Eusocial reproduction - the mass constrained colony
Eusocial colonies evolve as interacting units when interference competition is extreme
Constrained mass with eusocial colony: The cooperating family can evolve into an eusocial colony with thousands of offspring workers if the body mass is upward constrained for some reason. The increase in net energy is then selected into an increased reproduction, population density and interference competition; and this is selecting for a reproducing unit where thousands of sexually produced offspring workers are selected as interactors that defend the resource of the colony (Fig 1, right; Witting, 1997, 2002).
Fig. 1 Left: Projections for the evolution of female workers and a male-haploid female-diploid genome (HD) as selected by the two-fold cost of the male in eusocial hymenoptera like ant and bees. From Witting (1997). Right: An illustration of a feed-back selection that is blocked by an upward constrained body mass. Net energy is then selected into increased abundance and interference instead of mass, and this is causing the interacting unit to evolve into an eusocial colony (Witting, 1997, 2002); with the multitude of dots on each circle representing the worker caste of the colony
Life history: With a whole caste of offspring workers acting as the interactor of the eusocial colony, the sexual male is losing his original role as the main interactor of the reproducing unit. If the interacting role of the male is reduced to the transfer of his genome to the offspring, it follows that his two-fold cost is selecting for a male-haploid female-diploid genome and a worker caste of pure females; as seen in eusocial hymenoptera like ant and bees (Fig. 1, left; Witting, 1997, 2007). If instead the male is able to maintain some kind of ecological role and form a permanent pair with the sexual female, it follows that his energetic fitness component is selection for a diploid genome, and female and male workers; as seen in eusocial termites.
- 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. 2002. From asexual to eusocial reproduction by multilevel selection by density dependent competitive interactions. Theoretical Population Biology 61:171--195.
- Witting, L. 2007. Behavioural interactions selecting for symmetry and asymmetry in sexual reproductive systems of eusocial species. Bulletin of Mathematical Biology 69:1167--1198.