1. No category

II. Algal taxonomy
Division: Chlorophyta
(green algae)
Hierarchical system of classification:
I. General Characteristics
II. Morphology
III. Distinguishing Classes
IV. Classes in Detail
suffix:
Level:
Domain
Group
Division
Class
Order
Family
Genus
species
-phyta
p y
-phyceae
-ales
-aceae
example:
Eukaryote
Plantae
Chlorophyta
Ulvophyceae
p y
Ulvales
Ulvaceae
Ulva
fenestrata
~ 16,000 species
~ 90% freshwater
1
Groups (Kingdom)
DOMAIN
1.Bacteria- cyanobacteria (blue green algae)
2.Archae
3.Eukaryotes
2
“Algae”
Glaucophytes
1. Alveolates- dinoflagellates
Plantae
2. Stramenopiles- diatoms, heterokonyophyta
Rhodophyta
3. Rhizaria- unicellular amoeboids
Chlorophytes
4 Excavates- unicellular flagellates
4.
Chl b,
starch
5. Plantae- rhodophyta, chlorophyta, seagrasses
6. Amoebozoans- slimemolds
Charophytes
Land Plants
7. Fungi- heterotrophs with extracellular digestion
8. Choanoflagellates- unicellular
9. Animals- multicellular heterotrophs
3
4
Adapted from Sadava 2014
1
Phylogenetics of Chlorophyta
(morphological, molecular data)
I. General Green Characteristics:
4 classes:
1) Pigments: ?
Chlorophyta
a
Chlorophyceae
Trebouxiophyceae
Chl b,
starch
Ulvophyceae
3) Storage product?
Prasinophyceae
Encasement
of egg
2) Chloroplast structure?:
4) Flagella?
Charophytes
Charophyceae
Embryo, cuticle
Land plants
5
6
Classes:
II. Morphology
Chlorophyta:
Chlorophyceae = freshwater
easiest division to identify visually
• usually bright, grass-green color
Trebouxiophyceae = freshwater, soil and marine
p y
= marine macroalgae
g
Ulvophyceae
Prasinophyceae = primarily marine flagellates, some freshwater;
modern representatives of earliest green algae
Charophyceae = freshwater; all terrestrial plants are derived
from Charophycean class
7
8
2
For classes:
- any easy “rules” using external thallus morphology?
II. Morphology
Chlorophyta:
easiest division to identify visually
• usually bright, grass-green color
- Prasinophyceans are all unicells, but…
Charophyceans
Except -
photo: Morgan Bond
Snow algae
Dunaliella
Trentepohlia parasitic
on Monterey Cypress
9
Diversity in chloroplast shape: (unique to algae)
“napkin ring-shaped parietal”
Chlorophyceae
Ulvophyceae
Ulvophyceae
10
III. Distinguishing among classes based on:
“cup-shaped parietal”
“stellate (star-shaped)”
“axial
axial (plate
(plate-like)”
like)
“ribbon-like”
“reticulate (net-like)”
1. How flagella are attached/constructed:
• basal bodies orientation
• microtubule roots
2. Cell covering:
• scales vs. cell wall
“multiple discoid”
11
3. How cells divide:
• aspects of mitosis and cytokinesis
12
3
III. Distinguishing among classes based on:
Flagella- complex cellular projections used for movement
- bundle of nine fused pairs of microtubule doublets
surrounding two central single microtubules
"9+2"
1. How flagella are attached/constructed:
-basal bodies orientation
-microtubule roots
Basal bodies- attachment site of the flagella
- containing a microtubules 9 triplet configuration
forming a hollow cylinder
Flagella
Basal Bodies
Flagella
Microtubule roots
Basal Bodies
Cell
Microtubule roots
anterior
Cell
13
swimming direction
14
Basal Bodies: ONE per flagellum, located at base of
flagellum, anchoring into cell
-pairs of basal bodies may be
opposite
parallel
clockwise
counterclockwise
Microtubule roots:
-under the cell membrane at point of
attachment of basal bodies
- may be cruciate or broadband
Flagella
Basal Bodies
Microtubule roots
Cell
Flagella
Basal Bodies
Microtubule roots
Cell
15
cruciate
5
broad-band
16
4
III. Distinguishing among classes based on:
III. Distinguishing among classes based on:
2. Cell covering- scales vs. cell wall
Scales are made of complex
polysaccharides secreted from golgi
3. How cells divide:
(aspects of mitosis and cytokinesis)
Cell wall = usually cellulose
Chlorophyceae, trebouxiophyceae,
Ulvophyceae, charophyceae
prasinophyceae
•
open vs. closed mitotic spindle
•
phycoplast vs. phragmoplast
•
furrowing vs. cell plate formation in center of cell
closed
metacentric centrioles
17
III. Distinguishing among classes based on:
III. Distinguishing among classes based on:
3. How cells divide:
(aspects of mitosis and cytokinesis)
3. How cells divide:
(aspects of mitosis and cytokinesis)
•
open vs. closed mitotic spindle
•
phycoplast vs. phragmoplast
•
furrowing vs. cell plate formation in center of cell
furrowing
Phycoplast: microtubules
parallel to dividing plane
-rare in algae
Open
-during Mt nuclear
18
envelope breaks down
•
open vs. closed mitotic spindle
•
phycoplast vs. phragmoplast
•
furrowing vs. cell plate formation in center of cell
furrowing
Phragmoplast: double
microtubules perpendicular
to dividing plane
-land plants
furrowing = most algae
19
cell plate formation = a
few algae and land plants
20
5
V. Classes in detail - Chlorophyte Diversity:
Some new terms:
Isogamy – sexual fusion between flagellated gametes that
are similar in size and shape
5 classes:
Chlorophyceae
Anisogamy – sexual fusion between flagellated gametes of
distinctly different sizes
Trebouxiophyceae
Oogamy – sexual fusion between a flagellated gamete
(sp m) and
(sperm)
nd non-flagellated
n n fl
ll t d gamete
m t (egg)
(
)
Ulvophyceae
Prasinophyceae
Review:
Sporophyte: diploid, 2n, multicellular release spores in
alternation of generations
Charophyceae
Gametophyte: hapliod, 1n, multicellular release gametes in
alternation of generations
Land plants
21
22
Chlorophyceae
Class Chlorophyceae:
Microtubule Roots: cruciate
Basal Bodies: clockwise
1.
How flagella are attached/constructed:
• basal
b s lb
bodies
di s orientation
i t ti = clockwise
l k i
• microtubule roots = cruciate
Flagella
2. Cell covering:
• scales vs. cell wall = wall
3. How cells divide:
• spindle = closed
• microtubule organization = phycoplast
• division by = furrowing
Basal Bodies
Microtubule roots
Cell
23
24
6
Order: Volvocales Genus: Chlamydomonas
Class Chlorophyceae:
 7000+ spp
mostly freshwater
unicells, colonies, coenocytes, filaments,
 haplontic life history- 1N thallus, the zygote is the only diploid stage,
with “hypnozygote” = thick walled resting stage
 isogamous, anisogamous, and oogamous species
• Cup-shaped chloroplast, orange eyespot
Genera:
• Scientists sequenced and mapped genome in 2003
Chlamydomonas, Volvox, Dunaliella
• Used as a model to determine how gene expression works
25
• Use mutations to determine where genes are on chromosomes
26
Haplontic- Sexual reproduction in unfavorable conditions
Chlamydomonas life history:
Usually asexual
fluid conditions
Mt
moist but not
wet conditions
“palmelloid
stage”
27
(1/2)
(1/2)
Hypnozygote
= resting stage
28
7
Volvox life history
Genus: Volvox
• Oogamous
• Gonidia = specialized cells
that divide to become
daughter colonies
• Zoospore = spore with
flagella
• Spherical colonies of 500 – 40,000 cells
• Endospore = surrounds
zoospore
• Each colony contains a large number of somatic cells and a
small number of reproductive cells
• Mesospore = initially
surrounds endospore +
zoospore
• Zygotes are orange
29
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Chlorophyte Diversity
Genus: Dunaliella
5 “classes”:
Chlorophyceae
Trebouxiophyceae
Ulvophyceae
Prasinophytes
• Common in salt ponds: have special ion pumps
• Packed with beta-carotene to protect from UV irradiance
Charophyceae
• Commercial value (beta-carotene) = used for food coloring and
in pharmaceuticals
31
Land plants
32
8
Ulvophyceae
Class Ulvophyceae:
Microtubule Roots: cruciate
Basal Bodies: counter- clockwise
1.
How flagella are attached/constructed:
•
basal body orientation = counterclockwise
•
microtubule roots = cruciate
2.
Cell covering:
•
scales vs. cell wall = wall (scales in some reproductive unicells)
3.
How cells actually divide:
•
spindle = closed
•
microtubule organization = phragmoplast
•
division by = furrow
Flagella
Basal Bodies
Microtubule roots
Cell
33
Class Ulvophyceae:
34
Class Ulvophyceae:
 Mostly marine macroalgae, some freshwater too
 Mostly marine macroalgae, some freshwater too
 Haplontic, diplontic, or alternation of generations
 Haplontic, diplontic, or alternation of generations
 No hypnozygotes
 No hypnozygotes
Orders to know:
• Ulotrichales/Ulvales
• Trentepohliales
• Cladophorales
• Bryopsidales
35
• Dasycladales
36
9
Division: Chlorophyta
Ulvophyceans have diverse morphologies
Class: Ulvophyceae
Trebouxiophyceae Chlorophyceae Prasinophytes
Trentepohliales
Order: Ulotrichales
unbranched filament
Ulvales
Cladophorales
Dasycladales
Bryopsidales
b
branched
h d fil
filamentt
- Unicells, filaments, blades; uninucleate or multinucleate cells
- Simple, haplontic life histories; all with an attached Codiolum stage
formed by zygote; zygote undergoes meiosis, producing flagellated
meiospores
Focal genera: Ulothrix
coenocytic/siphonous
parenchymatous
37
38
Division: Chlorophyta
Order Ulotrichales – e.g. Ulothrix
Haplontic with codiolum phase
-1N thallus, the zygote is the only diploid stage
-Codiolum phase- cell wall is from 2N zygote with 1N spores inside
Class: Ulvophyceae
Trebouxiophyceae Chlorophyceae Prasinophytes
Trentepohliales
g
syngamy
1N gametes
2N
zygote
meiosis
occurs
in zygote
1N gametophytes
1N
codiolum
stage
• Cell wall of zygote
(2N) stays intact to
contain new
meiospores (N)
•Codiolum stage –
dormant until
favorable conditions
Order:
Ulotrichales
Ulvales
Cladophorales
Bryopsidales
Dasycladales
- Uninucleate cells with a single parietal chloroplast
- Parenchymatous thallus; mono- or distromatic, sheets or tubes
- All cells can reproduce (holocarpic reproduction)
- Isomorphic alternation of generations
Focal genera: Ulva
“sea lettuce”
1N zoospores
39
40
10
Order Ulvales e.g. Ulva
Isomorphic Alternation of Generations: organism having
a separate multicellular diploid sporophyte and haploid
gametophyte stage, sporophyte & gametophyte are
same sizes
Ulva spp
41
Ulva intestinalis =
• Distromatic
• Often ephemeral in
intertidal zone
• Fast growing, tasty
to herbivores
• Green tides!
• Tubular
• Euryhaline - tolerates
freshwater, often occurs
near seeps
42
Division: Chlorophyta
•Green tides!
Class: Ulvophyceae
Trebouxiophyceae Chlorophyceae Prasinophytes
Trentepohliales
Order:
Ulotrichales
Ulvales
Cladophorales
Bryopsidales
Dasycladales
- Large, multinucleate cells, connected end to end with cross walls
- Chloroplasts  reticulate or multiple discoid arrayed in reticulate network
- Isomorphic alternation of generations
Focal genera:
Cladophora, Chaetomorpha, Anadyomene
43
44
11
Order Cladophorales e.g. Cladophora
Japanese Cladophora spp: “marimo balls”
Isomorphic Alternation of Generations: organism having
a separate multicellular diploid sporophyte and haploid
gametophyte stage, sporophyte & gametophyte are
same sizes
• Size: up to 30 cm (formed by turbulent water + sediments)
• A folktale in which the hearts of a young couple who drown in a
lake turn into Cladophora balls
• Meditation – watch balls rising and falling
45
Temporate Cladophorales
Cladophora
Tropical Cladophorales
Chaetomorpha
Anadyomene
- “Pin cushion” alga
- Unbranched filaments
- Branched filamentous
- Modified basal cell w/rhizoidal
extensions
- Harbors inverts  Nutrients
46
• Protected species - three day festival to promote conservation
47
- Cells become progressively smaller
toward periphery
Ventricaria
- Made up of single central cell (big)
and lots of lateral cells (small)
-Small cells fill spaces between
large-celled filaments (veins)
48
12
Division: Chlorophyta
Class: Ulvophyceae
Order Bryopsidales
Trebouxiophyceae Chlorophyceae Prasinophytes
Focal genera:
Trentepohliales
Order:
Ulotrichales
Cladophorales
Ulvales
Bryopsidales
Dasycladales
- Coencocytic/siphonous thallus construction
- Lots of variability in form (uniaxial, multiaxial, etc.)
- Mostly biflagellate anisogamous reproduction; various life histories
Codium “dead man’s fingers”
Halimeda
Caulerpa
- Some calcified: major component of tropical sands  remains of
coralline greens form a layer >50 m thick at Great Barrier Reef
- Synchronous spawning in tropics
49
50
Morphology
Morphology
Uniaxial and multiaxial construction
Coenocytic/siphonous construction:
Multinucleate; no division of
cytoplasm with cell walls
“clotting compounds” quickly
repair wounds
51
Bryopsis
Codium “dead man’s fingers”
52
13
Morphology
Kleptoplastids
Codium fragile
Utricles
Gametangium
Utricles: peripheral portions of siphons may be inflated &
aggregated to form outer surface gametangia
(reproductive structures)
(Sacoglossan opistobranchs are thieves!)
Codium is ~ size of an apple =
~30 km of siphons
53
54
Order Bryopsidales: e.g.Codium
Diplontic: 2N thallus, the gametes are the only
haploid stage
- Common in siphonous greens
- Sacoglossan radula adapted to
host alga (length of tooth ~
thickness of siphon)
Codium fragile
- Pierce and suck out insides
- Stolen chloroplasts can last up
to a month or so
Elysia
55
56
14
Codium and scallop interaction on East Coast
Halimeda
Holocarpic reproduction in many tropical members of Bryopsidales
• Attach and grow on
scallops
• Weigh them down and
prevent escape from
predators
• Cast adrift in heavy storms
• Results in high mortality
57
- Anisogamous, dioecious = separate sexes
- Entire thallus turns into gametes
- Gametes migrate to surface overnight
- Major contributor to tropical sediment
58
Tropical siphonous greens, timing of growth, and herbivory
- New tissue put on at night (why?)
- New segments not fully calcified, but heavily defended chemically
- Chloroplasts stay in older segments until minutes before sunrise
- Increase in calcification = decrease in chemical defenses
- Thousands of individuals spawn synchronously
- Water visibility drops to ~ 1m downstream from reef, but disperses
within ~1/2 hr
- Empty thallus disintegrates (often within hrs)
- In some species:
gametes positively phototactic
zygotes are negatively phototactic
WHY??
59
60
15
Morphology
Caulerpa invasion
Caulerpa = uniaxial, but with trabeculae for support
trabeculae = ingrowths of wall material
• Native in southern Australia
• 1st introduced as a non-native in Mediterranean
• 2002: introduced at 2 sites in S. California  large eradication
attempted
• Grows fast, large, asexual reproduction, and resistant to cold temps
• Listed as one of the top 100 invasive species on earth
61
Division: Chlorophyta
Class: Ulvophyceae
Siphons form rhizoidal holdfast too
62
1930’s - Hammerling’s experiments with Acetabularia
Trebouxiophyceae Chlorophyceae Prasinophytes
Trentepohliales
Order:
Ulotrichales
Ulvales
Cladophorales
Bryopsidales
Dasycladales
- Extensive fossil record, group is 500 myo with 11 extant genera
- Tropical, shallow water spp
- Unicellular thalli with one nucleus and radial symmetry
Celebrity genus: Acetabularia
“mermaid’s wine glass”
63
mRNA
64
16
Division: Chlorophyta
Class: Ulvophyceae
- Often epiphytic/parasitic
Trebouxiophyceae Chlorophyceae Prasinophytes
Trentepohliales
Order:
Ulotrichales
Ulvales
Cladophorales
Bryopsidales
Dasycladales
- All terrestrial (~40 spp)
- Uninucleate, special urn-shaped gametangia, dispersed by wind?
- Branched filaments, numerous discoid plastids, orange due to
carotene containing lipid droplets (photoprotective?)
- Often epiphytic/parasitic
Focal genus: Trentepohlia
65
V. Classes in detail - Chlorophyte Diversity:
66
Class Trebouxiophyceae:
5 classes:
Chlorophyceae
Trebouxiophyceae
1.
Ulvophyceae
Prasinophyceae
How flagella are attached/constructed:
• basal
b s lb
bodies
di s orientation
i t ti = counterclockwise
t
l k i
• microtubule roots = cruciate
2. Cell covering:
• scales vs. cell wall = wall
Charophyceae
Land plants
67
3. How cells actually divide:
• spindle = closed; metacentric
• microtubule organization = phycoplast
• division by = furrow
68
17
Trebouxiophyceae
Microtubule Roots: cruciate
Basal Bodies: counter- clockwise
Class Trebouxiophyceae:
 mostly freshwater and terrestrial algae
 unicells, filaments, blades
Genera: Chlorella, Prasiola
Flagella
Basal Bodies
Microtubule roots
Cell
69
Genus:
Chlorella
70
Genus:
Prasiola
- Unicellular
- Diplontic- 2N thallus, the gametes are the only haploid stage
- Endosymbiont in freshwater animals
- Single, cup-shaped chloroplast
- Found in ultra-high intertidal (spray zone) in areas with high
guano
- “Nitrophilic”
- Used by Melvin Calvin to investigate carbon fixation in plants
(Calvin cycle)
- Thalli small (< 2cm), monostromatic blades
- Marketed as a dietary supplement
- Individuals higher on shore produce asexual (2N) spores
- Individuals lower on shore produce gametes, oogamous
71
72
18
IV. Classes in detail - Chlorophyte Diversity:
Prasiola Life History
5 classes:
Chlorophyceae
Trebouxiophyceae
Ulvophyceae
Prasinophyceae
Charophyceae
Land plants
73
74
Some Prasinophyceans
Class Prasinophyceae:
Microtubule Roots: cruciate
Basal Bodies: opposite
1.
How flagella are attached/constructed:
• basal
b s lb
bodies
di s orientation
i t ti = variable
i bl
• microtubule roots = variable
Flagella
2. Cell covering:
• scales vs. cell wall = scales
Basal Bodies
3. How cells actually divide:
• spindle = open or closed
• microtubule organization = phragmoplast or phycoplast
• division by = furrow
75
Microtubule roots
Cell
76
19
Class Prasinophyceae
Genus Tetraselmis
V. Classes in detail - Chlorophyte Diversity:
5 classes:
Chlorophyceae
Trebouxiophyceae
Ulvophyceae
modern representatives of ancestral green (most
primitive)
Prasinophyceae
unicellular flagellates
 freshwater and marine
Charophyceae
 one plastid with one pyrenoid
mostly asexual
Land plants
77
Class Charophyceae:
1.
Charophyceae
78
Microtubule Roots: broadband
Basal Bodies: parallel
How flagella are attached/constructed:
• basal
b s lb
bodies
di s orientation
i t ti = parallel
ll l
• microtubule roots = broad band
Flagella
2. Cell covering:
• scales vs. cell wall = wall
3. How cells divide:
• spindle = open
• microtubule organization = phragmoplast
• division by = furrow or plate
Basal Bodies
Microtubule roots
Cell
79
80
20
Algal Life Cycles
Class Charophyceae: Genera: Desmids, Chara
 most closely related to
terrestrial plants
Haplontic- 1N thallus, the zygote is the only diploid stage
usually unicells or filaments, but
sometimes colonies and more
complex forms
Mt
 freshwater
fuse
N
N
 haplontic- 1N thallus, the zygote is
grow
the only diploid stage
oogamous reproduction
Me
1N
spores
2N
zygote
 dormant zygotes
81
82
Class Charophyceae: Order Charales Genus Chara
Class Charophyceae: Order Zygnematales
Desmids
 Macroscopic
• 2 semi-cells that are mirror
images, nucleus is in center
 Freshwater
• asexual reproduction = mitosis
 Can be partially calcified
• sexual conjugation = pairing
between cells
 Central axis with whorls
of branches at nodes
• movement through mucilage
secretion
 Often smell of garlic
 Food and nursery habitat
for waterfowl
83
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21