Transcript Chapter 29

Do Now:
1. Identify each animal & identify each as
either a primary consumer or secondary
consumer.
2. Identify the relationship between them.
3. Explain how these organisms are
important to each other.
Do Now:
1. primary consumer & secondary consumer
2. Predator/Prey relationship.
3. Importance in terms of population
control/balance/health/evolution.
Chapter 5:
Ecosystems & living organisms
Evolution
• A process of change
through time
Theory of Evolution
1. Suggests that existing forms of
life on earth have evolved from
earlier forms over long periods
of time
2. Evolution accounts for the
differences in structures,
function, and behavior among
life forms as well as changes
(C)
Charles Darwin
1. Overproduction
• Within a population, there are
more offspring produced in
each generation than can
possibly survive.
2. Competition
• Natural resources; like food, water, and
space available to a population is
limited
• Because there are many organisms
with similar nutritional requirements,
there must be competition between
them for the resources needed to
survive
(C)
Darwin
• Charles Darwin devised a theory of
evolution based on variation and natural
selection as seen in the Galapagos islands.
• Included in his theory were six main ideas:
1. Overproduction
2. Competition
3. Survival of the Fittest
4. Natural Selection
5. Reproduction
6. Speciation
Do Now:
• List the six main ideas of Darwin’s Theory of
Evolution:
1.
2.
3.
4.
5.
6.
Competition
1. Different species living in the same
environment, or habitat, may require the
same resources.
When the resources are limited, competition
occurs among the species.
Intraspecific: competition within a population
Competition
2.Competition- is the struggle between
different species for the same limited
resources.
The more similar the needs of the species,
the more intense the competition.
Interspecific: competition between different
species.
Competition
3.Each species occupies a niche in the
community. A niche is the role the species
plays, and includes the type of food it eats,
where it lives, where it reproduces, and its
relationships with other species.
Competition
4.When two different species compete for the
same niche in a community, the weaker
species is usually eliminated establishing
one species per niche in a community.
Do now:
• How do the processes of _______ contribute to
natural selection?
–
–
–
–
overproduction of offspring
individual variation among individuals in a population
environmental limits on population growth (natural selection)
differential reproductive success
• HINT: Do not simply describe these four
observations; connect them into an integrated
response.
Do Now: Sample Answer
• Because more offspring are produced in a
population than survive to reproduce and
because individuals vary within the population,
some individuals will be better adapted (more
fit) for the current environmental conditions.
These individuals have a greater likelihood of
reproducing and passing their fitness to their
offspring. As a population approaches the
carrying capacity of its environment, the
individuals with the greatest fitness are most
likely to survive and reproduce.
• This is an ongoing process as organisms
respond to changes, however minute, in their
Do Now:
• Define ecological niche and explain the
role of limiting resources in the
determination of an organism's ecological
niche.
Do Now: Answer
• Every organism is thought to have its own role, or
ecological niche, within the structure and function of an
ecosystem. An ecological niche is basically determined
by all of a species’ structural, physiological, and
behavioral adaptations. Any resource at a suboptimal
level relative to an organism’s need for it or at a level in
excess of an organism’s tolerance for it is a limiting
resource.
• The resources can include mineral content of soil,
extremes of temperature, and amount of precipitation.
The limiting resources can affect part of an organism’s
life cycle. For example, the ring-necked pheasant was
introduced in North American but didn’t survive in the
southern United States because the eggs can’t develop
properly in the warm southern temperatures.
Limiting Factors Gause’s
Experiments
Limiting Factors Gause’s
Experiments
Which type of Competition?
Interspecific Competition!
Competitive Exclusion: one species is
excluded from a portion of a niche by another
as a result of interspecific competition.
(2 species with identical niches can’t coexist.)
Do Now:
• The Norway rat and the black rat were both
introduced to this country from Europe. The
Norway rat is found only in cities and inhabits
most cities in the U.S. The black rat can live in
cities and rural areas but in New Jersey is ONLY
found in rural areas. Some cities in New Jersey,
which previously had only black rats, now have
only Norway rats. Discuss this phenomenon in
terms of competitive exclusion, resource
partitioning and limiting resources.
Do Now Answers:
• No two species can indefinitely occupy the same niche in
the same community because competitive exclusion
eventually occurs.
• Interspecific competition for limiting resources will result
in the competitive exclusion of one of the species. In this
particular case, the black rat was driven from the cities
through competition of resources with the Norway rat.
• The two species of rats do not show evidence of
resource partitioning that would allow the rats to coexist
in the same habitat. Instead the black rat has confined
its habitat to the rural areas while the Norway rat has
taken over city existence.
Limiting Factors Gause’s Experiments
Variations
among members of a population make some of
them better adapted to the environment than others
It
is generally the best-adapted individuals that will
survive.
The
environment is the agent of natural selection
determining which species will survive.
3. Survival of the Fittest
Survival of the Fittest
Survival of the Fittest
(4)
Natural Selection
Traits which are beneficial to the
survival of an organism in a particular
environment tend to be retained and
passed on, and therefore, increase in
frequency within a population.
(variation)
(4)
Natural Selection
Traits which have low survival value to an
organism tend to diminish in frequency
from generation to generation.
(4)
Natural Selection
If environmental
conditions change,
traits that have low
survival value may
now have a greater
survival value.
Therefore, traits that
prove to be favorable
under new
environmental
conditions will
increase in frequency.
(differential
reproductive success)
Industrial Melanism
Do Now:
• Charles Darwin
concluded that inherited
traits favorable to survival
would be preserved over
time.
• Look at this graph of a
DDT spray program
aimed at eliminating a
mosquito species.
Explain the data
contained in the graph at
point I –VI and relate the
graph’s data to Darwin’s
conclusion.
•
•
•
•
The mosquito population is at a
sustainable level (I). When DDT
is initially introduced into the
population, the population of
mosquitoes declines (II) as most
of the mosquitoes have no
resistance to the DDT chemical.
However due to natural variations
within the mosquito population, a
few mosquitoes do have a trait
(resistance to DDT) that improves
their chances of survival and
reproductive success (III).
Those individuals that possess the
most favorable combination of
characteristics (better adapted for
the DDT environment) are more
likely to survive, reproduce, and
pass their traits to the next
generation – differential
reproductive success (IV).
As the spray program ends, the
mosquito population grows (V)
until it reaches a size where the
limiting resources of the
environment would keep the
extent of the population level (I
and VI).
Answer
Do Now:
How did an Insects resistant
to insecticides occur?
Ex: Insects resistant to insecticides
1. Genetic make-up of some insects make them
resistant to the effects of insecticides
2. Before the widespread use of insecticides, this
trait was of no particular survival value
3. With the increased use of insecticides, this trait
developed a very high survival value
4. Therefore, insects with resistance to insecticides
survived and reproduced much more
successfully than those lacking the trait
5. As a result, the frequency of insecticide
resistance has increased greatly in insect
populations
Important! The trait already exists within the genetic makeup of the organism.
Ex: Rats resistant to rodenticides
Not Immune!
5. Reproduction
• Individuals that survive and
then reproduce transmit
these variations to their
offspring
Do Now:
• The diagram represents a tree containing three
different species of warbler, A, B, and C. Each
species occupies a different niche.
A fourth species, D, which has the same
environmental requirements as species B, enters
the tree at point X. Members of species B will
most likely
(1.) live in harmony with species D
(2.) move to a different level and live with species A
or species C
(3.) stay at that level but change their diet
(4.) compete with species D
Natural selection can favor Resource
Partitioning: differences in resource use
among species.
Resource Partitioning
Effect of community complexity on Species richness
6. Speciation
• The development of a new
species occurs as variations or
adaptations accumulate in a
population over many
generations.
• Ex: primitive human  present
man?
• Canis lupus  Canis familiaris?
Speciation? “El Chupacabra”
Speciation
Prehistoric Giant Sloth
& modern 3 toed Sloth
How does the Iiwi and Lobelia
demonstrate Coevolution?
Answer
• Coevolution is the mutual evolutionary
influence between two species (the
evolution of two species totally
dependent on each other).
Predation
• Predators exert strong selective pressures
upon their prey. Coevolution is the result.
• Example:
• Brain size in Sperm whales = 7,820g in
response to Giant Squid.
• Human = 1,500g
CoEvolution
• Symbiosis is a result of Coevolution.
• Plants and pollinators proboscis
– Honeybee hairy bodiespollen transport
– Honeycreepers curved bill
Convergent Evolution
• Organisms evolve similar structures
though they are not closely related.
• Ex: Human eye
• & the Squid eye
•
•
Do
Now:
Consider species A and B within
an ecological community. These
species might interact in various
ways that represent gains, losses,
or no effect to the two species.
In 4 of the 6 cells below, enter the
terms that describe the types of
interactions might be occurring
between species A and B in the
community.
SPECIES B
SPECIES A
Positive
Positive
Negative
Neutral
Negative
Neutral
Do Now:
SPECIES A
SPECIES B
Positive
Negative
Neutral
Positive
mutualism
Predation (Species A is
prey)
Parasitism (Species A is
host)
Competitive exclusion of
Species A
commensalsim
Negative
Predation (Species A is
predator)
Parasitism (Species A is
parasite)
Competition
Limiting resources
--
Neutral
commensalism
--
Resource partitioning
Evolution of Diversity &
classification
The older 5 Kingdom system
1.
2.
3.
4.
5.
Monera
Protista
Fungi
Plant
Animal
• A dichotomous key is a tool that allows the user
to determine the identity of items in the natural
world, such as trees, wildflowers, mammals,
reptiles, rocks, and fish.
• Keys consist of a series of choices that lead the
user to the correct name of a given item.
"Dichotomous" means "divided into two parts".
Therefore, dichotomous keys always give two
choices in each step.
Step 1 The organism is unicellular
The organism is multicellular
Step 2 Is prokaryotic
Is Eukaryotic
Step 3 I am autotrophic
I am heterotrophic
Step 4 I absorb my nutrients from the
environment
I ingest my nutrients
Step 5 Primitive bacteria (Extremophyles)
True bacteria
Go To Step 2
Go To Step 3
Monera (to further break
down) Go To step 5
Protista
Green Plants
Go To Step 4
Fungi
Animals
Archeobacteria
Eubacteria
Six
-dom Taxonomic System
3 Major
Domains
Rotting Log Community:
Do Now:
• Draw a flow diagram of an old field
undergoing succession. What type of
succession is this?
Do Now answer:
• The change in an old field over the years
is an example of secondary succession.
• First year after cultivation ceases,
crabgrass dominates ->second year,
horseweed ->third year, other weeds such
as broomsedge, ragweed, aster ->years 515, pines -> oaks and other hardwoods
Ecosystem Formation
• Ecosystems tend to change
over a long period of time until
a stable ecosystem is formed.
• Both the living and nonliving
parts of an ecosystem change.
Ecological Succession
• The replacement of one kind of community with
another is called ecological succession.
• The kind of stable ecosystem that develops in a
particular geographical area depends on climate.
• Pioneer organisms- are the first plants to populate
an area. Lichens and algae may be pioneer
organisms on bare rock.
• Climax Communities- Succession ends with the
development of a climax community in which the
populations of plants and animals exist in balance
with each other and the environment.
Ecological Succession
Grasses shrubs  poplars (cottonwoods)  pine trees  oak
2. Symbiotic Relationships
• Different organisms may live together in a
close association.
• This is known as symbiosis.
• There are three types:
1. Commensalism 2. Mutualism 3.
Parasitism
• KEY:
+ = benefits
- = harmed
o = not affected
Commensalism
• (+ , o)
• In this relationship, one organism
benefits and the other is not affected.
• Ex: barnacles on a whale
Commensalism
(+ , o)
• Epiphytes (mosses, orchids, ferns,
bromeliad ) attach themselves to tree bark
and obtain their nutrients without harm to
the trees.
Mutualism
• (+ , +)
• In this relationship both organisms
benefit from each other.
• Ex: protozoan living in the digestive
tract of termites.
• Wood eaten by termites is digested by
the protozoan. The nutrients released
supply both organisms.
Mutualism
• (+ , +)
• In this relationship both organisms benefit
from each other.
• Ex:
Mycorrhizae (+ , +)
In this relationship both organisms
benefit from each other.
• Ex: Red Cedar and mycorrhizal fungi.
Parasitism
• (+ , - )
• In this relationship, the parasite
benefits at the expense of the host.
• Ex: athlete’s foot fungus on humans
tapeworm and heartworm in dogs.
Parasitism
• (+ , - )
• Pathogens (disease causing
agents) are parasites that often
cause the death of its host.
• Crown gall disease in plants.
Parasite/Host Relationship
Guinea worm/Human
Parasite/Host Relationship
Sea Lamprey/Fish
Parasitism
• Parasite/Host Relationship
• Varroa mite/Honeybee
Tracheal mites
Do Now:
• Define keystone species and discuss two
examples of organisms that are keystone
species.
Do Now Answer:
• A keystone species is vital in determining the nature and
structure of an entire ecosystem.
• The keystone species is often a predator, which exerts a
profound influence on a community in excess of that
expected by its relative abundance.
• Keystone species are usually not the most abundant
species in the ecosystem.
• One examples:
– the fig tree in a rainforest ecosystem. The fig tree is important in
sustaining fruit-eating vertebrates. While a supplemental fruit
normally, during the time of year when other fruits are less
plentiful, the fig trees sustain the fruit-eating vertebrates such as
the monkeys, birds, and bats.
– in a different ecosystem is the gray wolf. The gray wolf is a top
predator. If it were eliminated from the ecosystem, the
population of deer and other herbivores would increase
exhibiting grazing pressure and a loss of vegetation. That loss
would result in shortfall of habitat and food for smaller animals
and insects, thus decreasing the biodiversity of the ecosystem.
Keystone species
• These determine the nature and structure of an entire
ecosystem. Usually found in small numbers but have
a key influence.
• Examples: Wolves, Fig Trees
Do Now:
• Gray wolves originally ranged across North America but
were removed from Yellowstone and the American
Rocky Mountains in the 1930’s. The gray wolf was listed
as an endangered species in 1974. In an effort to
increase their numbers, a small number of gray wolves
were re-released into Yellowstone
• National Park in 1995. The wolves prey on elk, deer,
moose, and bison. They have decimated some coyote
populations and also threaten some rancher’s livestock.
– Identify and describe TWO major causes for the original decline
of this species.
– Describe TWO measures that have been taken to protect this
species.
– Make an ecological argument for protecting the gray wolf OR
make an economic argument against protecting the gray wolf.
Do Now Answers:
• Originally the gray wolf was trapped, poisoned, snared, and
hunted to extinction in most places by fur traders and ranchers.
• Under the provisions of the Endangered Species Act, wolves in
the northern Rocky Mountains were listed as endangered in 1974.
Because the gray wolf is on the endangered species list, the
Endangered Species Act forbids killing of an endangered species.
In addition, a program to reintroduce a small number of gray
wolves into Yellowstone National Park has helped the population
of wolves thrive. In the Yellowstone park area, the wolf was
declared an “experimental nonessential in the area so that
ranchers can kill Yellowstone wolves that attack their cattle and
sheep, and federal officers can remove any wolf that threatens
humans or livestock.
• FOR: The intensive hunting by wolf packs has helped reduce the
all-time high Yellowstone’s elk population, which in turn has
relieved heavy grazing pressure by elks on aspen, willow, and
cottonwood. As a result of a more lush and varied plant
composition, herbivores such as beavers and snow hares have
increased in number, which in turn support small predators such
as foxes, badgers, and martens.
• The reduction of the coyote population has allowed an increase in
coyote
Case Study
"The Effects of Coyote
Removal in Texas:
A Case Study in
Conservation Biology"
by
Margaret Carroll
Department of Biology
Framingham State College
Case Study
The Wolf, the Moose, and the Fir
Tree:
Who Controls Whom on Isle
Royale?
A case study of trophic interactions
by
Gary M. Fortier
Department of Small Animal Science
Delaware Valley College
Do Now:
Reintroduction plans?
Grand Mesa Colorado is drawing up a
proposal to adopt the procedures used by
Yellowstone National Park
To reestablish a Grey Wolf population.
What factors would you need to consider for
this plan to be successful.
Do Now Answers: things to
consider…
Yellowstone National
Park
• Mountain lions
• Major Prey species:
–
–
–
–
–
–
Bison
Moose
Elk (migratory)
Mule Deer
White Tail Deer
Antelope
• Large protected geography
• Varied topography
(elevations)
Grand Mesa Colorado
(Western CO)
• Mountain lions
• Major Prey Species
– Elk (migratory)
– Mule Deer
• Major Cattle Farming
• Fragmented lands
– Private + commercial
properties
Do Now:
• List and describe three animal prey
defenses against predators.
Answer:
• When confronted by a predator, animals have
many defensive adaptations. Woodchucks flee
into their underground burrows. Porcupines and
turtles have mechanical defenses, barbed quills
and hard shells.
• Some animals live in groups for protection. This
social behavior decreases the likelihood of a
predator catching one of them. The South
American poison arrow frog has poison glands
in its skin and bright warning coloration. Other
animals use camouflage to blend into their
surroundings
Do Now:
• Explain the circumstances under which a
prey organism would have coloration that
would make it more visible to a predator.
• Include three specific examples of
organisms that use this strategy.
Do Now Answers;
• If a prey has a chemical defense such as a
poison, toxin, or acrid spray, then it can afford to
have a bright warning coloration that would
caution experienced predators to avoid it. For
example the white stripe on a black skunk is
very recognizable and associated with acrid
chemicals sprayed from its anal glands.
• The poison arrow frog is brightly colored and
has poison glands in its skin. Likewise some
poisonous snakes have bright coloration
Defensive Adaptations
• Defenses against Predators
– Warning coloration
• poison, toxin, or acrid spray
– Camouflage
• Mimicry
• Cryptic
• Plant defenses against herbivores
– Thorns, toxins, poison berrys
Defensive Adaptations in Animals
Mimicry: resemblance to another species.
• Ex: Io moth
Defensive Adaptations in
Animals
Mimicry: resemblance to another species.
• Ex: Monarch and Vicorory Butterfly
Danaus plexippus
Limenitis archippus
Observational Extra credit:
Identify these 2 snakes.
How do you know which one is venous?
Defensive Adaptations in Animals
Mimicry: resemblance to another species.
• Ex: Coral snake vs. King Snake
Defensive Adaptations in Animals
• Chemical defenses: Sprays or by…
• Warning Coloration: avoidance of predators
by unpalatable animals.
– Ex: Poison Dart Frog.
Defensive Adaptations in
Animals
Crypsis (cryptic coloration) (Camouflage):
Blending into the surroundings for avoidance
of predators by palatable animals.
• Ex: Leafy Sea Dragon
Defensive Adaptations in Animals
Crypsis(cryptic coloration) (Camouflage):
Blending into the surroundings for
avoidance of predators by palatable
animals.
• Ex: Weedy Sea Dragon
What do you see?
What do you see?
What do you
see?
Predator/Prey Relationships!
Predator/Prey Relationships
Data collected from fur pelts from the Hudson Bay Company
Studies have shown that Endocrine
changes in populations may produce
behavioral changes which tend to limit
population growth. Therefore all
population changes may not be due to
predator/prey relationships alone.
Green Anole (indigenous) restricted by the
Brown Anole (foreign).
Green Anole
Brown Anole
Brown Anoles affected the realized Niche of the Green Anoles.
Cichlids (indigenous) restricted by the
Nile Perch (foreign).
http://www.african-angler.co.uk/210.jpg
Lake Victoria is about the size of the Republic of
Ireland, forms the headwaters of the River Nile.