The Environment Institute
The Australian Centre for Evolutionary Biology and Biodiversity
ACEBB Seminar Series
...
Pollinator-mediated floral
evolution and speciation in
southern African Iridaceae
Paul D. Rymer 1,...
Talk outline
• Diversification of flowering plants
– biodiversity hotspots in southern Africa
• Macroevolution
– Spara...
Diversification of flowering plants
• The “abominable mystery” Charles Darwin
Associated with a shift from...
Evolution of floral traits
Whittall & Hodges (2007) Nature, 447: 706-10
Biodiversity hotspots
• Southern Africa
– Cape Floristic Region
– Succulent Karoo
Vitals ...
Macroevolution
• Evolution of traits across a phylogeny
– Avoid bias and false trends (Felsenstein 1985)
Without co...
Sparaxis (Iridaceae)
Phylogenetic analysis
• Taxonomic relationships
– Monophyly of Sparaxis
– Species delimitation
• Evolution of traits
...
Sparaxis molecular phylogeny
Sparaxis is a
...
Sparaxis molecular phylogeny
• 2 major clades
...
Pollination syndromes
Ancestral trait reconstruction
Ancestral state = Bee pollination
Independent transitions – bee (to generalist) t...
Evolutionary trait shifts
Tube elongation Tube elongation
Long proboscis fly...
Macroevolution
Summary
• Developed a partially resolved molecular
phylogeny for the genus Sparaxis
– Confirm monophyly...
Population genetics
• Fills the gap between phylogenetics and
experimental ecology
• Coalescent analysis
– Estimate di...
Gladiolus carinatus species complex
GcB GcY
G. carinatus (blue ...
GcB GcY Gg Gq
GcB 1 0.33* 0.86 0.86
GcY 1 0.00 0.67
Gg 1 0.29
Gq...
Floral differentiation
Species differentiation – Gq isolated
– Gg and Gc partial overlap
Coalescent analysis
“Isolation-with-Migration” model (Hey & Nielsen 2004)
Genome scans
Genetic signatures of selection can be elucidated
from large genomic datasets, where genes with...
increased ...
Genome scans - species
Genome scans - morphs
Speciation candidate loci
Genetic divergence (Fst) As...
Neutral and selected loci
Population structure, but no differentiation of Gc-Gg
Neutral and selected loci
All species form distinct clusters
Population genetics
Summary
• Evidence for recent and continuous speciation
in the face of gene flow
• Facilitated by a...
Mating patterns
• Gene flow needs to be halted for speciation to
proceed to completion
• Assortative mating
– Sympatr...
Gladiolus longicollis (Iridaceae)
Corolla tube 8 – 12 cm
Hawkmoth syndrome
...
Hawkmoth pollinators
Pollinator behaviour
Long morph
Nectar Pollen Visits Seed
10.1 ± ...
Predictions
• Intermediate morphs will have reduced
reproductive success
• Most pollination events will be within morp...
Distribution pattern
Study population
Population
census
• 2 flowering seasons
• 4 day/night census
• Map & tag plants
• Measure traits
– Coro...
Genetic analysis
• Developed SSR markers
– 5 loci (Combined non-exclusion probability 0.00119)
Locus N ...
Mating patterns
MLTR (Ritland 1991) 2007 2008
Multilocus outcrossing = tm (SD...
Dispersal curves
Frequent short dispersal with fat tale (max 3.94km)
Correlation of tube length
• 2007 (low density) assortative mating
• 2008 (high density) significant mating among morp...
Mating patterns
Summary
• Assortative mating among morphs
• Between morph pollination events are NOT
infrequent... esp...
Current and future research
• Population genetic
– Hybrid determination
– Differential selection
• Reinforcement of ...
Current and future research
• Comparative analysis of hotspot evolution
– Western Cape
– Southwest Australia
• Converg...
Acknowledgements
Kew NHM
• Mark Chase • Ian Kitching
• Felix Forest
• Jan Schnitzler Gl...
General questions + comments
Pollination Ecoregion
Bee S. Karoo
Generalist Lowland
HBSPF Highland
LPF
Reinforcement
of traits
- coarse grained
• Compare virgin and
2nd contact areas
– Reproductive ecology
– Pop...
Quantitative genetics
• Common garden of material collected from
virgin areas and secondary contact areas
– Detect shi...
Scent analysis
(a) Linalool (b) Methyl benzoate (c...
Bimodal pattern
floral tube and moth tongue length
Anderson et al submitted to Evolution
Selection against intermediates
Cross pollination by hand
...
Is there any incompatibility
among morphs?
Pollen parent...
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The Australian Centre for Evolutionary Biology and Biodiversity
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Pollinator-mediated floral evolution and speciation in southern African Iridaceae
Pollinator-mediated floral evolution and speciation in southern African Iridaceae
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Pollinator-mediated floral evolution and speciation in southern African Iridaceae

Part 3 of the 2010 ACEBB seminar series, Dr Paul Rymer presents "Pollinator-mediated floral evolution and speciation in southern African Iridaceae." Abstract: Explaining the rapid diversification of flowering plants remains one of the greatest challenges facing evolutionary biologists. The pollinator-shift hypothesis developed by Grant (1949) and Stebbins (1970) is the most widely accepted explanation. However, pollinator mediated selection is yet to be shown to result in speciation. The focus of my investigation has been biodiversity hotspots in southern Africa, primarily because they harbour exceptional plant species diversity and endemism, and therefore the promise of detecting speciation in action. In an attempt to unravel the processes driving the evolution of floral traits and speciation, I have taken a multi-faceted approach. I will present my findings from three very different studies: 1. Macroevolution in Sparaxis (Iridaceae), 2. Population genetics in Gladiolus carinatus species complex (Iridaceae), 3. Mating patterns in Gladiolus longicollis (Iridaceae). These studies highlight the role of pollination in recent and continuous speciation events.
Published on: Mar 4, 2016
Published in: Education      
Source: www.slideshare.net


Transcripts - Pollinator-mediated floral evolution and speciation in southern African Iridaceae

  • 1. The Environment Institute The Australian Centre for Evolutionary Biology and Biodiversity ACEBB Seminar Series Pollinator-mediated floral evolution and speciation in southern African Iridaceae Dr Paul Rymer
  • 2. Pollinator-mediated floral evolution and speciation in southern African Iridaceae Paul D. Rymer 1,2, Vincent Savolainen 1,2 John C. Manning 3, Peter Goldblatt 4, Steven D. Johnson 5 1 Imperial College London, Silwood Park, UK 2 Royal Botanic Gardens Kew, Jodrell Laboratory, UK 3 South African National Biodiversity Institute, Kirstenbosch, S. Africa 4 Missouri Botanical Garden, St. Louis, U.S.A. 5 University of Kwa-Zulu-Natal, Botany and Zoology, S. Africa EUROPEAN COMMISSION Marie Curie Actions - IIF
  • 3. Talk outline • Diversification of flowering plants – biodiversity hotspots in southern Africa • Macroevolution – Sparaxis (Iridaceae) • Population genetics – Gladiolus carinatus species complex (Iridaceae) • Mating patterns – Gladiolus longicollis (Iridaceae) • Current and future research – Another ‘Great Southern Land’
  • 4. Diversification of flowering plants • The “abominable mystery” Charles Darwin Associated with a shift from wind to animal mediated pollination
  • 5. Evolution of floral traits Whittall & Hodges (2007) Nature, 447: 706-10
  • 6. Biodiversity hotspots • Southern Africa – Cape Floristic Region – Succulent Karoo Vitals CFR SK Hotspot Original Extent (km 2) 78.555 102,691 Hotspot Vegetation Remaining (km 2) 15.711 29,780 Endemic Plant Species 6.210 2,439 Area Protected (km 2) 10.859 2,567 Area Protected (km 2) in Categories I-IV* 10.154 1,890 http://www.biodiversityhotspots.org/
  • 7. Macroevolution • Evolution of traits across a phylogeny – Avoid bias and false trends (Felsenstein 1985) Without controlling for phylogeny, one or a few species-rich clades with a trait could strongly bias our interpretations and create an apparent trend where none actually exists
  • 8. Sparaxis (Iridaceae)
  • 9. Phylogenetic analysis • Taxonomic relationships – Monophyly of Sparaxis – Species delimitation • Evolution of traits – Floral traits and pollination syndromes Sampling (54 taxa) Sequencing • Outgroups (15) – Plastid loci (3106 bp) • 100% species (16) +  trnV, trnQ, rpl32 subspecies (6) – Nuclear loci (569 bp) • Multiple accessions  RPB2 (1-4/taxa)
  • 10. Sparaxis molecular phylogeny Sparaxis is a monophyletic genus, sister to Duthiastrum RAxML tree based on plastid and nuclear loci
  • 11. Sparaxis molecular phylogeny • 2 major clades • 5 subclades • Most species relationships remain unresolved RAxML tree based on plastid and nuclear loci
  • 12. Pollination syndromes
  • 13. Ancestral trait reconstruction Ancestral state = Bee pollination Independent transitions – bee (to generalist) to beetle – bee to long proboscid fly
  • 14. Evolutionary trait shifts Tube elongation Tube elongation Long proboscis fly Long proboscis fly Bee Symmetry Colour Bee + beetle Beetle
  • 15. Macroevolution Summary • Developed a partially resolved molecular phylogeny for the genus Sparaxis – Confirm monophyly and sister-species • Reconstructed ancestral characters – Two major transitions from bee to fly or beetle
  • 16. Population genetics • Fills the gap between phylogenetics and experimental ecology • Coalescent analysis – Estimate divergence times, historical gene flow & ancestral population sizes • Genome scans – Detect genetic signatures of selection – Identify candidate loci
  • 17. Gladiolus carinatus species complex GcB GcY G. carinatus (blue and yellow morph) Gg Gq G. griseus G. quadrangulus
  • 18. GcB GcY Gg Gq GcB 1 0.33* 0.86 0.86 GcY 1 0.00 0.67 Gg 1 0.29 Gq 1
  • 19. Floral differentiation Species differentiation – Gq isolated – Gg and Gc partial overlap
  • 20. Coalescent analysis “Isolation-with-Migration” model (Hey & Nielsen 2004)
  • 21. Genome scans Genetic signatures of selection can be elucidated from large genomic datasets, where genes with... increased population differentiation... may be candidates for selected loci (Nielsen 2005)
  • 22. Genome scans - species
  • 23. Genome scans - morphs
  • 24. Speciation candidate loci Genetic divergence (Fst) Association with floral traits Fragment Global Gq / Gq / Gg / Gg / Gg / GcB / timing number size shape colour size-label analysis Gg Gc Gc GcB GcY GcY 106-B species * 0.875 0.823 † -0.050 0.011 0.040 NS NS ** ** ** 134-G species * 0.580 0.884 † 0.168 0.148 0.241 0.016 ** NS ** ** ** † species, 91-G , 0.394 0.867 ‡ 0.308 † 0.314 ‡ 0.200 -0.002 NS NS ** ** ** morphs ‡ 324-B morphs * -0.014 0.561 0.390 † 0.362 † 0.508 † 0.051 NS NS ** ** NS 186-G morphs * -0.030 0.273 0.318 † 0.292 ‡ 0.318 ‡ -0.017 NS NS <0.001 <0.001 NS 169-B morphs ‡ 0.487 0.044 0.352 † 0.332 ‡ 0.247 -0.017 <0.001 <0.001 NS NS NS 89-B morphs ‡ 0.149 0.009 § 0.256 ‡ 0.347 † 0.200 0.017 NS NS NS NS NS 225.5-G morphs ‡ 0.329 0.034 0.232 ‡ 0.328 † 0.115 0.079 ** ** NS NS NS 187-G morphs † 0.077 0.172 0.416 * 0.332 ‡ 0.374 -0.021 NS NS <0.001 NS NS 154-B morphs † -0.037 § 0.316 0.348 † 0.314 ‡ 0.332 -0.024 NS NS ** <0.001 NS 291-B morphs ‡ 0.281 -0.004 § 0.219 -0.011 0.508 † 0.393 * NS NS NS NS **
  • 25. Neutral and selected loci Population structure, but no differentiation of Gc-Gg
  • 26. Neutral and selected loci All species form distinct clusters
  • 27. Population genetics Summary • Evidence for recent and continuous speciation in the face of gene flow • Facilitated by a few loci associated with shifts in floral traits
  • 28. Mating patterns • Gene flow needs to be halted for speciation to proceed to completion • Assortative mating – Sympatric / secondary contact • Floral traits may be ‘magic traits’
  • 29. Gladiolus longicollis (Iridaceae) Corolla tube 8 – 12 cm Hawkmoth syndrome • white • tubular flowers • open at night Corolla tube 3 – 6 cm • scented
  • 30. Hawkmoth pollinators
  • 31. Pollinator behaviour Long morph Nectar Pollen Visits Seed 10.1 ± high high high 1.9 mm 0.6 ± high density high 0.4 mm Short morph Nectar Pollen Visits Seed 2.7 ± none density none 0.5 mm 2.7 ± high high high 0.5 mm
  • 32. Predictions • Intermediate morphs will have reduced reproductive success • Most pollination events will be within morphs • Between morph pollination events will be infrequent and vary in reproductive success – Density dependent
  • 33. Distribution pattern
  • 34. Study population
  • 35. Population census • 2 flowering seasons • 4 day/night census • Map & tag plants • Measure traits – Corolla tube length – Dorsal tepal length – Height of flower – Leaf length – Colour (subsample) – Shape (subsample) – Scent (subsample) • Reproductive success – Capsule maturation – Seed production
  • 36. Genetic analysis • Developed SSR markers – 5 loci (Combined non-exclusion probability 0.00119) Locus N # alleles Ho He GL17 859 16 0.733 0.781 GL35 836 57 0.847 0.956 GL41 855 19 0.735 0.904 GL63 871 40 0.885 0.948 GL65 846 41 0.856 0.955 • Extracted DNA – 128 (2007) and 321 (2008) flowering plants – 30 (2007) and 32 (2008) progeny arrays • 600 germinated seed (95-100%)
  • 37. Mating patterns MLTR (Ritland 1991) 2007 2008 Multilocus outcrossing = tm (SD) 0.979 (0.074) 0.992 (0.100) Singlelocus outcrossing = ts (SD) 0.851 (0.025) 0.876 (0.031) Biparental inbreeding = tm-ts (SD) 0.128 (0.068) 0.116 (0.086) Correlation of outcrossing (SD) 0.129 (0.502) 0.923 (0.539) 1/(number of sires) = rp (SD) 0.290 (0.067) 0.383 (0.065) High levels of outcrossing with some biparental inbreeding Large variation in outcrossing rates in 2007
  • 38. Dispersal curves Frequent short dispersal with fat tale (max 3.94km)
  • 39. Correlation of tube length • 2007 (low density) assortative mating • 2008 (high density) significant mating among morphs
  • 40. Mating patterns Summary • Assortative mating among morphs • Between morph pollination events are NOT infrequent... especially at high densities
  • 41. Current and future research • Population genetic – Hybrid determination – Differential selection • Reinforcement of traits – Common garden experiment • Coevolution of hawkmoth pollination – Geographic mosaic
  • 42. Current and future research • Comparative analysis of hotspot evolution – Western Cape – Southwest Australia • Convergent evolution of floral traits • Role of standing genetic variation • Adaptation to climate change
  • 43. Acknowledgements Kew NHM • Mark Chase • Ian Kitching • Felix Forest • Jan Schnitzler Gladiolus longicollis • Kit Strange • Steve Johnson • Sandy-Lynn Steenhuisen Silwood • Ruth Cozien • Vincent Savolainen • Bruce Anderson • Martyn Powell • Ronny Alexandersson • Joaquin Hortal • Celine Devaux Sparaxis • Cuong Tang • John Manning • Peter Goldblatt • Clare Dean
  • 44. General questions + comments
  • 45. Pollination Ecoregion Bee S. Karoo Generalist Lowland HBSPF Highland LPF
  • 46. Reinforcement of traits - coarse grained • Compare virgin and 2nd contact areas – Reproductive ecology – Population genetics – Common garden
  • 47. Quantitative genetics • Common garden of material collected from virgin areas and secondary contact areas – Detect shifts + heritability of floral traits
  • 48. Scent analysis (a) Linalool (b) Methyl benzoate (c) Benzaldehyde 100 50 70 t = 16.06 t = 2.35 t = 0.74 P < 0.001 60 P = 0.47 80 40 P = 0.02 50 60 40 30 40 30 20 20 20 10 10 1.5 0 0 Short-tubed morph 0 Long-tubed morph Percentage of total ion count Short Long Short Long Short Long 1.0 (d) Ocimene (e) Phenylacetaldehyde (f) Benzyl acetate 80 35 40 t = 6.43 t = 3.71 t = 5.12 0.5 P < 0.001 30 P = 0.002 P < 0.001 30 Dimension 2 60 25 20 20 0.0 40 15 20 10 10 5 -0.5 0 0 0 Short Long Short Long -1.0 Short Long (g) Eugenol (h) Benzyl alcohol (i) Phenylethyl acetate -1.5 1.6 1.0 0.35 t = 1.53 t = 4.96 t = 4.89 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 1.4 0.30 P = 0.14 0.8 P < 0.001 P < 0.001 1.2 0.25 Dimension 1 1.0 0.6 0.20 0.8 0.4 0.15 0.6 0.10 0.4 0.2 0.2 0.05 0.0 0.00 0.0 Short Long Short Long Short Long
  • 49. Bimodal pattern floral tube and moth tongue length Anderson et al submitted to Evolution
  • 50. Selection against intermediates Cross pollination by hand Pollen limitation? Natural pollination Anderson et al submitted to Evolution
  • 51. Is there any incompatibility among morphs? Pollen parent Int Short Long Int Short Long Int Short Long 160 140 No significant reduction in seed set among crosses, Intermediates can have high seed set 120 except long mothers crossed with short fathers Mean seed set AB AB 100 BCD B BC AB AB 80 4 AD 26 60 AC 17 7 2 20 40 16 20 5 2 0 Int Int Int Short Short Short Long Long Long Anderson et al submitted to Evolution Ovule parent
  • 52. The Environment Institute The Australian Centre for Evolutionary Biology and Biodiversity Next seminar Environmental Genomics Dr Chris Hardy