Table Mountain Pine (Pinus pungens): Genetic Diversity and Conservation of an Imperiled Conifer

Table Mountain pine (Pinus pungens Lamb.) is an imperiled tree species endemic to the southern and central Appalachian Mountains. Generally reliant on fire for regeneration, its fragmented but widespread distribution has declined in recent decades. We quantified the genetic diversity of 26 populations across the range of the species using data from seven highly polymorphic simple sequence repeat (SSR) loci. The species was relatively inbred whereas differentiation among populations was relatively low. Differentiation was significantly but weakly associated with geographic distance among populations. We detected minor genetic differences between northern and southern seed collection zones established based on climate similarity. We conducted a series of simulations using SSR data from 498 seedlings, grown from seed collected from five natural stands of Table Mountain pine, to assess the genetic consequences of different strategies for deploying collected seed in ex situ conservation plantings. Results indicated that reducing the number of families in a planting would not substantially affect the conservation of common alleles but would affect the representation of rare alleles and overall allelic richness. These findings add to our limited knowledge of genetic variation across the distribution of this rare conifer and offer some guidance for its effective genetic conservation. Study Implications: Most of the results of this study point to an overall lack of genetic structure and geographic differences in genetic variation within Table Mountain pine, most likely the consequence of prolific interpopulation gene flow. The weak genetic differences between northern and southern seed zones indicate that they are not particularly useful for guiding future gene conservation efforts. The results of seedling sampling simulations demonstrated that it may be possible to meet the goals of conservation plantings by including fewer families per population and/or including families without regard to population.