Genetic consequences ofin situandex situconservation of forest trees

To counteract loss of genetic diversity crucial for current and future tree improvement, tree breeders have conserved forest genetic resources in situ in their natural ecosystems in protected areas or ex situ in plantations, seed orchards, and breeding arboreta. This article reviews the genetic consequences of these two conservation methods in terms of single-locus and multilocus population structure from electrophoretic studies of natural forests and breeding populations. Although natural forest populations have maintained high level of genetic diversity and exhibited low level of population differentiation, loss of genetic diversity would occur during the entire conservation process, from population establishment to management of breeding and production populations. Since forest trees are still at their earliest stage of domestication in Canada, loss of genetic diversity comes primarily from the initial sampling process during population establishment. We discuss the optimal sampling strategy during pop...