Population genetic structure in a bird-dispersed pine, Pinus albicaulis (Pinaceae)

Abstract

Whitebark pine (Pinus albicaulis) is the sole North American representative of Pinus subgenus Strobus section Strobi subsection Cembrae, a group of five species characterized by bird-dispersed seeds. Whereas population genetic structure has been described for several Eurasian Cembrae pines, the purpose of the present research was to quantify genetic diversity in whitebark pine and assess the distribution of genetic variation within and among populations interpreted within the context of this species' unique life history. Allozyme analyses were conducted on nine populations from the Greater Yellowstone Area. Genetic diversity, as measured by population means for percentage of loci polymorphic, number of alleles per locus, and expected heterozygosity was relatively low (i.e., 38.57, 1.66, 0.152) when compared with means reported for pines with wind-dispersed seeds. Genetic differentiation was also low (i.e., 0.025) relative to means reported for other gymnosperms including wind-dispersed pines. These populations are poorly differentiated, with the majority of all observed variation due to differences among individuals within populations. The data reported herein for whitebark pine populations are similar to those reported for other Cembrae pines and may reflect their recent evolutionary history, as well as life history, including documented bird dispersal of seeds.Key words: population genetic structure, plant evolutionary biology, bird dispersal, Pinus albicaulis, Pinaceae.