Transcript Plant land colonization PPT

Create a timeline with the following events:
a.
b.
c.
d.
e.
f.
g.
h.
Earth is born
First life
Multicellularity
Colonization of land
First vascular plants
First insects
Dinosaurs
Flowering plants
Create a timeline with the following events:
a.
b.
c.
d.
e.
f.
g.
h.
Earth is born 4.6 bya
First life 3.8 bya
Multicellularity 1 bya
Colonization of land 500 mya (or 1.2 bya)
First vascular plants 425 mya
First insects 400 mya
Dinosaurs 300 mya
Flowering plants 130 mya
LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 29
Plant Diversity I: How Plants
Colonized Land
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Guiding questions:
• Why did land plants come to be?
• What challenges did it pose?
• Name the 4 primary clades of all plants.
– Derived traits of them collectively
• Especially alternation of generations
– Ancestral traits of them collectively
• What are the derived characters unique to
seedless plants?
– Non-vascular (mosses)
– Vascular (ferns)
Concept 29.1: Land plants evolved from
green algae
• Green algae called charophytes are the closest
relatives of land plants
– Note that land plants are not descended from modern
charophytes, but share a common ancestor with
modern charophytes
© 2011 Pearson Education, Inc.
Adaptations Enabling the Move to Land
• In charophytes a layer of a durable polymer called
sporopollenin prevents exposed zygotes from
drying out
– Sporopollenin is also found in plant spore walls
• Why move to land?
• What challenges did the move pose?
© 2011 Pearson Education, Inc.
Figure 29.4
Red algae
Chlorophytes
1 m
Plantae
Embryophytes
Streptophyta
Charophytes
Viridiplantae
ANCESTRAL
ALGA
Derived Traits of Plants
• Four key traits appear in nearly all land plants
but are absent in the charophytes
1.
2.
3.
4.
Alternation of generations
Walled spores produced in sporangia
Multicellular gametangia
Apical meristems
© 2011 Pearson Education, Inc.
1. Alternation of Generations and
Multicellular, Dependent Embryos
• Plants alternate between two multicellular stages,
a reproductive cycle called alternation of
generations
• The gametophyte is haploid and produces
haploid gametes by mitosis
• Fusion of the gametes gives rise to the diploid
sporophyte, which produces haploid spores by
meiosis
© 2011 Pearson Education, Inc.
• The diploid embryo is retained within the tissue of
the female gametophyte
• Nutrients are transferred from parent to embryo
through placental transfer cells
• Land plants are called embryophytes because of
the dependency of the embryo on the parent
© 2011 Pearson Education, Inc.
Figure 29.5a
Gametophyte
(n)
Mitosis
n
Gamete from
another plant
Mitosis
n
FERTILIZATION
2n
Sporophyte
(2n)
Haploid (n)
Diploid (2n)
n Spore Gamete n
MEIOSIS
Key
Zygote
Mitosis
Alternation of generations
1 m
2. Walled Spores Produced in Sporangia
• The sporophyte produces spores in organs called
sporangia
• Diploid cells called sporocytes undergo meiosis
to generate haploid spores
• Spore walls contain sporopollenin, which makes
them resistant to harsh environments
© 2011 Pearson Education, Inc.
Figure 29.5c
Spores
Sporangium
Longitudinal section of
Sphagnum sporangium (LM)
Sporophyte
Gametophyte
1 m
Sporophytes and sporangia of Sphagnum (a moss)
3. Multicellular Gametangia
• Gametes are produced within organs called
gametangia
• Female gametangia, called archegonia, produce
eggs and are the site of fertilization
• Male gametangia, called antheridia, produce and
release sperm
© 2011 Pearson Education, Inc.
Figure 29.5d
Female
gametophyte
Archegonia,
each with an
egg (yellow)
Antheridia
(brown),
containing
sperm
Male
gametophyte
Archegonia and antheridia of Marchantia (a liverwort)
1 m
4. Apical Meristems
• Plants sustain continual growth in their apical
meristems
• Cells from the apical meristems differentiate into
various tissues
© 2011 Pearson Education, Inc.
Figure 29.5e
Apical meristem
of shoot
Developing
leaves
Apical meristems of plant
roots and shoots
Apical
meristem
of root
Root
100 m
Shoot
1 m
100 m
• Additional derived traits include
– Cuticle, a waxy covering of the epidermis
– Mycorrhizae, symbiotic associations between
fungi and land plants that may have helped plants
without true roots to obtain nutrients
– Secondary compounds that deter herbivores
and parasites
– Very useful to humans, too
© 2011 Pearson Education, Inc.
Figure 29.7
1 Origin of land plants (about 475 mya)
2 Origin of vascular plants (about 425 mya)
3 Origin of extant seed plants (about 305 mya)
Mosses
Land plants
ANCESTRAL
1
GREEN
ALGA
Nonvascular
plants
(bryophytes)
Liverworts
Hornworts
Pterophytes (ferns,
horsetails, whisk ferns)
3
Angiosperms
500
450
400
350
300
Millions of years ago (mya)
50
0
1 m
Know plant types, and key distinguishing elements
Seed plants
Gymnosperms
Vascular plants
2
Seedless
vascular
plants
Lycophytes (club
mosses, spike
mosses, quillworts)
• Seedless plants can be divided into
clades
– Bryophytes (non-vascular, e.g. mosses and their
relatives)
– Lycophytes and Pterophytes (vascular, e.g.
club mossess, ferns and their relatives)
– Seedless vascular plants are paraphyletic, and are
of the same level of biological organization, or
grade
© 2011 Pearson Education, Inc.
• A seed is an embryo and nutrients surrounded by
a protective coat
• Seed plants form a clade and can be
divided into further clades
– Gymnosperms, the “naked seed” plants,
including the conifers
– Angiosperms, the flowering plants
Table 29. 1
1 m
Concept 29.2: Mosses and other nonvascular
plants have life cycles dominated by
gametophytes
• Bryophytes are represented today by three phyla
of small herbaceous (nonwoody) plants
– Liverworts, phylum Hepatophyta
– Hornworts, phylum Anthocerophyta
– Mosses, phylum Bryophyta
• Bryophyte refers to all nonvascular plants,
whereas Bryophyta refers only to the phylum of
mosses
© 2011 Pearson Education, Inc.
Figure 29.UN01
Nonvascular plants (bryophytes)
Seedless vascular plants
Gymnosperms
Angiosperms
1 m
Bryophyte Gametophytes
• In all three bryophyte phyla, gametophytes are
larger and longer-living than sporophytes
• Sporophytes are typically present only part of the
time
© 2011 Pearson Education, Inc.
Figure 29.8-1
“Bud”
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
Spores
Male
gametophyte
(n)
Gametophore
Spore
dispersal
Female
gametophyte
(n)
Peristome
Sporangium
MEIOSIS
Mature sporophytes
Rhizoid
Seta
Capsule
(sporangium)
2 mm
Foot
Capsule with
peristome (LM)
1 m
Female
gametophytes
Figure 29.8-2
“Bud”
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
Sperm
Antheridia
Male
gametophyte
(n)
Egg
Spores
Gametophore
Spore
dispersal
Female
gametophyte
(n)
Peristome
Sporangium
MEIOSIS
Mature sporophytes
Archegonia
Rhizoid
FERTILIZATION
(within archegonium)
Seta
Capsule
(sporangium)
2 mm
Foot
Capsule with
peristome (LM)
1 m
Female
gametophytes
Figure 29.8-3
“Bud”
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
“Bud”
Antheridia
Male
gametophyte
(n)
Sperm
Egg
Spores
Gametophore
Spore
dispersal
Female
gametophyte
(n)
Peristome
Sporangium
MEIOSIS
Mature sporophytes
Archegonia
Rhizoid
FERTILIZATION
Zygote (within archegonium)
(2n)
Seta
Capsule
(sporangium)
Foot
Embryo
2 mm
Archegonium
Capsule with
peristome (LM)
Young
sporophyte
(2n)
Female
gametophytes
1 m
Animation: Moss Life Cycle
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Bryophyte Sporophytes
• Bryophyte sporophytes grow out of archegonia,
and are the smallest and simplest sporophytes of
all extant plant groups
• A sporophyte consists of a foot, a seta (stalk),
and a sporangium, also called a capsule, which
discharges spores through a peristome
• Hornwort and moss sporophytes have stomata for
gas exchange; liverworts do not
© 2011 Pearson Education, Inc.
Figure 29.9a
Thallus
Gametophore of
female gametophyte
Sporophyte
Foot
Seta
Marchantia polymorpha,
a “thalloid” liverwort
Marchantia
sporophyte (LM)
500 m
Capsule
(sporangium)
Plagiochila deltoidea, a
“leafy” liverwort
1 m
Figure 29.9b
An Anthoceros
hornwort species
Sporophyte
Gametophyte
1 m
Figure 29.9c
Polytrichum commune,
hairy-cap moss
Capsule
Seta
Sporophyte
(a sturdy
plant that
takes months
to grow)
Gametophyte
1 m
Annual nitrogen loss
(kg/ha)
Can bryophytes reduce the rate at which key nutrients are lost
from soils?
RESULTS
6
5
4
3
2
1
0
With moss
Without moss
1 m
Figure 29.11
(a) Peat being harvested from a
peatland
(b) “Tollund Man,” a bog mummy
dating from 405–100 B.C.E.
1 m
Concept 29.3: Ferns and other seedless
vascular plants were the first plants to
grow tall
• Why bother striving for being tall?
• What new feature allowed for height?
© 2011 Pearson Education, Inc.
Figure 29.UN03
Nonvascular plants (bryophytes)
Seedless vascular plants
Gymnosperms
Angiosperms
1 m
Derived Traits of Vascular Plants
• Living vascular plants are characterized by
1. Life cycles with dominant sporophytes
2. Vascular tissues called xylem and phloem
3. Well-developed roots and leaves
© 2011 Pearson Education, Inc.
Figure 29.12
Sporangia
1 m
Life Cycles with Dominant Sporophytes
• In contrast with bryophytes, sporophytes of
seedless vascular plants are the larger generation,
as in familiar ferns
• The gametophytes are tiny plants that grow on or
below the soil surface
• Seedless vascular plants have flagellated sperm and are
usually restricted to moist environments
© 2011 Pearson Education, Inc.
Figure 29.13-3
Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Spore
(n)
Rhizoid
Underside
of mature
gametophyte
(n)
Sporangium
Sporangium
Antheridium
Young
gametophyte
Mature
sporophyte
(2n)
Sorus
New
sporophyte
Sperm
Archegonium
Egg
Zygote
(2n)
Gametophyte
Fiddlehead (young leaf)
1 m
FERTILIZATION
Animation: Fern Life Cycle
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Transport in Xylem and Phloem
• Vascular plants have two types of vascular tissue:
xylem and phloem
– Xylem conducts most of the water and minerals and
includes dead cells called tracheids
– Water-conducting cells are strengthened by lignin and
provide structural support
– Phloem consists of living cells and distributes sugars,
amino acids, and other organic products
© 2011 Pearson Education, Inc.
Evolution of Roots and Leaves
• Roots were originally underground stems
• Leaves are organs that increase the surface area
of vascular plants, thereby capturing more solar
energy that is used for photosynthesis
• Leaves are categorized by two types
 Microphylls, leaves with a single vein
 Megaphylls, leaves with a highly branched
vascular system
• According to one model of evolution, microphylls evolved as
outgrowths of stems
• Megaphylls may have evolved as webbing between flattened
branches
© 2011 Pearson Education, Inc.
Figure 29.14
Overtopping
growth
Vascular tissue
Sporangia
Microphyll
Megaphyll
Other
stems
become
reduced
and
flattened.
(a) Microphylls
(b) Megaphylls
1 m
Webbing
develops.
Seedless plant diversity
2.5 cm
1 cm
Selaginella
moellendorffii,
a spike moss
Isoetes
gunnii,
a quillwort
Strobili
(clusters of
sporophylls)
Diphasiastrum
1 m tristachyum,
a club moss
Vascular plant diversity
Equisetum arvense,
field horsetail
Athyrium
filix-femina,
lady fern
Vegetative stem
1.5 cm
25 cm
Strobilus on
fertile stem
4 cm
Psilotum
nudum,
a whisk
fern
1 m
Applying ideas
Fern
Lycophyte trees
Horsetail
Tree trunk
covered with
small leaves
Lycophyte tree
reproductive
structures
How would the first large plants have affected global climate?
Processing the big points (flip your paper over)
• Can you name the derived traits of the
colonizing land plants (mosses)?
• Can you name the derived traits of
vascular, seedless plants (ferns)?
• What ancestral traits do plants share with
the protists from which they split?
Processing the big points
• Can you name the derived traits of the
colonizing land plants (mosses)?
1.
2.
3.
4.
Alternation of generations
Walled spores produced in sporangia
Multicellular gametangia
Apical meristems
As well as: cuticles, secondary compounds, symbioses
• Can you name the derived traits of vascular,
seedless plants (ferns)?
• What ancestral traits do plants share with the
protists from which they split?
Processing the big points
• Can you name the derived traits of the
colonizing land plants (mosses)?
• Can you name the derived traits of
vascular, seedless plants (ferns)?
1. Life cycles with dominant sporophytes
2. Vascular tissues called xylem and phloem
3. Well-developed roots and leaves
• What ancestral traits do plants share with
the protists from which they split?
Processing the big points
• Can you name the derived traits of the
colonizing land plants (mosses)?
• Can you name the derived traits of
vascular, seedless plants (ferns)?
• What ancestral traits do plants share with
the protists from which they split?
– Chloroplasts
– All eukaryotic cell functions and organelles
Figure 29: summary of common traits
Gametophyte
Mitosis
Mitosis
n
n
n
Spore
n
Gamete
MEIOSIS
Apical meristem
of shoot
Developing
leaves
FERTILIZATION
2n Zygote
Haploid
Diploid
Mitosis
Sporophyte
1 Alternation of generations
Archegonium
with egg
2 Apical meristems
Antheridium
with sperm
Sporangium
Spores
1 m
3 Multicellular gametangia
4 Walled spores in sporangia