A fistful of Astragalus: incipient speciation in the American

West?Brian J. Knaus1

Rich Cronn2

Aaron Liston1

1Oregon State University, Botany & Plant Pathology2USDA Forest Service PNW

11ssp.Potentilla glandulosaRosaceae

11ssp.Trifolium longipesFabaceae

11var.Arenaria congestaCaryophyllaceae

11var.Achillea millefoliumAsteraceae

12var.Lepidium montanumBrassicaceae

12var.Eriophyllum lanatumAsteraceae

12var.Ericameria parryiAsteraceae

13var.Eriogonum nudumPolygonaceae

13ssp.Sidalcea malvifloraMalvaceae

13var.Hymenopappus filifoliusAsteraceae

22ssp. & var.Ericameria nauseosaAsteraceae

30var.Eriogonum umbellatumPolygonaceae

35var.Astragalus lentiginosusFabaceae

countInfra-rankScientific NameFamily

USDA, NRCS. 2006. The PLANTS database (http://plants.usda.gov, 11 Nov. 2006), National Plant Data Center, Baton Rogue, LA 70874-4490 USA.

Datasets:

• Chloroplast simple sequence repeats.

1. Taxonomic hypothesis.

2. IBD hypothesis.

• Coalescence simulation (to propose an explanation for the empirical dataset).

1. Deme size and mutation rate.

2. Time since divergence.

689490632 varieties

1216endemicPalantiaA. l. var. wilsonii101endemicPalantiaA. l. var. ursinus1NANAendemicPalantiaA. l. var. trumbellensis1940widespreadPalantiaA. l. var. palans205endemicPalantiaA. l. var. mokiacensis105endemicPalantiaA. l. var. maricopae1218endemicLentiginosaA. l. var. sierrae2014endemicLentiginosaA. l. var. semotus2126endemicLentiginosaA. l. var. scorpionis91080widespreadLentiginosaA. l. var. salinus4373widespreadLentiginosaA. l. var. lentiginosus108endemicLentiginosaA. l. var. kernensis1223endemicLentiginosaA. l. var. ineptus2226widespreadLentiginosaA. l. var. floribundus108endemicLentiginosaA. l. var. antonius1316endemicLentiginosaA. l. var. albifolius201endemicDiphysaA. l. var. sesquimetralis1NANAendemicDiphysaA. l. var. piscinensis1124endemicDiphysaA. l. var. idriensis2855widespreadDiphysaA. l. var. chartaceus3839widespreadDiphysaA. l. var. araneosus1316endemicCoulterianaA. l. var. yuccanus1216endemicCoulterianaA. l. var. vitreus89114widespreadCoulterianaA. l. var. variabilis119endemicCoulterianaA. l. var. stramineus1256widespreadCoulterianaA. l. var. nigricalycis105endemicCoulterianaA. l. var. micans2331widespreadCoulterianaA. l. var. kennedyi814101widespreadCoulterianaA. l. var. fremontii3234endemicCoulterianaA. l. var. coachellae2431widespreadCoulterianaA. l. var. borreganus1531widespreadCoulterianaA. l. var. australis

CpSSR pop

s

Barneby's Specimen

sBarneby's

SampleDistributionRydbergian

SectionVariety

4 sections32 varieties

68 populations273 individuals

CpSSR Sample

Neighbor-Joining Tree

5 CpSSR markersPairwise distance

4 sections32 varieties

68 populations273 individuals

57 A. lentiginosus haplotypes

Neighbor-Joining Tree

5 CpSSR markersPairwise distance

4 sections32 varieties

68 populations273 individuals

57 A. lentiginosus haplotypes

“I think we chose a plant for the reasons one chooses a friend, not for splendor of apparel or purity of profile, but for character and individuality.”

-Rupert Barneby, of gardening with Dwight.

“Ta ta, Dwighteen! And you, Miss Parish, may radioactive daydreams nourish!”-Rupert Barneby, of Cymoteris ripleyi and

Phacelia parishii. Nuclear testing began at the Nevada Test Site in 1951.

Pugillus Astragalorum

I-XX(a fistful of Astragalus)

Geneland K = 7Hierarchical Bayesian analysis including x and y as

parameters(Only A. lentiginosus)

5 haploid SSR loci.

Demes of equal size.

Sample matching empirical dataset:

n= 113, 35, 97, 28.

No migration.

Stepwise mutation model.

One chromosome, one linkage block (e.g., chloroplast, mitochondrion, Y chromosome).

1,000 simulated datasets per parameter set.

Simcoal 2.1.2 Coalescent Simulation.

Parameters of interest:Deme size?

Mutation rate (µ)?

Time since divergence = 10,000 generations.

Mutation Rate

Deme size 10^-4 10^-5 10^-6 10^-7

10^3 191.1 69.8 12.5 2.6

10^4 259.2 188.9 51.0 8.4

10^5 271.7 259.9 156.6 34.2

Parameters of interest:Deme size ≈ 100,000.

Mutation rate (µ) ≈ 0.000 01.

Time since divergence =10,000.

Mean Number of Haplotypes

Parameters of interest:Deme size = 100,000.

Mutation rate (µ) = 0.00001

Time since divergence =???

1,000 simulated datasets per parameter set.

Generations since divergence =100

Majority ruleNJ treeEuclidean distance

Generations since divergence =1,000

Majority ruleNJ treeEuclidean distance

Generations since divergence =10,000

Majority ruleNJ treeEuclidean distance

Generations since divergence = 100,000

Majority ruleNJ treeEuclidean distance

Generations since divergence = 400,000

Majority ruleNJ treeEuclidean distance

Generations since divergence = 500,000

Majority ruleNJ treeEuclidean distance

Generations since divergence = 1,000,000

Majority ruleNJ treeEuclidean distance

FST’

FST

Generations

FS

T

ConclusionsA. lentiginosus as a species

appears to be retaining ancestral haplotypes, a process which slows cladogenesis.

• CpSSRs do not support the taxonomic hypothesis.

• CpSSRs do not support IBD hypothesis.

• Coalescence simulation proposes an explanation for a finding of ‘no pattern.’

Assuming:1. Lack of genetic bottlenecks.2. Large ancestral population size.3. Large contemporary population size.4. Expanding populations.

Funding:Funding:USDA FS PNW Research USDA FS PNW Research

StationStation NPSO field research grantNPSO field research grant

Nevada Native Plant SocietyNevada Native Plant SocietyHardman FoundationHardman Foundation

Bonnie C. Templeton AwardBonnie C. Templeton Award

Cronn Lab (USDA FS)Dr. Matt Horning

Rebecca HuotSue Huber

Angie RodriguezNancy Mandel

Dr. Randy JohnsonChris PoklembaDr. Brad St.Clair

Liston Lab (OSU BPP)Dr. Richard HalseDrs. Ken & Henny

ChambersDr. John SyringDr. Ann Wilyard

Paul SevernsMatt Parks

Jason Alexander (leaf tissue)

Dr. Nahla Bassil (USDA ARS)

Wambui NjugunaApril Nyberg

Dr. Bruce McCune (OSU BPP)Dr. Sarah JovanHeather LintzDr. Emily HoltHeather Root