Molecular phylogeny and evolution of floral characters of Artemisia and allies (Anthemideae, Asteraceae): evidence from nrDNA ETS and ITS sequences

Taxon (Impact Factor: 3.05). 01/2008; 57(1):66-78.

ABSTRACT To better understand the evolutionary history of the genus Artemisia (Anthemideae, Asteraceae) and its relationships to other genera of the subtribes Artemisiinae, Leucantheminae and Tanacetinae, 63 sequences of the external and 10 of the internal transcribed spacer of nuclear ribosomal DNA (ETS and ITS) were newly generated. Analyses were performed on the combined dataset using maximum parsimony, maximum likelihood and Bayesian inference. The combined analysis supports that all Artemisiinae genera included plus Hippolytia (subtribe Tanacetinae) and Nipponanthemum (subtribe Leucantheminae) constitute a monophyletic group. Within this group, a successive branching shows three monophyletic groups: (1) Nipponanthemum/Hippolytia/Brachanthemum; (2) the Dendranthema group; and (3) the Artemisia/Kaschgaria group. Within the latter, a new sister-group relationship is found between the monophyletic genus Kaschgaria and the Artemisia group, which comprises two main evolutionary lineages: (i) the Dracunculus clade including various Artemisia species and four Asian genera: Filifolium, Mausolea, Neopallasia and Turaniphytum; and (ii) the remaining subgenera of Artemisia plus the two North American genera: Picrothamnus and Sphaeromeria. Within this phylogenetic framework the evolution of two important characters (capitula and pollen type) in the group was inferred. Character reconstruction reveals that discoid capitula and Anthemis pollen type are the ancestral condition in the subtribe. The Artemisia/Kaschgaria lineage probably originated from an ancestor with disciform capitula, central hermaphrodite florets and Artemisia pollen type. Molecular evidence of several biogeographical migration routes of the genus Artemisia is presented.

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    ABSTRACT: Aim: Major habitat shifts are well documented for the Hawaiian flora, but examples of shifts to the highest Hawaiian habitats by plant lineages of lowland tropical ancestry have been lacking. We sought to determine whether Hawaiian Artemisia (Compositae—Anthemideae), which includes lowland and subalpine species, represents such an example, by investigating the origin and relationships of the Hawaiian taxa. Location: Hawaiian Islands and continental settings world-wide (except Antarctica and Australia). Methods: Molecular phylogenetic analyses of Hawaiian Artemisia in the context of world-wide diversity were conducted using nuclear and chloroplast DNA spacers. The timing of divergence events associated with inferred dispersals was estimated with calibration from fossil pollen records. Historical biogeographical analyses based on molecular trees and ecological modelling of the distributions of extant taxa were used to aid the interpretation of geographical and habitat shifts associated with diversification and long-distance dispersal. Results: Our findings indicate that the Hawaiian endemic species (A. australis, A. kauaiensis and A. mauiensis) constitute a clade sister to Southeast Asian A. chinensis, which, like the Hawaiian endemics, has ribbed fruit walls and, unlike other members of Artemisia except A. kauaiensis, has a distinct pappus, which is often associated with dispersal ability in Compositae. The clade encompassing A. chinensis and Hawaiian Artemisia was resolved to be most likely of Asian origin. The natural occurrence of A. chinensis in littoral habitats of Taiwan, Okinawa, and the Ryukyu and Bonin islands, and of A. australis in similar settings in the Hawaiian Islands, is likely to reflect the ancestral ecology of the Hawaiian clade, with subsequent colonization of inland, higher-elevation habitats, including subalpine shrubland, where A. mauiensis is endemic. Main conclusions: An ecological shift in Hawaiian Artemisia from tropical coastal habitats to drier and colder subalpine slopes is consistent with evidence from recent studies for repeated colonization of the Arctic by diverse lineages of Artemisia. Artemisia appears to be prone to such anticlimatic ecological shifts, which may explain this exceptional example of an ancestrally lowland tropical lineage in the Hawaiian high-montane flora.
    Journal of Biogeography 03/2013; 40(3):442-454. · 4.97 Impact Factor
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    Australian Journal of Botany 11/2010; 58(7):605-616. · 0.90 Impact Factor
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    ABSTRACT: Abstract Somatic chromosome numbers of 47 accessions representing 28 Artemisia species are provided from Iran. Two basic chromosome numbers, x = 8, 9, each with diploid, tetraploid and hexaploid levels, were found. Different chromosome numbers, 2n = 16, 16 ? 1B, 16 ? 5B, 32, 48, and 2n = 18, 18 ? 1B, 19, 36, 36 ? 1B, 36 ? 2B, 37, 49 ? 2B, 49 ? 3B, 51 ? 6B, 54, 54 ? 1B, 54 ? 3B, 54 ? 5B, in studied accessions were identified. Chromosome numbers are reported for the first time in three species, counts in four species are new for Iran, and other counts have been thoroughly compared to previous data. Forty percent of the studied accessions are polyploid and B-chromosome(s) are reported in 17 % of accessions. Aneuploidy and aneusomy are other relevant cytological phenomena. Some karyological parameters, total karyotype length, karyotype formula, mean value of centromeric indices, mean arm ratio, A1 and A2 indices, were estimated to characterize the karyotypes numerically. A1 and A2 indices showed that karyotypes tend to be asymmetric in polyploid and dysploid taxa. PCA analysis of all karyological parameters has shown some systematic and evolutionary implications. The consideration of all these chromosome numbers and cytogenetic mechanisms has led us to infer the different patterns of chromosomal evolution in the genus.
    Plant Systematics and Evolution 04/2013; 299(5):16. · 1.15 Impact Factor


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