Multilocus Diversity in an Outbreeding Weed, Echium piantagineum L.

Abstract

A population of E. plantagineum was surveyed for its genetic structure at 23 isozyme loci. More than half (13) of these loci were polymorphic, with an average number of three alleles per locus, a gene diversity of 38% and heterozygosity of 35%. More importantly, the distribution of multilocus heterozygosity over individuals was found to approximate that assuming independence among loci or no linkage disequilibrium. The population consisted of a vast array of multilocus genotypes. This pattern indicates that the outbreeding system encourages recombination sufficient to outweigh the effects on multilocus structure of bottlenecks in population size. Genic and genotypic variation presumably allows high levels of biochemical flexibility in populations of E. plantagineum. Such flexibility could hamper attempts at biological control.