The mechanical properties of proteins determine the laws of evolutionary change

Abstract

The general inorganic nature of traditional selection theory (based on differential growth between any two systems) is pointed out, wherefrom it follows that this theory cannot provide explanations for the characteristics of organic evolution. Specific biophysical aspects enter with the complexity of macro-molecules: vital physical conditions for the perpetuation of the system, irrevocable extinction (= death) and random change leading to novelty, are the result of 'complexity per se'. Further biophysical properties are a direct function of the pathway along which random mutation in nucleic acids is converted into continuous protein - (specifically enzyme) - function, from there into organismic phenotype with fitness components which may, or may not, correspond to identifiable structural units in DNA. The general machine-like properties of enzymes, in that there is no additive relationship between structural (amino acid) composition and functional output, is discussed in more detail. The continuous growth functions of molecular concentrations, directed by enzyme turnover, determine simple laws of growth and morphogenesis in the organic hierarchy and thus of phenotype. Thus, the combined effect of DNA-structure and of environmental parameters (temperature, pressure, pH, etc.) on protein function determines ultimately the actual phenotype and hence, quality and intensity of genotypic selection.

Mechanisms of Density-Dependent Population Regulation in the Marine Copepod Amphiascoides sp. (Harpacticoida)

“…Regulated reproduction and dispersal are the result of dynamic processes: more or fewer eggs are produced and dispatched earlier or later; development is more or less delayed; emigration is more or less intense. It had been shown in previous studies (Walker and Williams, 1976;Walker, 1979) that environmentally induced dynamic patterns will inevitably be fixed by irreversible accumulation of genetic effects if there is no active selection for their flexibility. Thus, the extreme flexibility of Amphiascoides' reproductive, density-dependent behaviour indicates its selective value.…”

Form and function: structural analysis in evolutionary morphology

“…The interaction of structural and functional networks within the organism produces an observable hierarchy of structure-function relationships (seeBock and von Wahlert 1967;Dullemeijer 1958Dullemeijer , 1968). This hierarchy results in constraints and limi tations on change which can occur in structural and functional elements(Jacob 1977;Walker 1979). The possible pathways for change in de sign are thus limited by the nature of interacting constraints within the hierarchy of structurefunction relationships.…”

Prediction of evolution? Somatic plasticity as a basic, physiological condition for the viability of genetic mutations

“…By 'parallelism' I understand the similarity of phenotype in different, related taxa (species, genera), which is genetically fixed in some taxa but physiologically/environmentally induced in others. For instance, certain plant species of swampy habitats form divided leaves under water and entire leaves if grown in air, while fully aquatic, related species form divided leaves only, and other swamp species form entire leaves only (Arber, 1920; further examples see Walker, 1979). Hereditary fixation of "direct effects" was already stressed by Lamarck (1809) and Darwin (1859).…”

“…Hereditary fixation of "direct effects" was already stressed by Lamarck (1809) and Darwin (1859). As a consequence of recent results from molecular biology, speciation as result of genetic fixation of environmentally/physiologically induced phenotypes was again explicitly proposed (Walker, 1979(Walker, , 1983West-Eberhard 1989).…”

“…In other words, organisms are pre-adapted for random genetic change and if not, genetic mutations are nonviable. Indeed, as regards metabolic rate change (phase shift, Walker, 1979) it makes no difference whether a specific change is induced by the environment or by mutation, the resulting phenotype will be the same. This explains the similarity between environmentally and genetically induced phenocopies within and between species, i.e.…”