Nuclear DNA C-values complete familial representation in gymnosperms

The gymnosperms area monophyletic yet diverse group of woody trees with app rox. 730 extant species in 17 families. A recent survey showed that DNA C-v alues were available for approx. 16 % of species, but for only 12 of the 17 families. This paper completes Familial representation reporting first C-v alues for the five remaining families Boweniaceae, Stangeriaceae, Welwitsch iaceae, Cephalotaxaceae and Sciadopityaceae, C-values for nine Ephedra and two Gnetum species are also reported. C-values are now available for 152 (2 1 %) species. Analysis confirins that gymnosperms are characterized by larg er C-values than angiosperms (modal IC of gymnosperms = 15.8 pg compared wi th 0.6 pg in angiosperms) although the range (IC = 2.25-32-20 pg) is smalle r than that in angiosperms (IC = 0.05-127.4 pg). Given complete familial co verage for C-values and increasing consensus in gymnosperm phylogeny, the p hylogenetic component of C-value variation was also investigated by compari ng the two datasets. This analysis revealed that ancestral gymnosperms (rep resented by cycads and/or Ginkgo; mean genome size = 14-71 pg) probably had larger genomes than ancestral angiosperms. (C) 2001 Annals of Botany Compa ny.