Regents Biology 2006-2007 Evidence for Evolution by Natural Selection.
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Transcript of Regents Biology 2006-2007 Evidence for Evolution by Natural Selection.
Regents Biology 2006-2007
Evidence for Evolutionby
Natural Selection
Regents Biology
A BRIEF HISTORY...
Charles Darwin The person who was most
influential to our understanding of evolution.
In 1831, at age 22, he joined the crew of the HMS Beagle as a naturalist for a 5 year voyage around the world.
Regents Biology
Darwin’s Findings
After Darwin returned to England in 1836 he filled notebooks with his ideas about species diversity and the process that he would later call evolution.
He did not rush to publish his ideas because they disagreed with the fundamental scientific beliefs of his day.
He asked his wife to publish his ideas when he died.
Regents Biology
Wallace’s Essay
In 1858, another naturalist, Alfred Russell Wallace wrote an essay describing his work in Malaysia that summarized the same ideas Darwin had been thinking about for 25 years.
Regents Biology
Origin of Species
Suddenly Darwin had incentive to publish the results of his work.
In 1859, his book On the Origin of Species presented evidence and proposed a mechanism for evolution that he called natural selection.
Regents Biology
EVOLUTION IS CHANGE OVER A PERIOD OF TIME!
Regents Biology
Evolution is NOT goal-oriented§An evolutionary trend does not mean that evolution is goal-oriented.
§Surviving species do not represent perfection.
§There is random chance involved as well
§Traits happen—Well suited to anenvironment, OR NOT!
Evolution is the survival of the fittest, but
sometimes it is survival of the just good
enough.
Regents Biology
Evidence supporting evolution Fossil record
shows change over time
Anatomical record comparing body structures
homology & vestigial structures embryology & development
Molecular record comparing protein & DNA
sequences
Artificial selection Human-caused evolution
Regents Biology
1. Fossil record Layers of rock contain fossils
new layers cover older ones creates a record over time
fossils show a series of organisms have lived on Earth (over a long period of time)
Regents Biology
Fossils tell a story…
the Earth is oldthe Earth is old
Life is oldLife is old
Life on Earth has changedLife on Earth has changed
Regents Biology
Fossil of Archaeopteryx lived about 150 mya links reptiles & birds
Today’s birds descended from ancestral species
Today’s birds descended from ancestral species
Evolution of birds
Regents Biology
Transition from sea to land 2006 fossil discovery of early tetrapod
4 limbs Missing link from sea to land animals
Regents Biology
Land Mammal
?
???
Where are the
intermediate
fossils?Where are the
intermediate
fossils?
Ocean Mammal
Complete seriesof transitional
fossils
We found the fossil — no joke!
Regents Biology
2. Anatomical recordAnimals with different structures on the surfaceAnimals with different structures on the surface
But when you look under the skin…But when you look under the skin…
It tells an evolutionary story of common ancestorsIt tells an evolutionary story of common ancestors
Regents Biology
Compare the bones The same bones under the skin
limbs that perform different functions are built from the same bones
How could thesevery different animals
have the same bones?
Regents Biology
Homologous structures Structures that come from the same origin
homo- = same -logous = information
Forelimbs of human, cats, whales, & bats same structure on the inside same development in embryo different functionson the outside evidence of common ancestor
Regents Biology
But don’t be fooled by these…
Analogous structures look similar on the outside same function different structure & development on
the inside different origin no evolutionary relationship
Solving a similar problem with a similar solutionSolving a similar problem with a similar solution
How is a birdlike a bug?
Regents Biology
Analogous structures Dolphins: aquatic mammal Fish: aquatic vertebrate
both adapted to life in the sea
not closely related
Watch the tail!
Regents Biology
Vestigial organs Structures on modern animals that have
no function remains of structures that were functional
in ancestors
evidence of change over time
eyes on blind cave fish
human tail bone
Regents Biology
Vestigial organs Hind leg bones on whale fossils pelvis on
snakeWhy would whales have pelvis & leg bones if they were always sea creatures?
Why would whales have pelvis & leg bones if they were always sea creatures?
Because they used to
walk on land!
Regents Biology
Convergent evolution 3 groups with wings
Does this mean they have a recent common ancestor?
Flight evolved 3 separate times — evolving similar solutions to similar “problems”
Flight evolved 3 separate times — evolving similar solutions to similar “problems”
NO!
They justcame up with the
same answer!
Regents Biology
Convergent evolution led to mimicry Why do these pairs look so similar?
Monarch malepoisonous
Viceroy maleedible
fly bee moth bumblebee
Which is the fly vs. the bee? Which is the moth vs. the bee?
Regents BiologyToo close to call for hungry birds!!
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Yuck!!!
Regents Biology
Comparative embryology Development of embryo tells an
evolutionary story similar structures during development
all vertebrate embryos have a “gill pouch” at one stage of development all vertebrate embryos have a “gill pouch” at one stage of development
Regents Biology
3. Molecular record
100 20 30 40 50 60 70 80 90 100 110 120
LampreyFrogBirdDogMacaqueHuman
328 45 67 125
Comparing DNA & protein structure everyone uses the same genetic code!
DNA
compare common genes compare common proteins
compare common genes compare common proteins
number of amino acids different from human hemoglobinnumber of amino acids different from human hemoglobin
Regents Biology
Building “family” treesClosely related species are branches on the tree — coming from a common ancestorClosely related species are branches on the tree — coming from a common ancestor
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How do we know natural selection can change a population? we can recreate a similar process “evolution by human selection”
4. Artificial selection
“descendants” of wild mustard“descendants” of wild mustard
Regents Biology
Selective BreedingHumans create the change over time
Humans create the change over time
“descendants” of the wolf“descendants” of the wolf
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Artificial Selection…and the examples keep coming!
I liked breeding pigeons!
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Unexpected consequences of artificial selection
Pesticide resistancePesticide resistance
Antibiotic resistanceAntibiotic resistance
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Insecticide resistance Spray the field, but…
insecticide didn’t kill all individuals variation
resistant survivors reproduce
resistance is inherited insecticide becomes
less & less effective