Download PLANT DIVERSITY EVOLUTION OF LAND PLANTS

10/18/2015
PLANT DIVERSITY
1
EVOLUTION OF LAND PLANTS
KINGDOM: Plantae
Spores
Leaf
Ancestral green
algae
• Flagellated
sperm for
reproduction
• Plenty of water
• Nutrients and
CO2 diffuse into
tissues
Stem
Roots
•
Flagellated
sperm
Holdfast
•
•
•
•
Mosses (470mya)
Non vascular plants
Need moisture to
reproduce
Can’t lose water
Nutrients in soil
CO2 in air
Gravity!!!
Vascular plants
• Stomata
• Roots and stems
connected by vascular
system
• Lignin to hold plant
upright
Ferns (425mya)
2
1
10/18/2015
THE PLANT LIFE CYCLE
Plants have a life cycle called: alternation of generations
HAPLOID ADULT
(male or female)
Haploid (n)
Gametophyte
plant (n)
Sperm (n)
Egg (n)
Spores (n)
DIPLOID Meiosis
ADULT
with sporangia
Diploid (2n)
Fertilization
DIPLOID
ZYGOTE
DIPLOID JUVENILE
Sporophyte
plant (2n)
3
THE PLANT LIFE CYCLE
The life cycle of a fern (vascular land plant)
A Fern Life Cycle
Key
Gametophyte
plant (n)
Haploid (n)
Diploid (2n)
Male
gametangium
Sperm
Spores
Female
gametangium
Egg
Sporangia
Meiosis
Mature
sporophyte
Fertilization
New sporophyte
growing from the
gametophyte
Zygote
4
2
10/18/2015
MOSSES
PHYLUM: Bryophyta
• Non‐vascular land plants (no, xylem, phloem, lignin)
• No true roots or leaves
• Form dense mats of many individuals (no lignin to stand up!)
• Live in moist environments
• Flagellated sperm
5
FERNS
PHYLA: Monilophyta and Lycophyta
• Vascular seedless land plants (xylem, phloem, lignin)
• Have true roots and leaves
• Spores can disperse in air but fertilization must happen in water
• Flagellated sperm
• Common in tropical and temperate
forests
6
3
10/18/2015
THE CARBONIFEROUS PERIOD
• Ferns were giant and very abundant. • They contributed to the increase in oxygen in Earth’s atmosphere and fossil fuels that we now use for energy. 7
VASCULAR PLANTS WITH SEEDS Evolved 360mya; account for 90% of plants today
ADAPTATIONS OF VASCULAR PLANTS W/SEEDS
• Pollen grains carry spores through the air (haploid)
• Pollination – male pollen grain lands on female reproductive part
• Fertilization – after pollination, sperm fertilizes egg(s) to create diploid zygote(s)
• A protective seed forms around the zygote(s) with food inside
• Seed gets carried off into the world
8
4
10/18/2015
GYMNOSPERMS (Vascular seed plants)
Many phyla; mostly cone‐bearing trees, ginko trees, cycads
• Sporangia found in male and female cones
• Pollen released in the air
• Fruitless; Slow growing; Long lived; Fire factoid (conifers)
Female
Sporangia
Longitudinal section of
female cone (holds ovules)
Male
Sporangia
Longitudinal section of
male cone (holds pollen)
9
GIANT SEQUOIA TREES
Example of a Gymnosperm
10
5
10/18/2015
ANGIOSPERMS(Vascular seed plants)
Many phyla; Flowering plants, grasses and fruits
• Male and female sporangia all located in the flower
• Produce fruit (see figure 17.7)
• Pollen travels in air or by animal carriers
Stigma
Style
Ovary
Carpel
(female parts)
Anther
Stamen
Filament (male parts)
Petal
Sepal
FRUIT: The ripened ovary of a flower
Ovule
Receptacle
11
ANGIOSPERM POLLINATION Invest energy into making structures to maximize pollination Lots of stamens for
wind pollination
Vibrant colors or scents can attract specific animals
Birds – red/orange
Beetles – sweet scents
Nectar to attract bees & stamens that rub on bees
12
6
10/18/2015
ANGIOSPERMS PRODUCE “FRUIT”
Fruits aid in dispersal of angiosperms
•
•
•
•
Dandelion seeds: air seed dispersal
Cocklebur fruits: seeds dispersed by attaching to animal fur
Edible fruits: seeds dispersed and given nutrients by animal poop!
Germination: The growth of a seed into a diploid sporophyte plant
Fruit
Seed dispersal
13
ANGIOSPERM CROPS
Wheat, corn, rice and spices are all dried angiosperm fruits
• Evolution has created a variety of human food sources
• Deforestation and agriculture has altered natural habitats
• Need ways to farm without deforestation
‐ GMOs can tolerate, insects, heat, drought
‐ Wild plants can be found that naturally tolerate heat and drought (African grains)
14
7
10/18/2015
EVOLUTION OF LAND PLANTS
You should know the order of evolution of mosses, ferns, gymnosperms and angiosperms and the characteristics of each.
Mosses
1
Land plants
Origin of land plants
(about 470 mya)
Nonvascular
plants
(bryophytes)
Liverworts
Ancestral
green
alga
Hornworts
500
450
400
350
300
Seed
plants
Gymnosperms
Origin of seed plants
3
(about 360 mya)
Vascular plants
Monilophytes (ferns,
horsetails, whisk ferns)
Seedless
vascular
plants
2
Lycophytes (club mosses,
spike mosses, quillworts)
Origin of vascular plants
(about 425 mya)
Angiosperms
0
Millions of years ago (mya)
15
FUNGAL DIVERSITY
16
8
10/18/2015
FUNGI Green algae
Other green algae
Brown algae
Land plants
Protists
Protists
Ancestral eukaryote
• Fungi are more closely related to animals than they are plants!
Red algae
Protists
Evolved from a heterotrophic protist
More protists
Fungi
Key
All unicellular
Both unicellular
and multicellular
All multicellular
Yep. Protists
Animals
17
KINGDOM: FUNGI Heterotrophs that acquire their nutrients by absorption.
Hyphae
(feeding structures)
• Have cell walls made of chitin
• Decomposers symbionts and parasites
• Asexual reproduction (molds!)
• Sexual reproduction (heterokaryotic stage)
Reproductive
structure
Spore-producing
structures (tips of hyphae)
Mycelium: a mass of hyphae
18
9
10/18/2015
FUNGAL DECOMPOSERS
Some fungi break recycle dead material into nutrients
• Important ecosystem function
• Can break down toxins and pollutants
• Reproductive structures of mushrooms on a dead log
• So… we eat reproductive parts of fungi………. Mmmm……
19
FUNGAL PARASITES 30% of fungi parasitize protists, plants and animals
•
•
•
•
•
White‐nose syndrome in bats
Andes Mountains frog die offs
Human infections
Dutch elm disease in 1926
Human food crops
20
10
10/18/2015
FUNGAL SYMBIONTS Lichens are associations of green algae or cyanobacteria with fungi
• Fungus gets food
• Benefit for algae?
• Lichens can tolerate harsh environments (temp, moisture, soil)
• Sensitive to air quality
• Some lichens are 1000s of years old!
Algal cell
Fungal
hyphae
Reindeer moss in the arctic tundra
Symbiosis: a relationship between two species living closely
21
FUNGAL SYMBIONTS Fungal mycorrhizae deliver nutrients to plants in exchange for food
• Fungi thread into root and form hair‐like projections into the soil
• Occurs in 80% of all plants; important in agriculture
• May have helped ancient plants to colonize land (present in mosses, fossil evidence)
22
11
10/18/2015
Green algae
Other green algae
Brown algae
Land plants
Protists
Protists
Ancestral eukaryote
Protists
Red algae
Key
All unicellular
Both unicellular
and multicellular
All multicellular
More protists
Fungi
Yep. Protists
Animals
23
ANIMAL DIVERSITY
24
12
10/18/2015
ANIMAL EVOLUTION
The first animals likely evolved from a heterotrophic protist 1 bya
• Evolved from soft to hard bodied organisms
• First animal fossil 575 mya
• Cambrian explosion
25
KINGDOM: Animalia Heterotrophs that acquire their nutrients by ingestion
•
•
•
•
Lack cell walls (have collagen for support)
Have specialized cells
Diploid organisms that reproduce sexually
Characterized by body plan
26
13
10/18/2015
ANIMAL BODY PLANS
Groups of animals can be distinguished by their body plans
• Radial animals are often sedentary (sessile) or drift passively
• Bilateral animals are often mobile
Bilateral Symmetry
(Lobster)
Radial Symmetry
(Anemone)
Posterior
Dorsal
Anterior
Ventral
27
KINGDOM: Animalia No true tissues
Sponges
Radial
symmetry
Lophotrochozoans
Flatworms
Invertebrates
Molluscs
Annelids
Nematodes
Arthropods
Deuterostomes
Ecdysozoans
Bilateral
symmetry
Cnidarians
Bilaterians
True
tissues
Eumetazoans
Ancestral
colonial
protist
Echinoderms
Chordates
28
14