Molecular variability of Field Maple populations (Acer campestre L.) in Bosnia and Herzegovina

Measures to preserve forest trees should focus on the preservation of intra-species genetic variability, which reflects a species' adaptive evolutionary potential enabling it to survive unfavourable conditions. Altogether 25 populations of Field Maple from Bosnia and Herzegovina were studied at ten nuclear microsatellite loci. A high level of genetic variability was identified as a result of the eco-geographical pattern, while ecological distance is a better predictor of genetic variability in the populations than geographical distance. The average genetic differentiation of the populations is low with the exception of sub-Mediterranean populations, above all the most southerly population (Trebinje). This indicates the fragmented distribution of the sub-Mediterranean populations, resulting in spatial isolation and the resultant increase in genetic divergence of these populations. Since the Trebinje population alone has not experienced a genetic bottleneck in the recent past (in one mutation model), the assumption is that this is a refugial population displaying a specific genetic structure. Three typical sub-Mediterranean populations (Trebinje, Ljubuški and Mostar) derive from a single source gene pool, suggesting a potential gene flow between populations over time. The results of the study may prove useful for the preservation of the species and its genetic diversity, particularly by means of in situ and ex situ conservation of the southernmost (peripheral) populations. The results obtained may also serve as a basis for further studies in other parts of the species' range, with a view to determining the interaction of ecological, geographical, climatic and migratory factors with the overall genetic variability.