Evolution and Biodiversity

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Dec 14, 2012 (4 years and 8 months ago)

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Evolution and Biodiversity

Chapter 4

Core Case Study: Life on Earth


Uniquely suited for life


Temperature range


Liquid water


Gravitational mass


Oxygen



Organisms contribute to relatively consistent
planetary conditions


resilient and adaptive



Biodiversity and sustainability


The Right Mix of Conditions

Fig. 4
-
1, p. 63

4
-
1 What Is Biological Evolution and How
Does It Occur?


Concept 4
-
1A

The scientific theory of evolution
explains how life on earth changes over time
through changes in the genes of populations.



Concept 4
-
1B

Populations evolve when genes
mutate and give some individuals genetic traits
that enhance their abilities to survive and to
produce offspring with these traits (natural
selection).

Theory of Evolution


4.7 billion years



Explains why life so diverse



Supported by
fossils
, chemical analysis of
primitive rock, DNA, and ice cores

Fossilized Skeleton of a Cenozoic
Herbivore

Fig. 4
-
2, p. 65

Population Changes over Time


Populations evolve by becoming genetically
different



Genetic variability


mutation



Natural Selection


Genetically favorable traits to survive and
reproduce



Trait


heritable and lead to
differential
reproduction



Faced with environmental change


Adapt


Migrate


Become extinct



Coevolution


Changes in gene pool of one species lead to
changes in gene pool of the other



Bats and moths

Science Focus: How Did We Become
Such a Powerful Species?


Key adaptations


also enabled us to modify
environment



Evolved very recently



Technology dominates earth’s life support
systems and NPP

4
-
2 How Do Geological and Climate
Changes Affect Evolution?


Concept 4
-
2

Tectonic plate movements,
volcanic eruptions, earthquakes, and climate
change have shifted wildlife habitats, wiped out
large numbers of species, and created
opportunities for the evolution of new species.

Plate Tectonics


Locations of continents and oceans determine
earth’s climate



Movement of continents allow species to move
and adapt



Earthquakes and volcanoes affect biological
evolution

Movement of Continents

Fig. 4
-
3, p. 67

Present

65 million years ago

135 million years ago

225 million years ago

Present

225 million years ago

65 million years ago

135 million years ago

Fig. 4
-
3, p. 67

Stepped Art

Earth’s Long
-
term Climate Changes


Cooling and warming periods


affect evolution
and extinction of species



Five mass extinctions


Eliminated half of the earth’s species


Many theories why this occurred



Opportunities for the evolution of new species


Northern Hemisphere over 18,000 Years

Fig. 4
-
4, p. 67




18,000

years before

present

Modern day

(August)

Northern Hemisphere

Ice coverage

4
-
3 What Is an Ecological Niche?


Concept 4
-
3

As a result of biological evolution,
each species plays a specific ecological role
called its niche.

Unique Roles for Species


Generalist species




Specialist species



Specialists prone to extinction


giant panda



Specialized Feeding Niches in Birds

Fig. 4
-
5, p. 68

Louisiana heron

wades into water

to seize small fish

Black skimmer

seizes small fish

at water surface

Ruddy
turnstone
searches
under shells
and pebbles

for small
invertebrates

Avocet sweeps bill
through mud and
surface water in
search of small
crustaceans, insects,
and seeds

Brown pelican
dives for fish,
which it locates
from the air

Dowitcher probes

deeply into mud in

search of snails,

marine worms, and

small crustaceans

Herring gull

is a tireless

scavenger

Flamingo feeds on

minute organisms

in mud

Scaup and other diving

ducks feed on mollusks,

crustaceans, and aquatic

vegetation

Piping plover
feeds on insects
and tiny
crustaceans on
sandy beaches

Knot (sandpiper)

picks up worms

and small crustaceans

left by receding tide

Oystercatcher feeds on

clams, mussels, and other

shellfish into which it

pries its narrow beak

Science Focus: Cockroaches


Existed for 350 million years


3,500 known
species



Highly adapted, rapidly producing generalists


Consume almost anything


Endure food shortage


Survive everywhere except polar regions


Avoid predation



Carry human diseases



4
-
4 How Do Extinction, Speciation, and
Human Activities Affect Biodiversity?


Concept 4
-
4A

As environmental conditions
change, the balance between formation of new
species and extinction of existing ones
determines the earth’s biodiversity.



Concept 4
-
4B

Human activities decrease the
earth’s biodiversity by causing the premature
extinction of species and by destroying or
degrading habitats needed for the development
of new species.


Speciation


Geographic isolation



Reproductive isolation



Millions of years in slow
-
producing species



Hundreds of years in rapidly reproducing
species



Geographic Isolation

Fig. 4
-
6, p. 70

Spreads
northward

and southward

and separates

Arctic Fox

Gray Fox

Different environmental

conditions lead to different

selective pressures and evolution

into two different species.

Adapted to cold

through heavier
fur, short ears,
short legs, and
short nose.
White fur
matches snow
for camouflage.

Adapted to
heat through
lightweight

fur and long
ears, legs, and
nose, which

give off more
heat.

Northern

population

Southern

population

Early fox

population

Extinction


Endemic species

vulnerable to extinction



Background extinction



Mass extinction



Balance between speciation and extinction
determines biodiversity of earth



Speciation generally more rapid than extinction



Extinction through Habitat Loss

Fig. 4
-
7, p. 70

Human Activities and Extinction


Cause premature extinction of species



Earth took millions of years to recover from
previous mass extinctions

4
-
5 How Might Genetic Engineering
Affect the Earth’s Life?


Concept 4
-
5

Genetic engineering enables
scientists to transfer genetic traits between
different species


a process that holds great
promise and raises difficult issues.

Humans Change Population Genetics


Artificial selection



slow process



Selective breeding



Crossbreeding


not a form of speciation



Genetic engineering


Results of Genetic Engineering


Genetically modified organisms

(
GMOs
)



Gene splitting rapid vs. artificial selection



Modified crops, new drugs, fast
-
growing animals


Steps in Genetic Engineering (1)

Steps in Genetic Engineering (2)

Fig. 4
-
8, p. 72

Fig. 4
-
8a, p. 72

Phase 1

Gene Transfer Preparations

Host cell

Enzymes integrate plasmid

into host cell DNA.

A. tumefaciens

(agrobacterium)

Agrobacterium takes up plasmid

Foreign gene integrated into

plasmid DNA, which can be

used as a vector

plasmid

Extract

plasmid

A. tumefaciens

Plant cell

Foreign gene

if interest

Extract DNA

Phase 2

Make Transgenic Cell

Fig. 4
-
8b, p. 72

Phase 3

Grow Genetically

Engineered Plant

Foreign DNA

Host DNA

Nucleus

Transgenic

plant cell

Cell division of

transgenic cells

Cultured cells

divide and grow

into plantlets

(otherwise

teleological)

Transgenic plants

with desired trait

Pros and Cons of Genetic Engineering


Pros


May help cure genetic defects


May improve organisms


May lead to development of secondary evolution



Cons


Ethical issues


Privacy issues


Designer babies


GMO crossbreeding with original organisms



Genetically Engineered Mice

Fig. 4
-
9, p. 73

Animation: Carbon Bonds

Animation: Stanley Miller’s Experiment

Animation: Evolutionary Tree of Life

Animation: Stabilizing Selection

Animation: Disruptive Selection

Animation: Moth Populations

Animation: Adaptive Trait

Animation: Speciation on an Archipelago

Animation: Evolutionary Tree Diagrams

Animation: Gause’s Competition Experiment

Animation: Species Diversity By Latitude

Animation: Humans Affect Biodiversity

Animation: Habitat Loss and Fragmentation

Animation: Transferring Genes into Plants

Video: Ancient Human Skull

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Video: Asteroid Menace

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Video: Bachelor Pad at the Zoo

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Video: Cloned Pooch

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Video: Creation vs. Evolution

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Video: Dinosaur Discovery

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Video: Glow
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in
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Video: Hsing Hsing Dies

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Video: Mule Clones

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Video: New Species Found

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Video: Penguin Rescue

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