Variability and differentiation of Larix cajanderi, L. dahurica and L. sibirica on shape of cone scales

Intra- and interspecific variability of three larch species of North Asia (Larix cajanderi, L. dahurica, L. sibirica) has been analyzed based on the shape of cone scales, using geometric morphometrics. L. cajanderi was represented by nine population samples of cones from three regions: Kamchatka, Yakutia, and Magadan Oblast. L. cajanderi cones were compared with L. dahurica cones from Evenkia and the Transbaikal region. Samples of L. sibirica cones were collected in three regions of South Siberia. Patterns of shape variation of cone-scales were investigated using principal component analysis (PCA) of partial warps of scales. The PCA-values (relative warps) were used as the features of shape of scales in conducting discriminant analysis. The study revealed similar main trends in variability of cone scale shapes, suggesting parallel variability of generative organs in Larix species of North Asia. The Mahalonobis (D-2) distances calculated from relative warps of scales vary from 14.7 to 25 when comparing the populations of L. sibirica and L. cajanderi. Between populations of closely related species, L. dahurica and L. cajanderi, D-2 vary from 6.4 to 15.5. Between populations of L. sibirica and L. dahurica, D-2 is 13.8-21.4 for the sample L. dahurica from Evenkia and 7.6-12.2 for the Transbaikal one. The shape of the cone scales of L. cajanderi differs from that of L. dahurica, proving that this is an independent species. The high degree of differentiation between the populations of L. cajanderi in Yakutia and Kamchatka indicates that they may belong to different geographical races.