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.
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