Progress 09/01/05 to 09/30/08
Outputs
OUTPUTS: The goals of this project include delimiting the generic boundary of Clerodendrum, resolving the phylogenetic relationships within Clerodendrum as well as between this genus and its allied genera, and embarking on a monographic account of the Asian Clerodendrum group that contains most ornamentals and environmental weeds. As a result of the funding provided in this grant, the P.I. (August-September 2006, September 2007) and the graduate research assistant (March, 2007) visited over a dozen herbaria in the US (Berkeley, Smithsonian Institution, Missouri Botanic Garden, Arnold Arboretum of Harvard University), Europe (Paris, Leiden, Kew, Natural History Museum London) and Asia (Kepong and Kuala Lumpur). These herbarium studies assisted the P.I. in his monographic revisions of the Asian Clerodendrum and the graduate research assistant for obtaining leaf tissue from recently collected herbarium specimens for DNA analyses and examining morphological characters that are
potentially diagnostic for the clades recovered from molecular work. Samples for over 70 species of Clerodendrum and allied genera (Amasonia, Aegiphila, Tetraclea, and Kalaharia) have been collected during the grant-supported period. DNA of these samples are stored in Dr. Richard Olmstead's lab at the University of Washington and available for our future use or upon request from other researchers. Approximately 250 DNA sequences, including four chloroplast DNA regions (trnT-L, trnD-T, trnL-F, and trnfM-S) and the nuclear ETS region, have been generated from this research and will be submitted to GenBank with corresponding publication. Some of the results from this research have been presented by the P.I. in the annual Botany meeting at Chicago in August, 2007. UW Biology graduate student, Yaowu Yuan, has been supported via a RAship from this grant for two years (Sep. 2005-Jun. 2007). Yuan has received training in skills and knowledge across the whole range of plant systematic study:
from herbarium work to literature analysis, molecular data collecting to phylogenetic analysis, scientific presentation to manuscript writing.
PARTICIPANTS: David Mabberley, UW Botanic Gardens, college of forest Resources. Richard Olmstead, UW Department of Biology Yao-wu Yuan, UW Department of Biology Dorothy Steane, University of Tasmania, School of Plant Science, Tasmania, Australia.
TARGET AUDIENCES: Academic biologists; forest botanists and foresters, particularly in Asia
Impacts
A framework phylogeny of Clerodendrum and its allied genera was well established from this research. Four major monophyletic groups were recovered from our analyses--the Asian Clerodendrum clade, the African Clerodendrum clade, the Oceanic Clerodendrum clade, and the New World that contains the genera Aegiphila, Amasonia, and Tetraclea. Kalaharia is sister to the big clade comprising the three Clerodendrum clades and the New World clade. While the Asian and African Clerodendrum clades are sister groups as suggested in previous studies, the Oceanic Clerodendrum clade and the New World clade are sister groups as well, contradicting traditional classifications. The Oceanic Clerodendrum clade is, therefore, proposed to be separated as genus Volkameria. This finding highlights that molecular analyses is important, sometimes indispensable, in taxonomic delimitation and circumscription. A few well-supported monophyletic groups within the Asian and African clade have been
revealed. Within the Asian Clerodendrum clade, a group of Chinese species emerges out as a monophyletic group, associated with its geographic distribution. Another clade composed of species from Australia and the Philippine islands is recovered, associated with the morphology of an extremely long floral tube. Within the African clade, three monophyletic groups were recovered. In particular, one of these three clades is represented by a single species, C. hildebrandtii, and is sister to all the remaining species in the African clade. Morphologically, this species is distinguishing and resembles an endemic Madagascar group that has 20 to 30 species. This finding reorients our future direction to the Madagascar group. By carefully examining the floral morphology in both living and herbarium specimens as well as flower images found from other sources, an intriguing pollination strategy, coincided as "Filaments Style Alternating Position Mechanism" by us, has been found in all Clerodendrum
as well as Amasonia, Tetraclea, Kalaharia, Oxera and Fradaya, with Aegiphila is the only exception. These genera comprises of a clade identified by a previous molecular study. Our results suggest this pollination strategy has evolved from the common ancestor of this clade and represents the first/only morphological synapomorphy defining this clade. This pollination strategy has shifted to a diclinous system in the genus Aegiphila, which, on the other hand, supports the monophyly of this genus. The discovery of the ancestral "Filaments Style Alternating Position Mechanism" and the more derived diclinous system, integrated with the phylogenetic relationships, indicates that the clade comprising Volkameria, Amasonia, Tetraclea, and Aegiphila originated in the Caribbean region and moved southward to central South America. This suggests that in future projects that are focused on Aegiphila, sampling from the Caribbean areas and Central America will be critical, although the highest
diversity of this genus is in northern South America. This finding highlights the importance of a phylogenetic framework in understanding phenotypic character evolution.
Publications
- No publications reported this period
|
Progress 10/01/05 to 10/01/06
Outputs
To delimit the generic limits of Clerodendrum, four relatively fast evolving chloroplast regions, trnT-L, trnD-T, trnL-F, and trnfM-S, have been sequenced for 18 species of Clerodendrum as well as 15 species of its new world closely related genera, Aegiphila, Amasonia, and Tetraclea. Four major Clerodendrum clades have been resulted from the cpDNA data. The "Oceanic Costal" clade is quite distinct from the remaining Clerodendrum taxa in DNA sequences. The P.I. examined specimens in several major herbaria in E US, Europe and Asia in summer 2006 and found this clade is indeed very different from other Clerodendrum spp. in calyx morphology and other features. Huxleya, an Australian endemic monotypic genus, is very closely related to C. inerme and well nested within the "Oceanic Costal" clade. The cpDNA phylogeny also indicates that this "Oceanic Costal" clade is more closely related to a new world clade composed of Aegiphila, Amasonia, and Tetraclea, than other
Clerodendrum clades, which suggests further disintegration is necessary to make the genus Clerodendrum monophyletic. Resurrecting generic status for the "Oceanic Coastal" clade is probably the best solution. After the "Oceanic Coastal" clade is removed, Clerodendrum is monophyletic and has interesting biogeographical features. Besides the "Asian" and "African" clades recognized earlier, an "Australian" clade emerged as sister group to the "Asian" clade, which includes all the weedy and most of the commercial ornamental taxa. That the "Asian" clade is derived from within the southern hemisphere lineages implies a southern hemisphere origin of the genus and subsequent dispersal from Australia to Asia. We are making efforts to obtain samples from Madagascar to further explore the biogeography. Within the new world clade, relationships among Aegiphila, Amasonia, and Tetraclea remain largely unresolved. However, there is no question that Amasonia is a monophyletic genus based on both
molecular and morphological evidence. The preliminary phylogeny of the genus Aegiphila from cpDNA data is incongruent with any traditional classifications, which suggests more extensive work needs to be done for this group - and this, involving work in Breazil, is now planned for the coming year.
Impacts
After the "Oceanic Coastal" clade is removed, Clerodendrum is monophyletic and has interesting biogeographical features. Besides the "Asian" and "African" clades recognized earlier, an "Australian" clade emerged as sister group to the "Asian" clade, which includes all the weedy and most of the commercial ornamental taxa. That the "Asian" clade is derived from within the southern hemisphere lineages implies a southern hemisphere origin of the genus and subsequent dispersal from Australia to Asia. We are making efforts to obtain samples from Madagascar to further explore the biogeography. Within the new world clade, relationships among Aegiphila, Amasonia, and Tetraclea remain largely unresolved. However, there is no question that Amasonia is a monophyletic genus based on both molecular and morphological evidence. The preliminary phylogeny of the genus Aegiphila from cpDNA data is incongruent with any traditional classifications, which suggests more extensive work needs
to be done for this group - and this, involving work in Breazil, is now planned for the coming year.
Publications
- No publications reported this period
|