POPULATION-STRUCTURE, GENETIC DIVERSITY, AND CLONE FORMATION IN QUERCUS-CHRYSOLEPIS (FAGACEAE)

Stands of canyon live oak (Quercus chrysolepis, Fagaceae) are maintain ed for fuelwood, fire management, recreation, and as habitat for wildl ife. Information about the link between the oak's reproductive ecology and its extent of genetic diversity is important in developing land m anagement policies that will maintain the long-term viability of popul ations. Basal sprouting is the primary means of reproduction following fire or cutting, and stands frequently include groups of visibly conn ected trees in a clustered distribution that suggests cloning. We dete rmined the extent to which clusters of trees were clonal and defined t he spatial pattern and diversity of genotypes fbr six populations acro ss nearly the entire east-west extent of the San Bernardino Mountains in southern California. We mapped over 100 trees at each of five sires and genotyped each tree for allozymes at seven polymorphic loci. We i dentified clones using these multilocus genotypes and detected an aver age of 34.4 +/- 7.3 (SD) clones per site, most of which had unique gen otypes. In general, clustered trees belong to single clones and most c lones consist of few trees (mean = 3.4 +/- 0.6 trees per clone). Howev er, clone size increased significantly with increased individual heter ozygosity, suggesting that selection may favor highly heterozygous clo nes. Clonal diversity and evenness were high relative to reports for m ost other clonal species; an average of 97% of clones had distinct gen otypes, and Simpson's index of diversity averaged 0.95 +/- 0.02. Popul ation genetic analyses of 319 clones from six sites revealed high gene tic diversity within sites (mean H-s = 0.443). Only a small proportion of the total genetic diversity was explained by variation among sites (mean G(ST) = 0.018), which is consistent with high gene flow among s ites (N-m = 9.5). We found no significant substructure among plots wit hin sites, and fixation indices within sites were generally small, sug gesting that either little inbreeding occurs, and/or few inbred progen y survive. However, spatial autocorrelation analysis of clones indicat ed fine-scale genetic structure at distances under 4 m, possibly due t o limited seed dispersal. Our data suggest that guidelines for seed co llection of canyon live oak for use in restoration can be specified in a manner similar to that recommended for conifer species within the r egion studied.