General Introduction and Characterization of the Marine Brown Algae: PtIPart I
Notes by Naomi Phillips Arcadia University
Edited by Suzanne Fredericq University of Louisiana at Lafayette and Brian Wysor Roger Williams University 1 Brown Algae: General
*Primarily marine class with 19 orders, >50 familiesfamilies,, 270+ genera, 2500 species **AllAll are multicellular *Range from simple filamentous forms to large complex plants (kelps)
2 Brown Algae: General
*Rich in terms of biodiversity
*Inhabiting great array of hbitthabitats
*Critical primary producers in pelagic and coastal environments and in both temperate and tropical regions around the world 3 Pelagic brown algae
*Pelagic beds in Sargasso sea, Gulf of Mexico *Support host of creatures, from crustaceans, fish to young turtles
4 Economic importance
Food, secondary products Sources of alginates Emulsifiers in everything from paint to ice cream From kelp beds on US West Coast
5 Brown Algae: General
Pigments Chl a & c & fucoxanthin Cell wall Cellulose and mucilage Plant body e.g., holdfast, stipe and blades Reproduction/meiosis/life history Most: sporic (haplodiplontic) One order: gametic (diplontic) 6 Life history: alternation of generations
Sporic meiosis: haplodiplontic: Laminariales
7 Life Histories
Gametic meiosis: Diplontic: Fucales
8 Survey of Protistan assemblage
*Dinoflagellates *Euglenophytes *Crytomonads The Heterokonts -Stramenopiles •Oomycota •Diatoms •Brown algae ------*Red algae *Green algae 9 HeterokontsHeterokonts--StramenopilesStramenopiles
Large heterogeneous group characterized by two heterokont flagella One smooth, one tinsel
Includes a variety of groups: Oomycetes Diatoms Brown algae Golden brown algae
10 Endosymbiosis events
11
J. Phycol. Feb. 2009 Heterokonts Brown * Algae
12
Kawai et al. 2003 Protist Current Taxonomic Treatment
Classifications historically emphasizes four features:
*Life history traits • sporic to gametic *Gamete types • isogamous to oogamous *Growth mode • diffuse, meristems, trichothallic, apical *Thallus morphology • filamentous to parenchymatous 13 Gamete types
14 Growth mode
Diffuse Apical Meristems 15 Evolutionary Relationships among Orders
-TditilhthTraditional hypotheses mak e a var itfiety of assump tions regardi ng primitive and derived character states
--GenerallyGenerally “simple to complex”: *Relationships among brown algal orders were proposed to reflect this progression *Basal groups have “simple” features *Didli*Derived lineages h ave more “comp l”ftlex” features
16 Traditional Hypothesis
17
Wynne & Loiseaux 1976 From simple to more complex
•Is not a new concept •Central theme in evolutionary thinking •Common ppgygremise to our thinking of how many things have evolved from land plants to animal systems
18 Land Plant Evolution
Evolution of the seed Vascular tissue 19
Gametophyte protection and retention Molecular Phylogeny
--MolecularMolecular data have been used to test the “simppple to complex” paradigm --MolecularMolecular data provides a very distinct picture of brown algal evoltilution: *“Simple” lineages are nested with more complex groups *Some early divergences involved “complex” lineages *Fucales nested within other lineages Basal in most traditional taxonomies
20 21
De Reviers et al. 2007 Molecular Phylogeny B B asal Lin
“Crown” group e
ages 22
De Reviers et al. 2007 Questions
•What are the relationships among basal lineages and the “crown” group?
•Did brown a lga l evo lu tion generall y f oll ow a “ si mpl e t o compl ex” pattern? –Pattern must be more comppjpplex than just “simple to complex” –General pattern still needs to be established
23 • Phylogeny from Phillips et al. (2008) J. Phycol . 44:394 • Lineages with ESTs (or genomic data) available (or expected) are in purple • Libraries that we have produced and sequenced are: – Schizocladia, Choristocarpus, Desmarestia 24