Evidence for contrasting size-frequency distributions of workers patrolling vegetation vs. the ground in the polymorphic African ant Anoplolepis custodiens
It is often hypothesized that ant species with substantial variation in worker body size should have schemes for allocating workers to different foraging tasks based on size. Here, we document in Anoplolepis custodiens ants preliminary evidence for a relationship between worker body size and the foraging surfaces on which workers walk. Workers of A. custodiens were collected in pitfall traps near their nest entrances and compared in size to workers exploring the branches of associated shrubs (Salsola sp.). Although ants of all sizes moved freely on the ground, the bushes were almost entirely populated by the smallest workers. These results suggest an effect of substrate on the foraging behavior of an understudied species and suggest that A. custodiens might be a good model to explore size-based behavioral differences in polymorphic ants.
KeywordsPolymorphism Division of labor Foraging Alloethism Size-matching Anoplolepis Polyethism
This work was financially supported by NSF IOS Grant 1455895 to JNP. We thank Charles Haddad at the University of the Free State in Bloemfontein, South Africa, for kindly confirming the species identification of Anoplolepis custodiens and Samantha Venter and Peter Carrick for help with identifying Salsola sp. We also thank Corrie Moreau and Shauna Price at the Field Museum of Natural History in Chicago, Illinois and Andrew Suarez at the University of Illinois Urbana-Champaign for their helpful comments on the experiment. All works were carried out in accordance with the applicable local provincial, federal South African, and international regulations.
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