Transcript video slide - ScienceToGo

Chapter 29
Plant Diversity I:
How Plants
Colonized Land
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Overview: The Greening of Earth
• For more than the first 3 billion years of Earth’s
history, the terrestrial surface was lifeless
• Since colonizing land, plants have diversified
into roughly 290,000 living species
• Plants supply oxygen and are the ultimate
source of most food eaten by land animals
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Overview: Multicellularity
• Advantages
•
Multicellular organisms can be larger and operate
more efficiently
•
Cells are specialized to perform specific functions
which benefit the whole organism
• Disadvantages
•
Multicellular organisms need to coordinate the
activities of their individual cells
•
They are restricted in their exploitation of habitats
because of their size.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-1
How did plants change the world?
Morphological and Molecular Evidence
•
Many characteristics of land plants also appear in a variety of algal
clades, mainly algae
•
However, land plants share four key traits only with charophytes:
–
Rose-shaped complexes for cellulose synthesis
–
Peroxisome enzymes
–
Structure of flagellated sperm
–
Formation of a phragmoplast
These rings of protewins embedded in the
Plasma membrane are found only in land plants and charophyte algae
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Concept 29.1: Land plants (Kingdom Plantae)
evolved from green algae!!!!!!
•
Green algae called charophytes are the closest relatives of land plants
•
Lower plants and green algae have flagellated sperm that is similar in
structure
•
Homologous chloroplasts – chlorophyll b
•
Mitosis/cytokinesis – similarities
•
Genetic similarities in nuclear genes and rRNA
•
Food reserves - starch
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Concept 29.1: Land plants (Kingdom Plantae)
evolved from green algae!!!!!!
•
Multicellular, photosynthetic, and immobile, all plants have cellulose
walls
•
Because most plants cannot move around, obtaining light for
photosynthesis and bringing gametes together for sexual reproduction
have been dominant themes in their evolution.
•
Plants originated in the sea, and some forms later colonized land. The
most successful land plants have vascular tissues that transport food
and water through the plant and support the body in the air.
•
Most successful vascular plants have adaptations freeing their
reproduction from dependence on water. (cuticle, stomates, reduced
gametophytes that are dependent on sporophytes)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-4
Red algae
Chlorophytes
Plantae
Embryophytes
Streptophyta
Charophytes
Viridiplantae
ANCESTRAL
ALGA
Living on Land compared to Water
•
•
Advantages
–
More light
–
Higher concentration of CO2
–
Nutrients in soil
Disadvantages
-
no support for plant body
-
Less water available for reproduction
-
Segregated resources (light and air above, water and minerals
below soil surface)
-
Extremes of temperature
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Derived Traits of Plants
•
Four key traits appear in nearly all land plants but are absent in the
charophytes:
–
Alternation of generations (with multicellular, dependent embryos)
–
Walled spores produced in sporangia
–
Multicellular gametangia
–
Apical meristems
•
Additional derived traits such as a cuticle and secondary compounds
evolved in many plant species
•
Symbiotic associations between fungi and the first land plants may
have helped plants without true roots to obtain nutrients
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
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. These spores germinate
into gametophytes.
•
The gametophyte produces gametes by mitosis.
•
The gametes fuse for form a diploid zygote which grows into the
sporophyte
In the evolutionary history of plants, the sporophyte generation has
increased in size, number of cells and complexity while the
gametophyte has decreased in size, number of cell and complexity. In
higher plants, the sporophyte is the dominant form.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-5a
Gametophyte
(n)
Mitosis
n
n
Spore
Gamete from
another plant
Mitosis
n
n
Gamete
MEIOSIS
FERTILIZATION
2n
Mitosis
Sporophyte
(2n)
Alternation of generations
Zygote
Fig. 29-5b
The multicellular, dependent embryo of land
plants is such a significant derived trait that
land plants are also known as embryophtes.
2 µm
Embryo
Maternal tissue
Wall ingrowths
10 µm
Placental transfer cell
(outlined in blue)
Embryo (LM) and placental transfer cell (TEM)
of Marchantia (a liverwort)
Fig. 29-5c
Spores (haploid)
Sporangium
Longitudinal section of
Sphagnum sporangium (LM)
Sporophyte (diploid) –
produces haploid spores
by meiosis
Gametophyte (haploid)
Sporophytes and sporangia of Sphagnum (a moss)
Fig. 29-5d
Female gametophyte
Archegonium
with egg –
fertilization
takes place
here
Antheridium
with sperm
sperm are
released
and swim
to egg
Male
gametophyte
Archegonia and antheridia of Marchantia (a liverwort)
Fig. 29-5e
Apical
meristem
of shoot
Shoot
Developing
leaves
100 µm
Apical meristems – areas of sustained
continual growth, cells differentiate
Into various types of tissues
Apical meristem
of root
Root
100 µm
Fig. 29-6
(a) Fossilized spores
• Fossil evidence indicates that
plants were on land at least 475
million years ago
• Fossilized spores and tissues
have been extracted from 475million-year-old rocks
(b) Fossilized
sporophyte tissue
The Origin and Diversification of Plants
•
Those ancestral species gave rise to a vast diversity of modern plants
•
Land plants can be informally grouped based on the presence or
absence of vascular tissue
•
Most plants have vascular tissue; these constitute the vascular plants
•
Nonvascular plants are commonly called bryophytes
•
Seedless vascular plants can be divided into clades
–
Lycophytes (club mosses and their relatives)
–
Pterophytes (ferns and their relatives)
•
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
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-7
1 Origin of land plants (about 475 mya)
2 Origin of vascular plants (about 420 mya)
3 Origin of extant seed plants (about 305 mya)
Hornworts
1
Mosses
Pterophytes (ferns,
horsetails, whisk ferns)
3
Angiosperms
450
400
350
300
Millions of years ago (mya)
50
0
Seed plants
Gymnosperms
Vascular plants
2
Seedless
vascular
plants
Lycophytes (club mosses,
spike mosses, quillworts)
500
Land plants
ANCESTRAL
GREEN
ALGA
Nonvascular
plants
(bryophytes)
Liverworts
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
Mosses are most closely related to vascular plants
Nonvascular plants (bryophytes)
Seedless vascular plants
Gymnosperms
Angiosperms
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Bryophytes - Mosses and other nonvascular plants
have life cycles dominated by gametophytes
•
The hapliod gametophyte is the dominant generation
•
The sporphyte is dependent on the gametopyhte
•
Must have water
•
to reproduce so that the sperm can swim to the egg
•
because no vascular tissue to carry water to plants parts,
therefore, plants are always low to the ground
•
Bryophyte sporophytes grow out of archegonia, and are the smallest
and simplest sporophytes of all extant plant groups.
•
Although bryophyte sporophytes are usually green and photosynthetic
when young, they cannot live independently. They remain attached to
their parental gametophytes, from which they absorb sugars, amino
acids, minerals, and water.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-8-1
“Bud”
Male
gametophyte
(n)
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
Spores
“Bud”
Gametophore
Female
gametophyte (n)
Spore
dispersal
Rhizoid
Peristome
Sporangium
MEIOSIS
2 mm
Mature
sporophytes
Seta
Capsule
(sporangium)
Foot
Capsule with
peristome (SEM)
Female
gametophytes
Fig. 29-8-2
Raindrop
Sperm
“Bud”
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
Antheridia
Male
gametophyte
(n)
“Bud”
Egg
Spores
Gametophore
Female Archegonia
gametophyte (n)
Spore
dispersal
Rhizoid
Peristome
FERTILIZATION
Sporangium
MEIOSIS
2 mm
Mature
sporophytes
Seta
Capsule
(sporangium)
Foot
Capsule with
peristome (SEM)
Female
gametophytes
(within archegonium)
Fig. 29-8-3
Raindrop
Sperm
“Bud”
Key
Haploid (n)
Diploid (2n)
Protonemata
(n)
Antheridia
Male
gametophyte
(n)
“Bud”
Egg
Spores
Gametophore
Female Archegonia
gametophyte (n)
Spore
dispersal
Rhizoid
Peristome
FERTILIZATION
Sporangium
MEIOSIS
Mature
sporophytes
Seta
Capsule
(sporangium)
Foot
(within archegonium)
Zygote
(2n)
Embryo
2 mm
Archegonium
Capsule with
peristome (SEM)
Young
sporophyte
(2n)
Female
gametophytes
Life Cycle of Mosses - Animation
•
http://www.sumanasinc.com/webcontent/animations/content/moss.html
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-9d
Polytrichum commune,
hairy-cap moss
Capsule
Seta
Sporophyte
(a sturdy
plant that
takes months
to grow)
Gametophyte
The Ecological and Economic Importance of
Mosses
•
Moses are capable of inhabiting diverse and sometimes extreme
environments, but are especially common in moist forests and
wetlands
•
Some mosses might help retain nitrogen in the soil
•
Sphagnum, or “peat moss,” forms extensive deposits of partially
decayed organic material known as peat – peat has long been a fuel
source in Europe and Asia
•
Sphagnum is an important global reservoir of organic carbon (good
CO2 sink)
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-10
RESULTS
Annual nitrogen loss
(kg/ha)
6
5
4
3
2
1
0
With moss
Without moss
Fig. 29-11
(a) Peat being harvested
(b) “Tollund Man,” a bog mummy – acidic, oxygen-poor conditions preserve organisms
Concept 29.3: Ferns and other seedless vascular
plants were the first plants to grow tall
•
Vascular tissue allowed these plants to grow tall
•
Seedless vascular plants have flagellated sperm and are usually
restricted to moist environments
Nonvascular plants (bryophytes)
Seedless vascular plants
Gymnosperms
Angiosperms
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Origins and Traits of Vascular Plants (xylem &
phloem tissue)
•
Living vascular plants are characterized by:
•
Life cycles with dominant sporophytes, however, the
gametophytes are photosynthetic and are not dependent on the
sporophyte for nutrition.
•
The gametophytes are tiny plants that grow on or below the soil
surface
•
Have roots that take up water from the soil and vascular tissue
that transports it to leaves and stems up in the sunlight
•
Must live in somewhat moist areas because their sexual
reproduction still depends on water for flagellated sperm to swim
in.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Life Cycles with Dominant Sporophytes
Fern Life Cycle Animation
• http://academic.kellogg.edu/herbrandsonc/bio1
11/animations/0124.swf
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-13-1
Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Sporangium
Sporangium
Sorus
Fiddlehead
Mature
sporophyte
(2n)
Fig. 29-13-2
Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Spore
(n)
Sporangium
Sporangium
Sorus
Fiddlehead
Antheridium
Young
gametophyte
Mature
gametophyte
(n)
Archegonium
Egg
Mature
sporophyte
(2n)
FERTILIZATION
Sperm
Fig. 29-13-3
Key
Haploid (n)
Diploid (2n)
MEIOSIS
Spore
dispersal
Spore
(n)
Sporangium
Sporangium
Antheridium
Young
gametophyte
Mature
gametophyte
(n)
Archegonium
Egg
Mature
sporophyte
(2n)
New
sporophyte
Zygote
(2n)
Sorus
Gametophyte
Fiddlehead
FERTILIZATION
Sperm
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
•
Phloem consists of living cells and distributes sugars, amino acids,
and other organic products
•
Water-conducting cells are strengthened by lignin and provide
structural support
•
Increased height was an evolutionary advantage
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Evolution of Roots
•
Roots are organs that anchor vascular plants
•
They enable vascular plants to absorb water and nutrients from the soil
•
Roots may have evolved from subterranean stems
Evolution of Leaves
•
Leaves are organs that increase the surface area of vascular plants,
thereby capturing more solar energy that is used for photosynthesis
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-15f
25 cm
Athyrium
filix-femina,
lady fern
The Significance of Seedless Vascular Plants
•
The ancestors of modern lycophytes, horsetails, and ferns grew to
great heights during the Devonian and Carboniferous, forming the first
forests
•
Photosynthesis dramatically increased the removal of CO2 from the
atmosphere
•
Increased photosynthesis may have helped produce the global cooling
at the end of the Carboniferous period
•
The decaying plants of these Carboniferous forests eventually became
coal
•
Coal was crucial to the Industrial Revolution, and people worldwide still
burn 6 billion tons a year.
•
Ironic that coal, formed from plants that contributed to global cooling,
now contributes to global warming by returning carbon to the
atmosphere.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 29-16
You should now be able to:
1.
Describe four shared characteristics and four distinct characteristics
between green algae and land plants
2.
Diagram and label the life cycle of a bryophyte
3.
Explain why most bryophytes grow close to the ground and are
restricted to periodically moist environments
4.
Describe three traits that characterize modern vascular plants and
explain how these traits have contributed to success on land
5.
Explain how vascular plants differ from bryophytes
6.
Diagram and label the life cycle of a seedless vascular plant
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings