1979] McCluskey & Soong — Rhythm Variables in Ants 99 
CANONICAL VARIABLE I 
Figure 2. The first two canonical axes, based on all 17 processed variables for 
which every one of the 25 cases (5 species X 5 replicates) was represented, and for 
which (phase variables) distribution was across few enough hours to assume linearity. 
The first axis represents the greatest possible difference between species, and the 
second, the greatest remaining difference orthogonal to the first. Output from the 
BMDP7M program, run so as to bypass the stepwise feature (as recommended by 
Pimentel and Frey, 1978). A = V. andrei; C = P. californicus; F = F. pilicornis; P = 
V. pergandei; R = P. rugosus. 
The results again suggest taxonomic differences in rhythm. The 
cosine-fitted acrophases of number out differed (P< .01) among the 
four species. 
Discussion • 
The study conditions were highly artificial—colony fragments 
(workers only, and in small number), no soil in the nest, tempera¬ 
ture high all 24 hours, etc. The fact that the rhythms were neverthe¬ 
less striking indicates that at least some of the natural field 
conditions (e.g., temperature cycle) are not necessary for such 
behavior. 
But the important thing was that the six species were now all 
under the same conditions. Evidently various species manifest dif¬ 
ferent patterns of rhythm even though in identical habitat; or to put 
it another way, it is not necessarily differences in field habitat that 
are responsible for the differences in rhythm. For a laboratory 
example of phase or pattern difference in another insect group, see 
Hardeland and Stang’s (1973) comparison of 40 species of Droso¬ 
phila. 
