I'm doing a biology project about evolution and I was wondering if ants, specifically the common carpenter or fire ant, has any vestigial features, and what may have been their function.
This sounds like a very interesting biology project! Vestigial traits are reduced or incompletely developed structures. These features are non-adaptive and have no function, but are clearly similar to functioning organs or structures in closely related species. Vestigial traits are homologous among related species and are evidence for common descent and a shared evolutionary history. In ants, vestigial traits have not been extensively studied and there are just a few examples. Remains of wings in the worker cast, called "gemma" have been described in some ant species: in pupae of the ponerine Diacamma ceylonenese (Baratte et al. 2005), in larvae of the red imported fire ant Solenopsis invicta (Bowsher et al. 2007), and in Pheidole morrisi (Sheibat et al. 2010). Vestigial spermatheca are present in some basal ant lineages (Gobin et al. 2008). These vestigial traits are particularly interesting as the queen caste still possesses functional wings and functional spermatheca, but the workers do not. Workers cannot fly and mate. Some ant lineages are sting-less, but possess vestigial traits of the sting apparatus, for example the entire Formicinae subfamily. This subfamily includes the genus Camponotus (carpenter ants). Other vestigial traits are the absence of functional eyes in army ant species (see photo of Eciton burchellii below). These ants are blind, but show remains of the eyes.
Soldier of the army ant Eciton burchellii with vestigial eye structures. Photo by Alex Wild (www.alexanderwild.com).
Here are the relevant citations:
Baratte S, Cobb M, Deutsch J and Peeters C. 2005. Morphological variations in the pre-imaginal development of the ponerine ant Diacamma ceylonense. Acta Zoologica 86: 25-31.
Bowsher JH, Wray GA, Abouheif E. 2007. Growth and patterning are evolutionarily dissociated in the vestigial wing discs of workers of the red imported fire ant, Solenopsis invicta. Journal of Experimental Zoology (Mol. Dev. Evol.) 308B:769-776.
Gobin B, Fuminori I, Billen J, Peeters C. 2008. Degeneration of sperm reservoir and the loss of mating ability in worker ants. Naturwissenschaften 95:1041-1048.
Shbailat S J, Khila A, and Abouheif E. 2010. Correlations between spatiotemporal changes in gene expression and apoptosis underlie wing polyphenism in the ant Pheidole morrisi. Evolution and Development 12: 580-591.
I hope this helps!
Steffi Kautz & the AntAsk Team