Apoptotic wing degeneration and formation of an altruism-regulating glandular appendage (gemma) in the ponerine ant Diacamma sp. from Japan (Hymenoptera, Formicidae, Ponerinae)

Abstract

We here show an example of morphological novelties, which have evolved from insect wings into the specific structures controlling social behaviour in an ant species. Most ant colonies consist of winged queen(s) and wingless workers. In the queenless ponerine ant Diacamma sp. from Japan, however, all female workers have a pair of small thoracic appendages, called "gemmae", which are homologous to the forewings and acts as an organ regulating altruism expression. Most workers, whose gemmae are clipped off by other colony members, become nonreproductive helpers, while only a single individual with complete gemmae becomes functionally reproductive. We examined histologically the development of gemmae, and compared it with that of functional wings in males. Female larvae had well-developed wing discs for both fore- and hindwings. At pupation, however, the wing discs started to evaginate and later degenerate. The hindwing discs completely degenerated, while the degeneration of forewing discs was incomplete, leading to the formation of gemmae. The degeneration process involved apoptotic cell death as confirmed by TUNEL assay. In addition, glandular cells differentiated from the epithelial cells of the forewing buds after completion of pupation. The mechanism of developmental transition from wing to gemma can be regarded as an evolutionary gain of new function, which can be seen in insect appendages and vertebrate limbs.

Social dominance modifies behavioral rhythm in a queenless ant

“…All eclosed females have thoracic appendages called "gemmae" and they have reproductive potential at eclosion. Gemma is considered to be a vestigial wing (Gotoh et al 2005; but see Baratte et al 2006a, b). In each colony, the only female that retains her gemmae mates and reproduces as the functional queen (i.e.…”

Ovarian development and insulin-signaling pathways during reproductive differentiation in the queenless ponerine ant Diacamma sp.

“…In the queenless ponerine ant genus Diacamma, prospective egg layers can be detected, because reproductive differentiation is triggered by highly ritualized dominance behavior that is easily inducible in the laboratory. In this genus, all eclosed females have the potential to become reproductives, but only a single female possessing "gemmae," i.e., vestigial wings whose presence determines reproductives (Fukumoto et al, 1989;Peeters and Higashi, 1989;Gotoh et. al., 2005), becomes a dominant egg layer called a "gamergate" (functional queen in queenless ants; Peeters and Crewe, 1985;Peeters, 1991).…”

Ergatoid queen development in the ant Myrmecina nipponica : modular and heterochronic regulation of caste differentiation

“…In conclusion, wing development in ergatoids may be regulated in a worker-like and ergatoid-specific manner depending on the forewing/ hindwing development and the developmental stages. As in other ant species (Sameshima et al 2004;Gotoh et al 2005), this degenerating process would be mediated by apoptosis.…”