Natural history and reproductive strategy of Crematogaster smithi.
This species is native to the mountain ranges of the southwestern United States. In addition to queens and workers, C. smithi has a third female caste that is specialized to produce unfertilized eggs and which seems to be correlated with a sex-ratio bias. To understand this polyphenism we focus on cuticular chemistry, population genetics and natural history.
|The evolution of male traits in ants of the genus Cardiocondyla
Ants of the genus Cardiocondyla are minute, colonies are easy to keep in the lab and they have been proven to be a great model organism. Crucial for comparative studies of the peculiar male polyphenism is a correct knowledge of the relationships among Cardiocondyla. This part of my work aims to keep the phylogeny updated. Together with M. Suefuji and A. Trindl we incorporate new specimen collected world-wide by sequencing both mtDNA and nDNA fragments.
|Genomic response to sex in Cardiocondyla obscurior,
In collaboration with John Wang (http://www.unil.ch/dee/page7725.html ) we aim to understand the genomics of sex. It has been shown that mated queens live longer than virgin queens. This is contrary to strategies described for some solitary insects where males may push short-term increase in fecundity of females accepting high costs and reduced longevity of the female. In contrast to solitary insects an ant queen has to rear workers prior to producing a next generation of sexual offspring. Hence an increase in longevity is of advantage for both mating partners as reproductive output increases. The process of egg production and associated substances such as vitellogenine has been suggested to reduce oxidative stress elements that are considered to impact longevity. Well, in C. obscurior it is not the production of fertilized eggs per se that increases life expectancy, as queens that were mated with sterilized males live just as long as regular mated queens. We aim to address some candidate genes underlying the different rates of aging. Using DNA microarrays developed for the closely related Solenopsis invicta we aim to find candidate genes associated with sex and aging.
|Chemical mimicry in Cardiocondyla
The male polyphenism in C. obscurior is accompanied by a chemical mimicry of young winged males, having similar profiles to those of young virgin queens (Cremer et al 2002, Nature 419: 897). This mimicry apparently protects winged males from being attacked by wingless males. The DFG-Project “Deception and chemical warfare in Cardiocondyla ant males” aims to clarify the basis of chemical female mimicry, in particular the nature, dynamics and stability of the pattern of cuticular hydrocarbons, the potential costs of mimicry for female-mimics and the fooled wingless males, and the evolutionary maintenance of this particular case of cheating. Our study combines gas chromatography, mass spectrometry, genetic analyses and behavioural observations and shall help to better understand the evolution of male fighting in Cardiocondyla and, more general, ofdishonest chemical communication in animals.
Cardiocondyla antmen are superheroes
Oettler J, Heinze J (2009). Polymorphism of female reproductives in the tramp ant Technomyrmex vitiensis (Hymenoptera: Formicidae: Dolchoderinae). Myrmecological news 12: 133-137
Gadau J, Strehl CP, Oettler J, Hölldobler B (2003) Determinants of intracolonial relatedness in Pogonomyrmex rugosus (Hymenoptera, Formicidae) - mating frequency and brood rates. Molecular Ecology 12, 1931-1938
Smith C, Oettler J, Kay A, Deans C(2006) First recorded mating flight of the hypogeic ant, Acropyga epedana, with its obligate mutualist mealybug Rhizoecus colombiensis. Journal Insect Science 7:11
Oettler J, Schmitt T, Herzner G, Heinze J (2008) Chemical profiles of mated and virgin queens, egg-laying intermorphs and workers of the ant Crematogaster smithi. Journal of Insect Physiology 54: 672-679
Suefuji M, Cremer S, Oettler J, Heinze J (2008). Queen number influences the timing of the sexual production in colonies of Cardiocondyla ants. Biol.Lett. doi:10.1098/rsbl.2008.0355
Oettler J, Johnson RA (2008). The old ladies of the seed harvester ant Pogonomyrmex rugosus: Foraging performed by two groups of workers. Journal of Insect Behaviour DOI 10.1007/s10905-008-9167-7