Transcript Fundamental niche

Chapter 4
Evolution and
Biodiversity
Earth: The Just-Right, Adaptable Planet,
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temp. w/in a narrow range (10-20 C)
Distance to sun-perfecto
O2 just right
Ozone!
Diversity and sustainability!
Figure 4-1
ORIGINS OF LIFE
• 1 billion years of chemical change to form
the first cells, followed by about 3.7 billion
years of biological change.
Figure 4-2
How Do We Know Which
Organisms Lived in the Past?
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2.
3.
4.
Our knowledge
about past life
comes from:
fossils
chemical analysis
cores drilled out of
buried ice
DNA analysis
Figure 4-4
Fossils
Why is the fossil record
incomplete?
1. Not all fossils have
been found
2. Some fossils have
decomposed
3.Some forms of life
left no fossils
Chemical analysis
Ice core samples
DNA Analysis
EVOLUTION
• Biological evolution by natural selection
involves the change in a population’s
genetic makeup through successive
generations. It takes time!
Natural Selection and Adaptation:
Leaving More Offspring With
Beneficial Traits
• Three conditions are necessary for biological
evolution:
1.Genetic variability
2. traits must be heritable
3. trait must lead to differential reproduction.
• An adaptive trait is any heritable trait that
enables an organism to survive through natural
selection and reproduce better under prevailing
environmental conditions.
http://www.youtube.com/watch?v=elBEeqJQEW0
Adaptation
1. Genetic variability?
MUTATION!!!!
-can happen from:
X-ray, radioactivity, UV
light, chemicals, or it
can be a random
natural event 
Can be harmless, harmful or
beneficial. (What happens when a
mutation is beneficial?)
2. Traits must be heritable???
BIG BICEPSNOT REALLY
HERITABLE
HERITABLE !!!!
3. Differential reproduction.
Since the
environment
can't support
unlimited
population
growth, not all
individuals get to
reproduce to
their full
potential. In this
example, green
beetles tend to
get eaten by
birds and
survive to
reproduce less
often than brown
beetles do.
Coevolution: A Biological Arms
Race
• Interacting species can engage in a back and
forth genetic contest in which each gains a
temporary genetic advantage over the other.
• Evolution: Library: Ancient Farmers of the Amazon
– This often happens between predators and prey
species.
Evolution: Library: Toxic Newts
Hybridization and Gene
Swapping: other Ways to
Exchange Genes
• New species can arise through
hybridization.
– Occurs when individuals to two distinct
species crossbreed to produce an fertile
offspring.
• Some species (mostly microorganisms)
can exchange genes without sexual
reproduction.
– Horizontal gene transfer
HYBRID
Common Myths about Evolution
through Natural Selection
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Survival of the fittest does not mean
survival of the strongest! It’s all about
who has the most reproductive success
Organisms do not develop certain traits
because they need them. (ex giraffe)
There is no such thing as genetic
perfection.
GEOLOGIC PROCESSES,
CLIMATE CHANGE,
CATASTROPHES, AND
EVOLUTION
• The movement of solid (tectonic) plates
making up the earth’s surface, volcanic
eruptions, and earthquakes can wipe out
existing species and help form new ones.
– The locations of continents and oceanic
basins influence climate.
– The movement of continents have allowed
species to move.
225 million years ago
65 million years ago
135 million years ago
Present
Fig. 4-5, p. 88
Climate Change and Natural
Selection
• Changes in climate throughout the earth’s
history have shifted where plants and
animals can live.
Figure 4-6
18,000
years before
present
Northern Hemisphere
Ice coverage
Legend
Continental ice
Sea ice
Modern day
(August)
Note:
Modern
sea ice
coverage
represents
summer
months
Land above sea level
Fig. 4-6, p. 89
Catastrophes and Natural
Selection
• Asteroids and meteorites hitting the earth and
upheavals of the earth from geologic
processes have wiped out large numbers of
species and created evolutionary
opportunities by natural selection of new
species.
ECOLOGICAL NICHES AND
ADAPTATION
• Each species in an ecosystem has a
specific role or way of life.
– Fundamental niche: the full potential range
of physical, chemical, and biological
conditions and resources a species could
theoretically use.
– Realized niche: to survive and avoid
competition, a species usually occupies only
part of its fundamental niche.
Generalist and Specialist Species:
Broad and Narrow Niches
• Generalist
species
tolerate a wide
range of
conditions.
• Specialist
species can
only tolerate a
narrow range
of conditions.
Figure 4-7
Number of individuals
Specialist species
with a narrow niche
Niche
separation
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Resource use
Fig. 4-7, p. 91
SPOTLIGHT
Cockroaches: Nature’s Ultimate
Survivors
• 350 million years old
• 3,500 different species
• Ultimate generalist
– Can eat almost
anything.
– Can live and breed
almost anywhere.
– Can withstand massive
radiation.
Figure 4-A
Specialized Feeding Niches
• Resource partitioning reduces
competition and allows sharing of limited
resources.
Figure 4-8
Avocet sweeps bill through
mud and surface water in
search of small crustaceans,
insects, and seeds
Ruddy
turnstone
Herring gull is a
searches
tireless scavenger
under shells
and pebbles
Dowitcher probes deeply
for small
into mud in search of
invertebrates
snails, marine worms,
and small crustaceans
Brown pelican
dives for fish,
which it locates
from the air
Black skimmer
seizes small fish
at water surface
Louisiana heron wades into
water to seize small fish
Flamingo
feeds on
minute
organisms
in mud
Scaup and other
diving ducks feed
on mollusks,
crustaceans,and
aquatic vegetation
(Birds not drawn to scale)
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Knot (a sandpiper)
picks up worms and
small crustaceans left
by receding tide
Fig. 4-8, pp. 90-91
Evolutionary Divergence
• Each species has
a beak specialized
to take advantage
of certain types of
food resource.
Figure 4-9
SPECIATION, EXTINCTION, AND
BIODIVERSITY
• Speciation: A new species can arise when
members of a population become isolated
for a long period of time.
– Genetic makeup changes, preventing them
from producing fertile offspring with the
original population if reunited.
Geographic Isolation
• …can lead to reproductive isolation,
divergence of gene pools and speciation.
Figure 4-10
Adapted to cold through
heavier fur,short ears, short
legs,short nose. White fur
matches snow for camouflage.
Arctic Fox
Northern
population
Early fox
Population
Spreads
northward
and southward
and separates
Southern
Population
Different environmental
conditions lead to different
selective pressures and
evolution into two different
species.
Adapted to
heat through
lightweight
fur and long
Gray Fox ears, legs,
and nose,
which give
off more
heat.
Fig. 4-10, p. 92
Extinction: Lights Out
• Extinction
occurs when
the population
cannot adapt to
changing
environmental
conditions.
The
golden toad of Costa Rica’s
Monteverde cloud forest has
become extinct because of
changes in climate.
Figure 4-11
Cenozoic
Era
Period
Millions of
years ago
Quaternary
Today
Tertiary
65
Mesozoic
Cretaceous
Jurassic
180
Triassic
Species and families
experiencing
mass extinction
Extinction Current extinction crisis caused
by human activities. Many species
are expected to become extinct
Extinction within the next 50–100 years.
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Extinction
Triassic: 35% of animal families,
including many reptiles and marine
mollusks.
Bar width represents relative
number of living species
250
Extinction
345
Extinction
Permian
Paleozoic
Carboniferous
Devonian
Permian: 90% of animal families,
including over 95% of marine
species; many trees, amphibians,
most bryozoans and brachiopods,
all trilobites.
Devonian: 30% of animal
families, including agnathan and
placoderm fishes and many
trilobites.
Silurian
Ordovician
Cambrian
500
Extinction
Ordovician: 50% of animal
families, including many
trilobites.
Fig. 4-12, p. 93
Effects of Humans on
Biodiversity
• The scientific consensus is that human
activities are decreasing the earth’s
biodiversity.
Figure 4-13
GENETIC ENGINEERING AND
THE FUTURE OF EVOLUTION
• We have used artificial selection to
change the genetic characteristics of
populations with similar genes through
selective breeding.
• We have used
genetic engineering
to transfer genes
from one species to
another.
Figure 4-15
Case Study:
How Did We Become Such a
Powerful Species so Quickly?
• We lack:
– strength, speed, agility.
– weapons (claws, fangs), protection (shell).
– poor hearing and vision.
• We have thrived as a species because of
our:
– opposable thumbs, ability to walk upright,
complex brains (problem solving).