Transcript Biology – Evolution and Natural Selection

Evolution
Change over time
Charles
Darwin
• A naturalist who served aboard research ship
called “The Beagle” in 1831
• Observed bird and animal species in Galapagos
• Made observations about species characteristics
• Published “On the Origin of Species”
• Formulated theory of evolution by natural
selection
Charles Darwin
• Was actually a creationist serving on the
beagle
• Claimed to be an orthodox Christian
• Many of his statements later will show that
he didn’t know what orthodox Christianity
was
• His daughters death had a huge impact on
his atheism, as I am sure any of us would
have been impacted
• Birds on different
islands had different
shaped beaks.
• Each beak style seemed
perfect for island’s food
supply.
• Darwin speculated that
each species of bird had
adapted to utilize the
food in its environment.
• Darwin explained these
changes with his theory
of evolution by natural
selection
Darwin’s
Observations
Adaptions
• Ability to adapt was internal
• Birds already had the heritable traits to
adapt to environment
• If you take the total information from all
those birds, you can come up with the
genetic information of that bird “Kind”
Evolution
Gradual changes in a population
or species over time
Natural Selection
The way these changes occur
This isn’t gradual
• Islands that at one were not habited by
any creature,
• Other creatures came and multiplied there
in short amount of time
• Possibly, something God provided for in
DNA of all organisms
• Finding that “junk” DNA is not junk, and
helps us to “be fruitful, multiply, and cover
the earth”
Patterns of Evolution
Artificial selection
When humans breed organisms with
certain traits to produce offspring
with those traits.
Examples: dog species, draft horses, garden
variety flowers
Artificial
Selection
Dairy cows have been bred by artificial selection for
large udders and high milk production. As a result, many
cows have udders so large that they cannot walk without
swinging their legs out to the side.
Are they new creatures?
• Artificial(or mass as per ch6) is just that,
artificial – we are imposing what we want
• The animals already had the information
• We are choosing the information we want
and breading out what we don’t want
• Loss of information
Patterns of Evolution
Natural selection
When organisms that have favorable
adaptations are selected by nature
survive and reproduce.
Examples: colors which blend in with habitat,
prehensile tail, beaks adapted to local food
sources
Favorable
• Just because it is favorable, doesn’t mean
that creature will have babies
• Mutations produce a decrease in fertility
• If you don’t reproduce, doesn’t matter how
big and bad you are
• Assumes favorable takes over
Adaptations
Opposable thumb: thumb that
allows grasping and holding
Designed that way
• Amazed that they would put a well
designed hand, by a human
• By a well designed hand, by God
• We were created in God’s image
• How else would we create, if we didn’t
have opposable thumbs?
Evolution by Natural Selection
In nature, organisms with the best
characteristics for surviving in an
environment will live longer and pass
those characteristics on to more
offspring. Eventually more of the
population will have these adaptive traits.
Mendelian Genetics
• It will only pass on to offspring if it is
Dominant
• If it is recessive and is passed, then it is
not a new trait, because the mate would
already have to have the recessive trait!
In nature, organisms produce too many
offspring for environment to support
Individuals will have a variety of characteristics
Individuals with good traits for survival will live and
reproduce more than others, passing on the good
traits to their offspring.
The population will eventually change in appearance
as this trait becomes more common.
Assumption
• Assumes favorable trait will take over
• Assumes that creature evolved instead of
changed within kind – bait and switch
fallacy
Two Types of Natural Selection
Divergent Evolution
When related
species become
more and more
different due to
different niches
Adaptive Radiation
One type of divergent evolution
One species in a new environment
changes into many new species, each
adapted to a particular food source and
way of life.
But they can still interbreed
• While yes the heritable traits will be
different through genetic drift,
• There is loss of information
• The two species however will still be able
to interbreed
• Zorse
• Liger
• Tigon
Divergent Evolution of
Hawaiian Honeycreepers
• A small bird migrated to an island
• Island had diverse ecosystem
(insects, nuts, berries, flowers &
nectar, worms, leaves…
• Eventually, many species of birds evolved
• Each had features adapted for one niche
– Different coloration
– Different beak shapes
– Different anatomical structures
Maui Parrotbill
`Amakihi
Breaks apart wood and
then pries out insect
larvae.
Eats insects and
nectar.
`Akohekohe
Feed primarily on insects
and nectar from `ohi`a
blossoms
Maui Creeper
Eats insects among the
leaves and branches.
The Po`ouli
Finds insects, spider and snails
under leaves and bark
'I'iwi Honeycreeper
Eats the nectar stored in
deep-throated flowers.
Anyone See the Bait and
switch?
• Eventually man species of birds ‘evolved’
• Very dogmatic
Homologous structures
• Structures from related individuals that have
become modified for a particular environment.
• Usually result from divergent evolution.
Evolutionary explanation
• Design is denied
• Discontinuity is minimized
• Similar anitomically but vastly different in
behavior
• Chimps vs Humans
– Don’t drive cars
– Classify themselves
– Make Hydrogen bombs
DNA – Construction Site
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•
•
•
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Sky Scraper vs. a Shed
Tools some the same, some different
Both good designs by the engineers
Timing, location, duration of tools
Blueprint – DNA
Does simplicity mean less designed?
Second Type of Natural Selection
Convergent evolution
When two or more
unrelated species
become more similar
due to similar
environments.
Organisms that have converged
due to similar environments
Analogous structures
• Structures on unrelated
species that are similar due to
similar functions.
• Analogous structures result
from convergent evolution.
Analogous Structures
Fish/shark and
Whale
• No common ancestry
• Similar body shape
and streamlining due
to common
environment.
• Structures have
become similar due to
convergent evolution.
Fallacy
• This is “begging the question”
• They already assume what they are trying
to prove
• Evolution is assumed, so they just add
another name to it
Evidence for Evolution and
Relatedness of Species
Types of evidence that shows if species
are related include:
– Fossil evidence
– Comparative anatomy
– Biochemistry
– Chromosomes
– Embryology
– Microevolution
All of these assume a worldview
• Worldviews tell you how to interpret
evidence
• Made of presuppositions
What are Fossils?
• Fossils - traces of dead organisms
• Fossils can be molds, footprints,
imprints, bones or entire organisms
Determining the Age of a Fossil
• Absolute age: carbon dating relies on
radioactive elements, which tell the actual
age of the fossil.
• Relative age: the age of a fossil can be
predicted by its location in a rock column
Candle Analogy
• Many assumptions about dating organism
• Carbon dating is only good for 5,000 yrs
max
• Relative age – circular reasoning
Fossil Evidence
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•
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Fossils can be found
in sedimentary rock
(mud, sand or clay).
Older fossils are
found lower in rock
Newer fossils are
found closer to the
surface
Evidence for Noah’s Flood
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Billions of dead things buried by water
95% of fossil record is marine creatures
Less than 1% are vertebrates
Cannot use arguments – “we don’t find
human and dinosaur fossils together” to
assume they didn’t live together
Sedimentary Rock
Geologic column: a tall segment with
many layers of sediment
Fossils on the bottom of the column are
older than those on the top.
Oldest
Youngest
Logical Fallacy
• Circular reasoning
• How old is this layer?
– As old as the fossil
• How old is this fossil?
– As old as this layer
Using Fossils to Understand Relationships
• The bone structure in fossils indicates how closely
related organisms may be
• The sequence of development the horse was
determined by the location in rock and the similarities
of the fossils
1. Hyracotherium
4. Merychippus
2. Orohippus
5. Pliohippus
3. Mesohippus
6. Modern day Equus
Disproved
• The actual series for the horse is reversed
• Evolutionists now have placed most of
these creatures in the lineage of camels
• Once again begging the question –
assuming what they are trying to prove
• evolution
Comparative Anatomy
• Similar
anatomy
indicates
closer
relationships
• Homologous
structures
show closer
relationships
Crocodile
forelimb
Whale
forelimb
Bird
wing
Worldviews
• Evolution
• Common designer
• -if it does the job? Why not repeat it in
other creatures?
Vestigial Structures
• Structures present in ancestors but no longer
needed.
• For example:
- appendix
Snake
Whale
- tailbones
humans (4)
gorilla (?)
- ear muscles
- pelvic girdle
Snakes
Whales
Vestigial sturctures
• In 1890 there were 190 in humans
• Today there are none
• vestigial- useless, then changed to not as
useful as it used to be, organs that could
be very very useful, but doing a different
job today. Rescuing device
• Current definition –
Vestigial Structures
• ‘any part of an organism that has
diminished in size during its evolution
because the function it served decreased
in importance or became totally
unnecessary”
• Almost everything then is vestigial!
• Eyebrows
• Nose
• Ears
Biochemistry
• ALL living organisms contain the same
genetic code
– the same four DNA nucleotides (AGCT)
– The same 20 amino acids
• More closely related species have more
similar:
– Nucleotide sequences in DNA
– Amino acid sequences in their proteins
All life uses the same
genetic code
In every living species,
the codon UAC in RNA
codes for the amino acid
tyrosine
DNA - Information
• Wouldn’t a common designer use a
common language for His creation?
• A French novelist doesn’t write her books
in Chinese does she?
• Neither does she take words from all other
languages and jumbles them together
hoping to have it make sense
Cytochrome C
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Cytochrome c is an enzyme in the
mitochondria of the body.
Humans have 104 amino acids in
cytochrome c
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•
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Chimpanzees have the identical aa
sequence as humans
Dogs differ in 13 of the amino acids
Snakes differ by 20 amino acids.
The more closely related the species, the
more amino acids they will have in common.
Cytochrome C – What more could you want? See the
difference in species? All leading up to man
R monkey
Rabbit
Cow
Chimp
Fruit fly Bullfrog Pigeon
human
What it is actually
Fruit fly
Bullfrog
Pigeon
Cow
Rabbit
R monkey
Chimp
Human
Actually there are equidistant -
Chromosomes
Closely related
species have
similar gene
sequences on
chromosomes
• Genetically,
chimpanzees
are 98.5
percent
identical to
humans.
• However, the
differences
between the
species are
profound.
• Small gene
differences
make for huge
differences in
traits
Genetic Differences
between
Chimpanzees and
Humans
Why was that picture used?
• 2% of our genes were used to compare to
chimps
• Say that the rest of our DNA is “junk”
• Chimps have 24 chromosomes we have
23
• Chimps have 10% more DNA
• Chimps telomeres(endcaps of genes) are
twice as long as ours
Embroylogy
• Embryos from different species show similar
features due to shared ancestry
• All vertebrates have
– Tails
– Gill pouch
Chick
Human
Already disproved
Pharyngeal Pouches –
Thymus gland
- Parathyroids
- Facial bone
- Inner ear
Yoke sac
- First blood cells
formed here
- Baby has different
blood type
Tail
- 3 muscles attach
here
- Spinal cord needs
to end somewhere
Microevolution
watching evolution occur
Sometimes, evolution occurs on a small
scale that we can watch over a period of a
lifetime
Logical Fallacy
• Replacing Evolution(goo to you) with
evolution(change)
• Fallacy of Equivocation
• We see plenty of animals change, but not
change from say a dog to a cat
Microevolution
In England, the industrial revolution resulted in heavy pollution
and soot-covered surroundings. Eventually the trend was
reversed and the pollution was reduced.
Researchers studied how a species of moth with two forms
adapted to its changing environment.
Already Disproved
• Of Moths and Men by Judith Hooper
• “All we gave observed is where the moths
do not spend the day. In 25 years we
have only found two betularia on the tree
trunks or walls adjacent to our traps” pg
xvii
In each environment, the form that was best
camouflaged lived longer and had more offspring
than the other, and eventually became the most
common form.
Perfect Picture!
• All these moths are put on the tree by pins
that you cannot see
• They are dead!
• Why is this still the icon of evolution?
Microevolution
watching evolution occur
The Moth study is one example of
microevolution
Physiological adaptations can develop rapidly
Non-resistant
bacterium
Antibiotic
Resistant
bacterium
The bacteria in a
population vary in
their ability to resist
antibiotics.
When the population is
exposed to an antibiotic,
only the resistant
bacteria survive.
The resistant bacteria
live and produce more
resistant bacteria.
Non-resistant
bacterium
Antibiotic
Resistant
bacterium
Today, penicillin no longer affects as many
species of bacteria because some species
have evolved physiological adaptations to
prevent being killed by penicillin.
Beneficial mutations?
• There are some beneficial mutations, as
you see in the previous slide
• But, it leads to a net loss of information or
it had less information
• Prior abilities are lost or where without an
ability
• Only traits already present are shown to
resist the antibiotics