ena-STUDY-Institute of Cytology & Genetics of SB RAS-02-06-2021-06:35:55:297-599
Estimating of range disjunction time of the Palearctic Admirals (Limenitis L.) with COI and histone H1 genes
Three species of the genus Limenitis (Nymphalidae: Limenitidinae) have split ranges (L. camilla, L.helmanni, L. sydyi) in the Palearctic. Their disjunction was earlier dated either to the Pleistocene but recently to the Boreal time of the Holocene. This genus also provides a case of an amphiberingean disjunction of the Palearctic L. populi vs four Nearctic species, which is helpful for relative dating. To evaluate the Eurasian disjunction time, we analysed the mitochondrial DNA fragment COI-Leu tRNA and part of the histone H1 gene. The former was sequenced in total in 50 specimens of the three species with Palearctic disjunct ranges. We detected a diverged nuclear copy (NUMT) of the COI gene in L. camilla, while the mitochondrial gene was shown to be identical in all specimens studied. The histone H1 gene was partially sequenced in 64 specimens of 8 species. In five species represented by a number of specimens, intra-species and intra-individual nucleotide substitutions and variation, due to the number of intra-genic repeats, for the region coding for the C-terminal domain of histone H1 was observed, with individuals found to possess more than two variants altogether, that was proved by cloning. Since the number of copies of histone H1 gene was estimated to vary in Limenitis as 30-80, this was interpreted as cis-heterogeneity across the histone gene cluster, which complicated data analysis. Although both sequences studied were variable, we revealed no fixed differences between the western and eastern range parts of all three species with Palaearctic disjunctions, 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 positively dated by molecular means, which, based on the existing estimations of the substitution rate in the COI region in arthropods, only imply they took place not less than 77-100 tya. This in line with their provisional dating by Dubatolov and Kosterin (2000) to the Subboreal time of the Holocele ca 2.5-5 tya.
Three species of the genus Limenitis (Nymphalidae: Limenitidinae) have split ranges (L. camilla, L.helmanni, L. sydyi) in the Palearctic. Their disjunction was earlier dated either to the Pleistocene but recently to the Boreal time of the Holocene. This genus also provides a case of an amphiberingean disjunction of the Palearctic L. populi vs four Nearctic species, which is helpful for relative dating. To evaluate the Eurasian disjunction time, we analysed the mitochondrial DNA fragment COI-Leu tRNA and part of the histone H1 gene. The former was sequenced in total in 50 specimens of the three species with Palearctic disjunct ranges. We detected a diverged nuclear copy (NUMT) of the COI gene in L. camilla, while the mitochondrial gene was shown to be identical in all specimens studied. The histone H1 gene was partially sequenced in 64 specimens of 8 species. In five species represented by a number of specimens, intra-species and intra-individual nucleotide substitutions and variation, due to the number of intra-genic repeats, for the region coding for the C-terminal domain of histone H1 was observed, with individuals found to possess more than two variants altogether, that was proved by cloning. Since the number of copies of histone H1 gene was estimated to vary in Limenitis as 30-80, this was interpreted as cis-heterogeneity across the histone gene cluster, which complicated data analysis. Although both sequences studied were variable, we revealed no fixed differences between the western and eastern range parts of all three species with Palaearctic disjunctions, 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 positively dated by molecular means, which, based on the existing estimations of the substitution rate in the COI region in arthropods, only imply they took place not less than 77-100 tya. This in line with their provisional dating by Dubatolov and Kosterin (2000) to the Subboreal time of the Holocele ca 2.5-5 tya.