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Division: OchrophytaOr

(Heterokontophyta, Chromophyta, Phaeophyta)

~ 16,999 species99% marine

Algal Evolution:

3.9 bya = Cyanobacteria appear and introduce photosynthesis

2.5 bya = Eukaryotes appeared (nuclear envelope and ER thought to come from invagination of plasma membrane)

1.6 bya = Multicellular algae -Rhodophyta (Red algae) &Chlorophyta (Green algae)

900 mya= Dinoflagellates & Invertebrates appeary g pp

490 mya = Phaeophyceae (Brown algae) & land plants & coralline algae & crustaceans & mulluscs

408mya= Insects & Fish

362 mya = Coccolithophores & Amphibians & Reptiles

290mya- Gymnosperms

145 mya = Diatoms & Angiosperms

DOMAIN1.Bacteria- cyanobacteria (blue green algae)2.Archae3.Eukaryotes

Groups (Kingdom)

1. Alveolates- dinoflagellates

2. Stramenopiles- diatoms, ochrophyta

3. Rhizaria- unicellular amoeboids

4 Excavates- unicellular flagellates

“Algae”

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4. Excavates- unicellular flagellates

5. Plantae- rhodophyta, chlorophyta, seagrasses

6. Amoebozoans- slimemolds

7. Fungi- heterotrophs with extracellular digestion

8. Choanoflagellates- unicellular

9. Animals- multicellular heterotrophs

DOMAIN1.Bacteria- cyanobacteria (blue green algae)2.Archae3.Eukaryotes

Groups (Kingdom)

1. Alveolates- dinoflagellates, coccolithophore

2. Stramenopiles- diatoms, ochrophyta

3. Rhizaria- unicellular amoeboids

4. Excavates- unicellular flagellates

Chromista

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5. Plantae- rhodophyta, chlorophyta, seagrasses

6. Amoebozoans- slimemolds

7. Fungi- heterotrophs with extracellular digestion

8. Choanoflagellates- unicellular

9. Animals- multicellular heterotrophs

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DOMAIN Eukaryotes

Chromista = 17,500 spp. chloroplasts derived from red algae contains Alveolates & Stramenopiles according to Algaebase

Group Stramenopiles- 13,500 spp two unequal flagella, chloroplasts 4 membranes

Division Ochrophyta- 13, 235 spp. - many classes unicellular• class: Aurearenophyceae- 32• class: Bacillariophyceae- 9657 pennate diatoms• class: Bolidophyceae-14

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class: Bolidophyceae 14• class: Chrysophyceae- 595• class: Coscinodiscophyceae- 2199 centric diatoms• class: Dictyochophyceae- 106• class: Eustigmatophyceae- 36• class: Fragilariophyceae-785 • class: Pelagophyceae- 16• class: Phaeophyceae-2059 brown algae• class: Picophagophyceae-4• class: Placidiophyceae-2• class: Raphidophyceae- 28• class: Synurophyceae- 314• class: Xanthophyceae- 557

DOMAIN Eukaryotes

Chromista = 17,500 spp. chloroplasts derived from red algae contains Alveolates & Stramenopiles according to Algaebase

Group Stramenopiles- 13,500 spp two unequal flagella, chloroplasts 4 membranes

Division Ochrophyta- 13, 235 spp. diatoms & brown algae

Class Phaeophyceae- 2059 spp. of brown algaeClass Bacillariophyceae- 9659 spp of pennate diatoms

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Class Bacillariophyceae 9659 spp. of pennate diatoms Class Coscinodiscophyceae- 2199 spp. of centric diatoms

Hierarchical system of classification:

Level: suffix: example:Domain EukaryotaGroup ChromistaDivision -phyta OchrophytaClass -phyceae Phaeophyceae

Algal taxonomy

p y p yOrder -ales Laminariales

Family -aceae LessoniaceaeGenus Egregia

species menziesii

Ochrophyta Characteristics:

1) Pigments?

2) Chloroplast structure?

3) Storage product?

4) Flagella?2

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•laminaran and mannitol are most abundant

•Always sugars, never starch

•Storage products found in pyrenoids

Phaeophyceae Storage Products:

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Phaeophyceae Storage Products :Mannitol function

•important in osmoregulation- algae make more mannitol to use up ions-> algal salinity decreases

Seawater is hypotonic (less saline) than most algal cells

•transporting organic material to different parts of the thallus in large species

•lowers freezing point

Heterokont flagella:

Anterior “flimmer flagellum”•used for movement• long flagellum with two rows of stiff hairs (“mastigoneme”) • directed forward

Posterior “whiplash flagellum”

Phaeophyceae Flagella:

Posterior whiplash flagellum•used for steering• short, smooth flagellum• directed backward• contains flavin which functions as a photoreceptor

• an eyespot acts a shading structure or light reflector

Flagella attached laterally not apically5

Phaeophyceae Metabolites:Tannins - polyphenolic compoundsTerpenes -aromatic hydrocarbons

- Anti-endophyte, -epiphyte, and anti-herbivory

-Stored in special vesicles called physodes in the cytoplasm

M t th ll ll b i t ti ith l i t

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-May strength cell walls by interacting with alginates

-Block UVB protecting algae from radiation damage

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- Advanced forms: complex multicellular thalli

- Not unicellular (except gametes and spores)

- Simplest forms are branching filaments

- More complex forms are parenchymatous and pseudoparenchymatous

- Differentiation of cortex (outer pigmented cells) and medulla (inner non-pigmented cells)

Phaeophyceae Thallus Morphology:

- Medullary cells primarily for storage or transport

- Some browns quite large over 40 meters long

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Phaeophyceae Morphology of Cell Walls

Two main components:

1. Cellulose microfibrils (1-10% of thallus dry weight)Function: structural support

2. Alginic acid surrounds the microfibrills (35% of thallus dry weight)Function: elasticity; flexibility; prevent desiccation; and

osmoregulation (ion exchange)

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Phaeophyceae Alginates:Alginates = salt form of alginic acid; primarily in intercellular matrix

•Alginates = Alginic acid + an Ion

• Details of how alginates are used in helping ion h t ll d t d exchange are not well understood.

• One proposed mechanism is that preferentially using some ions and not others helps to balance overall ion levels.

• Common ions that are used to make alginates are Ca, Na and Mg

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Phaeophyceae Alginates:

Human uses for alginates - Ice-cream prevents ice crystal formation

- Frosting water retaining properties; prevent drying

- Paints emulsifying agent; keeps pigments suspended and y g g p p g pprevents brush streaking

- Pharmaceuticals

- Food “kombu” in Japan; dried and shredded laminarians

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Algal life histories : Terminology

Sporophyte: diploid, 2n, multicellular release spores

Sporangia = structure where spores are formed

Spore (mitospore, meiospore): unicellular, must settle & grow, product of mitosis(Mt) or meiosis (Me)

Gametophyte: hapliod, 1n, multicellular release gametes

Gametangia = structure where gametes are formed

Gamete: unicellular, must fuse or die, product of mitosis(Mt) or meiosis (Me)

Gametangia = structure where gametes are formed

Sporangia = structure where spores are formed

Phaeophyceae Reproduction:

Unilocular = all spores/gametesare produced in a single compartment

“unangia”

Plurilocular = divided into many small chambers (locules); one spore/gamete per chamber

“plurangia”10

uniseriate multiseriate

How do the male gametes find the female ones?

Phaeophyceae Reproduction:Functional Anisogamy =

look the same but have different behaviors

Pheromones = chemicals produced to elicit a specific behavioral or physiological response from another individual.

Many Phaeophyceans produce sexual pheromones, all are chemically similar (unsaturated hydrocarbons). Similarity high cross-reactivity

Male gametes are VERY sensitive to pheromones: very low concentration will elicit a response 11

Phaeophyceae Reproduction:

female gamete male gamete

Functional Anisogamy = look the same but have different behaviors

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Phaeophyceae habitat:

• Mostly marine (or at least brackish water)

• Intertidal and subtidal

• Dominate colder waters

Northern hemisphere:

# of red species > # of brown species

# of red individuals << # of brown individuals

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Browns are less diverse but more abundant

Division: Ochrophyta- 16,999 speciesClass: Phaeophyceae – 2,060 species

Order: 19 orders but we will focus on 61. Fucales -591 species2. Ectocarpales-787 species3. Dictyotales- 272 speciesy p4. Ralfsiales- 35 species5. Desmerestales- 29 species6. Laminariales- 148 species

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Distinguishing among orders based on

1. Life History and Reproduction• Isomorphic/heteromorphic alt. of gen.; diplontic• Isogamous, anisogamous, oogamous

2. Macrothallus Construction:• Filamentous• Parenchymatous• Pseudoparenchymatousp ym

3. Growth• Diffuse• Apical• Intercalary• Trichothallic• Meristodermal-a surface layer of cells (epidermis) that is

capable of dividing (is meristematic)

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Division: Ochrophyta- 16,999 speciesClass: Phaeophyceae – 2,060 species

Order: 19 orders but we will focus on 61. Fucales -591 species

- Usually saxicolous- Unattached in some cases

l l Genus: Fucus

SilvetiaPelvetiopsisSargassumStephanocystis

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- Unilocular gametangia

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Order: Fucales

1. Life History and Reproduction

2. Macrothallus Construction:

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3. Growth

Life History of FucalesDiplontic: 2N thallus, the gametes are the only

haploid stage

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Receptacle- swollen tips of fucoids where meiosis occurs- terminal portion of a branch bearing numerous

embedded conceptacles

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Conceptacles - chambers where the gametes are stored

Monoecious- having the male & femalereproductive structure borne on the same individual plants-one house

Dioecious- having the male & female reproductive structure borne on separate individual plants; said of the species

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separate individual plants; said of the species-two houses

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Oogonia- female reproductive cell containing one or more egg (gamete)

Conceptacles

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Antheridia- a male reproductive structureproducing motile male gametes

Fucus Silvetia PelvetiopsisMid Mid- high High

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Midrib Playdough stipe Flattened stipe

8 eggs per oogonium 2 eggs per oogonium1 egg per oogonium

Sargasso Sea in the Atlantic

=Unattached Sargassum spp rafts

Sargassum:

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Stephanocystis Sargassum

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Pneumatocysts--a large float containing gas found in Ochrophyta-provide buoyancy to lift the blades toward the surface,

allowing them to receive more sunlight for Ps- can hold O2, CO2, CO

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Cystoseria osmundacea Sargassum muticum-catenate series -singly

Division: Ochrophyta- 16,999 speciesClass: Phaeophyceae – 2,060 species

Order: 19 orders but we will focus on 62. Ectocarpales-787 species

- Saxicolous or epiphytic- Uniseriate filaments

ll l

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- Opportunistic spp, excellent colonizers-Female gametes releases pheromone

ectocarpene

Genus: EctocarpusHaplogloia

Order: Ectocarpales:

1. Life History and Reproduction:

2. Macrothallus Construction:

3. Growth:

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Life History of Ectocarpales:Isomorphic Alternation of Generations

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Unangia ovoid

Haplogloia andersonnii –heteromorphic alternation of generation

diplohaplontic

Sporophyte (2N)

Gametophyte (1N)- microscopic disk

Division: Ochrophyta- 16,999 speciesClass: Phaeophyceae – 2,060 species

Order: 19 orders but we will focus on 63. Dictyotales- 272 species

- Saxicolous- Common in tropical waters;

ls f d l ll s btid lalso found locally subtidal- Pheromone= dictyotene

Genus DictyotaPadina

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Order: Dictyotales

1. Life History and Reproduction:

2 M cr th llus C nstructi n:2. Macrothallus Construction:

3. Growth:

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Life history of Dictyota

• Reproductive structures in “sori” = cluster of gametangia or sporangia

• Tetraspores (non-flagellated) released by 2N sporophyte

• Gametophyte dioecious

• Large egg one per “oogonium” = female reproductive structure containing one or more eggs

• Sperm single hairy flagella but has second basal body

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Life History of Dictyota:Isomorphic Alternation of Generations

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A Dictyota Story:(Stachowicz and Hay 2000)

Southern Sites + Libinia dubia, the

decorator crab Northern Sites+ Libinia dubia, the

Cape HatterasLocal adaptationAssociational defences

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decorator crab + Dictyota menstrualis,

the chemically defended brown alga (diterpenes)

+ Omnivorous fishes+ Crabs are specialists

in decoration preference

Libinia dubia, the decorator crab

+ No chemically noxious algae

+ Carnivorous fishes

+ Crabs are generalists in decoration preference

The only calcified Phaeophycean: Padina

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Increased Grazing

Division: Ochrophyta- 16,999 speciesClass: Phaeophyceae – 2,060 species

Order: 19 orders but we will focus on 64. Ralfsiales- 35 species

- Saxicolous or epiphytic- Common intertidally, tropics to poles

st s i t l st lif hist st- crustose in at least one life history stage

Genus: RalfsiaAnalipus

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Order: Ralfsiales

1. Life History and Reproduction:

2 M h ll C i2. Macrothallus Construction:

3. Growth:

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Analipus japonicus-perennial crustose base up to 5cm with erect axes

that die back in the fall

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Ralfsia

Division: Ochrophyta- 16,999 speciesClass: Phaeophyceae – 2,060 species

Order: 19 orders but we will focus on 65. Desmerestailes- 29 species

- Saxicolous- Low intertidal to subtidal

“ d d”- “Acid weed”

Genus Desmarestia

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Order: Desmarestiales

1. Life History and Reproduction:

2. Macrothallus Construction:

3. Growth

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Life History of Desmarestiales

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- Morphology variable within the genus

-Subtidal, but grows well in high light (very abundant if disturbance has removed other plants or canopy, e.g. El Nino, or urchin grazing)

- Disappears with kelp growth due to canopy cover; shading

- ”Acid weed”: cells accumulate sulfate ions from seawater which reacts with water to produce sulfuric acid or malic acid, stored in vacuoles

=ANTIHERBIVORY, pH 0.8-1.8, bleaches other algae

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