Virus are selected from a sub-linear dependence of mass specific metabolism on mass
This dependence [ β ∝ wβββ• ] of mass specific metabolism on mass is the likely cause for the evolution of a cell. Although extremely low levels of metabolism are not dependent on a compartment like a cell, the evolution of an advanced intrinsic metabolism is dependent on the development of a cell where the molecules of the metabolic pathways can concentrate (e.g., Oparin, 1957; Miller and Orgel, 1974; Maynard:Smith and Szathmary, 1995; Michod, 1999; Wachtershauser, 2000; Koch and Silver, 2005). The increase in net energy for self-replication with increased metabolism may then be the primary selection that drives the evolution of a cell and all its associated mass; let it be the mass of the metabolic molecules, the mass of the cell membrane, and the mass of the underlying heritable code.
For the self-replication rate to increase with mass, the net energy that is generated from an increase in mass specific metabolism with mass will have to outbalance the quality-quantity trade-off, that generates a proportional decline in replication with mass. A self-replicating cell with heredity and an internal metabolism can then be selected only from the sub-sets of the potential biochemistry that have an initial pre-mass exponent for the dependence of mass specific metabolism on mass that is larger than unity [ ββ,0• = max(ββ•) > 1; Witting, 2016b].
A biochemical replicator with a ββ,0• exponent below unity is thus unable to evolve an intrinsic metabolism by natural selection. Unlike selected self-replicators, these replicators cannot increase replication by an increase in mass specific metabolism. This is because the energetic demands of the offspring mass is increasing stronger than the increase in net energy that is generated by the increase in mass. The replicators may instead increase their rate of replication by a mass that evolves towards zero, with the side effect that they are shutting down their metabolic processes.
- Koch, A.L., and S.Silver 2005. The first cell. Advances in Microbial Physiology 50:227--259.
- MaynardSmith, J., and E.Szathmary 1995. The major transitions in evolution. W.H. Freeman Spektrum, Oxford.
- Michod, R.E. 1999. Darwinian dynamics. Evolutionary transitions in fitness and individuality. Princeton University Press, Princeton.
- Miller, S.L., and L.E. Orgel 1974. The origins of life on the Earth. Prentice-Hall, Englewood Cliffs, NJ.
- Oparin, A.I. 1957. The origin of life on Earth. Academic Press, New York.
- chtershauser, 2000Wachtershauser:2000Wachtershauser, G. 2000. Origin of life: life as we don't know it. Science 289:1307--1308.
- Witting, L. 2016a. The natural selection of metabolism and mass selects allometric transitions from prokaryotes to mammals. Preprint at bioRxiv http://dx.doi.org/10.1101/084624.
- Witting, L. 2016b. The natural selection of metabolism and mass selects lifeforms from viruses to multicellular animals. Preprint at bioRxiv http://dx.doi.org/10.1101/087650.