Submitted to: Heredity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/1/2003
Publication Date: 3/1/2003
Citation: RICHARDS, C.M., EMERY, S.N., MCCAULEY, D.E. GENETIC AND DEMOGRAPHIC DYNAMICS OF SMALL POPULATIONS OF SILENE ALBA. HEREDITY. 2003. v.90.p.181-186. Interpretive Summary: The focus of the study was to investigate the role of genetic variation in population viability. The field data presented made use of long-term census data of a plant metapopulation conducted yearly in the Southern Appalachian Mountains of Virginia. By examining the demographic trajectories over a five-year period and correlating these data with molecular maker data, we showed that genetic diversity plays a significant role in population viability. This represents the first longitudinal study of this kind in a plant system.
Technical Abstract: Small local populations of Silene alba, a short lived herbaceous plant, were sampled in 1994 and again in 1999. Sampling included estimates of population size and genetic diversity, as measured at six polymorphic allozyme loci. When averaged across populations, there was very little change between samples (about 1.5 generations) in population size, measures of within population genetic diversity such as number of alleles or heterozygosity, or in the apportionment of genetic diversity within and among populations as measured by Fst. However, Individual populations changed considerably, both in terms of numbers and with regard with genetic composition. Some populations doubled in size between samples, while others were shrank by more than 75%. Similarly, heterozygosity and allele number increased more than two-fold in some populations and decreased more than three-fold in others. When population-specific change in number and change in measures of genetic diversity were considered together, significant positive correlations were found between the demographic and genetic variables. It is speculated that some populations were released from demographic consequences of inbreeding depression by gene flow.