ITS•797 bp long, 161 parsimony informative characters•Branch and bound search using parsimony criterion found 15 trees of length 419 and consistency index of 0.8258.

Bootstrap Analysis•Monophyly of sections Auricula (98%) and Aleuritia (100%) is strongly supported. The monophyly of section Crystallophlomis (55%) is less well supported.•Monophyly of subgenera Auriculastratum (98%) and Aleuritia (100%) is well supported.•Monophyly of clades based upon chromosome number 2n=22 (100%), 2n=18 (100%) and 2n=66 (98%) is strongly supported. •Intrasectional relationships were not well resolved.

matK•872 bp long, 79 parsimony informative characters•Branch and bound search using parsimony criterion found 3 trees of length 147 and consistancy index of 0.939.

Boostrap Analysis•Monophyly of section Aleuritia (100%), subgenera Aleuritia (100%) and the clades based on chromosome number 2n=18 (100%) and 2n=22 (100%) are well supported.•Other clades suggested by the ITS topology are similar but are not well supported.

•Evaluate congruence of chloroplast and

nuclear phylogenies•Test molecular support of traditional

sectional classifications•Test Kelso’s hybridization hypotheses•Explore distribution of breeding systems

and chromosome number

Preliminary phylogenetic analyses of ITS and matK sequences support:

•Monophyly of sections Aleuritia and Auricula•Base chromosome number as a useful taxonomic character

Preliminary support of Kelso’s hypotheses•homostylous species grouped with proposed heterostylous progenitors

P.eximia with P. tschuktchorumP. stricta with P. farinosaP. incana and P. laurentiana with P. mistassinicaP. borealis with P. modesta

•need increased matK and ITS sampling to further resolve the relationships

equal sample sizes would allow statistical tests of congruence

Traditional ClassificationOver 400 species worldwide in 37 sections (Richards 1993)Based on 15 taxonomic characters, the most informative include:

Chromosome numberPresence of multicellular hairsPollen typeBreeding system

Molecular techinques can provide many more informative characters that can improve resolution of relationships.

Breeding SystemsThree breeding systems, according to Richards (1993)Primary homostyly

•Self-fertile populations with a single morphology and mating type

Heterostyly•Populations a mix of two flower morphs•Morphology and a sporophytic self incompatibility system prevent intramorph fertilization

Secondary Homostyly•Self-fertile with a single floral morphology•Develop when hybridization, and most often polyploidy occurs and recombination disables the heterostyly supergene

Hybridization HypothesisAn association between secondary homostyly, polyploidy, and extreme arctic or alpine conditions has been reported in Primula.

• Kelso (1991, 1987) proposed an explanation based on the secondary contact hypothesis (Stebbins 1985).

Evidence of hybridization may be evaluated by statistical tests of congruence between nuclear and chloroplast trees

P. nutans (2n)

P. mistassinica (2n)

P. anvilensis (2n)

P. farinosa (2n)

P. modesta (2n)

P. tschuktchorum (2n)

P. egaliksensis (4n)

P. incana (6n)

P. laurentia (8n)

P. scotia (6n)

P. scandinavica (8n)

P. borealis (4n) Heterostyle

P. eximia (2n)

P. stricta?

HeterostylesHeterostyles Secondary HomostylesSecondary Homostyles

Implications for sectional circumscription, relationships and evolution of breeding systemsSuring, Erik,*1 Elena Conti1, Sylvia Kelso2

1University of Alaska Fairbanks 2Colorado College

Reciprocal herkogamy found in heterostylic primulas. Compatible pollinations are indicated by the arrows. Polymorphisms associated with distyly include anther andstigma length, pollen size, and stigmatic papillae size (from Barret and Cruzan, 1994).

ITS Maximum Parsimony Tree. The numbers on top of the branches are bootstrap values and the numbers below are distance values. Sectional, and subgeneric groupings are shown. Chromosomal and breeding system distributions are shown. Highlighted taxa are secondary homostyles.

P.angustifoliaP.glutinosa

P.minima

P.spectabilisP.clusiana

P.palinuri

P.nutans

P.secundiflora

P.tschuktschorum

P.eximia.1P.eximia.2

P.borealis

P.modesta

P.laurentiana

P.mistassinica

P.incana

P.farinosa

P.stricta

P.frondosa

P.scandinavica

98

100

72

100

100

88

5558

100

89

82

72

36

21

14

22

8

10

9

17

15

45

43

1813

22

54

10

0

46

10

5

9

0

15

2

47

10

66

4

SectionCrystallophlomis

SectionAuricula

SectionAleuritia

ArmerinaSikkimensis

SubgenusAleuritia

SubgenusAuriculastrum

2n=66

2n=22

2n=18

2n=72

2n=126

2n=54

2n=72

2n=36

2n=198

ITS

•A diploid, heterostylic taxon of Primula occupied a contiguous area

•Glacial retreat allowed separated and partially differentiated diploid taxa to come into contact and hybridize, giving rise to polyploid taxa•Recombination in the heterostyly supergene gave rise to secondary homostylous taxa

•Diploid, heterostylous populations of Primula became isolated because of habitat fragmentation caused by climate changes, for example Quaternary glacial peaks

•Secondary homostylous taxa successfully colonized the new habitats opened by glacial retreat.

100

100

99

85

100

85

54

50

7

20

44

40

5

316

0

21

10

0

0

11

2

11

2

0

SectionCrystallophlomis

SectionAuricula

SectionAleuritia

ArmerinaSubgenusAleuritia

SubgenusAuriculastrum 2n=66

2n=22

2n=18

Sikkimensis

P.angustifolia

P.borealis.1

P.borealis.2

P.stricta

P.laurentiana

P.nutans

P.eximia

P.tschuktschorum

P.secundiflora

P.glutinosa

P.palinuri

P.minima

2n=36

2n=126

2n=72

matK Maximum Parsimony Tree. The numbers on top of the branches are bootstrap values and the numbers below are distance values. Sectional, and subgeneric groupings are shown. Chromosomal and breeding system distributions are shown. Highlighted taxa are secondary homostyles.

matK

Regions SequencedInternal Transcribed Spacer (ITS)•Nuclear sequence•Non-coding region

maturase K gene (matK)•Chloroplast gene•Maternally inherited

Both have been used in other intrageneric plant studiesFrom Johnson & Soltis 1994 Boxed areas represent coding regions

Leu F

C26A R

ITS 1F ITS 2R ITS 4R

ITS 3F

P. veris

P. farinosa

Funding was provided by the UAF Office of Arctic Research Undergraduate Research Opportunities Program and The Research Foundation.