Flegr, 2010, 2013; Roughgarden, 1991; Scheu & Drossel, 2007; Song et al., 2011; Williams, 1975 pp. 145–146, 149–154, 169).…”

“…Moreover, the assumption of Flegr (2008, 2010, 2013) that the contextually dependent fitness value of alleles is a major factor in maintaining high long‐term genetic variability of sexual populations seems to be empirically supported (see Otto, 2009). This hypothesis was also supported by the results of certain experimental studies, for example, long‐term patterns of fitness and genetic variability (Renaut, Replansky, Heppleston, & Bell, 2006) or dynamics of adaptation (Colegrave, Kaltz, & Bell, 2002; Kaltz & Bell, 2002) in sexually and asexually reproducing Chlamydomonas .…”

A virtue made of necessity: Is the increasing hierarchical complexity of sexual clades an inevitable outcome of their declining (macro)evolutionary potential?

“…We have already demonstrated elsewhere (Flegr 2008(Flegr , 2010(Flegr , 2013(Flegr , 2015Flegr 2017b, 2018) 141 that the gradual reduction of (macro)evolutionary potential, intraspecific and interspecific disparity are real 142 trends, which have been documented in various eukaryotic clades by a long series of paleontological and 143 paleobiological observations (see also General Discussion). The cause of this "macroevolutionary freezing" 144 1 Similar or comparable claims were made also by several other theoretical biologists (see, e.g.…”

Positive effects of multiple gene control on the spread of altruism by group selection

“…In the present study, we tested a verbal model [18] based on the frozen plasticity theory [19]. This model suggests an increased probability of persistence of the altruistic behavioral patterns, when they are coded by several substitutable genes, in comparison to their persistance in case, when they are coded by single gene with large effect.…”