Ant colony size and the scaling of reproductive effort

Abstract

1 Reproductive effort typically scales as mass0·75 in unitary organisms, but less is known about such scaling in colonial organisms. 2 I compiled data on worker and reproductive number at maturity for 65 ant species and found an interspecific allometry (alate number = worker number0·73) whose exponent was significantly < 1, even after a phylogenetic correction. 3 When I analyzed 15 species for which biomass data were available, I found an interspecific isometry (alate biomass = worker biomass0·89) whose exponent was not significantly different from 1. Analysis of maximum species biomass values, rather than averages, strengthened this isometry, yielding a slope b = 1·01 that was also not distinguishable from 1. 4 Species with larger colony size at reproduction tended to couple investment in proportionately fewer alates with investment in larger male and female alates. 5 This comparative analysis suggests a trade-off between alate size and number, and provides a framework for studying the diversity of colony life histories and the mechanisms generating allometries.