biol 108 chp 10 pt 2

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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