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Parallel evolutionary patterns in multiple lineages of arctic Artemisia L. (Asteraceae)
Natalia V Tkach1, Matthias Heinrich Hoffmann, Martin Röser
1Institute of Biology, Department of Geobotany and Botanic Garden, Martin-Luther-University Halle-Wittenberg, Neuwerk 21, D-06099, Halle, Germany.
Evolution; International Journal of Organic Evolution
|November 3, 2007
Summary
Artemisia plants independently adapted to Arctic habitats multiple times. Reduced plant height and enlarged flower heads, not higher polyploidy, characterize Arctic lineages, suggesting alternative strategies for Arctic survival and reproduction.
Area of Science:
- Plant evolutionary biology
- Arctic flora
- Phylogenetics
Background:
- Arctic plant evolution shows similarities to temperate alpine regions.
- High ploidy levels are often observed in Arctic flora.
- Artemisia (wormwood) offers a model for studying independent adaptation.
Purpose of the Study:
- To investigate adaptive traits in independently evolved Arctic Artemisia lineages.
- To compare Arctic lineages with their sister groups to identify evolutionary patterns.
- To test hypotheses regarding ploidy levels, morphology, and ecological preferences in Arctic adaptation.
Main Methods:
- Phylogenetic analysis using 3'-ETS and ITS DNA sequences for 133 taxa.
- Comparative analysis of morphology, karyology, distribution, and ecological data.
- Testing for significant differences between Arctic lineages and sister groups.
Main Results:
- Artemisia independently colonized Arctic habitats 13-18 times.
- Arctic lineages exhibit reduced plant height.
- No higher polyploidy was found in Arctic lineages compared to sister groups.
- Enlarged flower heads evolved repeatedly in Arctic lineages, likely for pollinator attraction.
Conclusions:
- Independent adaptation to Arctic environments is common in Artemisia.
- Reduced stature and enhanced floral displays are key adaptations, potentially substituting for polyploidy.
- These traits may promote outcrossing and heterozygosity in challenging Arctic conditions.
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