Transcript BGSS2006_most_variable

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).
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40 varieties
originally species
 Local endemics/edaphic specialists.
 Disjunct populations.
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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%
North, mesic
South, arid
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 distinction
 AFLP data suggests varieties are
differentiated
 Cp SSRs show evidence of
introgression/shared ancestral states
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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 PNW
OSU Botany & Plant Pathology
Hardman Foundation
Native Plant Society of Oregon
Nevada Native Plant Society
Morphometrics
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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)
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Three varieties
Two populations per variety
7-8 individuals per population
184 markers scored