Mating frequency of Leptothorax nylanderi ant queens determined by microsatellite analysis S. Foitzik 1, 2 , M. Haberl 3 , J. Gadau 1 and J. Heinze 1, 2 1 LS Verhaltensphysiologie und Soziobiologie, Theodor-Boveri-Institut (Biozentrum der Universität), Am Hubland, D-97074 Würzburg, Germany 2 Present address: Zoologisches Institut I, Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, e-mail: sfoitzik@biologie.uni-erlangen.de 3 Zoologisches Institut, Universität München, Luisenstrasse 14, D-80333 München, Germany, e-mail: haberl@zi.biologie.uni-muenchen.de Key words: Multiple mating, relatedness, Leptothorax, microsatellites. Summary The queen mating frequency of the ant Leptothorax nylanderi was investigated by analyzing three (GA) n repeat microsatellite loci in queens and workers in 12 colonies from a single German popu- lation. Microsatellite genotypes indicate that all queens were inseminated by a single male. The genotypes of the males produced in queenright colonies suggest that they were offspring of the queen. Introduction The question why females mate with several males (polyandry) has become a cen- tral issue in evolutionary biology (Keller and Reeve, 1995). Though one might perhaps expect that in social insects queens should prefer to mate with a single male because multiple insemination lowers the relatedness among her offspring, poly- andry appears to be the rule in honey bees (e.g., Adams et al., 1977; Haberl and Moritz, 1994; Estoup et al., 1994) and has also been documented in numerous spe- cies of ants (e.g., Cole, 1983). It has been suggested that queens mate multiply a) to increase the genetic variability of their offspring, b) to manipulate the workers’ interests concerning sex allocation and the origin of males, c) decrease the risk of producing a large number of diploid males, or d) because of single males trans- mitting insufficient sperm (for reviews see Keller and Reeve, 1994; Bourke and Franks, 1995; Boomsma and Ratnieks, 1996). In two recent reviews, studies according to which Leptothorax nylanderi queens mate multiply (Plateaux, 1970, 1978, 1981) have been cited in respect with genetic variability hypothesis (Keller and Reeve, 1994) and worker reproduction (Bourke and Franks, 1995), respectively. Using allozyme markers it has since been shown Insectes soc. 44 (1997) 219 – 227 0020-1812/97/030219-09 $ 1.50+0.20/0 © Birkhäuser Verlag, Basel, 1997 Insectes Sociaux Research article