DeepBrown: A Tree of Life Study of the Heterokont Algae

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DeepBrown A Tree of Life Study of the Heterokont
Algae
Participating Institutions University of Texas at
Austin, CCMP- Bigelow Laboratory for Ocean
Sciences, University of Washington, St. Cloud
State University, Leiden University and Kobe
University.
Website http//ccmp.bigelow.org/deepbrown/
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What makes a heterokont a heterokont?

• Heterokonts (or stramenopiles) are a group of
  protists with unequal flagella at some stage in
  there life history (exceptions exist).
• Their chloroplasts when present are surrounded
  by 4 membranes (secondary endosymbiosis with a
  red alga)
• 16 currently recognized classes, but this
  fluctuates
• Basic systematics is still highly active
• several small classes are newly discovered
• Current classification is a mix of formal
  phylogenetic and informal phenetic

Pleuronematic, Tinsel, or Flimmer Flagellum with
mastigonemes
Acronematic Flagellum
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Plate 1, Figs 1-16. Representatives from most
heterokont algal classes as well as 3 colorless
stramenopile representatives. 1. Thalassiosira,
2. Bolidomonas, 3. Chrysamoeba, 4.
Pseudopedinella, 5. Nannochloropsis, 6.
Pelagomonas, 7. Pylaiella, 8. Phaeothamnion, 9.
Glossomastix, 10. Heterosigma, 11. Synura, 12.
Schizocladia, 13. Tribonema, 14. Symbiomonas, 15.
Opalina, 16. Schizochytrium. Representatives from
the new classes, Chrysomerophyceae,
Aurearenophyceae and Synchromophyceae are not
shown.
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Heterokonts are nested well within
chromalveolates but branching order within
chromalveolates and within heterokonts is very
poorly resolved
heterokont algae
stramenopiles
Solid triangles groups with plastids combined
nSSU and rbcL (amino acid sequence) Andersen,
2004. Am. J. Bot.
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SSU tree from Goertzen Theriot 2003 Morphology
and molecules agree 1 Most classes are
monophyletic. 2 Relationships among classes are
poorly understood. N.B. Under Total Taxa,
heterokonts are monophyletic, this was
not robust.
e.g., relationships very sensitive to taxon
sampling.
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GOALS

• To analyze the phylogenetic relationships of
  heterokont algae
• Conduct a combined data study based on 7
  nuclear, mitochondrial and plastid gene sequences
  from 270 heterokont algal species and 30
  colorless stramenopiles (outgroup).
• Sequence 30 chloroplast genomes of heterokont
  algae

Multigene Pilot Study
We began by performing a pilot study with 27 taxa
across the algal and colorless heterokonts in
order to assess the utility of candidate genes
before expanding to the full 300 taxa
proposed. NUCLEAR CHLOROPLAST MITOCHONDRIAL SS
U rRNA rbcL Cox1 LSU rRNA D1-D2
regio psbC Cob Actin atpB nad5 ?-tubulin
nad4 ?-tubulin nad2 Heat shock protein
90 Heat shock protein 70 Elongation factor
1? Elongation factor 2 RNA polymerase
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Why not morphology as a primary character?

• The main reason is impracticality.
• many characters are ultrastructural, requiring a
  great deal of tedious and expensive sectioning,
  TEM observation, 3-D reconstruction of flagellar
  roots and so forth.
• at best, an exemplar approach can be taken.
• Many of the characters so far proposed are
  autapomorphies anyway (viz., groups are easily
  diagnosed relationships between are highly
  obscure because of lack of characters not
  conflict).

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Minimum Criterion

• Alignable.
• All data to date, SSU, rbcL, morphology
  independently, unequivocally, agree on a few
  points monophyly of diatoms, phaeophytes,
  chrysophytes plus synurophytes.
• minimal criterion for ACCEPTANCE is that the
  pilot study returns these results
• NOT a criterion for rejection
• If it returns non-monophyly, but its signal is
  congruent with other such genes we will continue
  investigating it.
• Input from other groups working on protistan
  lineages, particularly chromalveolate.

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SSU MP
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arbitrarily rooted rbcL MP
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? -Tubulin MP
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? -Tubulin clones MP
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Multigene Summary
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