Baskauf et al.,1994

Baskauf, C.J., D.E. McCauley, W.G. Eickmeier, Evolution (1994) 48: 180-188  

Genetic analysis of a rare and a widespread species of Echinacea (Asteraceae)

   Echinacea tennesseensis is an endangered species known from only a few populations near Nashville, Tennessee. The population genetics of this highly localized endemic is compared with that of its widespread prairie relative E. angustifolia var. angustifolia using allozyme electrophoresis data at 18 loci. The endemic has lower levels of genetic variability with fewer polymorphic loci (23% vs. 40%), fewer alleles per locus (1.3 vs. 1.9), and lower levels of heterozygosity (0.069 vs. 0.152). Most variability occurs within rather than among populations, for both species. Morphological similarities between E. tennesseensis and E. angustifolia have resulted in a lack of consensus regarding their taxonomic distinctiveness, but the two are genetically distinct. Inter-population divergence within each species occurs at significantly higher genetic identity values (mean identity of 0.991 and 0.984 for E. tennesseensis and E. angustifolia, respectively) than does divergence between the species (mean identity of 0.826). In addition, E. tennesseensis diverges from morphologically distinctive E. purpurea at a similar mean genetic identity value of 0.813. Thus, the rare E. tennesseensis has less genetic variability than the widespread E. angustifolia, and the two differ genetically at a level similar to that found between E. tennesseensis and a more morphologically distinctive Echinacea species.

Back to descriptive text

Back to publications list