Eur. J. Entomol. 106: 457–469, 2009 http://www.eje.cz/scripts/viewabstract.php?abstract=1476 ISSN 1210-5759 (print), 1802-8829 (online) Contrasting levels of polymorphism in cross-amplified microsatellites in two endangered xerothermophilous, obligatorily myrmecophilous, butterflies of the genus Phengaris (Maculinea) (Lepidoptera: Lycaenidae) ROBERT RUTKOWSKI 1, MARCIN SIELEZNIEW2 and AGNIESZKA SZOSTAK3 1Department of Molecular and Biometrical Techniques, Museum and Institute of Zoology, Polish Academy of Sciences, Wilcza 64, PL-00-679 Warszawa, Poland; e-mail:
[email protected] 2Department of Invertebrate Zoology, Institute of Biology, University of Bialystok, ĝwierkowa 20B, PL-15-950 Biaáystok, Poland; e-mail:
[email protected] 3Ks. St. Konarskiego 15, PL-08-400 Garwolin, Poland Key words. Lycaenidae, Phengaris arion, P. rebeli, genetic polymorphism, cross-amplification, Poland Abstract. We analysed the polymorphism of cross-amplified microsatellite loci in two endangered butterflies of the genus Phengaris, which inhabit warm grasslands. Specimens of P. arion and P. ‘rebeli’ collected in Poland showed contrasting levels of variability in the investigated loci. All six tested microsatellites were highly variable in P. arion, whereas in P. ‘rebeli’ one locus was monomorphic and the other four loci showed a rather low level of polymorphism. Genetic differentiation was small or moderate among P. arion populations and high among P. ‘rebeli’ populations. We hypothesise that these differences reflect: (1) the relatively high genetic variability of P. arion compared with other members of the genus, indicated by previous studies on allozymes; (2) the small, in the majority of cases, genetic differentiation among populations of P. arion, which suggests recent gene flow; (3) a decrease in the genetic variability and increased isolation of peripheral populations of P.