The mass-rescaling selection of body mass allometries
A large amount of the phenotypic variation across natural species is explained by body mass allometries (Kleiber, 1932; Peters, 1983; Calder, 1984), where traits like mass specific metabolism (β) are given as power functions of mass
β ∝ wb
with the exponent (b) being the slope on double logarithmic scale; ln(β) ∝ b ln(w).
The allometric exponents that describe the mass-rescaling response of the life history to the evolutionary changes in mass are given primarily by the invariant density regulation
fe[εN] ∝ fι[VNH(d-1)/d/fe] ∝ fs[βH1/d/V] ∝ w0
that evolves from the population dynamic feed-back selection on mass.
With foraging speed (V) being proportional with biotic time (T) on the body mass axis (Garland, 1983; Calder, 1984), we may exchange V with T in these functions, and insert power relations wx for the relevant traits in the invariant regulation. Combined with i) the ε=αβ relation between net energy, resource handling and pace, ii) the λ = 1 condition of the population dynamic equilibrium, and iii) the T ∝ 1/β scaling from metabolic trade-off selection, we obtain the following equations for the allometric exponents (see Witting, 1995, 2016 for details):
t + n + (d-1)h/d = 0,
b – t + h/d = 0,
n + e = 0,
t = - b,
e = 1 + b,
a = 1,
p + t + e = 1,
[time periods: T∝wt; abundance: N∝wn; home range: H∝wh; pace and mass specific metabolism: β∝wb; energetic state: ε∝we; resource handling: α∝wa; survival: P∝wp].
When these equations are solved we obtain the results in Table 1. 1/4 and 3/4 exponents follow from two dimensional interactions (2D; d=2), and the corresponding exponents for three dimensional interactions are 1/6 and 5/6, and 1/2 for one dimensional interactions.
- Calder, W. A.I. 1984. Size, function, and life history. Harvard University Press, Cambridge.
- Garland, T. 1983. Scaling the ecological cost of transport to body mass in terrestrial mammals. The American Naturalist 121:571--587.
- Kleiber, M. 1932. Body and size and metabolism. Hilgardia 6:315--353.
- Peters, R.H. 1983. The ecological implication of body size. Cambridge University Press, Cambridge.
- Witting, L. 1995. The body mass allometries as evolutionarily determined by the foraging of mobile organisms. Journal of Theoretical Biology 177:129--137.
- Witting, L. 1997. A general theory of evolution. By means of selection by density dependent competitive interactions. Peregrine Publisher, Århus, 330 pp, URL http://mrLife.org.
- Witting, L. 2016. The natural selection of metabolism and mass selects allometric transitions from prokaryotes to mammals. Preprint at bioRxiv http://dx.doi.org/10.1101/084624.