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.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.

Pictures!

Pictures!

Pictures!

Pictures!

Pictures!

Astragalus lentiginosus

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.

Divergence within the most variable species of Astragalus

Morphometrics - measuring of herbarium specimens.

Chloroplast Simple Sequence Repeats (CpSSR)

Amplified Fragment Length Polymorphism (AFLP)

Morphometrics - measuring of herbarium specimens.

Samples are accessible (some vars. are rare).

Applies statistical test to existing circumscription.

Explore climatic parameters

PCA axis 1 = 50.2%; axis #2 = 25.9%

South,

arid

North,

mesic

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?

Neighbor-joining dendrogram from a matrix of Manhattan distances.

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.

Principle coordinates analysis on Dice distances

Neighbor-joining dendrogram from a matrix of Manhattan distances.

Conclusions

Morphology implies lack of distinctionAFLP data suggests varieties are

differentiatedCp SSRs show evidence of

introgression/shared ancestral states Can be tested with nuclear data!

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 PNWOSU Botany & Plant PathologyHardman FoundationNative Plant Society of OregonNevada Native Plant Society

Morphometrics

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

Chloroplast Simple Sequence Repeats (CpSSR)

Three markers (expand to 5).Six varieties.ca. 4 individuals per population.

Amplified Fragment Length Polymorphism (AFLP)

Three varietiesTwo populations per variety7-8 individuals per population184 markers scored