Phylogenetics - Plants
2. Reinstatement of Raukaua Seem., a genus of the Araliaceae centred in New Zealand
3. Evolution of Stilbocarpa, a megaherb from New Zealand's sub-antarctic islands
4. Phylogeny and biogeography of the Chilean Pseudopanax laetevirens.
6. Systematic relationships of New Zealand endemic Brassicaceae inferred from rDNA sequence data
1. Phylogenetic relationships of Pseudopanax species (Araliaceae) inferred from parsimony analysis of rDNA sequence data and morphology
A. D. Mitchell and S. J. Wagstaff
Plant Systematics and Evolution. 208: 121-138.
Abstract: Sequence data from internal transcribed spacer (ITS) regions of rDNA and data from morphology, cytology and wood anatomy are used to study phylogenetic relationships in Pseudopanax. The molecular and non-molecular data are analysed as independent data sets and in combination using parsimony. Results supported the conclusion that the genus Pseudopanax is polyphyletic. Pseudopanax species emerge in two major monophyletic groups. The Anomalus group contains Pseudopanax anomalus, P. edgerleyi, and P. simplex; these species share a common ancestor with Cheirodendron trigynum and more distantly with Pseudopanax gunnii. The second major monophyletic group consists of two smaller groups: the Arboreus group, including Pseudopanax arboreus, P. colensoi, P. kermadecensis, P. laetus, and P. macintyrei, and the Crassifolius/Discolor group, including P. chathamicus, P. crasssifolius, P. discolor, P. ferox, P. gilliesii, P. lessonii, and P. linearis. Meryta species are close relatives of the Pseudopanax Arboreus and Crassifolius/Discolor groups. Phylogenetic tree shown here
2. Reinstatement of Raukaua Seem., a genus of the Araliaceae centred in New Zealand
A. D. Mitchell, D. G. Frodin, M. J. Heads
New Zealand Journal of Botany. 35: 309-315.
Abstract: The genus Pseudopanax C. Koch sensu Philipson is recognised as polyphyletic. Morphological and anatomical characters are described that support the monophyly of Pseudopanax anomalus, P. edgerleyi and P. simplex. Reinstatement of the genus Raukaua Seem. is recommended to accommodate these species. The new combinations R. anomalus and R. simplex are made. Relationships among Pseudopanax and Raukaua are may be seen on the next page
3. Evolution of Stilbocarpa, a megaherb from New Zealand's sub-antarctic islands
A. D. Mitchell, C. D. Meurk, S. J. Wagstaff
New Zealand Journal of Botany. 37: 205-211.
Abstract: Challenges to the traditional circumscription of Apiaceae
and Araliaceae are emerging as a result of phylogenetic analysis
of DNA sequences. Traditionally classified as Araliaceae, Stilbocarpa emerges with Schizeilema and Azorella, both members of the Apiaceae.
In our analyses of nuclear ITS sequences, these three genera comprise
a distinct Southern Hemisphere lineage. The humid climate, cool equable
temperatures, locally abundant nutrients and the absence of herbivores
are ecological features of the sub-antarctic islands that may have
contributed to the evolution of the unusual megaherb, Stilbocarpa,
from these diminutive apiaceous ancestors. Phylogenetic tree shown
here
4. Phylogeny and biogeography of the Chilean
Pseudopanax laetevirens.
A. D. Mitchell, S. Wagstaff
Submitted to the New Zealand Journal of Botany.
Abstract: Nuclear ribosomal DNA sequences and morphology are used in phylogenetic analyses to assess relationships of the Chilean Pseudopanax laetevirens. Close relatives of P. laetevirens are P. gunnii, an endemic to Tasmania, Raukaua species from New Zealand, and Cheirodendron tryginum from Hawaii. Analyses suggest that P. laetevirens is the sister species to P. gunnii. The current distribution of these taxa may be explained by vicariance and extinction during in the late Eocene or early Miocene with the common ancestor having a Gondwanic origin. Cheirodendron may have also had a southern origin and is the result of long distance dispersal to the North-West. Phylogenetic tree shown here
5. Phylogenetic relationships of species of Gingidia and related genera (Apiaceae, subfamily Apioideae)
A. D. Mitchell, C. J. Webb, S. J. Wagstaff New Zealand Journal of Botany. 36: 417-424.
Abstract: Five genera of Australasian apioid Apiaceae (Gingidia, Scandia, Lignocarpa, Anisotome, and Aciphylla) have a complex taxonomic history with the circumscription of, and inferred relationships among, the currently accepted genera based on only morphological characters. This molecular and phylogenetic study focuses on the relationships among the taxa currently included within Gingidia using the other genera as outgroups. Phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer region sequences for 17 species from these genera, and comparison with Smyrnium to root the trees, indicate that Gingidia is polyphyletic as currently circumscribed, the species belonging in two distinct monophyletic groups. However, morphological characters do not support these two groups, making taxonomic interpretation difficult. The monophyletic G. montana group includes the ditypic endemic genera Scandia and Lignocarpa, suggesting that they should not be maintained. The second monophyletic group includes G. decipiens and G. flabellata with species of Anisotome. Although our sampling of Anisotome and Aciphylla is limited, nothing in the analysis of the molecular data is inconsistent with earlier suggestions, based on morphological data, that Gingidia, Scandia, Lignocarpa, Anisotome, and Aciphylla form a monophyletic group.
6. Systematic relationships of New Zealand endemic Brassicaceae inferred from rDNA sequence data
A. D. Mitchell and P. B. Heenan
Systematic Botany. 25: 98-105.
Abstract: Phylogenetic relationships of New Zealand endemic Brassicaceae were studied using nuclear internal transcribed spacer (ITS) sequences. Three major monophyletic groups are supported. The first includes Arabidopsis spp. Camelina microcarpa, Cheesemania spp., Ischnocarpus novae-zelandiae, Pachycladon novae-zelandiae, and Erysimum witmannii; the second comprises only Lepidium spp., and the third includes Barbarea spp., Cardamine spp., Iti lacustris, and Rorippa spp. The Lepideae was found to be polyphyletic as genera from this tribe emerge in three distinct monophyletic groups distributed among taxa from other Brassicaceae tribes. Results support a monphyletic Notothlaspi and suggest species of this genus are not closely related to Thlaspi, the genus to which Hooker provisionally assigned N. australe. The cosmopolitan genus Cardamine was found to be paraphyletic by the inclusion of the monotypic genus Iti. The association of Iti with New Zealand Cardamine is of particular significance as the relationships of this monotypic genus have proven elusive. This study highlighted the difficulty of using fruit type and cotyledon arrangement for defining tribes of the Brassicaceae. Phylogenetic tree shown here
Juvenile specimens of Pseudopanax crassifolius
Stilbocarpa polaris. Thanks Joy and Bob Coghlan for the photo. Abstract at the bottom of this page
Limestone cliffs at Napenape, East Coast, South Island, New Zealand.
Rakia River, South Island, New Zealand.
Napenape, East Coast, South Island, New Zealand |
