Carbon-Nitrogen Balance and Termite Ecology
Termites, feeding on dead plant matter with a carbon to nitrogen ratio much higher than their own tissues, have to balance their C and N inputs. Two classes of C-N balancing mechanisms are possible: adding N to inputs, or selectively eliminating C. Termites achieve both of these mechanisms with the aid of microorganisms (symbionts). We first show that a termite can utilize food resources, thus attain productivity, only to the extent that the C-N balance capabilities of the termite-symbionts system allow. Two hypotheses follow: (i) `one-piece' termites (species nesting in and consuming wood) tend not to possess C-eliminating symbionts, whereas `separate' termites (species foraging outside their nests) tend to have a full range of C-N balance symbionts; this advantage for separate termites results in their observed greater productivity and colony size; and (ii) only separate termites have a sterile worker caste because their ability to utilize resources, which is conferred by their C-N balancing symbionts, makes the increase in a true (sterile) worker's contribution to the reproductives' fitness, combined with their higher nest stability, great enough to exceed the threshold for the evolution from false to true workers.
Proceedings of the Royal Society of London Series B
- Pub Date:
- September 1992