Dear Enemy Phenomenon in the leaf-cutting ant Acromyrmex lobicornis: behavioral and genetic evidence

DIMARCO, R., A.G. FARJI-BRENNER & A.C. PREMOLI

BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY

SPRINGER

Año: 2010 vol. 21 p. 304 - 310

0340-5443

The defense of territory through aggressive behavior is well known in animals. However, some territorial animal species respond less aggressively to intrusions by their neighbors than to intrusions by nonneighbors to minimize the costs of continuous fights, a phenomenon termed the dear enemy phenomenon (DEP). Although several studies show the existence of this phenomenon, little is known about the mechanism behind it. One possible explanation is the lower degree of genetic divergence between neighbors compared with nonneighbors. We tested the DEP hypothesis and whether genetic divergence among nests might drive the DEP in the leaf-cutting ant Acromyrmex lobicornis in Patagonia, Argentina, through behavioral and genetic studies. Individuals from nearby colonies interacted less aggressively than individuals from distant colonies. However, levels of genetic divergence between focal–close and between focal–nonneighbor nests attained similar values. Our results support the dear enemy hypothesisbut suggest that the differential aggressiveness toward neighbors relative to nonneighbors is unrelated to genetic divergence among nests. Other possible causes of this behavior, such as habituation, are discussed.