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Divergence within the most variable species of Astragalus

Divergence within the most variable species of Astragalus. Brian J. Knaus Department of Botany and Plant Pathology Oregon State University. Why Astragalus lentiginosus ?. Most specious (ca. 2300 species) genus of vascular plant.

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Divergence within the most variable species of Astragalus

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  1. Divergence within the most variable species of Astragalus Brian J. Knaus Department of Botany and Plant Pathology Oregon State University

  2. Why Astragalus lentiginosus? • Most specious (ca. 2300 species) genus of vascular plant. • Most morphologically diverse species of New World Astragalus (Fabaceae). • 40 varieties • originally species • Local endemics/edaphic specialists. • Disjunct populations. • Parallel divergence • Long distance dispersal • vicariance • Widespread, intergrading varieties.

  3. Pictures!

  4. Pictures!

  5. Pictures!

  6. Pictures!

  7. Pictures!

  8. Astragalus lentiginosus

  9. Divergence within the most variable species of Astragalus • Question: do varieties of A. lentiginosus represent evolutionary groups? (Hey 2001) The mind of the species problem. TREE 16(7): 326-329. • Preliminary data to be expanded upon.

  10. Divergence within the most variable species of Astragalus • Morphometrics - measuring of herbarium specimens. • Chloroplast Simple Sequence Repeats (CpSSR) • Amplified Fragment Length Polymorphism (AFLP)

  11. Morphometrics - measuring of herbarium specimens. • Samples are accessible (some vars. are rare). • Applies statistical test to existing circumscription. • Explore climatic parameters

  12. PCA axis 1 = 50.2%; axis #2 = 25.9% South, arid North, mesic

  13. Chloroplast Simple Sequence Repeats (CpSSR) • Chloroplast is high target number = its easy to work with. • Universal primers are available. • Haploid and uniparentally inherited = 1/4 effective population size of the nuclear genome. • Tracks seed flow (not pollen). • Hybridization?

  14. Neighbor-joining dendrogram from a matrix of Manhattan distances.

  15. Amplified Fragment Length Polymorphism (AFLP) • Nuclear marker. • Easy to screen 100s of markers. • Large genomic footprint - allows us to explore interindividual genetic variation as well as interpopulation and intervariety variation. • Annonymous, dominant.

  16. Principle coordinates analysis on Dice distances

  17. Neighbor-joining dendrogram from a matrix of Manhattan distances.

  18. Conclusions • Morphology implies lack of distinction • AFLP data suggests varieties are differentiated • Cp SSRs show evidence of introgression/shared ancestral states • Can be tested with nuclear data!

  19. Thank you! • Rich Cronn, Aaron Liston, Mitch Cruzan (PDX), Tom Kaye (IAE), Steven Sharrow. • Members of the Cronn Lab & Liston Lab. • Dana York, Kathy Davis, Dell Heter, Gretel Enck, Patrick & Christine Whitmarsh, Jenna Straface. Funding: USDA FS PNW OSU Botany & Plant Pathology Hardman Foundation Native Plant Society of Oregon Nevada Native Plant Society

  20. Morphometrics • Four varieties. • Seven characters (from keys). • Explore climatic trends. • Ln transformed data.

  21. Chloroplast Simple Sequence Repeats (CpSSR) • Three markers (expand to 5). • Six varieties. • ca. 4 individuals per population.

  22. Amplified Fragment Length Polymorphism (AFLP) • Three varieties • Two populations per variety • 7-8 individuals per population • 184 markers scored

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