Algae Lecture Notes PDF

Evolution and Diversity of Algae With focus on m rine m cro lg e Am nd S voie, November 2024 a a a a a a a...

Evolution and Diversity of Algae With focus on m rine m cro lg e Am nd S voie, November 2024 a a a a a a a a  About me Research scientist in botany at the Canadian Museum of Nature Fell in love with seaweeds during a marine plants course at UNB Completed a PhD on the taxonomy of a speci ic group of red algae (the genus Polysiphonia) f Biodiversity of Algae What are algae? Algae Mostly photosynthetic organisms (but excluding land plants) “A heterogeneous assemblage of organisms … largely de ned by ecological traits”. Graham et al. 2009 Freshwater, marine, terrestrial Not a natural group protist.i.hosei.ac.jp Chris Garden Photography Chlorococcum sp. Dasya sp. Macrocystis pyrifera fi  Algae The scienti c study of algae = phycology From the Greek “phykos” for seaweed Photosynthetic organisms are found scattered throughout the tree of life Reyes-Prieto et al. 2007 Glaucocystis sp. Chaetoceros sp. Peridinium sp. Euglena sp. wikipedia.org Sarah Rushforth protist.i.hosei.ac.jp thoughtco.com fi  Importance of Algae Algae are of fundamental importance in global ecosystems They produce 50 - 80% of the world’s oxygen Marine algae absorb carbon dioxide during photosynthesis and act as a carbon sink They form the base of aquatic food webs Large marine algae like kelp form underwater forests that create 3D habitats and promote diversity www.microscopy-uk.org.uk Eukaryotic Supergroups Burki et al. 2020 Primary and secondary endosymbiosis are an important part of understanding algal diversity The origin of mitochondria and chloroplasts Theory: Mitochondria and chloroplasts evolved by endosymbiosis Mitochondria + chloroplasts were formerly small prokaryotes that began living within larger cells Bene cial for both endosymbiont + host Outer mitochondrial/chloroplast membrane is a remnant of a food vacuole fi On several occasions during eukaryotic evolution, red and green algae underwent secondary endosymbiosis, in which they were ingested by a heterotrophic eukaryote Burki et al. 2020 Archibald 2009  TSAR Supergroup Telonemi , Str menopil , Alveol t nd Rhiz ri Huge group, up to half of Eukaryotic diversity Stramenopila: Diatoms – unicellular autotrophs Produce organic molecules, key source of food in aquatic environments wired.com Fossilized diatoms = diatomaceous earth a a a a a a a a  TSAR Supergroup Telonemi , Str menopil , Alveol t nd Rhiz ri Noctiluca scintillans Stramenopila: Brown algae – multicellular, autotrophic Some marine seaweeds, kelp Alveolata: Padmakumar et al. 2016 Ceratium tripos Dino agellates - unicellular autotrophs, heterotrophs, mixotrophs Produce toxins (red-tide); live with corals britannica.com fl a a a a a a a a  TSAR Supergroup Telonemi , Str menopil , Alveol t nd Rhiz ri Rhizaria: Chlorarachniophytes Ameboid, coccoid and agellate cells Most Rhizaria non-photosynthetic Eg. Foraminiferans have porous shell (test) made of calcium carbonate, pseudopodia for feeding + locomotion Hirakawa et al. 2011 a a a fl a a a a a  TSAR Supergroup Telonemi , Str menopil , Alveol t nd Rhiz ri Non photosynthetic: Water molds (Oomycetes, Stramenopila) Decompose dead plants + animals in freshwater; can be plant parasites Ciliates (Alveolata) Use cilia to move + sweep food into mouth Apicomplexans (Alveolata) Many human parasites including malaria (genus Plasmodium) Diversity of Ciliates a a a a a a a a Burki et al. 2020  Haptista and Cryptista Haptista includes centrohelids (hetrotrophic) and haptophytes (algae) Coccolithophores are haptophytes Marine plankton Blooms can be seen from space USGS Cryptista includes cryptomonads (algae) and katablepharids (heterotrophic) Dr. Jeremy Young Burki et al. 2020  Excavata Have an “excavated” feeding groove Autotrophic, heterotrophic, mixotrophic Photosynthetic: Euglena Parasitic examples: Giardia, Trypanosoma (sleeping sickness) Gerd Guenther/Science Photo Library/Getty Images Burki et al. 2020  Archaeplastida Mostly photosynthetic Plastids derived from primary endosymbiosis Monophyly based on genetic evidence Includes glaucophytes, red algae, green algae, charophytes, and embryophytes (land plants) Land plants, charophytes and green algae = Viridiplantae as they have many shared characters britannica.com Archibald 2009  Algae 30,000 to 50,000 species worldwide Many groups cryptic and poorly known Ranging in size from 2 µm to 50+ meters in size Not a monophyletic group Important in terrestrial and aquatic habitats Seaweeds Marine macroalgae Found in coastal regions around the world  Seaweeds Primary producers Support higher trophic levels Add three-dimensional structure to the intertidal and subtidal Carbon sink Cultural and economic importance  Laminaria digitata Ulva sp. Phycodrys rubens Three main groups: red algae (Rhodophyta), brown algae (Phaeophyceae) & green algae (Chlorophyta) Green Algae Examples of many types of green algae Lewis and McCourt 2004 Lewis and McCourt 2004  Green Algae Chlorophyll a and b Accessory pigments do not mask chlorophyll Chloroplasts with two membranes and stacked thylakoids Starch is stored in the plastid Mostly freshwater, but a few groups exclusively marine  Green Algae Kingdom: Plantae Trebouxia sp. Phylum: Chlorophyta Phylum Chlorophyta includes 3 classes: Chlorophyceae, Trebouxiophyceae, and Ulvophyceae Only Trebouxiophyceae and Ulvophyceae have macroscopic, http://protist.i.hosei.ac.jp marine species Isomorphic alternation of generations  Examples in Atlantic Canada Ulva fenestrata Acrosiphonia sonderi Photos by Jordan Chalfant Red Algae  Red Algae Plastids with two membranes and unstacked thylakoids Plastids do not contain starch – oridean starch is stored in the cytoplasm Flexible cell wall (extracellular matrix) Accessory pigments phycoerythrin and phycocyanin obscure the colour of chlorophyll a Red algae lack agella and centrioles at all phases of their life history Cells are connected by pit-plugs fl fl  Red Algae Kingdom: Plantae Phylum: Rhodophyta multicellular and mostly marine unicellular unicellular rare freshwater unicellular Yoon et al. 2006 Pyropia leucostica (Bangiophyceae) Red algae are highly diverse (>7000 species worldwide)  Red Algal Reproduction Alternation of generations (biphasic or triphasic) Oogamy Smaller, non-motile male gamete fuses with larger, non-motile female gamete Alternation of generations can be isomorphic or heteromorphic Special terminology Examples in Atlantic Canada Palmaria palmata Chondrus crispus Photos by Jordan Chalfant Brown Algae brown algae  Stramenopiles / Heterokonts Two synonymous names for the same diverse clade of eukaryotes Both refer to the arrangement of agella Unicellular species have two agella of unequal length Multicellular species produce motile unicells with unequal agella during certain life phases A unicellular stramenopile with two distinct agella fl fl fl fl  Stramenopiles Infrakingdom: Stramenopila Kingdom: Chromista Phylum: Ochrophyta Includes: brown algae (Phaeophyceae), diatoms (Bacillariophyceae), golden algae (Chrysophyceae), yellow- green algae (Xanthophyceae) many other groups Brown algae (Fucus) in the low intertidal zone, Blacks Harbour, NB Kelp forests in Labrador (Saccharina latissima)  Stramenopiles Carbohydrate storage product known as chrysolaminarin or laminarin, stored in vacuoles One or more plastids per cell, with four membranes Thylakoids occur in stacks of three The golden-brown or brown colour is due to the accessory pigment fucoxanthin  Brown Algae Infrakingdom: Stramenopila Kingdom: Chromista Phylum: Ochrophyta Class: Phaeophyceae There are >250 genera and >1500 species of brown algae Ectocarpus  Brown Algae Almost exclusively seaweed Marine and macroscopic All are multicellular Body forms vary from microscopic laments to giant kelps A few freshwater species Conspicuous component of the intertidal and subtidal zones of temperate and polar regions Have developed more specialization of tissues than other algae fi  Brown Algal Reproduction Alternation of generations Gametophyte (N) Sporophyte (2N) Alternation of generations can be isomorphic or heteromorphic Flagellate reproductive cells Alternation of generations (heteromorphic) Examples from Atlantic Canada Photos by Jordan Chalfant Ascophyllum nodosum Saccharina latissima Fucus distichus  Di erences and similarities Brown algae Green algae Red algae Plastid membrane 4 membranes 2 membranes 2 membranes Thylakoids stacked stacked unstacked Accessory fucoxanthin phycoerythrin & pigments phycocyanin Starch laminarin, stored in stored in plastids oridean, stored in vacuoles the cytoplasm Gametes motile, two agella motile, two nonmotile, lacking agella agella Alternation of isomorphic or usually isomorphic or generations heteromorphic isomorphic heteromorphic, some triphasic fl fl fl ff fl Seaweed Research at the CMN Seaweed biodiversity Focusing on the Arctic & understudied groups A combination of molecular techniques (DNA barcoding) and morphology give the best results Students on Ice Foundation Thank you!