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Unformatted text preview: Kingdom Protista Kingdom Brown algae Green algae Simple Eukaryotes Red algae J e Kingdom Protista Kingdom
Division Phaeophyta, first brown plants first
land plants evolve • Recent plants, ~500 mya • “Standard” eukaryote cells No multinucleate cells Motile cells usual • Non-standard chloroplasts Things we will cover for brown algae
• General features - defining characteristics • Morphological lineages – - use morphology to anticipate evolution - reveal variations in life history & gametes • Ecology – understanding interactions with environment and other species • Commercial interests – exploit ecology & life history • Evolution – diversity & change over time General features General Ocean lovers
Ocean Forests 2,000 species (60 in HI oceans) 250+ genera (29 in HI) Morphological Range:
filaments to complex multicell organisms Recently arrived eukaryotes well suited to coastal habitats Intertidal Reef algae Natives and invasives Subtidal Diversity Diversity General features
photosynthesis Storage Products Products Growth • Chlorophyll a • Chlorophyll c • Fucoxanthin Others
• Carotenoids • UV absorbing molecules Photosynthesis Photosynthesis & Pigments
• Light energy is harvested by the cell sunlight • Only specific colors are absorbed • Other colors are reflected back to your eye thylakoids Chl a, c a, Chl a, c a, fucoxanthin Chlorophyll a & c
Tetrapyrrole Ring Phytol Chain of Chl a missing in Chl c General features
photosynthesis Storage Products Products
• Laminarin • Mannitol
Sugar (C) Sugar (C) Starch (C) (C) • Every cell can divide Growth • Chlorophyll a • Chlorophyll c • Fucoxanthin • Multicellular organisms:
Fragments regrow • True tissues
Others • Carotenoids • UV absorbing molecules Cell wall structure Cell
Two essential parts:
• fibers of cellulose (rigid), a glucose polymer • gels of polysaccharides (flexible) as ALGINATE Cell wall structure Cell
Two essential parts:
• fibers of cellulose (rigid), a glucose polymer • gels of polysaccharides (flexible) as ALGINATE “Copolymer” blocks of sugars Guluronic (G) Mannuronic (M) General features General
What is in a typical phaeophyte cell?
• Unusual membrane system around chloroplast and nucleus • Pyrenoid large, stalked and surrounded by laminarin starch • Chloroplasts have grana Evolution of eukaryotes Xenogenous hypothesis Xenogenous
heterotrophs Simple cells phagocytosis Autotrophs - green and red algae Mereschowsky, 1905; 1910 General features General
How are phaeophyte cells unusual?
• “New” membranes around chloroplast & nucleus First step: Second step: Repeated endosymbioses Second eukaryote Life History as a Life “Strategy” Zygotic Meiosis Life History
Gamete DOES NOT OCCUR IN BROWN ALGAE
Zygote Gamete Meiosis Meiosis is associated with Zygote Germination Morphological lineages Morphological
• Evaluate adult form to gain insight in possible evolutionary processes. • Step-by-step acquisition of new traits via genetic change. • Examine reproductive cells and other characters as additional data. • Useful means to construct evolutionary hypotheses to test with molecular data. Life History as a Life “Strategy” Meiosis is associated with Spore Production Growth & Growth morphology
Ectocarpus Genetic change Morphological Lineage #1 Order Ectocarpales All cells appear virtually identical internally Hincksia
Evolution has taken a simple shape to more complex but related forms: forms • Multi filamentous genera Ralfsia Diversity
Order Ectocarpales Ectocarpus Ralfsia Hincksia sp Life history by Life observation
Same motile cell has 2 behaviors ? Where’s meiosis ? Life History as a Life “Strategy”
recognition zygote germling isogametes Ectocarpus sp.
mitosis mitosis meiosis spores adults germlings mitosis Life History as a Life “Strategy” Meiosis is associated with Spore Production Reproduction Reproduction and gametes
2 Gametes – opposite strains always fuse Equally sized gametes Isogamy Unequal gametes Anisogamy Zygote – diploid cell via fusion of gametes Egg & sperm gametes Oogamy egg Minimal diversity Minimal in gamete shape…
• But flagella of swimming cells
are unequal in length and HAIRY Equal length flagella Iso kont Swimming gametes have 2 flagella like greens Unequal length flagella Hetero kont Laterally inserted Minimal diversity Minimal in gamete shape…
These males gametes show the limited diversity among brown algae Reds – spermatium Greens – biflagellate to stephanokont males Minimal diversity in spore shape
• Most brown algal spores swim • 2 flagella • Settlement ? Diversity Tropical Orphans
Scytosiphon sp. Hydroclathrus sp. Rosenvingea sp. Colpomenia sp Spatoglossum sp. Growth & Growth morphology Morphological Lineage #2 Order Dictyotales Dictyota Dictyopteris Evolution has taken a simple filament: Multiseriate tissues create sheets or blades From apical cell or meristem areas
Padina Diversity Diversity
Order Dictyotales Dictyota sp. Padina sp. Life History as a Life “Strategy”
recognition zygote oogametes meiosis tetra spores Dictyota
mitosis spores mitosis adults germlings Life History as a Life “Strategy” Meiosis is associated with Spore Production Growth & Growth morphology Morphological Lineage #3 Order Laminariales Laminaria Alaria Evolution has taken a simple shape: • constrained into lamina • large sporophyte generations Macrocystis Diversity Diversity
Order Laminariales Ecology Ecology
Kelp forests sustain coastal diversity
epiphytic pelagic benthic understory Life History as a Life “Strategy”
Macrocystis Life History as a Life “Strategy” Ecklonia cava
Spores Egg and sperm Growth & Growth morphology
Ectocarpus Morphological Lineage # 4 Order Fucales Dictyopteris sp Sargassum obtusifolium Sargassum thunbergii Gunma Japan Diversity Order Fucales Sargassum cristaefolium Guam Life History as a Life “Strategy” Meiosis is associated with Gamete Production Life History as a Life “Strategy” juvenile
recognition zygote Sargassum sp.
oogametes adult meiosis vegetative cell detail Life History as a Life “Strategy”
1 free living entity Cells must pass through this cycle
• to add new genetic individuals to population Ecology of Hawaiian Reef Algae.
w Biomass 6000 5000 4000 3000 2000 1000 0 Frondose Algae of Wakiki, by M S. Doty 1969 ,m Dictyotales, o Fucales representatives on reefs et wt, g/m 2 Du 1 4 250 ra t 7 200 ion 9 150 of 12 100 stu 13 17
0 50 dy eef R r , ion eg m fro m o re sh All browns were native species Most abundant biomass near shore ...
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- Spring '08