Life-history evolution in ants: the case of Cardiocondyla

Abstract

Ants are important components of most terrestrial habitats, and a better knowledge of the diversity of their life histories is essential to understand many aspects of ecosystem functioning. The myrmicine genus Cardiocondyla shows a wide range of colony structures, reproductive behaviours, queen and male lifespans, and habitat use. Reconstructing the evolutionary pathways of individual and social phenotypic traits suggests that the ancestral life history of Cardiocondyla was characterized by the presence of multiple, short-lived queens in small-sized colonies and a male polyphenism with winged dispersers and wingless fighters, which engage in lethal combat over female sexuals within their natal nests. Single queening, queen polyphenism, the loss of winged males and tolerance among wingless males appear to be derived traits that evolved with changes in nesting habits, colony size and the spread from tropical to seasonal environments. The aim of this review is to bring together the information on life-history evolution in Cardiocondyla and to highlight the suitability of this genus for functional genomic studies of adaptation, phenotypic plasticity, senescence, invasiveness and other key life-history traits of ants.

Keywords: Formicidae; alternative reproductive tactics; inbreeding; lethal fighting; male polyphenism; queen number.

Figure 1.

(a) Heads of wingless males of four species of the ant genus Cardiocondyla with different reproductive strategies (from top to bottom: C. obscurior – males kill freshly eclosed rivals and besmear other adult males with hindgut secretions; C. ‘latifrons’, males kill freshly eclosed rivals; C. minutior, males kill freshly eclosed rivals; C. batesii, males mutually tolerant; photos by S. Frohschammer). (b) Queens, workers and brood in a laboratory colony of C. mauritanica.