biol 108 chp 10 pt 2
TRANSCRIPT
The Origin and
Diversification of Life
on Earth
BIOL 108 Intro to Bio Sci
Chapter 10 pt 2
Rob Swatski Assoc Prof Biology
HACC-York 1
10.9 Similar structures don’t always reveal common ancestry.
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The mapping of species’ characteristics onto phylogenetic trees
Physical features
DNA sequences
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Convergent Evolution
and analogous traits
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Analogous traits: Features that are produced by convergent
evolution
Homologous traits: Features that are inherited from a common
ancestor
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How do you know whether traits are homologous or analogous?
DNA analysis
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Which structures below are homologous?
1. Human forearm and a monkey’s forearm
2. Fish fin and whale fin
3. Butterfly wing and bat wing
4. All of the above
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Take-Home Message 10.9
Evolutionary trees are best constructed by comparing genetic similarity among
organisms.
Convergent evolution can cause distantly
related organisms to appear much more
closely related. 10
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10.10 Macroevolution is evolution above the species
level.
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Take-Home Message 10.10
The process of evolution in conjunction
with reproductive isolation…
…is sufficient to produce speciation,
diversification, and the rich diversity of life on
earth. 15
10.11 The pace of evolution is not constant.
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Take-Home Message 10.11
The pace at which evolution occurs can be rapid or very
slow.
In some cases, the fossil record reveals rapid periods
of evolutionary change punctuated by longer
periods with little change.
In others cases, species may change at a more gradual,
but consistent, pace.
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10.12 Adaptive radiations are times of extreme diversification.
When a small number of species diversifies into a much larger
number of species
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Colonizers find a large number of opportunities for adaptation and diversification.
Galapagos finches
Hawaiian fruit flies 21
innovations such as the wings and rigid skeleton that appeared in insects
helped them to diversify into the most successful group of animals
more than 800,000 species today!
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The ability of multiple species to evolve via adaptive radiations is due
to _______ over time.
1. Macroevolution
2. Microevolution
3. Punctuated equilibrium
4. Gradual change
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Take-Home Message 10.12
Adaptive radiations tend to be triggered by:
1) mass extinctions of potentially
competing species
2) colonization of new habitats
3) the appearance of evolutionary
innovations
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10.13 There have been several mass extinctions on earth.
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Background Extinction
extinctions that occur at lower rates during periods other than periods of mass extinctions
occur mostly as the result of natural selection
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Background and Mass Extinctions Have Different Causes
Mass extinctions are due to extraordinary and sudden changes to the environment.
Background extinctions occur mostly as the result of natural selection.
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Take-Home Message 10.13
As new species are being created, others are lost
through extinction.
Extinction may be a consequence of natural
selection or large, sudden changes in the environment.
Mass extinctions are periods during which a large number of species on earth become extinct over a short
period of time.
These periods are usually followed by periods of
unusually rapid adaptive radiations and
diversification of the remaining species.
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10.14 All living organisms are divided into one of three groups.
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Classification Systems
The two-kingdom system • Animal and plant
The five-kingdom system • Monera, plant, animal, fungi, and protists
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Classification Takes a Leap Forward
Carl Woese, an American biologist, and his colleagues
Examined nucleotide sequences
Tracking changes
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Woese’s approach is not perfect.
Are viruses alive?
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Take-Home Message 10.14
All life on earth can be divided into three
domains—bacteria, archaea, and eukarya—which reflect
their evolutionary relatedness to each other.
Plants and animals are just two of the four kingdoms in
the eukarya domain, encompassing only a small
fraction of the domain’s diversity.
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10.15 The bacteria domain has tremendous biological diversity.
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Bacteria Are a Monophyletic Group
All bacteria have a few features in common:
single-celled organisms with no nucleus or organelles
one or more circular molecules of DNA
several methods of exchanging genetic information
asexual organisms
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Which single-celled organism below is considered to be most closely related to
the first cell to exist on our planet?
1. Plants
2. Protists
3. Bacteria
4. Archeae
5. Animals
6. Fungi
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Take-Home Message 10.15
Bacteria have evolved a broad diversity of metabolic and reproductive abilities
relative to Eukarya.
The bacteria all share a common ancestor and have a few features in common:
• All are prokaryotic, asexual, single-celled organisms with no nucleus or organelles.
• All have one or more circular molecules of DNA as their genetic material.
• All have several methods of exchanging genetic information.
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10.16 The archaea domain includes many species living in
extreme environments.
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Several Physical Features Distinguish Archeans from the Bacteria
Archaeans’ cell walls contain polysaccharides not found in either bacteria or eukaryotes.
Archeans have cell membranes, ribosomes, and some enzymes similar to those found in eukaryotes.
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Take-Home Message 10.16
Archaea, many of which are adapted to life in extreme environments, physically
resemble bacteria but are more closely related to eukarya.
Because they thrive in many habitats that humans have not yet studied well, including the deepest seas and oceans, they may turn out to be much more
common than currently believed.
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10.17 The eukarya domain consists of four kingdoms.
Plants, Animals, Fungi, and Protists
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Take-Home Message 10.17
All living organisms that you can see with the naked eye are eukarya, including all plants, animals, fungi,
and protists.
The eukarya are unique among the three domains in that they have cells with
organelles.
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Humans can be classified as…
1. Homo sapiens
2. Eukarya
3. Animals
4. Vertebrates
5. All of the above
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