Algal Evolution: Division: Ochrophyta Or 3.9 bya = Cyanobacteria appear and introduce photosynthesis (Heterokontophyta, Chromophyta, Phaeophyta) 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 appear 490 mya = Phaeophyceae (Brown algae) & land plants & coralline algae & crustaceans & mulluscs 408mya= Insects & Fish 362 mya = Coccolithophores & Amphibians & Reptiles ~ 16,999 species 99% marine 290mya- Gymnosperms 145 mya = Diatoms & Angiosperms DOMAIN Groups (Kingdom) DOMAIN Groups (Kingdom) 1.Bacteria- cyanobacteria (blue green algae) 1.Bacteria- cyanobacteria (blue green algae) 2.Archae 2.Archae “Algae” 3.Eukaryotes 3.Eukaryotes 1. Alveolates- dinoflagellates, coccolithophore 1. Alveolates- dinoflagellates Chromista 2. Stramenopiles- diatoms, ochrophyta 2. Stramenopiles- diatoms, ochrophyta 3. Rhizaria- unicellular amoeboids 3. Rhizaria- unicellular amoeboids 4. Excavates- unicellular flagellates 4. Excavates- unicellular flagellates 5. Plantae- rhodophyta, chlorophyta, seagrasses 5. Plantae- rhodophyta, chlorophyta, seagrasses 6. Amoebozoans- slimemolds 6. Amoebozoans- slimemolds 7. Fungi- heterotrophs with extracellular digestion 7. Fungi- heterotrophs with extracellular digestion 8. Choanoflagellates- unicellular 8. Choanoflagellates- unicellular 9. Animals- multicellular heterotrophs 3 9. Animals- multicellular heterotrophs 4 1 DOMAIN Eukaryotes DOMAIN Eukaryotes Chromista = 17,500 spp. chloroplasts derived from red algae Chromista = 17,500 spp. chloroplasts derived from red algae contains Alveolates & Stramenopiles according to Algaebase contains Alveolates & Stramenopiles according to Algaebase Group Stramenopiles- 13,500 spp two unequal flagella, chloroplasts 4 Group Stramenopiles- 13,500 spp two unequal flagella, chloroplasts 4 membranes membranes Division Ochrophyta- 13, 235 spp. - many classes unicellular Division Ochrophyta- 13, 235 spp. diatoms & brown algae • class: Aurearenophyceae- 32 • class: Bacillariophyceae- 9657 pennate diatoms Class Phaeophyceae- 2059 spp. of brown algae • class: Bolidophyceae-14 Class Bacillariophyceae- 9659 spp. of pennate diatoms • class: Chrysophyceae- 595 Class Coscinodiscophyceae- 2199 spp. of centric diatoms • 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 5 6 • class: Xanthophyceae- 557 Algal taxonomy Ochrophyta Characteristics: Hierarchical system of classification: 1) Pigments? Level: suffix: example: Domain Eukaryota Group Chromista 2) Chloroplast structure? Division -phyta Ochrophyta Class -ppyhyceae Phaeoppyhyceae Order -ales Laminariales Family -aceae Lessoniaceae Genus Egregia 3) Storage product? species menziesii 4) Flagella? 2 2 Phaeophyceae Storage Products: Seawater is hypotonic (less saline) than most algal cells •laminaran and mannitol are most abundant Phaeophyceae Storage Products : •Always sugars, never starch •Storage products found in pyrenoids Mannitol function •important in osmoregulation- algae make more mannitol to use up ions-> algal salinity decreases •transporting organic material to different parts of the thallus in large species •lowers freezing point 4 Phaeophyceae Flagella: Phaeophyceae Metabolites: Heterokont flagella: Tannins - polyphenolic compounds Anterior “flimmer flagellum” Terpenes -aromatic hydrocarbons •used for movement • long flagellum with two rows of - Anti-endophyte, -epiphyte, and anti-herbivory stiff hairs (“mastigoneme”) •directed forward -Stored in special vesicles called physodes in the cytoplasm Posterior “whiplash flagellum” -May streng th cell walls by int eracti ng with alg ina tes •used for steering • short, smooth flagellum -Block UVB protecting algae from radiation damage •directed backward • contains flavin which functions as a photoreceptor • an eyespot acts a shading structure or light reflector Flagella attached laterally not apically 5 4 3 Phaeophyceae Thallus Morphology: Phaeophyceae Morphology of Cell Walls - Advanced forms: complex multicellular thalli - Not unicellular (except gametes and spores) Two main components: - Simplest forms are branching filaments 1. Cellulose microfibrils (1-10% of thallus dry weight) - More complex forms are parenchymatous and pseudoparenchymatous Function: structural support - Differentiation of cortex (outer pigmented cells) and medulla (inner non-pigmented cells) - Medullary cells primarily for storage or transport 2. Alginic acid surrounds the microfibrills (35% of thallus dry weight) - Some browns quite large over 40 meters long Function: elasticity; flexibility; prevent desiccation; and osmoregulation (ion exchange) 6 7 Phaeophyceae Alginates: Phaeophyceae Alginates: Alginates = salt form of alginic acid; primarily in intercellular matrix Human uses for alginates -Ice-cream prevents ice crystal formation •Alginates = Alginic acid + an Ion -Frosting water retaining properties; prevent drying • Details of how alginates are used in helping ion -Paints emulsifyygging agent; keep ppgs pigments susp ended and exchange are not well underst ood . prevents brush streaking • One proposed mechanism is that preferentially using -Pharmaceuticals some ions and not others helps to balance overall ion - Food “kombu” in Japan; dried and shredded laminarians levels. • Common ions that are used to make alginates are Ca, Na and Mg 8 8 4 Algal life histories : Terminology Phaeophyceae Reproduction: Gametangia = structure where gametes are formed Sporophyte: diploid, 2n, multicellular release spores Sporangia = structure where spores are formed 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 uniseriate multiseriate Gametangia = structure where gametes are formed Unilocular = all spores/gametes Plurilocular = divided into are produced in a single compartment many small chambers Gamete: unicellular, must fuse or die, product of mitosis(Mt) or (locules); one spore/gamete meiosis (Me) “unangia” per chamber “plurangia” 10 Phaeophyceae Reproduction: Phaeophyceae Reproduction: Functional Anisogamy = Functional Anisogamy = look the same but have different behaviors look the same but have different behaviors How do the male gametes find the female ones? female gamete male gamete 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 12 5 Division: Ochrophyta- 16,999 species Phaeophyceae habitat: Class: Phaeophyceae – 2,060 species • Mostly marine (or at least brackish water) Order: 19 orders but we will focus on 6 • Intertidal and subtidal 1. Fucales -591 species 2. Ectocarpales-787 species • Dominate colder waters 3. Dictyotales- 272 species Northern hemisphere: 4. Ralfsiales- 35 species # of red species > # of brown species 5. Desmerestales- 29 species 6. Laminariales- 148 species # of red individuals << # of brown individuals Browns are less diverse but more abundant 13 14 Distinguishing among orders based on Division: Ochrophyta- 16,999 species 1. Life History and Reproduction • Isomorphic/heteromorphic alt. of gen.; diplontic Class: Phaeophyceae – 2,060 species • Isogamous, anisogamous, oogamous Order: 19 orders but we will focus on 6 2. Macrothallus Construction: 1. Fucales -591 species •Filamentous - Usually saxicolous • Parenchymatous •Pseudoppymarenchymatous - Unattached in some cases -Unilllocular gametangia 3. Growth Genus: Fucus • Diffuse •Apical Silvetia •Intercalary Pelvetiopsis • Trichothallic • Meristodermal-a surface layer of cells (epidermis) that is Sargassum capable of dividing (is meristematic) Stephanocystis 15 14 6 Life History of Fucales Diplontic: 2N thallus, the gametes are the only Order: Fucales haploid stage 1. Life History and Reproduction 2. Macrothallus Construction: 3. Growth 25 26 Receptacle Monoecious- having the male & female - swollen tips of fucoids where meiosis occurs reproductive structure borne on - terminal portion of a branch bearing numerous the same individual plants embedded conceptacles -one house Dioecious- having the male & female reproductive structure borne on separate individual plants; said of the species Conceptacles -two houses - chambers where the gametes are stored 27 28 7 Conceptacles Fucus Silvetia Pelvetiopsis Mid Mid- high High Oogonia- female reproductive cell containing one or more egg (gamete) Midrib Playdough stipe Flattened stipe Antheridia- a male reproductive structure producing motile male gametes 1 egg per 29 8 eggs per oogonium 2 eggs per oogonium oogonium30 Sargassum: Sargassum Sargasso Sea in the Atlantic Stephanocystis =Unattached Sargassum spp rafts 31 32 8 Pneumatocysts- Division: Ochrophyta- 16,999 species -a large float containing gas found in Ochrophyta Class: Phaeophyceae – 2,060 species -provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for Ps Order: 19 orders but we will focus on 6 -