The natural selection of metabolism and mass selects allometric transitions from prokaryotes to mammals

Abstract

Inter-specific body mass allometries can evolve from the natural selection of mass, with ±1/4 and ±3/4 exponents following from the geometry of intra-specific interactions when density dependent foraging occurs in two spatial dimensions (2D, Witting 1995). The corresponding values for three dimensional interactions (3D) are ±1/6 and ±5/6.But the allometric exponents in mobile organisms are more diverse than the prediction. The exponent for mass specific metabolism tends to cluster around -1/4 and -1/6 in terrestrial and pelagic vertebrates, but it is strongly positive in prokaryotes with an apparent value around 5/6 ( De-Long et al. 2010). And a value around zero has been reported in protozoa, and on the macro evolutionary scale from prokaryotes over larger unicells to multicellular vertebrates (Makarieva et al. 2005(Makarieva et al. , 2008.I show that mass specific metabolism can be selected as the pace of the resource handling that generates net energy for self-replication and the selection of mass, and that this selection of metabolism and mass is sufficient to explain metabolic exponents that decline from 5/6 over zero to -1/6 in 3D, and from 3/4 over zero to -1/4 in 2D. The decline follows from a decline in the importance of mass specific metabolism for the selection of mass, and it suggests i) that the body mass variation in prokaryotes is selected from primary variation in mass specific metabolism, ii) that the variation in multicellular animals are selected from primary variation in the handling and/or densities of the underlying resources, iii) that protozoa are selected as an intermediate lifeform between prokaryotes and multicellular animals, and iv) that macro evolution proceeds along an upper bound on mass specific metabolism.

The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals

“…The development of such a theory is the aim of this article. To approach the goal, I use the framework of Malthusian relativity (MR, see Witting, 1997Witting, , 2008Witting, , 2017 to deduce a natural selection that is sufficient to explain the metabolism, body masses, major life-history transitions, and interspecific allometries that are observed within and across lifeforms from viruses over prokaryotes and larger unicells to multicellular animals. The proposed selection describes how mobile lifeforms with elevated metabolic rates, large body masses, and reduced sexual reproduction are selected as a deterministic consequence of the origin of replicating molecules.…”

“…The primary selection of metabolism was recently incorporated into the feed-back selection of MR in relation to the evolution of interspecific allometries (Witting, 2017). This showed that massspecific metabolism can be selected as a proxy for the pace of the resource handling that generates net energy for self-replication.…”

“…By describing the physiological and ecological constraints on the selection of metabolism and mass, Witting (2017) was able to solve the resulting equations and predict the range of allometric exponents from first principles of self-replication. This showed how the optimal density regulation and physiological trade-offs link selection on the home range and population density to selection on metabolism, life periods, net energy, and mass.…”

“…The majority of MR is developed in earlier work (Witting, 1995(Witting, , 1997(Witting, , 2007(Witting, , 2008, with the this article being an extension of Witting (2002aWitting ( , 2017. A complete understanding of the proposed selection requires familiarity with the latter two papers that deal with the natural selection of major life-history (Witting, 2002a) and allometric (Witting, 2017) transitions.…”

“…I will use the same life-history model to cover the entire span of organisms. It is based on a formulation of the per-generation replication (λ) of an average variant in an age-structured population at the population-dynamic equilibrium (denoted by superscript *), where p is the probability to survive to reproduce, R = t r ϵ∕βw is lifetime reproduction (unitless number), t r the reproductive period in physical time (SI unit s), ε the densitydependent net energy that is available for self-replication per unit physical time (SI unit J/s), w the body mass as measured by biotic (combustion) energy (SI unit J), and β a unitless scaling parameter that accounts for energy that is metabolized by the offspring (see Witting, 2017 for details).…”