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General Introduction and Characterization of the Marine Brown Algae:

Part I

Notes by Naomi PhillipsArcadia University

Edited by Suzanne FredericqUniversity of Louisiana at Lafayette

andBrian Wysor

Roger Williams University

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*Primarily marine class with 19 orders, *Primarily marine class with 19 orders, >50 families>50 families, , 270+ genera, 270+ genera, 2500 species2500 species

**All are multicellularAll are multicellular

*Range from simple filamentous forms to large complex plants *Range from simple filamentous forms to large complex plants (kelps)(kelps)

Brown Algae: GeneralBrown Algae: General

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*Rich in terms of biodiversity*Rich in terms of biodiversity

*Inhabiting great array of *Inhabiting great array of

habitatshabitats

*Critical primary producers in *Critical primary producers in

pelagic and coastal environmentspelagic and coastal environments

and in both temperate and and in both temperate and

tropical regions around the worldtropical regions around the world

Brown Algae: General

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*Pelagic beds in Sargasso *Pelagic beds in Sargasso sea, Gulf of Mexicosea, Gulf of Mexico

*Support host of creatures, *Support host of creatures, from crustaceans, fish to from crustaceans, fish to young turtlesyoung turtles

Pelagic brown algae

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Economic importance

Food, secondary productsFood, secondary productsSources of alginatesSources of alginates

Emulsifiers in Emulsifiers in everything from paint to everything from paint to ice creamice creamFrom kelp beds on US From kelp beds on US West CoastWest Coast

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Pigments Pigments Chl a & c & fucoxanthinChl a & c & fucoxanthin

Cell wallCell wallCellulose and mucilageCellulose and mucilage

Plant bodyPlant body

e.g., holdfast, stipe and bladese.g., holdfast, stipe and bladesReproduction/meiosis/life historyReproduction/meiosis/life history

Most: sporic (haplodiplontic)Most: sporic (haplodiplontic)One order: gametic One order: gametic

(diplontic)(diplontic)

Brown Algae: General

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Life history: alternation of generations

Sporic meiosis:haplodiplontic:Laminariales

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Life Histories

Gametic meiosis:Diplontic:Fucales

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Survey of Protistan assemblageSurvey of Protistan assemblage

*Dinoflagellates*Dinoflagellates

*Euglenophytes*Euglenophytes

*Crytomonads*Crytomonads

The Heterokonts-StramenopilesThe Heterokonts-Stramenopiles

•OomycotaOomycota

•DiatomsDiatoms

•Brown algaeBrown algae

----------------------------------------------------------------------------------

*Red algae*Red algae

*Green algae*Green algae

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Heterokonts-StramenopilesHeterokonts-Stramenopiles

Large heterogeneous group characterized by Large heterogeneous group characterized by two heterokont flagellatwo heterokont flagella

One smooth, one tinselOne smooth, one tinsel

Includes a variety of groups:Includes a variety of groups:OomycetesOomycetesDiatomsDiatomsBrown algaeBrown algaeGolden brown algaeGolden brown algae

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Endosymbiosis events

J. Phycol. Feb. 2009

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*

Kawai et al. 2003 Protist

BrownAlgae

HeterokontsHeterokonts

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Current Taxonomic TreatmentCurrent Taxonomic Treatment

Classifications historically emphasizes four features:Classifications historically emphasizes four features:

*Life history traits*Life history traits• sporic to gametic sporic to gametic

*Gamete types*Gamete types• isogamous to oogamousisogamous to oogamous

*Growth mode*Growth mode• diffuse, meristems, trichothallic, apicaldiffuse, meristems, trichothallic, apical

*Thallus morphology*Thallus morphology• filamentous to parenchymatousfilamentous to parenchymatous

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GameteGamete types types

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DiffuseDiffuse

MeristemsMeristems

ApicalApical

Growth modeGrowth mode

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Evolutionary Relationships among OrdersEvolutionary Relationships among Orders

-Traditional hypotheses make a variety of assumptions regarding -Traditional hypotheses make a variety of assumptions regarding primitive and derived character statesprimitive and derived character states

-Generally “simple to complex”:-Generally “simple to complex”:

*Relationships among brown algal orders were proposed to *Relationships among brown algal orders were proposed to reflect this progressionreflect this progression

*Basal groups have “simple” features*Basal groups have “simple” features

*Derived lineages have more “complex” features*Derived lineages have more “complex” features

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Traditional Traditional HypothesisHypothesis

Wynne & Loiseaux 1976

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From simple to more complex

•Is not a new concept

•Central theme in evolutionary thinking

•Common premise to our thinking of how many things

have evolved from land plants to animal systems

19Vascular tissue

Gametophyte protection and retention

Evolution of the seed

Land Plant Evolution

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Molecular PhylogenyMolecular Phylogeny

-Molecular data have been used to test the “simple to complex” -Molecular data have been used to test the “simple to complex” paradigmparadigm

-Molecular data provides a very distinct picture of brown algal -Molecular data provides a very distinct picture of brown algal evolution:evolution:

*“Simple” lineages are nested with more complex groups*“Simple” lineages are nested with more complex groups

*Some early divergences involved “complex” lineages*Some early divergences involved “complex” lineages

*Fucales nested within other lineages*Fucales nested within other lineages

Basal in most traditional taxonomiesBasal in most traditional taxonomies

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De Reviers et al. 2007

22““Crown” groupCrown” group

Basal L

ineag

esB

asal Lin

eages

Molecular PhylogenyMolecular Phylogeny

De Reviers et al. 2007

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•What are the relationships among basal lineages and the “crown” What are the relationships among basal lineages and the “crown” group?group?

•Did brown algal evolution generally follow a “simple to complex” Did brown algal evolution generally follow a “simple to complex” pattern? pattern?

–Pattern Pattern mustmust be more complex than just “simple to complex” be more complex than just “simple to complex”

–General pattern still needs to be establishedGeneral pattern still needs to be established

Questions

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• Phylogeny from Phylogeny from Phillips et al. (2008) Phillips et al. (2008) J. Phycol.J. Phycol. 4444:394:394

• Lineages with ESTs Lineages with ESTs (or genomic data) (or genomic data) available (or available (or expected) are in expected) are in purplepurple

• Libraries that we Libraries that we have produced and have produced and sequenced are: sequenced are:

– Schizocladia, Schizocladia, Choristocarpus, Choristocarpus, DesmarestiaDesmarestia