1979] 
Haskins & Haskins — Rhytidoponera metallica 
309 
#2 X #3 (Old Group II X Group I)—Violent attack (A) 
#2 X #5 (Old Group II X Ashton)—Agitation, mutual repulsion, 
no actual attack (B) 
#3 X #4 (Old Group I X Ashton)—Violent attack (A) 
#3 X #5 (Old Group I X Sutherland)—Violent attack (A) 
#4 X #5 (Ashton X Sutherland) 
Test #1—Violent attack (A) 
Test #2—Violent attack (A) 
Summary and Conclusions: 
These tests seem to point to three conclusions: 
1. The capacity to make compatibility distinctions between well- 
separated populations is highly developed in R. metallica, a nor¬ 
mally aggressive species, despite the “diffuseness” of its colonial 
structure, characterized by the physical nature of the colonies 
themselves, the circumstance that communities consist only of 
monomorphic workers showing a minimum of morphological or 
habitus differentiation inter se even between ordinary and fertile 
laying workers, rather numerous in populous colonies. 
However, consistent with this “looseness” of colony structure, 
groups of workers taken from the same general area but at dis¬ 
tances clearly too great to permit continual communal contact 
under natural conditions retain some compatibility, the tolerance 
seeming to decrease with distance. Thus a picture of a rather 
“viscous” population seems more applicable in this context than 
that of well-defined colonial entities. 
2. Compatibility distinctions were found to be consistently retained 
between groups originally drawn from the same natural popula¬ 
tions but then isolated under identical laboratory conditions for 
up to more than thirteen years. Similar compatibility was exhib¬ 
ited between a group collected from a specific field location when 
tested shortly after capture against other groups collected at the 
same locality more than four years earlier and maintained in the 
laboratory over the interval under environmental conditions 
obviously very different. Thus differing environmental and nutri¬ 
tional histories do not seem to influence compatibility reactions 
in any observable way. 
