Symbiosis

1
Biological Evolution
Biological Evolution
Biological Evolution
2
How Do We Know Which Organisms Lived in the Past?

• Our knowledge about past life comes from fossils,
  chemical analysis, cores drilled out of buried
  ice, and DNA analysis.

Figure 4-4
3
EVOLUTION, NATURAL SELECTION, AND ADAPTATION

• Biological evolution by natural selection
  involves the change in a populations genetic
  makeup through successive generations.
• genetic variability
• Mutations random changes in the structure or
  number of DNA molecules in a cell that can be
  inherited by offspring.

4
Natural Selection and Adaptation Leaving More
Offspring With Beneficial Traits

• Three conditions are necessary for biological
  evolution
• Genetic variability, traits must be heritable,
  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.

5
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.
• This often happens between predators and prey
  species.

6
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

7
Limits on Adaptation through Natural Selection

• A populations ability to adapt to new
  environmental conditions through natural
  selection is limited by its gene pool and how
  fast it can reproduce.
• Humans have a relatively slow generation time
  (decades) and output ( of young) versus some
  other species.

8
Common Myths about Evolution through Natural
Selection

• Evolution through natural selection is about the
  most descendants.
• Organisms do not develop certain traits because
  they need them.
• There is no such thing as genetic perfection.

9
GEOLOGIC PROCESSES, CLIMATE CHANGE, CATASTROPHES,
AND EVOLUTION

• The movement of solid (tectonic) plates making up
  the earths 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.

10
225 million years ago
225 million years ago
135 million years ago
65 million years ago
Present
Fig. 4-5, p. 88
11
Climate Change and Natural Selection

• Changes in climate throughout the earths history
  have shifted where plants and animals can live.

Figure 4-6
12
18,000 years before present
Northern Hemisphere Ice coverage
Modern day (August)
Note Modern sea ice coverage represents summer
months
Legend
Continental ice
Sea ice
Land above sea level
Fig. 4-6, p. 89
13
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.

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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.

15
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
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Specialist species with a narrow niche
Generalist species with a broad niche
Niche separation
Number of individuals
Niche breadth
Region of niche overlap
Resource use
Fig. 4-7, p. 91
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SPOTLIGHTCockroaches Natures 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
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Specialized Feeding Niches

• Resource partitioning reduces competition and
  allows sharing of limited resources.

Figure 4-8
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Avocet sweeps bill through mud and surface water
in search of small crustaceans, insects, and
seeds
Ruddy turnstone searches under shells and
pebbles for small invertebrates
Herring gull is a tireless scavenger
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
Black skimmer seizes small fish at water surface
Louisiana heron wades into water to seize small
fish
Piping plover feeds on insects and
tiny crustaceans on sandy beaches
Oystercatcher feeds on clams, mussels, and other
shellfish into which it pries its narrow beak
Flamingo feeds on minute organisms in mud
Scaup and other diving ducks feed on mollusks,
crustaceans,and aquatic vegetation
Knot (a sandpiper) picks up worms and small
crustaceans left by receding tide
(Birds not drawn to scale)
Fig. 4-8, pp. 90-91
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Evolutionary Divergence

• Each species has a beak specialized to take
  advantage of certain types of food resource.

Figure 4-9
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Insect and nectar eaters
Fruit and seed eaters
Greater Koa-finch
Kuai Akialaoa
Amakihi
Kona Grosbeak
Crested Honeycreeper
Akiapolaau
Maui Parrotbill
Apapane
Unknown finch ancestor
Fig. 4-9, p. 91
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SPECIATION, EXTINCTION, AND BIODIVERSITY

• Speciation A new species can arise when member
  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.

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Geographic Isolation

• can lead to reproductive isolation, divergence
  of gene pools and speciation.

Figure 4-10
24
Adapted to cold through heavier fur,short ears,
short legs,short nose. White fur matches snow for
camouflage.
Arctic Fox
Northern population
Different environmental conditions lead to
different selective pressures and evolution into
two different species.
Spreads northward and southward and separates
Early fox Population
Adapted to heat through lightweight fur and long
ears, legs, and nose, which give off more heat.
Southern Population
Gray Fox
Fig. 4-10, p. 92
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Extinction Lights Out

• Extinction occurs when the population cannot
  adapt to changing environmental conditions.

• The golden toad of Costa Ricas Monteverde cloud
  forest has become extinct because of changes in
  climate.

Figure 4-11
26
Species and families experiencing mass
extinction
Bar width represents relative number of living
species
Millions of years ago
Era
Period
Current extinction crisis caused by human
activities. Many species are expected to become
extinct within the next 50100 years.
Extinction
Quaternary
Today
Cenozoic
Tertiary
Extinction
65
Cretaceous up to 80 of ruling reptiles
(dinosaurs) many marine species including
many foraminiferans and mollusks.
Cretaceous
Mesozoic
Jurassic
Triassic 35 of animal families, including many
reptiles and marine mollusks.
Extinction
180
Triassic
Permian 90 of animal families, including over
95 of marine species many trees, amphibians,
most bryozoans and brachiopods, all trilobites.
Extinction
250
Permian
Carboniferous
Extinction
345
Devonian 30 of animal families, including
agnathan and placoderm fishes and many trilobites.
Devonian
Paleozoic
Silurian
Ordovician
Extinction
Ordovician 50 of animal families, including
many trilobites.
500
Cambrian
Fig. 4-12, p. 93
27
Effects of Humans on Biodiversity

• The scientific consensus is that human activities
  are decreasing the earths biodiversity.

Figure 4-13
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Terrestrial organisms
Silurian
Permian
Jurassic
Devonian
Devonian
Cambrian
Ordovician
Cretaceous
Marine organisms
Pre-cambrian
Carboniferous
Number of families
Quaternary
Tertiary
Millions of years ago
Fig. 4-13, p. 94
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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
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Genetic Engineering Genetically Modified
Organisms (GMO)

• GMOs use recombinant DNA
• genes or portions of genes from different
  organisms.

Figure 4-14
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Phase 1 Make Modified Gene
E. coli
Insert modified plasmid into E. coli
Genetically modified plasmid
Cell
Extract Plasmid
Extract DNA
Plasmid
Gene of interest
DNA
Remove plasmid from DNA of E. coli
Identify and remove portion of DNA with desired
trait
Insert extracted (step 2) into plasmid (step 3)
Identify and extract gene with desired trait
Grow in tissue culture to make copies
Fig. 4-14, p. 95
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Phase 2 Make Transgenic Cell
A. tumefaciens (agrobacterium)
Foreign DNA
E. Coli
Host DNA
Plant cell
Nucleus
Agrobacterium inserts foreign DNA into plant cell
to yield transgenic cell
Transfer plasmid copies to a carrier agrobacterium
Transfer plasmid to surface of microscopic metal
particle
Use gene gun to inject DNA into plant cell
Fig. 4-14, p. 95
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Phase 3 Grow Genetically Engineered Plant
Transgenic cell from Phase 2
Cell division of transgenic cells
Culture cells to form plantlets
Transfer to soil
Transgenic plants with new traits
Fig. 4-14, p. 95
34
Phase 3 Grow Genetically Engineered Plant
Stepped Art
Fig. 4-14, p. 95
35
How Would You Vote?

• To conduct an instant in-class survey using a
  classroom response system, access JoinIn Clicker
  Content from the PowerLecture main menu for
  Living In the Environment.
• Should we legalize the production of human clones
  if a reasonably safe technology for doing so
  becomes available?
• a. No. Human cloning will lead to widespread
  human rights abuses and further overpopulation.
• b. Yes. People would benefit with longer and
  healthier lives.

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THE FUTURE OF EVOLUTION

• Biologists are learning to rebuild organisms from
  their cell components and to clone organisms.
• Cloning has lead to high miscarriage rates, rapid
  aging, organ defects.
• Genetic engineering can help improve human
  condition, but results are not always
  predictable.
• Do not know where the new gene will be located in
  the DNA molecules structure and how that will
  affect the organism.

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Controversy Over Genetic Engineering

• There are a number of privacy, ethical, legal and
  environmental issues.
• Should genetic engineering and development be
  regulated?
• What are the long-term environmental consequences?

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Case StudyHow 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).

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Symbiosis

• Living Together

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Three Types of Symbiosis

• Mutualism
• both species benefit
• Commensalism
•   one species benefits, the other is unaffected
• Parasitism
•   one species benefits, the other is harmed

41
Mutualism

• Both organisms benefit from the relationship

Otters and Kelp
The otters help the kelp by eating the sea
urchins which endanger it. The kelp provides and
anchor for the otters while they sleep.
42
Lichen

• Lichen is really two organisms algae and fungus.
  The fungus needs food but cannot make it. The
  algae makes food but needs some way to keep
  moist. The fungus forms a crust around the algae
  which holds in moisture. Both organisms benefit.

43
The Chital and the Tree-pie

• The tree-pies help the chital by stripping the
  dead velvet from the antlers. This provides them
  with nourishment Therefore both species are
  benefiting from this symbiotic behavior.

44
Cleaner Fish and the Moray Eel

• The cleaner fish eats parasites and food bits out
  of the inside of this moray eel. It gets a meal
  and is protected from predators by the fierce eel.

45
Yucca Plants and Yucca Moths

• Each type of Yucca plant can only be pollinated
  by a specific kind of Yucca moth.
• That moth can only live on that kind of Yucca.

46
Swollen Thorn Acacia Tree and Ants

• The tree provides a nursery for the ants in the
  thorns and makes special food for the ant babies.
• In return the ants sting and attack any other
  plants or insects that try to invade the tree.

47
Commensalism

• One species benefits while the other is uneffected

The cattle egret and cows
The cattle help the egret who look for
grasshoppers and beetles that are raised by the
cows. Now and then they sit on the back of a cow,
looking for ticks and flies. This does not effect
the cattle in any way.
48
Barnacles and Whales

• Barnacles need a place to anchor. They must wait
  for food to come their way. Some barnacles hitch
  a ride on unsuspecting whales who deliver them to
  a food source. This does not effect the whale in
  any way.

49
Oak Gall Wasps and Oak Trees

• The oak gall wasp stings the oak tree.
• the tree then grows a GALL which is a nest for
  the wasps babies.
• When the larva hatch, they eat their way out of
  the gall.
• Does not help or hurt the oak tree

50
Parasitism

• One species benefits while the other is harmed

Mistletoe is an aerial parasite that has no roots
of its own and lives off the tree that it
attaches itself to. Without that tree it would
die. It slowly chokes out the life of the host
tree.
51
Bedbugs

• Bedbugs are small, nocturnal parasites that
  come out of hiding at night to feed on
  unsuspecting humans.  They feed exclusively on
  blood!  Their bites often result in an allergic
  reaction.

52
Tapeworms

• The definitive host of the cucumber tapeworm is a
  dog or a cat (occasionally a human). Fleas and
  lice are the intermediate host. the dog or cat
  becomes contaminated when the eggs are passed in
  the feces, and the flea or louse ingests the
  eggs.  The dog or cat (or human) is infected when
  they ingest a flea or louse.  Hence the
  importance of controlling fleas on your pet!

53
Which type of symbiosis is it?

• Mutualism, commensalism, parasitism

Fleas/dogs Lice/humans Clownfish/sea
anemone Crocodile bird/crocodile Joshua
tree/pronuba moth
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Predation one species feeds on another ?
enhances fitness of predator but reduces fitness
of prey
(/ interaction)
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Types of predators
Carnivores kill the prey during
attack Herbivores remove parts of many prey,
rarely lethal. Parasites consume parts of
one or few prey, rarely lethal. Parasitoids
kill one prey during prolonged attack.
56
Diet breadth
consumes only one prey type
narrow diet
specialist
generalist
broad diet
consumes many prey types
57
Why are ecological interactions important?
Interactions can affect distribution and
abundance.
Interactions can influence evolution.
58
How has predation influenced evolution?
Adaptations to avoid being eaten
spines (cactii, porcupines) hard shells (clams,
turtles) toxins (milkweeds, some newts) bad taste
(monarch butterflies) camouflage aposematic
colors mimicry
59
Camouflage blending in
60
Aposematic colors warning
61
Is he crazy???
62
Mimicry look like something that is
dangerous or tastes bad
63
Mimicry look like something that is
dangerous or tastes bad
Mullerian mimicry convergence of several
unpalatable species
64
Mimicry look like something that is
dangerous or tastes bad
Batesian mimicry palatable species mimics
an unpalatable species
model
mimic
mimics
model
65
Why are ecological interactions important?
Interactions can affect distribution and
abundance.
Interactions can influence evolution.
66
Predator-prey population dynamics are connected
Predators kill prey ? affects prey death rate
dNprey/dt rNprey
pNpreyNpredator
change in prey population
deaths due to predation
per capita rate of growth without predation
67
Predator-prey population dynamics are connected
Predators kill prey ? affects prey death rate
dNprey/dt rNprey
pNpredatorNprey
predation rate

• prey population size depends on number of
  predators
• with few predators, prey population grows
• with many predators, prey population shrinks

68
Predator-prey population dynamics are connected
Predators eat prey ? affects predator birth rate
dNpredator/dt cpNpreyNpredator dNpredator
death rate
change in predator population
births due to predation
69
Predator-prey population dynamics are connected
Predators eat prey ? affects predator birth rate
dNpredator/dt cpNpreyNpredator dNpredator
conversion rate of prey to baby predators
predation rate

• predator population size depends on number of
  prey
• with many prey, predator population grows
• with few prey, predator population shrinks

70
Predator-prey population dynamics are connected
? affects prey death rate ? affects predator
birth rate
Predators kill and eat prey
dNprey/dt rNprey
pNpredatorNprey
dNpredator/dt cpNpreyNpredator dNpredator

• with few predators, prey population grows
• with many prey, predator population grows
• with many predators, prey population shrinks
• with few prey, predator population shrinks

N
time
71
Lotka-Volterra models describe predator and
prey population cycling. Real world predator
and prey populations can cycle in
size. http//phet.colorado.edu/en/simulation/natur
al-selection
72
Why are ecological interactions important?
Interactions can affect distribution and
abundance.
Interactions can influence evolution.
73
Keystone species affect community structure

Predators can allow coexistence of competing prey
competitors
Barnacles Mussels
Balanus
Mytilus
(Paine 1966)
74
Keystone species affect community structure

Predators can allow coexistence of competing prey
Starfish
predator
Pisaster
competitors
Barnacles Mussels
Balanus
Mytilus
(Paine 1966)
75
How can we test the effect of a predator on
community structure?
Starfish
Pisaster
Barnacles Mussels
Balanus
Mytilus
76
Removal experiment
- mussels are the dominant competitor -
competitive exclusion of barnacles
starfish removed
mussels
of inter- tidal zone
barnacles
time
77
What is the effect of the predator on the
structure of this community?
- starfish allow coexistence of competitors
starfish removed
mussels
of inter- tidal zone
barnacles
time
78
How do starfish promote coexistence?
Starfish
Pisaster
Barnacles Mussels
Balanus
Mytilus
Starfish are picky they prefer mussels
(dominant competitor), which allows barnacles
(weaker competitor) to coexist.
79
Keystone species affect community
structure disproportionately to their
abundance. Picky predators can promote
coexistence among competing prey
species. Competitive exclusion is prevented when
the dominant competitor is the preferred prey.
80
Competiton

• is a contest between individuals, groups,
  nations, animals, etc. for territory, a niche, or
  a location of resources. It arises whenever two
  or more parties strive for a goal which cannot be
  shared. Competition occurs naturally between
  living organisms which co-exist in the same
  environment.

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• Intraspecific
• A form of competition in which members of the
  same species vie for the same resources in an
  ecosystem (e.g. food, light, nutrients, space).
• Example two same species trees growing beside
  each other competing for the same water, sun,
  nutrients.

• Interspecific
• A form of competition in which members of the
  different species vie for the same resources in
  an ecosystem (e.g. food, light, nutrients,
  space).
• Ex A taller tree in a forest out competing a
  smaller tree underneath it.