General Introduction and Characterization of the Marine Brown Algae:

P t IPart I

Notes by Naomi PhillipsArcadia University

Edited by Suzanne FredericqUniversity of Louisiana at Lafayette

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University of Louisiana at Lafayetteand

Brian WysorRoger Williams University 1

Brown Algae: GeneralBrown Algae: General

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

**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)

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Brown Algae: General

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

*Inhabiting great array of *Inhabiting great array of h bit th bit thabitatshabitats

*Critical primary producers in*Critical primary producers inCritical primary producers in Critical primary producers in pelagic and coastal environmentspelagic and coastal environmentsand in both temperate and and in both temperate and

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pptropical regions around the worldtropical regions around the world

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Pelagic brown algae

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

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Economic importance

Food, secondary productsFood, secondary productsSources of alginatesSources of alginates

Emulsifiers in Emulsifiers in everything from paint toeverything from paint toeverything from paint to everything from paint to ice creamice cream

From kelp beds on US From kelp beds on US West CoastWest Coast

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Brown Algae: General

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

Cell wallCell wallCellulose and mucilageCellulose and mucilageCellulose and mucilageCellulose and mucilage

Plant bodyPlant bodye.g., holdfast, stipe and bladese.g., holdfast, stipe and bladese.g., holdfast, stipe and bladese.g., holdfast, stipe and blades

Reproduction/meiosis/life historyReproduction/meiosis/life historyMost: sporic (haplodiplontic)Most: sporic (haplodiplontic)

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One order: gametic One order: gametic (diplontic)(diplontic)

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Life history: alternation of generations

Sporic meiosis:haplodiplontic:haplodiplontic:Laminariales

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Life Histories

Gametic meiosis:Gametic meiosis:Diplontic:Fucales

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Survey of Protistan assemblageSurvey of Protistan assemblage

*Dinoflagellates*Dinoflagellates*Euglenophytes*Euglenophytes*Crytomonads*CrytomonadsThe HeterokontsThe Heterokonts StramenopilesStramenopilesThe HeterokontsThe Heterokonts--StramenopilesStramenopiles

••OomycotaOomycota••DiatomsDiatomsDiatomsDiatoms••Brown algaeBrown algae

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*Red algae*Red algae*Green algae*Green algae 9

HeterokontsHeterokonts--StramenopilesStramenopiles

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

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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Golden brown algaeGolden brown algae

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Endosymbiosis events

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J. Phycol. Feb. 2009

*BrownAlgae

HeterokontsHeterokontsAlgae

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Kawai et al. 2003 Protist

Current Taxonomic TreatmentCurrent Taxonomic Treatment

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

*Life history traits*Life history traits•• sporic to gameticsporic to gameticsporic 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

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Thallus morphologyThallus morphology•• filamentous to parenchymatousfilamentous to parenchymatous

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GameteGamete typestypes

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Growth modeGrowth mode

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DiffuseDiffuse

MeristemsMeristems

ApicalApical

15MeristemsMeristems

Evolutionary Relationships among OrdersEvolutionary Relationships among Orders

T diti l h th k i t f ti diT diti l h th k i t f ti di--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*D i d li h “ l ” f t*D i d li h “ l ” f t

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

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Traditional Traditional HypothesisHypothesis

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Wynne & Loiseaux 1976

From simple to more complex

•Is not a new concept•Is not a new concept•Central theme in evolutionary thinking•Common premise to our thinking of how many things p g y ghave evolved from land plants to animal systems

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Land Plant Evolution

19Vascular tissue

Evolution of the seed

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Gametophyte protection and retention

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” p pp pparadigmparadigm--Molecular data provides a very distinct picture of brown algal Molecular data provides a very distinct picture of brown algal

l til tievolution: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” lineagesSome early divergences involved complex lineagesSome early divergences involved complex lineages*Fucales nested within other lineages*Fucales nested within other lineages

Basal in most traditional taxonomiesBasal in most traditional taxonomies

2020

2121

De Reviers et al. 2007

Molecular PhylogenyMolecular PhylogenyBB

22“Crown” group“Crown” group

Basal Line

Basal Line 22eages

eages

De Reviers et al. 2007

Questions

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

Did b l l l ti ll f ll “ i l t l ”Did b l l l ti ll f ll “ i l t l ”••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” p j p pp j p p––General pattern still needs to be establishedGeneral pattern still needs to be established

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

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

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

SchizocladiaSchizocladia

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–– Schizocladia, Schizocladia, Choristocarpus, Choristocarpus, DesmarestiaDesmarestia

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