Chloroplast DNA haplotype variation within and among populations of Coreopsis grandiflora (Asteraceae)

Abstract

An intraspecific chloroplast DNA (cpDNA) restriction site survey within Coreopsis grandiflora was used to evaluate the correspondence of genetic variation with patterns of morphological differentiation and geographical separation. Eight frequent-cutting restriction enzymes were used with a sample of 273 individuals representing 14 populations from two geographical regions. Thirteen distinct CpDNA haplotypes were detected, differing by as many as 22 restriction site changes, or an estimated 0.674% nucleotide sequence divergence. The survey detected sufficient cpDNA variation for analyses of intraspecific and intrapopulational genetic structure and yielded evidence for interpopulational gene flow, a cpDNA polymorphism that transcends the species boundary, and possible cpDNA introgression. Patterns of genetic diversity do not strictly correspond to either morphological variation or geographical distribution; this may be a result of either CpDNA introgression or the maintenance of a cpDNA polymorphism through the speciation event that gave rise to C grandiflora.