A population genetic analysis of Ziziphus celata, and endangered Florida shrub

Ziziphus celata (Rhamnaceae) is an endangered shrub known from five sites in the Lake Wales Ridge region of Florida. Genetically effective population sizes are difficult to determine because Z. celata spreads clonally via root sprouts. Allozymes were used to investigate clonal structure and to describe genetic diversity within the species. Five (25%) of the 20 putative loci resolved for 13 enzyme systems were polymorphic. The species was multiclonal; however, all populations except one consisted of single multilocus genotypes. Although no viable seeds have been found in the wild, seeds have been produced ex situ by open-pollinated crosses between cultivated accessions. These observations, in conjunction with the allozyme data, suggest that Z. celata is not sexually reproducing in situ because most populations consist of a single selfincompatible individual. If so, the longterm persistence of Z. celata in the wild may require population restoration in the form of providing genotypic diversity that would foster sexual reproduction. The successful ex situ production of seedlings with different multilocus genotypes provides hope for population restoration and for reconstituting the genotypic diversity of this endangered shrub.