Norway maple (Acer platanoides) and pedunculate oak (Quercus robur) demonstrate different patterns of genetic variation within and among populations on the eastern border of distribution ranges

Abstract

Norway maple (Acer platanoides L.) is a key species of broadleaved forests whose population genetics is poorly studied using modern genetic tools. We used ISSR analysis to explore genetic diversity and differentiation among 10 Russian populations on the eastern margin of the species range of distribution, and to compare the revealed patterns with the results of our population genetic studies of pedunculate oak (Quercus robur L.). In the first set comparatively high heterozygosity and allelic diversity were found (expected heterozygosity H<sub>E</sub> = 0.160 ± 0.033, number of alleles n<sub>a</sub> = 1.440 ± 0.080, effective number of alleles n<sub>e</sub> = 1.271 ± 0.062) in comparison with strongly fragmented and geographically isolated small maple stands of the second set (H<sub>E</sub> = 0.083 ± 0.011, n<sub>a</sub> = 1.281 ± 0.031, n<sub>e</sub> = 1.136 ± 0.019). A relatively high genetic differentiation among populations was detected (the proportion of the inter-population component of total genetic variation, G<sub>ST</sub> = 0.558 ± 0.038). In the Cis-Urals, local groups of populations that are confined to the northern, middle and southern parts of the Urals were identified. On the contrary, the current significant fragmentation of the pedunculate oak distribution area in the same study area did not lead to any noticeable genetic differentiation among the majority of populations, the values of the population genetic diversity were very similar in different parts of the Southern Urals.