Patterns of genetic diversity that result from bottlenecks in Scots Pine and the implications for local genetic conservation and management practices in Bulgaria

As one of the principal coniferous species of commercial importance in Bulgaria, Scots Pine has been subjected to strict management, which has posed a challenge for the conservation and management of its gene pool. In this study, we measured genetic diversity and population structure using 6 microsatellite loci in 12 populations from Bulgarian mountain ranges. Our analysis showed good intrapopulation divergence (18.22%; AMOVA) and genetic evidence of bottlenecks. "NJ-IAM" and "non-admixing" clusters divided the populations into 3 large groups. Our microsatellite analysis was consistent with the documented "mountain effect" influence on genetic diversity. Two methods-the Coalescent Bayesian model and M-stat analysis-implicated recent bottlenecks for all populations, suggesting that the genetic structure of Bulgarian Scots Pine was shaped over a long period (one thousand generations; i.e. 20,000 years) by the interaction of genetic and autoecological processes. Our results suggest that conservation and management practices should strive to maintain this genetic differentiation, specifically by emphasizing reforestation efforts with stocks from local provenances to avoid nonlocal introductions.