Estimating range disjunction time of the Palearctic Admirals ( Limenitis L.) with COI and histone H1 genes

Three species of the genus Limenitis (Nymphalidae) ( L. camilla , L. helmanni , L. sydyi ) have split ranges in the Palearctic. Their disjunction was dated either to the Pleistocene or to the Subboreal time of the Holocene. This genus also exhibits an amphiberingean disjunction, L. populi vs four Nearctic species. To evaluate the disjunction time in Eurasia, we analysed a fragment of the mitochondrial COI gene and a major part of the histone H1 gene. The former was sequenced in 51 specimens of three species with Palearctic disjunctions. We detected a diverged nuclear copy of the COI gene in L. camilla . The histone H1 gene was sequenced in 64 specimens of 8 species . In five species, intra-species and intra-individual nucleotide substitutions and variation in the number of intra-genic repeats were observed and studied by cloning of individual gene copies, with individuals found with more than two variants. With 30–80 copies of histone H1 gene in Limenitis genomes, as estimated by real time PCR, this was interpreted as cis-heterogeneity across the histone gene cluster. No fixed differences between the western and eastern range parts were found in L. helmanni , L. camilla and L. sydyi , although in the former more alleles of both sequences were found in the eastern part. This suggests the range disjunctions to be too recent to be dated by molecular means and they may only be estimated to have taken place not more than 77–100 tya. This fits their provisional dating by Dubatolov and Kosterin (Entomologica Fennica 11(3), 141-161, 2000 ) to the Subboreal time of the Holocene.