Transcript Evolution

Evolution
Chapters 16 and 17
• Why should we study evolution?
• What exactly is evolution?
To help you build a solid foundation to
answer this question here is a very
brief history…
• Initially, Europeans believed Earth was only a
few _________________ years old
• New evidence indicating an older Earth began to
accumulate, especially in the new field of
________________
• James ___________ and Charles __________
put together geologic evidence showing that
– the Earth was not a few thousand years old
but much ____________
– the rate in the past was the ________ as it is
now.
The true concept of deep time is
unimaginable for most people.
We will look at this more later.
____________ and Population Growth
• If a ___________________ is unchecked,
eventually, there would not be enough
living space or food for everyone
Evidence was accumulating that
species change over time.
But how do species change over time?
_____________’s Evolutionary Hypotheses
• Organisms could change during their lifetimes
by selectively using (or not using) various
parts of their bodies
• Organisms want to ____________ and
_____________ so they do (acquired traits)…
This makes them more successful
• Individuals could pass these acquired traits on
to their _________________, enabling species
to change over time
What was wrong with ______________’s
Evolutionary Hypotheses?
• Organisms do not have an inborn drive to
____________ ________ ____________
• ______________ __________: traits that
____________ be passed on to offspring
–Ex. Tailless rats, plants grown in various
altitudes
What was wrong with Lamarck’s
Evolutionary Hypotheses? (cont.)
• Evolution does not mean that over time a species
becomes “____________”
• Evolution does ______ progress in a
______________________ path
– Environments change and species either adapt
to survive in their environments or _____ _____
– A trait that works well for one
______________________ might not work so
well in another
Charles Darwin
• Charles Darwin studied all of these ideas
• He also studied ______________ ______________
• He knew that
– Many ___________ vary within a species
– Variations in ________ are selected for or against
when _______________ plants and animals
• Darwin applied this idea to all _________________,
not just ________________ organisms
Darwin Traveled Around the World
Darwin’s First Observation
During His Travels
• Species ________ ____________:
different animal species that have the
same niche (job) inhabited separated, but
ecologically similar, habitats around the
world.
• Example:
Australia’s Emu
Africa’s Ostrich
S. America’s Rhea
Darwin’s Second Observation During
His Travels
• Species ________ ____________: different,
yet related, animal species often occupy
different habitats within a local area.
• Ex. Galapagos Island tortoises and
mockingbirds, two species of rheas in South
America
Volcán Wolf tortoise
Sierra Negra tortoise
Abingdon Island tortoise
Chatham Island tortoise
Darwin’s Third Observation During His
Travels
• Species ________ ________ _______: some fossils
of extinct animals were similar to living species.
• Ex. armadillos and glyptodont
Darwin’s Conclusions:
_______________ ____ ___________
• If more individuals are born than can ____________
individuals must compete for limited ____________
• Darwin called this the “_______________ ______
__________________”
Darwin’s Conclusions:
___________
• Individuals naturally have variation of their
________________ traits within a species
• ________ variations increase or decrease an
individual’s ability to survive
Darwin’s Conclusions:
_____________
• _________________: Any heritable characteristic
that increases an organism’s ability to survive and
__________________ in its environment
• ____________________ can involve
– body parts or structures (claws, thumbs, tails)
– colors (camouflage, mimicry)
– physiological functions (digesting certain foods,
photosynthesis)
– behaviors (not moving when danger is near, hearding)
• Adaptation occurs over ________________ ______
in an individual lifetime (acclamation)
Darwin’s Conclusions:
_________ __ ___ ________
• ____________: How well an organism can survive
and __________________ in its environment
• This ________ ______ mean the
biggest/strongest/healthiest/fastest/etcetera
organisms survive.
• This means the individual that passes their genes
on to the most _______________. Examples?
– Sneaker male cuttlefish Video
– Sneaker male tree frog Video
Darwin’s Conclusions:
_______ _________
• ____________ _______________: Is the process by
which organisms with variations most suited to
their local ____________________ survive and
leave more ________________
• The environment, not humans, influences ________
• In order for natural selection to occur ______ things
must happen…
Natural Selection
1. More ___________ are born than
can _______
2. There is natural _______ variation
3. There is a variable _______ among
individuals
4. Competition for limited _________
Darwin’s Conclusions:
________ ________
• Over long __________ (deep) time and through
environmental variations successful ___________
evolve into new ____________
• If you go far enough back all organisms are
___________
Principle of ______ _______: all species
both living and extinct are descended
from ______ ancestors
Evidence of Evolution
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Biogeography
Fossil Record
Anatomy
Cellular and Molecular
Analogous Structures & Imperfections
Testing Natural Selection
Evidence of Evolution:
____________
• The distribution of many species does not make
sense, unless they shared a _____________ ancestor.
• If species were unchanging, then you would expect to
find the ________ species in areas with ___________
environmental conditions around the world.
• Evolutionary theory, however, predicts that modern
species should be found _________ to where their
_________________ were, regardless of the
environmental conditions.
• This is the major type of evidence that convinced
Darwin.
Galapagos Iguana
Green Iguana
• Evolutionary theory predicts that islands that have
similar ___________________, but are in different
parts of the world, will ______ be populated with
the same species.
• Instead, these islands should be populated with
plant and animal species that are closely related to
the species on the ____________ _____________,
even if the environment there is very different from
the island.
Evidence of Evolution:
________ ________
• The _____________________ order of the major
groups seen in the fossil record shows a succession
of species that is predicted by evolutionary theory
• The ___________ ___________ shows transitions
between groups, which are evidence that these
groups have a ______________ history
• Example:
Evidence of Evolution:
_______ _______
– ______ appear before amphibians, which appear before
reptiles, which appear before ______________
– Mammals are thought to have evolved from a reptilian
ancestor, and this transition is thoroughly documented
with a series of fossil _________ (reptiles ->mammal-like
reptiles -> reptile-like mammals -> mammals).
– _________________ between fossils and modern species
(two exceptionally well-documented cases include horses
and humans).
– Whale fossil with ________ __________ is a link between
modern whales and their hypothesized terrestrial ancestor
Evidence of Evolution: _________
Evolutionary theory predicts that different species
will evolve different forms of shared
(________________) traits.
• _______________ structure: when two traits are
similar, regardless of the function of the trait
• _____________ structure: are structures that are
currently of little use to the organism (i.e. they
have no known current function). They are the
historical remnants of structures that did have a
function in earlier ancestors, and provide evidence
for shared __________________.
Evidence of Evolution: __________ (cont.)
• Examples of ___________________ structure
– All vertebrate embryos look very similar during
the earlier stages of development, including
having gill pouches and tails
– Tetrapod limbs and bones
– Plant leaves modified for various functions
– Hind limb bones that baleen whales & snakes
don’t use (Homologous & Vestigial)
– Goosebumps (Homologous & Vestigial)
– Ear muscles in humans (Homologous & Vestigial)
Evidence of Evolution:
__________ and ___________
• The genetic code is ________________—all plants,
animals, fungi, bacteria, and protists use the same
genetic code.
• All organisms are made of ________, which consist
of membranes filled with water containing genetic
material, proteins, lipids, carbohydrates, salts and
other substances.
• The cells of most living things use _________ for
fuel while producing ______________ as building
blocks and messengers.
Evidence of Evolution:
__________ and ___________
• Many of the ______________ reactions occurring in
your own cells, in the cells of a fungus, and in a
bacterial cell are quite different from one another;
however, many of them are exactly the same and
rely on the exact same molecules. ______ is one
such molecule; it is essential for powering cellular
processes and is used by all modern life.
• Examples:
– the similarity between the typical animal and
plant— only ______ structures are unique to one
or the other
– Roundworms, for example, share 25% of their
genes with humans.
Evidence of Evolution:
__________ _________ & _____________
• Evolutionary theory predicts that different organisms will
independently evolve similar solutions to the same
functional problem (analogy).
• ______________ structure: when a trait in two different
species is similar and they have the same function
• Analogies are the result of _________________ evolution
• ______________ Evolution: Process in which two distinct
lineages evolve a similar characteristic ______________ of
one another.
• Evolutionary theory predicts that some traits will not be
“perfectly” adapted
• Example of __________________ Structures
– the wings of bats, birds, and insects all serve the
same basic function (flight) and are similar in
appearance. They are not similar because of
shared ancestry (the common ancestor of bats,
birds and insects did not have wings). Bat wings
consist of flaps of skin stretched between the
bones of the fingers and arm. Bird wings consist of
feathers extending all along the arm.
Evidence of Evolution:
__________ _________ & _____________
• Example of ____________________
– Giant panda’s “thumb”, a modified wrist bone
– Hiccups: The first air-breathing fish and amphibians
extracted oxygen using gills when in the water and
primitive lungs when on land—and to do so, they had
to be able to close the entryway to the lungs, when
underwater. In hiccupping, we use ancient muscles to
quickly close the glottis while sucking in. One of the
reasons it is so difficult to stop hiccupping is that the
entire process is controlled by a part of our brain that
evolved long before consciousness
Evidence of Evolution:
_________ _______ ____________
• ______________ selection provides a model
for ________________ selection
– People have been artificially selecting
domesticated plants and animals for thousands of
years.
– These activities have amounted to large, longterm, practical experiments that clearly
demonstrate that species can change dramatically
through selective breeding.
Evidence of Evolution:
_________ _______ ____________
• Experiments demonstrate selection and adaptive
advantage
– Colorful guppies vs drab guppies
– Cholera
Male guppy
Female guppy
Evidence of Evolution:
_________ _______ ____________
• We can see nested hierarchies in taxonomies
based on common descent
– Groups of related organisms share suites of similar
characteristics and the number of shared traits
increases with relatedness
Evolution of Populations
• Does evolution work on genotype or phenotype?
– _______________ because it is the whole organism
that survives and reproduces… or does not
Evolution of Populations:
__________ of ___________
• __________________
• Recombination in Sexual Reproduction:
Crossing over during meiosis
Evolution of Populations:
__________ _______ Traits
• The number of phenotypes is determined by the
number of genes that control the trait
• __________ ________ Trait: usually 2-3 phenotypes
Evolution of Populations:
__________ _______ Traits
• Homozygous recessive or dominant usually
results in two different phenotypes
• Heterozygous might result in third phenotype
Evolution of Populations:
___________ _______ Traits (cont.)
If an allele is dominant
(over a recessive allele)
does that mean that it is more
common in the population? Why?
______
• Natural Selection works on the ________ of the
individual regardless of if the trait is dominant or
recessive. This affects the whole population.
Uncommon Dominant Traits
Common Recessive
Hair straight & red;
White forelock eyes blue
Polydactyl
Kitten
with 23
toes
Evolution of Populations:
________________ Traits
• ______________ Traits: Trait controlled by 2+
genes with 2 or more alleles each. Usually
results in a range of the _________________
Evolution of Populations:
How does evolution affect _______ Traits?
• ____________________ Selection: One extreme is
selected for (or against)
• _________________ Selection: Both extremes are
selected against so the middle is selected for
• _________________ Selection: Both extremes are
selected for and the middle is selected against
_________
_________
_________
Evolution of Populations:
____________ _________
• __________________: random changes in allele
frequency caused by a series of chance
occurrences that cause an allele to become more
or less common in a population
Evolution of Populations:
_________ ______ (a type of genetic drift)
• ___________ ______: a change in allele frequency
followed by a major reduction in the size of a
_________________
Evolution of Populations:
Founder Effect (a type of genetic drift)
• ______________ ____________: a few individuals
become isolated from the larger population. These
individuals reproduce within this secluded group
_________________ the initial genetic diversity
Veiled chameleon on Hawaii
What conditions cause evolution to
occur in a balanced system?
• ___________________ ________________
– This is an active selection for or against a trait
What conditions cause evolution to
occur in a balanced system?
• __________ population size
– Changes in individuals of a _________ population
can quickly spread to the whole population
What conditions cause evolution to
occur in a balanced system?
• ________________ or ____________________
– A change in the amount of alleles or the
arrival/departure of alleles
Haemochromatosis is caused by one specific mutation in the HFE gene, located on
chromosome 6. In Australia, all patients can actually be traced back to one single
immigrant carrying the mutation.
What conditions cause evolution to
occur in a balanced system?
• _______________: A change in the genetic material
What conditions cause evolution to
occur in a balanced system?
• ____________ __________: The process by which
organism that are most suited to their environment
survive and reproduce most successfully; A.K.A
survival of the fittest