Chapter 5:
Evolution and
Community Ecology
Mr. Manskopf
Notes Can Also Be Found at
http://www.manskopf.com
Section 1: Evolution
►Describe
the four primary mechanisms of
biological evolution
►Describe how speciation and extinction
affect the diversity of life on Earth.
►TERMS: evolution, gene mutation, genetic
drift, natural selection, fitness, adaptation,
artificial selection, speciation, extinction.
Incredible Diversity of Life
► 1.5
to 1.8 million
known species
► Possibly 13-20 million
► Tropical Rain Forests,
Coral Reefs and
everywhere else
Evolution
►What
YOU?
makes you,
What
makes
each
species
unique
and
different?
Genes
►Sequences
of DNA
codes for each
particular trait
►Tall, small, blue
eyes, human,
goldfish, pine tree
►Evolution is a
change of genes
over time
Evolution
►“Change
over
time”
►Change of Gene
Pool over time
►Why would genes
change over
time?
4 Ways Evolution Occurs
►Mutation
►Migration
►Genetic
Drift
►Natural Selection
Mutation
Accidental
change in DNA
that can give rise
to variation
among
individuals
Migration
Movement of
individuals
into
(immigration)
or out of
(emigration)
a population
Sometimes called “Gene Flow”
Gene Flow (Migration)
Genetic Drift
Evolution that
occurs by chance
• Natural Disasters
• Run in with
human nets, etc.
Natural Selection
► Process
by which
traits useful for
survival and
reproduction are
passed on more
frequently than
those that are
not
3 Conditions for Natural Selection
(1) Organisms
produce more
offspring than
can survive.
•
Nature has
limitations
(limiting factors)
•
Struggle for
survival
3 Conditions for Natural Selection
(2) Individuals vary in
characteristics, some of
which are heritable
► Not every species is
same
► Some fish are faster,
darker, smaller
► Genes different
► Heritable Differences
3 Conditions for Natural Selection
(3) Individuals vary in
fitness, or reproductive
success
► Survival
of Fittest
► Fittest for its environment
► Adaptation: an inherited
trait that increases an
organisms chance of
survival and reproduction.
http://www.youtube.com/watch?
v=xkwRTIKXaxg
► Travel
to Ecuador to see how the process of
natural selection operates
Adaptations
Desert plants have small or
no leaves at all
The insect
that blends
in and is
able to
survive
may be
more likely
to
reproduce.
Big ears of
desert jack
rabbit allow it to
cool off quickly
White coat of
Adaptations polar bear
helps in
hunting
Results of
Long neck of giraffe
natural
allow it to reach
food selection all
around us
NATURE
SELECTS
Did You Know? Darwin privately researched natural selection for two
decades before publishing On the Origin of Species.
Impacts of Natural Selection:
Resistance
Resistance
Resistance: the ability
of one or more
organisms to tolerate
a chemical designed
to kill it
► Able to survive and
reproduce
► Pesticide resistance
► Antibiotic resistance
Why is
this a
problem
?
Artificial Selection: How Humans
Use Evolution
Artificial Selection:
selective breeding
of organisms by
humans
►Selecting certain
desirable traits
►Size, sweetness,
color, shape,
►Very common
Artificial Selection
Artificial Selection
Selecting desirable traits
and breeding only those
with those traits.
Speciation: How did we get
millions of species?
QuickTime™ and a
decompressor
are needed to see this picture.
Speciation
• Process by which new
species are generated
• Can occur in a number
of different ways; the
most important way is
called allopatric
speciation– Geographic
Isolation
• Has resulted in every
form of life on Earth—
today and in the past
The canyon is a barrier to dispersal by small mammals, and
as a consequence the isolated populations can diverge.
http://www.youtube.com/watch?v=S4wnJp6sq_I
Extinction
•
The disappearance of species from
Earth
•
Generally occurs gradually, one
species at a time, when
environmental conditions change
more rapidly than the species can
adapt
•
There are five known mass
extinction events, each of which
wiped out a large proportion of
Earth’s species.
Biodiversity has increased over time, but mass extinctions are
also natural events (5 major events)
How do we get this data?
Did You Know? During the Permo-Triassic extinction 250
million years ago, 70% of all land species and 90% of all
marine species went extinct.
Extinctions
► Species
gone forever
► NORMAL
► Mass Extinction: short
period of time when
large number of species
go extinct (65 MYA)
► Currently in mass
extinction…caused by
humans
► Rapid climate change
Extinctions
The zebra mussel has
completely displaced 20 native
mussel species in Lake St. Clair.
Section 1: Evolution Review
► Describe
the four primary mechanisms of
biological evolution
► Describe how speciation and extinction
affect the diversity of life on Earth.
► TERMS: evolution, gene mutation, genetic
drift, natural selection, fitness, adaptation,
artificial selection, speciation, extinction
Section 1 Quiz
1) Which of the following best describes a successful
individual in evolutionary terms?
A.
A successful individual possesses traits that are
different from the traits of the rest of the population.
B.
A successful individual produces many offspring that
possess unique traits.
C.
A successful individual is well adapted to its
environment and produces offspring that survive to pass on
genes.
D.
A successful individual will be well adapted to its
environment and produce a few high quality offspring.
A.
A successful individual possesses traits that are
different from the traits of the rest of the population.
2) In the history of the world, how many
mass extinctions have occurred?
A. 5
B. 7
C. 10
A.
5
D. 13
3) In a mass extinction, the rate of
extinction exceeds
A. 99 percent.
B. 85 percent.
C. the rate of environmental change.
D. the rate of background extinction.
D. the rate of background extinction
4) A reintroduced population of wolves in a
national park is 90% grey and 10% black,
consistent with the wolf population in other
regions. After several generations in isolation,
the national park’s wolf population is 60%
grey and 40% black. The wolf population has
likely experienced
A. natural selection. B. genetic drift
Evolution that occurs
B. genetic drift.
by chance
C. mutations.
D. migration.
5) When the environment changes too
quickly for an organism to adapt, what
will occur?
A) Evolution
B) Speciation
C) Genetic Drift
D) Extinction
D. Extinction
True or False
6) Two populations of a deer species
are separated when a glacier forms.
After the glacier melts, the two
populations have become different
species. This is an example of allopatric
speciation.
TRUE
Short Answer
7) A disaster wipes out 50 percent of a small
population of birds. Prior to the disaster,
about half the birds had a green wing patch
and half had a blue wing patch. Several
generations after the disaster, only 10% have
a blue wing patch, and 90% have a green
wing patch. What do you infer happened, and
why?
The bird population experienced genetic drift as the
result of a sudden catastrophe. The disaster
reduced genetic diversity in the population and
changed the proportion of birds with a green wing
patch vs. a blue wing patch.
Short Answer
8) Pronghorn are a species of extremely fast
hooved mammal that live on the plains of
western North America. They are so fast that no
current North American predator can catch
them. During the ice age, cheetahs occupied
North America. Speculate about how pronghorn
became so fast.
Pronghorn probably evolved in an evolutionary “arms
race” with the cheetah population. They became
faster and faster to escape from cheetahs, which were
probably fast enough to catch them.
Section 2: Species Interaction
► Discuss
the factors that influence an
organisms niche
► Compare and contrast predation, parasitism,
herbivory
► Describe mutualism and commensalism
► TERMS: niche, tolerance, resource
partitioning, predation, coevolution,
parasitism, symbiosis, herbivory, mutualism,
commensalism.
Species Interaction
What resources
are the plants in
this picture
competing for?
Competition for
resources all
around us
► Describes
Niche
an
organism’s use of
resources and
functional role in a
community
► Habitat
► Food It Eats
► When, How
Reproduces
► What organisms does
it interact with
Niche Impacted By Tolerance and
Competition
•
Affected by an
organism’s
tolerance—its ability
to survive and
reproduce under
changing
environmental
conditions
•
Often restricted by
competition
Tolerance Limits
Fundamental vs. Realized Niche
Fundamental =
Without
competition
Realized = With
competition
(restricted niche)
►Organisms
Competition
compete when
they seek the same limited
resource.
►In
rare cases, one species
can entirely exclude another
from using resources.
►To
reduce competition,
species often partition
resources, which can lead to
character displacement.
Resource Partitioning
► The
zebra mussel has completely displaced
20 native mussel species in Lake St. Clair.
Predation (+/-)
► The
process by which a predator hunts,
kills, and consumes prey
► Causes
cycles in predatory and prey
population sizes
Predator/Prey
Cycles
Predation
► Defensive
traits
such as
camouflage,
mimicry, and
warning
coloration have
evolved in
response to
predator-prey
interactions.
Predation
► Some
Rough-Skinned Newt
Did You Know? A single rough-
skinned newt contains enough poison
to kill 100 people. Unfortunately for
the newt, its predator, the common
garter snake, has coevolved resistance
to the toxin.
predator-prey
relationships are
examples of
coevolution, the
process by which
two species evolve
in response to
changes in each
other.
Coevolution
The Madagascar star orchid
produces nectar at the
bottom part of its slim, footlong throat. After observing a
specimen, Charles Darwin
predicted the existence of a
moth with a proboscis long
enough to reach that nectar.
Sure enough, decades later
the giant hawk moth of
Madagascar was discovered.
Parasitism and Herbivory
(+/–)
•
Parasitism: One
organism (the
parasite) relies on
another (the host) for
nourishment or for
some other benefit
•
Herbivory: An animal
feeding on a plant
Parasitism and Herbivory
(+/–)
Malaria is a
disease caused by
a parasite called
Plasmodium that is
spread to humans
by the bite of an
infected Anopheles
mosquito.
Parasitism and Herbivory
(+/–)
Mutualism (+/+) and
Commensalism (+/0)
•
Mutualism: a
relationship in which
two or more species
benefit
•
Commensalism: a
relationship in which
one species benefits
while the other is
unaffected
Mutualism (+/+) and
Commensalism (+/0)
Clown Fish and Sea
Anemones demonstrate
mutualism because
Anemones provide the
Clown Fish with protection
from predators while
Clown fish defend the
Anemones from Butterfly
fish who like to eat
Anemones.
Mutualism (+/+) and
Commensalism (+/0)
Barnacles
adhering to
the skin of
a whale or
shell of a
mollusk
Section 2 Review Species
Interaction
► Discuss
the factors that influence an
organisms niche
► Compare and contrast predation, parasitism,
herbivory
► Describe mutualism and commensalism
► TERMS: niche, tolerance, resource
partitioning, predation, coevolution,
parasitism, herbivory, mutualism,
commensalism.
Section 2 Quiz
1) Madagascar, several species of lemur eat
bamboo, but each species specializes in one part
of the bamboo—one species eats mature
bamboo stalks, one species eats bamboo shoots,
and one species eats leaves. This is an example
of
► A. speciation.
► B. resource partitioning.
B. Resource
► C. competition.
Partitioning
► D. niche partitioning.
2) In the example above, one lemur species eats
only bamboo shoots. Bamboo shoots contain a high
level of cyanide, a toxic chemical. This lemur species
has developed a tolerance for a certain amount of
cyanide. What do you think will happen over time?
A.
The level of cyanide in the bamboo population
will increase.
B.
The level of cyanide in the bamboo population
will decrease.
C.
The level of cyanide in the bamboo population
will remain the same.
D.
The level of cyanide in the lemur population
will decrease.
A.
The level of cyanide in the bamboo population will
increase.
3) Two species of finch live in the same
environment. Over time, one develops a
larger beak to consume larger seeds,
while the other develops a narrow beak
to consume more delicate seeds. This is
an example of
A. resource partitioning.
B. character displacement.
C. coevolution.
D. competitive exclusion.
C.
coevolution.
4) An interaction in which an individual
of one species kills and consumes an
individual of another is called
A. predation.
B. parasitism.
C. herbivory.
D. symbiosis.
A.
predation
5) In the western United States, at the
southern edge of their range, moose are
sometimes so severely infested with ticks
that they die. The tick/moose
relationship is best described as
A. predatory.
B. parasitic.
C. symbiotic.
D. mutualistic.
B.
parasitic.
6) A beehive depends on pollen from
flowers to survive. Flowers depend on bees
to pollinate them. The relationship among
these two sets of organisms is
A. parasitic.
B. commensalist.
C. herbivory
D. mutualistic.
D. mutualistic.
7) A niche restricted by competition is a
A. fundamental niche.
B. realized niche.
C. resource partitioned niche.
D. displaced niche.
B.
realized niche
8) A deer browsing on a shrub is an
example of
A. predation.
B. parasitism.
C. herbivory.
D. photosynthesis.
C.
herbivory.
True or False
You have many species of
bacteria living in your gut that
help you with digestion. This
relationship is best defined as
commensalism.
False: Mutualism
Short Answer
9) Explain the difference between
mutualism and commensalisms, with
examples.
In mutualism and commensalism, both species are
unharmed. In mutualism, both species benefit, as in
the example of the hawk moth pollinating the
flower; the flower is pollinated and the moth is fed.
In commensalism, one species benefits while the
other doesn’t experience a negative or a positive
effect. Trees providing shade and moisture to
desert shrubs is an example of commensalism.