Adventures Among Ants - Mark W. Moffett [161]
33. The slow growth of army ant colonies, for example, may reflect their high worker death rate; see S Powell 2004, Polymorphism and ecology in the New World army ant genus Eciton, Ph.D. thesis, University of Bristol, England, 2004.
34. M Hammond 1980, A famous “exemplum” of Spartan toughness, Classical J. 75: 97–109.
3. Division of Labor
1. MW Moffett 1986, Marauders of the jungle floor, National Geographic 170: 272–286.
2. Formally, only the minor workers, being a discrete size group, should be called a “caste” in this species; the medias, the majors, and possibly the giants, being distinguished only by their relative frequency in a size continuum, are “subcastes.” Marauder ant division of labor is described in MW Moffett 1987, Division of labor and diet in the extremely polymorphic ant Pheidologeton diversus, Natl. Geogr. Res. 3: 282–304.
3. AL Mertl, JFA Traniello 2009, Behavioral evolution in the major worker subcaste of twig-nesting Pheidole: Does morphological specialization influence task plasticity? Behav. Ecol. Sociobiol. 63: 1411–1426; and EO Wilson 1984, The relation between caste ratios and division of labor in the ant genus Pheidole. Behav. Ecol. Sociobiol. 16: 89–98.
4. See, e.g., DE Wheeler, HP Nijhout 1984, Soldier determination in Pheidole bicarinata: Inhibition by adult soldiers, J. Insect Physiol. 30: 127–135. Caste sizes and frequencies can vary with locality, suggesting evolution to suit local needs: L Passera, E Roncin, B Kaufmann, L Keller 1996, Increased soldier production in ant colonies exposed to intraspecific competition, Nature 379: 630–631.
5. The individuals of a size that is scarce, such as those falling at the midpoint between the peak sizes for media and major workers of Pheidologeton diversus, might carry out the same tasks as workers of the more common sizes but accomplish those tasks relatively poorly, or they may be of a size relatively less often needed. Alternatively, they could execute different tasks than other workers—tasks that happen to require relatively few individuals.
6. Quoted in Drew G. Faust, This Republic of Suffering (New York: Alfred Knopf, 2008), p. 59.
7. Nathan Rosenstein, personal communication. For more examples relating to humans, see Robert L. O’Connell, Ride of the Second Horseman: The Birth and Death of War (New York: Oxford University Press, 1997).
8. U Maschwitz, M Hahn, P Schönegge 1979, Paralysis of prey in ponerine ants, Naturwissenschaften 66: 213–214.
9. MW Moffett 1989, Trap-jaw ants, National Geographic 175: 394–400. Related species have a broader diet; see W Gronenberg, CRF Brandao, BH Dietz, S Just 1998, Trap-jaws revisited: The mandible mechanism of the ant Acanthognathus, Physiol. Entomol. 23: 227–240.
10. SN Patek, JE Baio, BL Fisher, AV Suarez 2006, Multifunctionality and mechanical origins: Ballistic jaw propulsion in trap-jaw ants, Proc. Natl. Acad. Sci. 103: 12787–12792.
11. MW Moffett 1986, Trap-jaw predation and other observations on two species of Myrmoteras, Insectes Soc. 33: 85–99.
12. George F. Oster and Edward O. Wilson, Caste and Ecology in the Social Insects (Princeton: Princeton University Press, 1978), pp. 281–286.
13. This is true for both cold-and warm-blooded animals; see, e.g., AA Heusner 1985, Body size and energy metabolism, Annu. Rev. Nutr. 5: 267–293. James Waters (pers. comm.) found a similar decrease in metabolic rate with colony size in Pogonomyrmex californicus (expressed per capita). My “energy to spare” hypothesis is supported, for example, by the greater