Download Chapter 15- Plant Evolution

Evolution
In the 18th century, people became more mobile
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Why are the different animals and plants in
different geographic areas? How do we
explain this diversity?
As fossils were discovered: why don’t these
organisms exist anymore and why do the
things living today look totally different from
these fossils?
Until mid 19th
century:
Each species was
individually created
and has remained
unchanged over
time
Lamarck
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Organisms acquire
characteristics and
pass them on
WRONG!!!
Lamarck proposed:
Each species is a
unique individual
creation but changes
over time
(c) Descent with modification
Darwin and Wallace:
Species descend from
a common ancestor
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Influences on Charles Darwin
Lyell
- Earth is older than previously thought
- Small changes over time have produced
the geology that we see today
Malthus.
- Populations grow resources limit growth.
Darwin and the theory of evolution
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Descent with
modification leads to
evolution of new species
The process of natural
selection explains how
The Voyage of HMS Beagle
Credit. Dr. R. Rothman
Figure 22.7 Descent with modification
The Hawaiian Silversword Alliance
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Darwin’s observations of natural populations:
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Evolution: How Does Evolution Really Work?
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Overproduction of offspring.
Variation within populations exists and is
inherited from the parents
Struggle for resources and thus survival.
Differential survival and reproduction.
Natural Selection - Adaptation
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Individuals have different fitness. Fitness is the
ability to survive and reproduce offspring
Artificial Selection
Adaptations
Source: http://www.orchids.mu/Species/Angraecum/Angraecum_sesquipedale.htm
Evolution = process of change over time
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How do fossils form?
Evidence comes from a variety of sources
1) fossils
2) biogeography
3) anatomical similarities
- Homology
- Convergent evolution
5) Molecular data
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Figure 25.1 A gallery of fossils
Figure 15.04
Homology and Convergent Evolution
Biogeography
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Biogeography is the study of the geographic
distribution of organisms
Organisms of the Galapagos are more
similar to those of mainland South
America rather than other tropical islands.
Related species are found in distant
geographic areas.
Figure 25.4 The history of continental drift
Key: C = Cassowary; E = Emu; e = Elephant Bird; K = Kiwi; m = Moa; O = Ostrich;
R = Rhea.
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Continental Drift
explains some species
distributions
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Molecular Evidence
Microevolution and Macroevolution
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Microevolution – changes within species
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Macroevolution – how species evolve
How does Microevolution happen?
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Mutations: Chromosomal Changes
It occurs at the population level
Mutations
Migration
Genetic Drift
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Genetic drift
Migration
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Deletion
Translocation
Inversion
Insertions
The frequency of alleles increases or decreases
due to random chance
(can also be due to selective forces like habitat
loss or mass overhunting)
Grass in the foreground is growing on mine tailings
The same species is growing in the background
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Bottleneck Effect
Macroevolution is due to isolation
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Geographic Isolation
Reproductive Isolation
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Macroevolution
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Ecological Isolation
factors such as climate or soils may play a
role in isolation
Dutchman Breeches
Reproductive Isolation
Geographic isolation
Ecological isolation
Eastern redbud – east of
Mississippi
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Western Redbud – California,
Utah, Nevada and Arizone
Role of Hybridization in Evolution
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Hybrids may be significant or important in
evolutionary change, depending on how the
characteristics of the parents were
combined.
Introgression - Backcrossing between
hybrid and parent.
Polyploidy - New cell wall fails to develop
between two daughter cells.
Sterility - Chromosomes do not pair up
correctly.
Squirrel Corn
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Apomixis
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Sterile Hybrids may reproduce asexually.
Apomixis includes the development and
production of seeds without fertilization.
- May be highly successful.
Dandelions and Wild Blackberries
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Required for Reproduction or Display
Copyright © McGraw-Hill Companies Permission Required for Reproduction or Display
Figure 15.10
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