Download Evolution and Natural Selection

Evolution
Artificial selectionhumans select which traits will be passed on
Natural selectionthe environment determines which traits will be passed
on
Struggle for existenceorganisms fight for resources
Fitnessbest traits for the environment
Adaptationan INHERITED good trait
Survival of the fittestthose organisms best suited to the environment will
survive and reproduce
How did squids acquire this ability?
Why?
http://www.youtube.com/watch?v=5Il14q63sv4
Imagine you are an ancient species of giraffe…
Goal: Eat the leaves on the tree.
But there are rules.
• Tall Giraffes eat first
• Can only eat 5 leaves at a time
• Can not hop, jump or stand on
tippy toes or any other object.
(like a chair)
• As soon as leaves are out of
reach sit down.
• Must take turns. 1 at a time.
• Do not throw leaves away
• Do not exhort yourself. Eat the
easiest leaves to get first.
NATURAL SELECTION
ACTS ON THE
PHENOTYPE,
NOT THE GENOTYPE!!
It only matters how the
organisms traits are
expressed- nature doesn’t
know exactly what the
genes are inside, only what
it looks like or acts like
This giraffe could be TT or Ttyou cannot tell from the outside!!!
Artificial
selection/selective
breeding
• Darwin noticed that
humans “selected”
and bred certain
plants and animals to
get the desired traits.
• Nature provides the
variation. Humans
choose the most
useful.
http://learn.genetics.utah.edu/content/variation/artificial/ Natural vs artificial
The ability of an individual organism to
survive and reproduce in it’s natural
environnent is called what?
A. Evolution
B. Natural Selection
C. Adaptation
D. Fitness
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Natural Selection
• He also noticed that some organisms in
nature were “selected” to survive and
reproduce in certain environments
Example:
Finches on different islands looked so different
from one another because their beaks were
shaped to eat different foods (in different
habitats).
Darwin also
believed that
natural selection
produced
organisms with
different
structures, niches,
and habitats
Survival of the Fittest
• Members of a population that have desirable
traits (the most “fit”) will have a greater chance to
survive and reproduce in that environment.
• The most “fit” will be “selected” to thrive,
reproduce, and survive.
• Those with less desirable traits will be “selected”
to die or leave fewer offspring.
http://www.pbs.org/wgbh/evolution/educators/teachstuds/svideos.html
hummingbirds
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How is Natural Selection related
to species fitness?
A. Fitness
B. Adaptation
C. Artificial Selection
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more examples.
The ability of an individual to survive and
reproduce in its environment is called fitness.
An adaptation is any INHERITED characteristic
that increases an organism’s chances of survival.
EVOLUTION takes place over a period of time.
And is used to describe entire generations not
simply individuals.
Fitness is a result of
A. Going to the gym
B. Adaptations
C. Artificial Selection
D. Natural Selection
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anymore examples.
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I do not understand what is being
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more examples.
Risk Box
In 5 generations of birds,
some were able to survive
and reproduce better than
others.
Give some possible reasons
why it might be more
difficult for the lighter birds
to survive and reproduce?
Watch this:
http://www.pbs.org/wgbh/nova/evolution/e
volution-action.html evolution interaction
What to put on the notecard:
• Observations
• Questions
What is the definition of a species?
Members of the same species can successfully reproduce.
Descent with modification: Every living species has
evolved, over time, with changes, from other species
Common descent:
all living organisms
are related
Watch this:
http://learn.genetics.utah.edu/content/vari
ation/recipe/
Q: Which of these best illustrates natural selection?
A. An organism with favorable genetic variations
will tend to survive and breed successfully.
B. A population monopolizes all of the resources
in its habitat, forcing other species to migrate.
C. A community whose members work together
utilizes all existing resources and migratory routes.
D. The largest organisms in a species receive the
only breeding opportunities.
Q: A species of finch has been studied on one of
the geographically isolated Galapagos Islands for many
years. Since the island is small, the lineage of every bird for
several generations is known. This allows a family tree of
each bird to be developed. Some family groups have
survived and others have died out. The groups that survive
probably have
A. interbred with other species.
B. inherited some advantageous variations.
C. found new places on the island to live.
D. been attacked by more predators.
Advantagesomething that helps
Disadvantagesomething that harms
Peppered moths –
natural selection in action
• Two forms- one dark, one light.
• In less polluted areas with cleaner
bark on trees and buildings, the
light moths were better
camouflaged, and were more likely
to pass on their light genes
•In heavily polluted areas, the dark
moths were more common because
they were better camouflaged.
• This shows that the environment
can causes changes in species over
several generations.
Next slide
Evidence for evolution
Fossil record: what are fossils, How old is the Earth? How can scientists use
fossils to document (record) the fact that life on Earth has changed over time?
Have all the fossils been found?
http://www.pbs.or
g/wgbh/evolution/
educators/teachst
uds/svideos.html
Whales
Geographic distribution
of living things: Why
were there so many
differences between the
finches on the
Galapagos? What is it
called when species
evolve, over time, with
changes, from other
species? What did
Darwin find on different
continents, but in similar
habitats?
Homologous body structures: how are certain body
parts similar (in animals with backbones)? How and
why have their limbs adapted? Give examples of
homologous structures. What are vestigial organs?
Similarities in
Embryology: How
do the early-stage
embryos of
vertebrates
compare to each
other? What do
these similarities
mean? How do
embryonic cells
develop? What do
they develop into?
http://www.pbs.org/wgbh/nova/
evolution/guess-embryo.html
guess the embryo
Genetic variation:
differences in alleles
and genes within and
among populations
(all lions are not
exactly alike, all
beetles, pine trees,
humans, giraffes- are
not exactly alike.
Genetic variation is caused by
1. Mutations
2. Gene shuffling during sexual
reproduction- during meiosis and
crossing over
3. Gene flow, or migration
Evolution is any change in the relative
frequency (percentage) of alleles in a
population
Gene pool- all the alleles
in a population
What is the definition of a species?
Members of the same species can
successfully reproduce.
Whale evolution:
http://www.youtube.com/watch?v=8cn0kf8
mhS4&feature=related