Cardiocondyla is one of the few ant genera in which winged dispersing males coexist with wingless fighter males, which predominantly mate inside their maternal nests. Male polymorphism is not genetically determined but induced by environmental conditions (e.g., a decrease in temperature). The factors leading to the production of winged males were studied in more detail by exposing colonies of C. obscurior to a specific set of rearing conditions. A "stressful" environmental condition (rearing temperature lowered on average by 5°C) experienced for at least two days, the decrease of temperature by a minimum of 3°C, and the addition of protein-rich food triggered the development of winged males. In contrast, a smaller decrease in temperature, starvation, encounters with workers from other species, and encounters with alien, conspecific winged males did not induce the production of winged males. Colonies differed strongly in their reaction to changing environmental conditions, which might indicate a difference in their threshold sensitivity. The results are discussed and compared with data from other dimorphic insect species.
The ant genus Cardiocondyla is characterized by wingless, ergatoid males, which in some species replace the typical winged male. Depending on species, ergatoid males engage in lethal fighting for access to sexual females, establish territories within their nests, or are mutually tolerant. Here we investigate, whether the morphology of ergatoid males and in particular the shape of their mandibles reflect phylogeny or male behaviour. In contrast to the worker mandible, which is relatively similar in shape in the ten species examined, mandibles of ergatoid males show a great variation in size and shape not only between the two clades of Cardiocondyla but also among species belonging to Cardiocondyla clade A. This diversity appears to reflect the diverse reproductive tactics of ergatoid males of different species, with extremely long, anteriorly oriented mandibles associated with indirect killing of adult competitors, while particularly short mandibles possibly constitute an adaptation to a tactic in which ergatoid males crush the cuticle of young rivals., Christine V. Schmidt, Jürgen Heinze., and Obsahuje bibliografii