Download evolution - Net Start Class

Evolution Unit
• Chapter 15, Darwin’s Theory of Evolution
– Puzzle of life’s diversity
– Ideas that shaped Darwin’s thinking
– Darwin presents his case
• Chapter 16, Evolution of Populations
– Genes and variation
– Evolution as genetic change
– Process of speciation
• Chapter 17, History of Life
–
–
–
–
Fossil record
Earth’s early history
Evolution and multicellular life
Patterns of evolution
Why Care About Evolution?
1. Curiosity about the origins of life, how all the species
came into being, how the living world came into
being.
2. Curiosity about what may happen to the natural world
in the future.
3. Predict what new life forms research will discover in
the future.
4. Evolutionary theory can help predict which
strains of flu, AIDS, and West Nile virus will
be most deadly next year.
5. Desire to learn about all life, past,
present and future.
6. Want to pass this biology class
and the TAKS test.
Definitions to Know
Box 1
• Scientific Theory = a well-supported, testable
explanation of phenomena that have occurred in the
natural world.
• Evolution = change over time, the process by which
modern organisms descended from ancient Box 2
organisms
• Is Evolution Fact or Fiction?
– Scientists believe it’s Fact.
• Proof?
– Fossils
– Speciation
– Geological evidence
– DNA evidence
– Etc.
Charles Darwin (1809-1882)
• British naturalist famous for his theories of
evolution and natural selection.
• Like several scientists before him, Darwin believed
all the life on earth evolved (developed gradually)
over millions of years from a few common
ancestors.
• In 1831, Darwin took a trip around the world on the
ship, the M.S. Beagle, where he collected
evidence that led him to propose his famous
Theory of Evolution.
There’s a huge
tortoise lurking behind
me, interesting. And
he has weird birds on
his back.
Charles Darwin
Box 3
Darwin’s Voyage on M.S. Beagle
Box 4
Ewww,
nasty.
Starting point:
1831, England
Ending point:
1836, England
I spent 5 years on a
ship, can you
imagine what that
was like? What we
all smelled like?
Did you know there are no rabbits in Australia?
No kangaroos in England? No monkeys in
North America? No elephants in Alaska?
Darwin’s observations showed him there were Box 5
patterns to the diversity of life on Earth. Organisms
are adapted to the environment where they live.
The Galapagos Islands
• The most important, influential stop on Box 7
Darwin’s trip was the Galapagos Islands
• 1000 km west of S. America, a cluster
of islands isolated by miles of sea
• The islands had different climates, and
therefore, had different varieties of animals
I’m
and
plants
That’s my
lonesome
Box 7
friend Finchy!
George
Animals Darwin studied:
1.
Giant Tortoises
3. Finches
2. Iguanas
Galapagos Turtles
Each turtle lives on a
certain island, and their
shells are different, islanddependent! Brilliant!
Box 8
Pinta
Tower
Marchena
Pinta Island
Intermediate shell Fernandina
Hood Island
James
Saddle-backed shell
Santa Cruz
Isabela
Santa Fe
Floreana
Isabela Island
Dome-shaped shell
Hood
The shape of each turtle’s shell is
different and the different shapes
depend on the turtle’s habitat.
Scientists Who Influenced
Darwin
• Discovery of fossils helped shaped the scientists
•
Box 13
of Darwin’s time
2 biologists who influenced Darwin were James
Hutton and Charles Lyell, they helped scientists
Box 14
recognize that:
1. Earth is many millions of years old (Hutton)
2. The same natural process happening THEN are still
happening NOW (Lyell)
•
Jean Baptiste de Lamarck
–
–
–
Box 16
Living things have changed over time
Living things respond to their environments
Through either use or disuse, organisms acquired or
lost certain traits during their lifetime, and these traits
could be passed on to the next generation
Thank you. I’m
pretty smart.
Lamarck here,
nicely done
Darwin!
Box 15
More on Lamarck
• Giraffe stretching it’s neck to reach
leaves will lead to offspring with longer
necks.
• Disproved after discoveries of genetics
and how traits are inherited. Also
consider common sense, if you lost
your arm in an accident, that doesn’t
mean your child will only have one
arm.
Thomas Malthus (1798)
• English economist who introduced the concept of
human population growth and the problem of too
many people, too little space
• Populations don’t grow uncontrollably,
there is a limit to population growth
• Why do some survive and some die?
She’s about to be shark
bait. Sharks are perfect
predators, perfect
killing machines.
He has no heart, he’s a
mathematician.
Thomas Malthus
Box 17
Too many people,
too little space,
let the shark have
her!
What took him so long? 25 years
later….
• In 1858, Alfred Wallace sent Darwin an essay with the same
Box 18
ideas about evolution!
• They presented their work together at a conference, but….
You stole MY idea!
• This pushed Darwin to publish
Cheat! Thief!
his work, before Wallace
You’re famous and
I’m not!
• The Origin of the Species
– Proposed a mechanism for evolution, called
Natural Selection
– Presented evidence that evolution has
been happening for millions of years
I procrastinated, and
came close to losing my
chance for fame! And I
aged quite a bit.
Shut up Wallace, you sore
loser. Survival of the fittest
and all that.
So, what is Natural Selection?
1. There is variation in traits.
Ex. Some beetles are
green and some are brown.
2. Some organisms are better
suited to survive and
therefore reproduce more.
Ex. Green beetles tend to
get eaten by birds and
therefore reproduce less
than brown beetles.
3. There is heredity.
Ex. The survivng brown
beetles have babies with
the same beneficial trait.
4. End result: The better trait,
brown, allows the beetles to
reproduce more therefore
making the population of
brown beetles more
numerous than green
beetles, eventually all
beetles will be brown.
Darwin’s Finches
• Darwin also collected finches, birds, matching their beak and
body shapes with different islands- just like the tortoises.
• Beak shapes in the finches indicated their type of diet, what
Box 9
they ate, and this told him where they lived
Box 10 and 11
The finches of the Galapagos Islands provide a classic example of
Adaptive Radiation —the evolutionary process through which a
single lineage gives rise to species occupying diverse
environmental niches.
In one model of how species form, geographical separation
leads to evolutionary divergence (growing apart).
Tree Finch
Ground finch
In other words, if you get
separated from your own
species, you evolve or change
in response to your
environment.
Darwin’s
Finches
FYI, each beak is
designed for a
different purpose.
Box 12
Leaves
Seeds and Fruit
Seeds
Insects
Grubs
Tool using
Eeek! It’s the C Gang,
they won’t leave me
alone!
Use it or lost it
Oh, I’ve GOT to
grow that claw!
Look, it’s Crabby,
what a jerk. Hey,
Crabby, you loser!
You just wait! I’ll
get you one day!
Stay away from me!
Hi! I’m Crabby.
I want to be
superior, how
can I do that?
The Next Day……
Ha Ha! Are you
scared? Huh? Are
you scared you little
twerps!
Where are you going?
Run away! Run away!
I know! I’ll grow
a huge claw, and
I’ll squash those
other crabs!
Let’s drop him!
Yeah, thanks dad!
Boy, dad sure did know
what he was doing when
he developed this huge
claw- weapon!
Artificial Selection and Natural Selection
• Variation exists in nature and animal and plant breeders use this
through artificial selection
– A farmer may like a see a plant with bigger tomato and use
the seeds of that plant for next year’s crop
– Or he may breed the two best milk cows to get a cow who is
an even better producer of milk
• Darwin’s greatest contribution was his concept of natural
selection
Box 20
• In the struggle for survival, the most fit- the fastest prey, the
strongest predator, the one with the sharpest claws, wins the
Box 22
game of survival. Survival of the fittest. Box 21
• Fitness = the ability to survive and reproduce in a specific
environment
Box 23
Adaptation = any inherited
characteristic that increases an
organisms chance of survival
How is your fitness?
Did you notice how fat
Wallace was? NOT fit.
Box 19
Proof for Evolution
Beaver
Muskrat
Beaver and
Muskrat
Coypu
• Fossil record = Darwin argued that
the fossil record provided evidence
that living things have been evolving
for millions of years Box 24
Capybara
Coypu and
Capybara
They all look
like rats to me.
• Geographic Distribution of living
Box 25
species:
Descent with modification, says that
similar species in similar
environments but in different
locations, were products of different
evolution paths
Fossils
• Darwin didn’t just observe and collect living animals,
he also collected fossils.
• Fossils = preserved remains of ancient organisms Box 6
• This led to questions like….
– “Where did all these organisms go?” “Why aren’t
they still here?” “Why do they resemble organisms
we have living today?”
This is too much
of a coincidence.
Glyptodon = dead
Armadillo=
alive
Homo sapiens- existed
from about 200
thousand years ago
(TYA) to the present
Australopithecinesexisted between 5 and
2 million years ago
Homo hablis- existed
2.4 to 1.5 million
years ago
Neanderthal man- existed
from about 250 to 30
thousand years ago
Homo erectusexisted around 1.8
million years ago
Do we look
alike?
Homologous Body Structures
Box 26
Homolgous structures all•
develop from the same
embryo tissues but have
different functions in the •
adult organism.
What does Homo mean?
– Homo = same, similar
Remember these?
– Homozygous- same allele for a trait, tt, TT
– Homologous chromosomes- same chromosome,
one from mom one from dad
Turtle
Alligator
Ancient lobe-finned fish
Bird
Mammal
Vestigial organs
• Why do we need our appendix?
• It’s useless now, but it may have served some
function in our past
• Vestigial organs = organ with little or no
Box 27
function, left over from the past, ex. appendix
If you can live without
it, with no medical
help, then it’s useless!
Evidence for Evolution
1. Resistance to antibiotics and
insecticides.
2. Endosymbiotic Theory and
Biochemical compounds
3. Homologous structures
4. Embryo development
5. Vestigial Structures
6. Fossil Record
Evidence for Evolution: 1. Resistance to
Antibiotics and Insecticides
Antibiotic resistance – antibiotics kill the
microbes that make you sick, if you do not
finish all of the medication all the microbes
are not killed. They build up resistance to
the antibiotics and they will make
populations that are resistant, causing the
antibiotic to no longer work for you.
Insecticide – same as antibiotic, over time the
insecticide becomes less and less effective.
Evidence for Evolution:
2. Endosymbiotic Theory and biochemical
compounds
• Even small cell organelles show signs of evolution.
• The Endosymbiosis Theory was proposes that
mitochondria and chloroplast were both
descendants of bacteria.
• Related species have similar RNA and DNA in their
cells. Chimpanzees and humans contain very
similar DNA sequences.
Evidence for Evolution:
3. Homologous Structures
• Similar structures with different functions.
suggests that all vertebrates share a common
ancestor.
Evidence for Evolution: 4. Embryo
Development
• At some time in their
development all
vertebrate embryos have
a tail, buds that become
limbs, and gill slits.
• The tail remains in most
adult vertebrates, in
humans it disappears
before birth, the gill slits
turn into structures found
in the throat.
Tails
Evidence for Evolution: 5. Vestigial
Structures
• Structures that have reduced functions
or no function at all, but were once used
by ancestors.
Ex. Human appendix is a vestigial
structure, it has absolutely no function but
was once used by our ancestors. Also the
human tailbone
Evidence for Evolution: 6. Fossil Record
Fossils – any sign of earlier life, usually found
in the soil or sedimentary rock.
Fossil records show the evolution of life
because they show the change in our Earth
and it’s inhabitants over time.
Paleontologists – scientists who study fossils.
Ch. 16, Evolution of Populations
• Why are we all so different?
• Variation in populations is the raw
material for evolution
• 2 main sources of variation:
– Mutations = any change in a
Box 28
sequence of DNA, some are
harmful, some are beneficial and
some don’t have any effect at all
– Gene shuffling = mixing of genes
Box 29
due to random sexual mating
• 23 pairs of chromosomes can
produce 8.4 million different
combinations of genes
• Crossing over during Meiosis
Variation and Gene Pools
• Genetic variation is studied in POPULATIONS,
not individuals
• Members of a population share a Gene Pool
• Gene pool = consists of all genes, including all the
different alleles that are present in a population
– Why?
– They descended from a common ancestor
• Relative frequency of an allele = number of
times an allele occurs in a gene pool
• So, evolution is any change in the relative
frequency of alleles in a population
Box 29
Box 30
Natural Selection and
Speciation
Box 31
• Natural Selection= (Dr. Malone’s definition) when Write as much as you
want from this
individuals who have what it takes survive and
paragraph
reproduce best; survival of the fittest, it’s a dog eat
dog, you got to step on someone else to get where
you want to go, world
• Founder Effect = when a population shrinks down toBox 32
only a few members, then rebounds so all of the
future members have the “founder’s” genes
• Speciation = when natural selection and Box 33
other random effects lead to the creation
of a new species
– Reproductive Isolation = populations become
reproductively isolated from each other, so it
Box 34
leads to evolution of a new species
This is why cats and dogs can’t
have cat-ogs, or is it do-cats?
Dogats? Cadogs?
If all our women moved to
China, could we continue to
interbreed? Ha ha. Don’t
think so!
Speciation
• Behavioral Isolation = when two populations can
interbreed, but their different behaviors, or
reproductive strategies, just don’t turn each other
on, get it?
• Geographic Isolation = two populations are
separated by geographic barriers, like mountains or
oceans and they can’t interbreed
•Temporal Isolation = two populations are
separated by different reproductive times
I say go
for it!
Move mountain!
Move mountain!
It’s too
far to fly!
Box 35
Box 36
Box 37
Speciation, an example
• The scene: a population of wild fruit
flies minding its own business on
several bunches of rotting bananas,
cheerfully laying their eggs in the
mushy fruit...
• Disaster strikes: A hurricane washes the bananas and the
immature fruit flies they contain out to sea. The banana bunch
eventually washes up on an island off the coast of the
mainland. The fruit flies mature and emerge from their slimy
nursery onto the lonely island. The two portions of the
population, mainland and island, are now too far apart for gene
flow to unite them. At this point, speciation has not occurred —
any fruit flies that got back to the mainland could mate and
produce healthy offspring with the mainland flies.
• The populations diverge: Ecological
conditions are slightly different on the island,
and the island population evolves under
different selective pressures and
experiences different random events than
the mainland population does. Morphology,
food preferences, and courtship displays
change over the course of many
generations of natural selection.
• So we meet again: When another storm
reintroduces the island flies to the mainland,
they will not readily mate with the mainland
flies since they've evolved different
courtship behaviors. The few that do mate
with the mainland flies, produce inviable
eggs because of other genetic differences
between the two populations. The lineage
has split now that genes cannot flow
between the populations
Ch. 17, The History of Life
Box 38
• Paleontologists (pay-lee-un-TAHL-uh-jists) =
scientists who study fossils, history written into
stone
• The fossil record:
– Provides evidence about the history of life
on Earth
– Shows how species have changed over
Box 39
time (evolved)
• 99% the species that have lived on Earth
Box 40
are extinct!!!!
• Fossils form in sedimentary layers of rock
– Fossils at the top are younger than fossils
at the bottom, common sense,
I’m extinct. There are and will
or relative dating
be no others like me, it’s so
tragic.
Help!
Box 43
How old are Fossils?
Box 41 and 42
Half-Life = length of
time it takes for ½ of
the radioactive atoms
in a sample to decay
• Relative dating is comparing fossils with other
fossils to see estimate the age of each, but it’s not
very precise
• Radioactive Dating- calculating the age of fossils
based on the amount of remaining radioactive
isotopes they contain
Do you remember?
Isotopes = an element with a different number of neutrons in its atom
How many
neutrons in C-12?
6
Carbon-12
6
Carbon-14
6
C
12
How many neutrons in C-14?
C
14
Radioactive!!!
8
Geologic Time Scale
You are HERE
Era
(millions of
Period
Time years ago)
Era
1.8–present
Tertiary
65–1.8
Cretaceous
145–65
Devonian
410–360
Jurassic
208–145
Silurian
440–410
Triassic
245–208
Ordovician
505–440
Cambrian
544–505
Box 44
Paleozoic Era
Mesozoic Era
Cenozoic Era
Permian
Era
290 – 245
Quaternary
Geologists divide the time
between Precambrian and the
present into 3 eras:
1.
2.
3.
of
Time (millions
years ago)
Period
Carboniferous 360–290
Which era does Tyrannosaurus
Rex belong to?
Jurassic
Period
Time
Vendian
650–544
Patterns of Evolution
•
•
Macroevolution = large-scale evolutionary patterns
occurring over long periods of time
Important topics in macroevolution:
1. Extinction = over 99% of all species that have
ever lived on earth are now dead, extinct.
2. Adaptive Radiation = a single species evolving
over time into diverse forms that live in different
ways
Box 45
Box 46
Macroevolution Cont.
3. Convergent Evolution = unrelated organisms come
to resemble one another
Box 48
4. Co-evolution = process by which 2
species evolve in response to changes in
each other over time
-Predator- prey pressures, what food is
available, pollination, etc.
Box 47
Macroevolution Cont.
Box 49
5. Punctuated equilibrium = the pattern of long stable
periods of time interrupted by brief periods of more
rapid change
Yikes! I’m outta
here! He’s crazy!
Hee hee! I’m coming
to get you!
Have you ever heard of survival
of the fittest…
What about survival of the
sneakiest???
Discussion Questions
• When it comes to crickets, what does fitness mean?
• Is calling good or bad for a cricket's fitness?
• Give some examples of selection at work in this
cricket story.
• How does selection favor calling? How does
selection favor not calling?
Did you know?
• Some ribbon worms will eat
themselves if they can’t find any food.
Did you know?
• Ants don't sleep.
Did you know?
• The average person walks the
equivalent of twice around the
world in a lifetime.
The man who began his journey
depressed and weighing more
than 400 pounds has walked
2,800 miles across the United
States.
It has taken 40-year-old Steve
Vaught 13 months to travel from
Oceanside to New York City, but
he has done it. Almost.
Did you know?
• No word in the English language
rhymes with "month".
Did you know?
• The female lion does more than 90%
of the hunting while the male simply
prefers to rest. !!
We already knew that though didn’t
we!
Did you know?
• The grizzly bear can run as fast as the
average horse!!
Did you know?
• Why do we might feel warmer wearing a
dark-colored jacket than a light-colored
one? . Dark colors absorb light energy.
Light colors and white reflect light
energy. When light shines on your dark
jacket, the jacket fabric absorbs light
energy. The absorbed light energy
causes electrons in the atoms of the
jacket to vibrate. This activity releases
heat energy, which makes the jacket—
and you—warmer. That's why we like to
wear more dark colors in winter and more
light colors in summer.
Did you know?
• The world's
largest rodent is
the Capybara.
An Amazon
water hog that
looks like a
guinea pig, it
can weigh more
than 100
pounds.
Did you know?
• A dolphin is the only other mammal
that has sex for pleasure.
Did you know?
• A typical bed usually houses over 6
billion dust mites.
Did you know?
• Many fish can change sex during the
course of their lives. Others, especially
rare deep-sea fish, have both male and
female sex organs.