Download Evolution Spring 2010

Evolution
Spring 2010
Charles Darwin
Charles Darwin
Naturalist on HMS
Beagle
World Travel (18311836)
North
America
Great
Britain
Europe
Asia
ATLANTIC
OCEAN
PACIFIC
OCEAN
Pinta
Marchena
Santiago
Fernandina
Isabela
0
40 km
PACIFIC
OCEAN
Equator
PACIFIC
OCEAN
Pinzón
Genovesa
Equator
Daphne
Islands
Santa Santa
Cruz
Fe
Florenza
0
40 miles
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South
America
Australia
Cape of
Good Hope
And
es
The
Galápagos
Islands
Africa
Cape Horn
San
Cristobal
Española
Tasmania
New
Zealand
Tierra del Fuego
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Strange Animals of the
Galapagos Islands
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Darwin’s Finches
14 Different Species
Species = group of same basic organism that naturally interbreed to produce fertile offspring
More finch species than anywhere else on earth!
Only finch species in the world to eat insects
Ancestor was probably from where?
How did they get to the Galapagos?
They are now geographically isolated – separated from mainland finches
Galapagos Woodpecker Finch
Subspecies = members of the same species, yet possess easily
recognizable different traits
Also called: races, breeds, varieties
Hundreds to thousands
of years of breeding
(artificial selection)
Ancestral dog (wolf)
Races of Humans
5 Basic Races are known to exist
Asian
Amerind
Negroid
Caucasoid
Aborigine
Mating Between Different
Species
• Donkey and
horse = mule
• Lion and tiger =
liger or tiglon
Gene Pool –
sum total of all of
the genes of a
particular species
of organism
Members of different
species are
reproductively
isolated from each
other – “closed” gene
pools
Just what does Evolution mean?
Evolution – Change in organisms with the
passage of time
History
1.Previous Beliefs: Species fixed
2.Lamarck: Evolution – Slow change in
species with time
Process:
– Law of Use and Disuse
– Inheritance of Acquired Characteristics
Example: Necks of giraffes,
swimming iguanas
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Example: Evolution of Giraffe
Neck
• Fossils show evidence of a short – necked
ancestor
Giraffe “cousin” – Okapi (Africa)
Lamarckian Giraffe Evolution
• Short necked ancestor
• Environmental change – loss of
grass/low plants to eat
• Giraffes stretch their necks to reach
trees; necks elongated
• Acquired trait – longer neck
• Passed to offspring
• Occurred generation after
generation
• Soon all had long necks
Darwin’s Theory of Evolution –
Natural Selection
Darwin:
• Overpopulation – Competition, Struggle for
Existence
• Variations exist within populations
• Variations are inherited
• Not all will survive
• Survival of the fittest (best adapted)
***Resulting unequal reproduction is basis for
“Natural Selection”
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Overpopulation
Maple Tree Seeds
Frog Eggs
Genetic variations exist in every Population
Variations are inherited
Same species of Garter Snake
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Not all will survive – Who does
survive?
Darwinian Giraffe Neck Evolution
• Short – necked ancestor
• Environmental change – loss of grass/low plants to eat
• Creates competition for available food due to now
overpopulation; not enough to feed all; struggle for
existence
• Different lengths of necks exist in the normal giraffe population =
Variations
• Variations are inherited
• Not all giraffes will survive
• Longer necks giraffes survive and pass on the longer neck
Lamarckian vs. Darwinian
Giraffe Neck Evolution
What about the swimming iguanas
on the Galapagos?
• How would Darwin explain their evolution?
• Ancestor – probably a land iguana from
where?
• How did it get to the Galapagos?
Evolution of the Galapagos
Finches
Adaptations
Adaptations = features of an organism that promote its
survival and reproduction; genetic features passed
down to offspring; Adaptations are what evolve
Adaptations - Types
1. Structural – involve anatomical features of an organism
Ex. human opposable thumb, flat surface of a leaf
2. Biochemical – involve an organism’s biochemistry
Ex. Human blood clotting chemicals, cactus
waterholding leaves
3. Behavioral – involve an organism’s behaviors
Ex. Birds migrating, plants grow toward the light
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Examples of Adaptations
What evolutionary adaptations do
you see?
A flower mantid in
MalaysiaAdaptation?
Camouflage
Leaf mantid in
Costa Rica
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Five different species of canines, the results of
thousands to millions of years of natural selection
African wild dog
Coyote
Wolf
Fox
Jackal
Thousands to
millions of years
of natural selection
Ancestral canine
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Can humans control evolution? Eight breeds of dogs (all
members of the same species), the results of hundreds to
thousands of years of artificial selection (Selective Breeding)
Hundreds to thousands
of years of breeding
(artificial selection)
Ancestral dog (wolf)
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Evidence for Evolution (Change)
Grand Canyon Layers
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Fig 13.3 Fossil Picture Gallery
A Skull of Homo erectus
B Petrified tree
E Fossilized organic matter of a leaf
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C Ammonite casts
D Dinosaur tracks
G “Ice Man”
F Insect in amber
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Evidence
– Fossil record
– Life began where?
– Water
• A. Progression from old to young rock layers; simple to complex;
Prokaryotes to Eukaryotes; unicellular to multicellular,
Invertebrate to Vertebrate; Fish-like to amphibian to reptile to
bird; reptile to mammal
B. Intermediate forms
• Examples: Baliosaurus
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Fossil Intermediate Forms
• Archeopteryx
Living Intermediate Forms
Monotremes
• Egg-laying mammals
• Platypus, spiny
anteater
• Australia
• Missing link?
• Part mammal/part
reptile
What possible animal and plant
evolutionary progressions does the
Fossil Record show?
• Animal Evolution
• Simple one-celled to
complex multicellular
• Invertebrates to
vertebrates
• Dominant species
• Age of Fishes - Devonian
Fish to Amphibians
• Primitive and modern fish capable of
living on land for short periods of time
• Paddle like fins
• Advantages to being on land?
• May have evolved into amphibians
• Amphibians – frogs and salamanders
• Resemblance to fish ancestors?
• Why not perfect for life on land?
Amphibians to Reptiles
• Reptiles – lizards,
snakes, turtles,
alligators
• How better adapted for
life on land?
• Scales, lungs, better
legs, shelled egg
• Became dominant
vertebrate on land
for millions of years
Dominant Dinosaur Reptiles
Reptiles to Birds
• Archeopteryx fossil
• What shows bird
connections
to reptilian
ancestors?
• Shelled egg, scales
• Some – small claw on
wing
• Genes for
bony tail and teeth
Reptiles to Mammals
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Monotremes
What is better about
mammals?
Reproduction?
Placentals – develop
totally internally
Marsupials – not
perfect
Some reptiles may
have been warmblooded
Why might mammals
have survived a
meteor type of
catastrophe?
Method of Reproduction
• HUGE contributor to determining a
species “success” at survival
• Current dominant animal species?
• Mammals (Humans)
• What might dominate in the future???
What about plants?
• First type of plants?
• Algae
• Then, simple land plants
(ex. Mosses)
• What next?
• Conifers
• Never became dominant
• Method of reproduction?
• Cones, too slow
• “Naked seeds” Gymnosperms
Flowering Plants - Angiosperms
• Current dominant type of
plant on earth
• Method of reproduction?
• Flowers
• “Covered seeds” angiosperms
• In ovary/fruit
• Why more successful
than conifers?
Homologous Structures
2. Comparative anatomy
• Homologous structures: Organisms w/body part that
has similar INTERNAL structure
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Indicates common ancestor
May or may not have similar function
Ie: Mammal limb structure: whale fin, bat wing, etc
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Figure 13.4A Homologous
structures: vertebrate forelimbs
Human
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Cat
Whale
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Bat
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Comparative Anatomy Cont’dVestigial Organs
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May be vestigial: no longer useful
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Whale hind-leg bones
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Other examples
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Vestigial Leg Bones in Horse
Evolution
Horse Evolution
Human Appendix
Caecum – Digestive Structure for Digesting Plant Cellulose
Various Sizes of Caeca
Caecum – Koala Bear
Vestigial Human Structures
Thymus gland
Human Embryonic Tail
More Comparative Anatomy
• Analogous structures: Organisms with parts that
have similar function, but different internal
structure
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Not from common ancestor
Can be misleading
Examples
Shark Vs. Dolphin
Analogous Structures?
Comparative Embryology
3. Comparative embryology: Similar stages in
embryonic development in closely related species
• Examples
Pharyngeal
pouches
Post-anal
tail
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Chick embryo
Chap 13 & 19 Evolution
Human embryo
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Comparison of Vertebrate
Embryos
Protein Comparisons-Molecular
Biology
4. Molecular Biology
• Basic DNA biochemistry
Ex. Humans and Bonobo
chimps share about
98% of the same DNA; some
sources believe it is higher
Ex. Bird genes for teeth/tails
• Protein similarities
Ex. Hemoglobin - activity
• Other similar biochemicals
Ex. bird and reptile Feathers and scales
Waste products
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Can evolution be “fast”? Evolution of pesticide
resistance in an insect population
Antibiotics – How
do humans
contribute to
evolution?
Chromosome with gene
conferring resistance
to pesticide
Additional
applications of the
same pesticide will
be less effective, and
the frequency of
resistant insects in
the population
will grow
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Chap 13 & 19 Evolution
Pesticide application
Survivor
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Population Genetics
Population Genetics
– Population: Individuals of
same species living in the
same place at the same time
– Species: Can interbreed &
produce fertile offspring
– Evolution measured by
change in allele frequency in
the gene pool (All the genes
in a given population)
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Endangered Species
Endangered Species
– Small numbers
– Homogeneity (Little variation)
– Environmental change could kill all
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Mutation & Sexual
Recombination
Variation Causes
– Mutations:
Changes in DNA
(Important in
evolution only if
in sex cells)
– Sexual
recombination
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• Crossing over
• Random
fertilization
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Concept Check
Which of the following define a species?
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A population of organisms that can breed together and
produce fertile offspring.
Organisms that share observable and measurable
phenotypic traits.
Organisms that share a common and unique genetic history.
Organisms that share common and unique adaptations to fit
specific roles in an ecological community.
All of the above define a species depending on the question.
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Answer
Which of the following define a species?
– All of the above define a species depending on the
question.
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Concept Check
These two meadowlarks are two separate species,
the Eastern, Sturnella magna and the
Western,Sturnella neglecta? Though they look very
similar and have similar habitats they are considered
different species because:
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The two do not normally interbreed.
Their ranges do not overlap.
They have different songs.
They do not share the same habitat area.
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Answer
These two meadowlarks are two separate
species, the Eastern, Sturnella magna and the
Western,Sturnella neglecta? Though they look
very similar and have similar habitats they are
considered different species because:
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The two do not normally interbreed.
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Concept Check
There are several other species pairs like these Meadowlarks in the Great
Plains (orioles, chickadees, yellow-rumped warblers and flickers). Some
are considered separate species and others aren’t, even though they do
appear quite different. Which of the following might have geologically
isolated these different bird populations leading to speciation?
– The Mississippi River.
– Recent (geologically) continental glaciation.
– Prairie fires in the spring.
– Hurricanes from the Gulf of Mexico
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Answer
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The Mississippi River.
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Geographic Isolation
• Separation of populations of organisms by
physical factors
• Examples of isolating physical factors: mountain,
ocean, river, desert
• “Real” world examples: Grand Canyon Squirrels
Kaibab squirrel – north rim
Abert squirrel – south rim
Mountains as a Geographic
Isolating Factor
• Mule deer (western U.S.)
• White-tailed deer (eastern U.S.)
Reproductive Isolation
• Two organisms are unable to breed; their gene pools
“closed” to each other
Speciation
• If organisms become reproductively isolated, they
may eventually become so different, they can
no longer reproduce
• At this point, they are said to be two different
species.
• Speciation – the evolution of new species from a common
ancestor
• New species may have similar anatomy and share
homologous structures
• May possess vestigial structures
• May have similar biochemistry Ex: DNA, wastes, blood, proteins
• May have similar development Ex: live birth, eggs
• May use phyletic “trees” or cladograms to
show speciation
• Usually requires MANY years and generations to occur
Bird Speciation from a Common
Ancestor
Butterfly Evolution
Bears and Relatives
Evolutionary Tree/Speciation
Horses – Evolutionary Tree/Speciation
Carnivore Evolutionary
Tree/Speciation
Reptiles/Birds Evolutionary
Tree/Speciation
Primate Evolutionary
Tree/Speciation
Adaptive Radiation
• The evolution of many new species from a common
ancestor
• Actually is just another way to say speciation
• Usually occurs due to individuals adapting to
new environments
• Adaptive – development of adaptations to “fit” new
environments
• Radiation – to spread out, become different
Divergence (Divergent
Evolution)
• Diverge = to split apart
• Another way to speak of speciation or
adaptive radiation
• It is the evolution of one species (common
ancestor)
into 2 or more new species with
different characteristics
Convergent Evolution
• Converge = to come together
• Convergence (convergent evolution) is a pattern of
evolution where two organisms develop
similarities to each other due to their evolution
in similar environments
• Similarities could be analogous structures
• What are some examples we covered earlier?
• Ex: dolphin/whale flipper and streamlined body
compared to shark
moth and hummingbird wings
• Can be misleading, causing one to believe organism’s
are related or share a common ancestor when they
do not
Darwin’s Finches- Back to
where we started…….
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14 species
Unique species – insect eaters, woodpecker finch
Why so many different types?
Geographic Isolation from mainland South America
Geographic Isolation within the islands
Did we evolve our aliens according
to Darwin’s Theory of Natural
Selection?
• Overpopulation/Competition for
resources/Struggle
for existence
• Variations exist
• Variations are inherited
• Not all will survive
• Survival of the fittest