Generic relationships within and between the gymnosperm families Podocarpaceae and Phyllocladaceae based on an analysis of the chloroplast gene rbcL

Citation
Jg. Conran et al., Generic relationships within and between the gymnosperm families Podocarpaceae and Phyllocladaceae based on an analysis of the chloroplast gene rbcL, AUST J BOT, 48(6), 2000, pp. 715-724
Citations number
69
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
AUSTRALIAN JOURNAL OF BOTANY
ISSN journal
0067-1924 → ACNP
Volume
48
Issue
6
Year of publication
2000
Pages
715 - 724
Database
ISI
SICI code
0067-1924(2000)48:6<715:GRWABT>2.0.ZU;2-C
Abstract
Analysis of sequences of the chloroplast gene rbcL for 76 taxa of Podocarpa ceae (representing all genera except Parasitaxus) and five species of Phyll ocladaceae were undertaken with respect to their relationships to each othe r and to 28 coniferalean outgroup taxa from seven families. The results ind icate that Podocarpaceae are polyphyletic unless expanded to include Phyllo cladaceae. Within Podocarpaceae, Sundacarpus is placed in a clade with Prum nopitys, and Falcatifolium is paraphyletic as a basal grade to Dacrydium. P hyllocladus is in an unresloved clade with Halocarpus, Manoao/Lagarostrobos and Prumnopitys/Sundacarpus. The separation of Afrocarpus from Podocarpus and its placement instead as sister to Nageia and Retrophyllum is supported . Podocarpus s. str. is monophyletic, with both subgenera identified, albei t poorly supported. The analysis placed Lepidothamnus and Saxegothaea in an unresolved basal polytomy within the family. There were no clear outgroup relationships with the family. These results differ from the morphological clades found by Kelch (1997), and disagree strongly with his 18S-sequence-b ased phylogeny (Kelch 1998). However, jackknife support values indicate tha t although the genera are well supported, relationships both within and bet ween them are not, suggesting that intergeneric relationships in the family require further study. There is also some congruence between our results a nd those of the gymnosperm 18S study by Chaw et al. (1997), although their study included only three Podocarpaceae and one Phyllocladaceae species.