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Post- fertilization Events Distinguishing between Orders of Florideophyceae Triphasic Life Histories :Terminology Connecting filament or Ooblast filament = tube that carries the zygote nucleus from fertilized egg to internal auxiliary cell where it is cloned and differentiates into carpospores (in some Orders!) Auxiliary cell = vegetative cell (N) that receives the 2N zygote nucleus after fertilization (in some Orders!) cp Gonimoblast = 2N filaments bearing carposporangia in the carposporophyte (ALL Florideophyceans have this) Auxiliary cell present oo Auxiliary branch & carpogonial branch arise from same supporting cell Auxiliary cell absent Gominoblast initiated from carpogonium Auxiliary cell present Ooblast filament transfers zygote nucleus to auxiliary cell Gonimoblast initiated from a fused carpogonium & auxiliary cell Gonimoblast initiated from auxiliary cell Division: Rhodophyta- 7117 species 3.Class: Florideophyceae-6767 species 3.Class: Florideophyceae Auxiliary cell absent 1.Order Nemaliales Gominoblasts initiated from carpogonium Pit plugs characterized by 2 cap layers Order: 29 orders but we will focus on 5 1. Nemaliales -273 species 2. Rhodomeniales-382 species 3. Ceramiales- 2662 species 4. Gigartinales- 880 species p 5. Corallinales- 725 species Spermatium 2N carpospores on gonimoblast filaments Tricogyne Carpogonium Carpogonial branch 14 1N female gametophyte 2N carposporophyte on 1N female gametophyte 1 3.Class: Florideophyceae 2. Order Rhodomeniales 3.Class: Florideophyceae 1.Order Nemaliales Genus: Cumagloia - cylindrical with branchlets - multiaxial - saxicolous - intertidal Auxiliary cell formed before fertilization Auxiliary branch & carpogonial branch arise from same supporting cell Gominoblast initiated from a fused carpogonium & auxiliary cell Spermatium 2N carpospores on gonimoblast i bl filaments Carpogonium Carpogonial branch S A S Auxiliary Cell Supporting Cell 1N female gametophyte 3.Class: Florideophyceae 2. OrderRhodomeniales Genus: Rhodomenia 2N carposporophyte on 1N female gametophyte 3.Class: Florideophyceae 2. Order Rhodomeniales Genus: Botryocladia -Subtidal, saxicolous - Mucus-filled sacs - Multiaxial - “sea grapes” -Subtidal, saxicolous - Associated with juvenile fish - Dichotomous branching - Multiaxial 2 3. Class: Florideophyceae 3. Order: Ceramiales Auxiliary cell develops from supporting cell of carpogonial branch after fertilization Genus: Ceramium Ooblast filament forms between carpogonium & auxiliary cell Gominoblast initiated from axiliary cell Spermatium Tricogyne 3.Class: Florideophyceae 3. Order Ceramiales Genus Polysiphonia After fertilization Carpogonium Carpogonial Branch S Supporting cell 1N female gametophyte - Prominent trichoblasts which leave scars after they fall off. - Number of pericentral cells helps to identify to species - Polysiphonous S A S A Ooblast filament trasfers zygote nucleus 2N carpospores on gonimoblast filaments 2N carposporophyte on 1N female gametophyte 3. Class: Florideophyceae 3. Order: Ceramiales Genus: Ceramium 3.Class: florideophyceae 3. Order Ceramiales Genus Microcladia - saxicolous or epiphytic - fully corticated - distichous - uniaxial - saxicolous or ephiphytic - fully or partially corticated - uniaxial alternate pectinate 3 3.Class: Florideophyceae 4. Order Gigartinales Auxiliary cell present BEFORE fertilization but on a distant branch Ooblast filament transfers zygote nucleus to auxiliary cell Gominoblast initiated from auxiliary cell Spermatium Ooblast filament trasfers zygote nucleus Supporting Cell A A Auxiliary Cell 2N carpospores on gonimoblast filaments 3.Class: Florideophyceae 4. Order Gigartinales Genus Mazzaella Common local species: •M. flaccida – yellow/green; mid to upper intertidal •M. splendens – red/purple; low intertidal Iridescence • Proteinaceous cuticle • Multiple layers • Alternating opaque and translucent layers • Layering produces light interference patterns that give iridescent appearance when submerged • Adaptive advantage unknown 2N carposporophyte on 1N female gametophyte 1N female gametophyte 3.Class: Florideophyceae 4. Order Gigartinales Genus Mazzaella 3.Class: Florideophyceae 4. Order Gigartinales Genus Mastocarpus species complex 2N carposporophytes on female gametophyte 1N gametophytes - multiaxial - filamentous medulla Gametophyte Carposporophyte Tetrasporophyte 2N tetrasporophyte 4 3. Class: Florideophyceae 4. Order: Gigartinales Genus: Constantinea 3.Class: Florideophyceae 4. Order Gigartinales Genus Endocladia - uniaxial - thallus covered with bumps (antiherbivory) - very high intertidal - saxicolous - can facilitate recruitment of other algae (Fucoids) - cup and saucer algae - intertidal to subtidal Other spp in Gigartinales are important for carageenan production 3. Class: Florideophyceae 5. Order: Corallinales • Isomorphic alternation of generations • Reproductive structures in conceptacles • Cell walls impregnated with CaCO3 ( (anti-herbivory) i h bi ) • More calcified red algae than any other algae • Ecological importance: stabilize reefs, induce invert settlement • Especially sensitive to desiccation – occur IN tidepools (not nearby surfaces) 3. Class: Florideophyceae 5. Order: Corallinales • Fossils from 500 million years ago • A crustose coralline alga g in AK is ~700 years old – oldest alga known on earth?!! 5 How do coralline algae become calcified? Coralline Algae and Global Warming Carbon reaction in seawater: What is known: • Sequestering of Calcium ions from the water column, synthesis of calcium carbonate (CaC03) into cell wall • Synthesis of calcium carbonate (precipitation) requires high pH (basic/alkaline) • High g rates of fp photosynthesis y correlate with high g rates of f calcification CO2 + H20 H2C03 Carbonic acid more acidic • Highest in young tissue (growth at apices and intergenicula) Bicarbonate Increasing CO2 pushes h RXN in i this hi 2 CO3 + H+ Carbonate more basic direction • Photosynthesis may raise the pH immediately outside cells • Calcification is 10x faster in the light than the dark HCO3 + H+ • Global warming likely to lead to a lower in pH (raise in acidity of the world’s oceans • Acidic environment is bad for calcification process big (complicated) trouble for calcified critters and algae!! • Lots of current research on this 3. Class: Florideophyceae 5. Order: Corallinales Supporting cell acts as an auxiliary cell Carpogonial branches located in conceptacles Gominoblast initiated from a fusion of cells in carpogonial branch Spermatium Geniculate corallines Intergeniculum (hard part between genicula) 2N carpospores on gonimoblast filaments Non-geniculate corallines Supporting Cell Crustose Encrusting Carpogonial Branch Geniculum (flexible joint) • upright •articulated or Unattached Branching Tricogyne Carpogonium 1N female gametophyte 2N carposporophyte on 1N female gametophyte 6 3. Class: Florideophyceae 5. Order: Corallinales Genus Bossiella 3. Class: Florideophyceae 5. Order: Corallinales Genera Corallina - Common intertidaly - Intergenicula typically “heartshaped” - Common intertidally - Conceptacles p on tips p -Finely branched, more so than Bossiella or - Conceptacles in pairs on the face of a segment, not margins Calliarthron - Intergenicula are thin and tubular and smaller than those on Bossiella or Calliarthron 3.Class: florideophyceae-6767 species 5. Order Corallinales- 725 species Genus Caliarthron -Common intertidally -Intergenicula n g n u typically yp y “wingnut-shaped” - Intergenicula are larger than Corallina 3. Class: Florideophyceae 5. Order: Corallinales Genus Lithothamnion • rhodolith •unattached • free-living • non- geniculate form g habitat for lots of inverts! • biogenic - Conceptacles mainly on margins of segments - Calcareous sections are larger than Corallina 7 Distributional Limits World Rhodolith Distribution •Depth -light limited in deep, dessicated in shallows •Water motion-need intermediate amount of hydraulic energy •Sedimentation -smothered by fine sediments low DISTURBANCE high Rhodolith Beds New Report Foster 2001 Biogenic Ecosystems – Foundation Species Kelp Forests Seagrass Meadows buried by siltation ‘intact’ rhodolith bed ‘reduced’ size, cover sand Rhodolith beds, reefs that rock and roll Coral Reefs Rhodolith Beds 8 What are other important features of rhodolith beds? Form complex habitat for a variety of orgamisms Cover extensive ares of the seafloor, globally distributed Rhodolith Bed Community Cryptofauna/Infauna Epifauna/Epiflora • hard bottom species • soft bottom species Seasonal Macroalgal Species Scinaia confusa Halymenia hollenbergii Sporochnus bolleanus Kallymenia pertursa 9 Growth Rate L. muellerii 0.6 mm/yr L. margaritae 5.6 mm/yr S. trichotomum 7-8 mm/yr Catalina rhodoliths 1.6 mm/yr Internal Banding New growth Coralline algae as global palaeothermometers Baja California Banding reflects sea surface temperature signal using SrCO3 and M CO3 MgCO They are found in Pleistocene and Pleiocene fossil deposits Lithothamnion glaciale Kamenos et al. 2008 10 Post-fertilization in a nutshell auxiliary cell? No Yes Before After Ceramiales – Ooblast? (has ooblast) Yes. Gigartinales – Auxiliary cell is anywhere in thallus No. Rhodymeniales – Fusion with carpegonium Nemaliales – Gonimoblasts from carpegonium Corallinales – Fusion of carpegonium with carpegonial branch * Supporting cell acts as auxiliary cell 11
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