CHLOROPLAST DNA HAPLOTYPE VARIATION WITHIN AND AMONG POPULATIONS OF COREOPSIS-GRANDIFLORA (ASTERACEAE)

An intraspecific chloroplast DNA (cpDNA) restriction site survey withi n Coreopsis grandiflora was used-to evaluate the correspondence of gen etic variation with patterns of morphological differentiation and geog raphical separation. Eight frequent-cutting restriction enzymes were u sed with a sample of 273 individuals representing 14 populations from two geographical regions. Thirteen distinct cpDNA haplotypes were dete cted, differing by as many as 22 restriction site changes, or an estim ated 0.674% nucleotide sequence divergence. The survey detected suffic ient cpDNA variation for analyses of intraspecific and intrapopulation al genetic structure and yielded evidence for interpopulational gene f low, a cpDNA polymorphism that transcends the species boundary, and po ssible cpDNA introgression. Patterns of genetic diversity do not stric tly correspond to either morphological variation or geographical distr ibution; this may be a result of either cpDNA introgression or the mai ntenance of a cpDNA polymorphism through the speciation event that gav e rise to C. grandiflora.