evolution ch 15 and ch 16 evolution change in a population over time. does evolution mean man comes...
TRANSCRIPT
evolution
evolutionCh 15 and Ch 16
EVOLUTION
Change in a population over time.
Does Evolution mean Man comes from Monkey?
Charles Robert Darwin (1809 –1882)
•He was the individual who contributed more to our understanding of evolution than anyone was else.
•Grew up amidst wealth, comfort, and country sports
•Unimpressive student, thought of becoming a country physician (like his father) or a clergyman
•FYI…born on the same day as Abraham Lincoln
o Darwin served as naturalist aboard the H.M.S. Beagle on a British science expedition around the world
o Traveld from 1831-1836
o During his travels, Darwin made numerous observations and collected evidence that led him to propose a revolutionary hypothesis about the way of life changes over time.
HMS Voyage
Galapagos Islands
Darwin's Work
• When the ship would anchor Darwin would collect plant and animal specimens.
• He would study and observe these during travel time at sea.
• His curiosity and analytical nature were ultimately the keys to his success as a scientist.
Darwin's Work
• His primary focus was on how and why some animals and plant life were found in some specific areas but not others that had similar ecosystems..
• Why are there no rabbits in Australia? Why no kangaroos in England? Even though both habitats seemed perfect for them!
• He also began to study preserved remains of ancient organisms called fossils.
• Why had animals changed so drastically? Why had some changed very little?
Darwin's Work
• The Galapogos Islands was a port that influenced Darwin’s theories the most.
• Several islands that although close together had very differenct climates.
• Darwin worked primarily with tortoises, inguanas and finches.
• He made observations about these and other animals.
• He focused on how these animals were similar to other species but very unique to the islands.
INFLUENCES ON DARWIN
1. Essay of Population by Thomas Malthus – stated that human population increases faster than the food supply
2. Principles of Geology by Charles Lyell – stated that the earth is changing slowly and the forces that acted on it in the past are still at work
INFLUENCES ON DARWIN3. Jean-Baptiste Lamarck- He publishes his hypothesis of
the inheritance of acquired traits. The ideas are flawed, but he is one of the first to prose a mechanism explain how organism change over time.
o He thought that if an animal somehow altered a body structure, it would pass that change on to its offsprings. By example…if you lifted weights all the time you could pass on big muscles to your children.
INFLUENCES ON DARWIN
3. The discovery of fossils in South America which were similar in appearance to modern armadillos, but their size indicated they were a different species.
4. The Galapagos Island discoveries which showed the tortoises and finches were slightly different from island to island, i.e. variations.
INFLUENCES ON DARWIN
5.The use of selective breeding to create new varieties; Animal and plant breeders were able to create new organisms by selectively breeding parents for desired traits.
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Alfred Wallace
•About 20 yrs. after Darwin’s voyage, another young Englishman went on a venture to South America and wrote Darwin a letter outlining a theory he’d been developing
•Darwin was astonished, Wallace was describing the same natural selection that he had been contemplating for 20 years, but never had the nerve to publish
• 18 months later Darwin went on the write On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life in 1859
• The Origin of Species
Darwin's Conclusion
• In his book Darwin proposed the idea of natural selection to explain how species evolve.
• He then presented evidence that evolution has been taking place for millions of years and still continutes
• His work caused a sensation!!• But what did he actually say….
Darwin's Conclusion
• One of Darwin's important insights was that member of each species vary from one another in important ways.
• He focused on how variations of species matters…and in fact was used even then.
Artificial Selection
• Artificial selection- Breeding organisms with specific traits in order to produce offspring with identical traits.
• Humans have been doing this for years with both plants and animals.
Natural Selection
• Darwin was convinced that artificial selection worked in nature.
• Organisms produce more offspring than can survive. For example fish sometime lay millions of eggs
• In any population, individuals have variations. (size, color, speed)
• Individuals, with certain useful variations, such as speed or being able to avoid predators, will survive in their environment, passing those variations to the next generation.
• This is often referred to as Survival of the Fittest.
Natural Selection
• Overtime, offspring with certain variations make up most of the population and may look entirely different from their ancestors.
• Darwin proposed this idea of natural selection to explain how species change over time.
Natural Selection
• How is one moth better adapted than the other?
• Which one will survive and pass on its characteristics to its ofspring?
Natural Selection
•Mimicry!!
Natural Selection
•Mimicry!!
Natural Selection
•Camouflage!
Natural Selection
•Camouflage!
Divergent Evolution
• Divergent evolution, the pattern of evolution in which species that once were similar to an ancestral species diverge, or become increasingly distinct.
• Divergent evolution occurs when populations adapting to different environmental conditions changes becoming less alike as they adapt, eventually resulting in a new species.
Divergent Evolution
Divergent Evolution
Convergent Evolution
• A pattern of evolution in which distantly related organism evolve similar traits is called Convergent Evolution
• This occurs when unrelated species occupy similar environments indifferent parts of the world
• Because they share similar environmental pressures, they share similar pressures of natural selection.
Convergent Evolution
BIOLOGICAL EVOLUTION
• 1. The fossil record• 2. Anatomical evidence• 3. DNA similarities• 4. Embryological evidence
If Evolution is real…how can we prove it?
1. FOSSIL RECORDS• A fossil is any preserved part
or trace of an organism that once lived.
• Fossils may be formed when all or part of an organism is buried before it can be eaten or before it decays.
FOSSIL RECORDS• Fossils are often found in sedimentary
rock.• Sediments such as mud, silt, and sand
have deposited layers on top of one another and are subjected to great pressure.
FOSSIL RECORDS• Fossils are important because they
provide a record of early life and evolutionary history.
• Fossils are found throughout the world.
• While many fossil records are incomplete the sequences of evolution can become more clear.
Categories of Fossils
1. Imprints2. Molds3. Casts4. Petrified fossils5. Intact fossils
Imprint Fossils• An imprint fossil
forms when an object is pressed into mud, such as a leaf or insect.
• As it slowly dissolves, the mud surrounding it can harden and a space is left.
• A mold of the original object is formed, which fills with sediment and becomes a fossil.
Mold Fossils• Formed when hard
body parts such as teeth, shells, or bones form depressions, that are the size and shape of the body part, in the rock that are shaped like the organism’s part
• The part decomposed and leaves its specific shape because the sediment had already hardened around the original part
Cast Fossils• Formed when the
original materials decompose and the resulting mold is filled with another material.
• Now think of of something like a bone buried in sediment. The sediment hardens around the bone, and the bone rots away, creating a mold. Over time, minerals fill in the mold and harden, creating a cast of the bone, or a cast fossil.
Petrified Fossils
•Formed when the hard parts of an organism are gradually replaced by minerals
Intact Fossils
• Occur when an entire organism or part of an organism is preserved intact
• Smaller organisms may be trapped in amber, the sap of trees
• Larger animals have been trapped in tar or ice, which prevented their decay
2. Anatomical Similarities
• Many evolutionist study the structural similarities between organisms to determine their common ancestry.
Homologous Structures
• Structures with a common evolutionary origin are called Homologous Structure.
• Scientist view organisms with homologous structures to evolve from a common ancestor.
Homologous Structures
• Structures that are similar due to evolutionary origin, such as the forearm bones of humans, birds, porpoises, and elephants, are called homologous.
Homologous Structures
Analogous Structures
• The body parts of organisms that do NOT have a common evolutionary relationships origins but are similar in functions are called Analogous Structures.
Analogous Structures
Vestigial Structures
• Vestigial structures are remnants of once-useful structures that are no longer used.
• Limb bones can be found deep inside the body of a whale. This shows they once had use for legs.
• A snake also has the same type of hind limb bone remnants.
• Humans have a tail bone and an appendix that we do not use
• Horses have toe bones. • Examples like these can be found in other species as well.
Vestigial Structures
Embryological Differences
• An embryo is the earliest stage of growth and development of both plants and animals.
• Similarities among the young embryos suggest evolution from a distance common ancestor.
Embryological Differences
Embryological Differences
Embryological Differences
BioChemistry Differences
• Biochemistry also provides evidence for evolution.
• It reveals information between individuals and species.
• Comparisons of the DNA or RNA of different species produces biochemical evidence for evolution.
• The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.
evolution
• Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms.
evolution
evolution
• The millions of different species of plants, animals, and microorganisms that live on earth today are related by descent from common ancestors.
•Biological classifications are based on how organisms are related.
•Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships.
•Species is the most fundamental unit of classification.
evolution
EVOLUTION
Chapter 16
Variation and Gene Pool
• Lets review just a little.
• Mendel concluded that traits are controlled by alleles and you must have two for every trait.
• Some plants or animals have several different alleles in their gene pool that determine a specific trait. (more that 2 choices…like blood type. A, B, or O)
• Genetic Variation is studied in populations.
• Populations are a group of the same species that live together
• Because members of the same population interbreed they share a common group of genes.
• A Gene Pool consists of all genes, including all different alleles, that are present in a population.
• The Relative Frequency of an allele is the number of times that the allele occurs in a gene pool.
• Example: B (black fur) has a relative gene frequency of 40%, while b (white fur) has a relative gene frequency of 60%/
Variation and Gene Pool
Genetic Equilibrium
• Genetic Equilibrium- When the ratio of genes in a population remain constant over a long time.
• In genetic terms, evolution is any change in the relative frequency of alleles in a population.
• Remember..evolution does NOT happen to individuals but rather to populations
• Biologist can explain how variation is produced.
• The two main sources of genetic variation are:– Mutations.– Genetic shuffling that results from sexual
reproduction. Crossing Over of homologous pairs during meiosis.
Genetic Variations
Genetic Drift
• GENETIC DRIFT – When genes in a population change due to random chance. Disrupts genetic equilibrium. Usually seen in small populations.
• Example: Amish population in Pennsylvania. – Very small population.– When a young man had a mutation that caused
multiple fingers and short stature. It spread through the population and caused a change in the ratios.
• This is a condition where there is always balance in the frequency of genes in a population.
• It states that allele frequency in a population will remain constant unless one or more factors cause those frequencies to change. (add this)
• That means there is never any evolution. • It has a complicated equation.
Hardy Weinburg Equilibrium
• In order for the principal to remain constant 5 conditions must be meet
1. Random Mating
2. Large Population
3. No immigration or emigration
4. No Mutations
5. No Natural Selection
Hardy Weinburg Equilibrium
Process of Speciation
• We realized that these 5 conditions cannot always be met…but when do these lead to the formation of new species or speciation.
• The gene pools for two populations must become separated for them to become new species.
• When the members of two population cannot interbreed and produce fertile offspring Reproductive Isolation has occurred.
• Another type of isolating mechanism, Behavioral Isolation, occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.
Process of Speciation
• Geographic Isolation- Two populations are separated by geographic barriers such as rivers, mountains, or bodies of water.
• Temporal Isolation- Two or more species reproduce at different times.
Process of Speciation
• Natural selection can affect the distribution of phenotypes in any of three ways: directional selection, stabilizing selection, or disruptive selection
Natural Selection on Polygenic Traits
• Directional Selection- Favors the extreme…when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end.
Directional Selection
• Stabilizing Selection- favors the average; Individuals near the center of the curve have higher fitness than individuals at either end of the curve.
Stabilizing Selection
• Disruptive Selction- small or large are most successful; individuals at the upper and lower ends of the curve have higher fitness than those in the center.
Disruptive Selection
EVOLUTION IN
TENNESSEE HISTORY
The “Monkey Trial”(Tennessee v. John Scopes)
•The “Roaring 20’s”•Younger modernists no
longer asked whether society would approve their behavior
•Alcoholic prohibition• Jazz Age•Babe Ruth
1925• Worst tornadoes in U.S. history
• Hitler published Volume 1 of Mein Kampf; founds the SS
• Capone takes control of Chicago mob
• Pres. Calvin Coolidge takes the Oath of Offfice
• B.B. King, Malcom X, and Paul Newman are born
• In Tennessee…
The Butler Law• Feb. 1925, Gov. Austin Peay
signs “The Butler Law” (introduced by John Butler)
• making it unlawful “to teach any theory that denies the story of divine creation as taught by the Bible and to teach instead that man was descended from a lower order of animals”
Dayton, Tennessee
Above: downtown Dayton
Right: Rhea Co. High School
Robinson Drug Store• ACLU advertised to offer services to anyone willing to challenge the new law• local group of men saw an opportunity to put town on the map
John Scopes
• 24 yrs. old, from Illinois
• Part-time teacher & football coach
• Assigned readings on evolution from “Hunter’s Civic Biology”
The Case• Group at drug store (including
school superintendent) “summoned” Scopes
• Scopes showed the men the book he used (drug store also sold textbooks) and the assigned reading
• Asked Scopes if he would be willing to be part of test trial; Scopes agreed
The Case• Friends of Scopes agreed to prosecute,
local attorneys Herbert & Sue Hicks
• John Neal, law school dean from Knoxville drove to Dayton, volunteered to defend Scopes
• William Jennings Bryan heard about the case and went to assist prosecution
• Clarence Darrow heard about case and Bryan, so he went to assist defense
William Jennings Bryan• “The Great
Commoner”• 3-time Democratic
Pres. candidate• Sec. of State under
Woodrow Wilson• Had been leading
“crusade” to banish Darwin from American classrooms
Clarence Darrow
• Perhaps the most famous American lawyer of 20th century
• Well known for defending labor leaders and radicals, as well as high-profile murderers
• Leopold-Loeb; wealthy Chicago teens murdered schoolmate; Darrow helped them escape death penalty
• agnostic
TRIAL HIGHLIGHTS• Town had carnival-like atmosphere
• 6 blocks around courthouse became “Monkeysville” - - preachers, carnival games, live monkeys
• “watched” world-wide by radio and newspapers (WGN)
Quinn Ryan and WGN radio made history in Dayton. The Scopes trial was the first live broadcast of a trial in American history. It took a lot of money and planning to make it happen. WGN radio, just a year old at the time, spent $1,000 a day to broadcast the trial live. They rented AT&T cables stretching all the way from Chicago to Dayton, Tennessee. Their listeners in Chicago and beyond would have a front row seat at what was already being called "the trial of the century."
• Nearly 1,000 people (300 standing) packed courtroom on 1st day, July 10
Above: Rhea Co. courthouseTop right: Judge John T. Raulston
Right: judge & jury
http://www.pbs.org/wgbh/amex/monkeytrial/index.html
• The monkey trial also inspired music -- humorous songs like "You Can't Make a Monkey Out of Me," "Monkey Business Down in Tennessee" and serious folk songs. Tom Morgan, who lives in the hills above Dayton, performs songs inspired by the trial, like this song about John Scopes:
• Then to Dayton came a manWith his ideas new and grandAnd they said we came from monkeys long ago.But in teaching his beliefMr. Scopes found only griefFor they would not let their old religion go.
• You may find a new beliefIt will only bring you griefFor a house that's built on sand is sure to fall.And wherever you may turnThere's a lesson you will learnThat the old religion's better after all.
GOAL OF DEFENSE• Not win acquittal, but
rather to obtain a decleration by higher court, preferably U.S. Supreme Court, that laws forbidding teaching of evolution were unconstitutional
• L-R: Dudley Field Malone (international divorce attorney), Scopes, Darrow
From left: John Scopes, defense attorney Dr. John R. Neal, and George Rappleyea, manager of the Cumberland Coal and Iron Co. and one of the original organizers of events leading up to the trial.
GOAL OF PROSECUTION
• Uphold the Butler Law
• Moral victory for fundamentalism
• Right: Bryan
Trial Highlights• On Thurs. July
16, trial was moved outdoors due to heat, to accommodate crowds, and fear of courtroom on 2nd floor collapsing
• Crowd of 5,000
VERDICT
• Jury deliberated for 9 minutes
• GUILTY• Judge
Raulston fined Scopes $100
RESULTS• A year later, the Tennessee Supreme
Court reversed the decision on a technicality; the fine should have been set by the jury, not Judge Raulston
• Rather than send the case back for further action, TN Supreme Court dismissed the case
• Court commented, “Nothing is to be gained by prolonging the life of this bizarre case.”
RESULTS
• The Butler Act remained on the books for another 40 years, until the legislature repealed it in 1967.
• What happened in the 1960’s (related to science)?
What happened to Scopes?
• Left Dayton and became a petroleum engineer
• Died in 1970
William Jennings Bryan• Died 5 days after the
trial in Dayton• After eating an
enormous dinner, he lay down to take a nap and died in his sleep
• Darrow’s comment when told he died of a broken heart, “Broken heart nothing; he died of a busted belly.” Buried in Arlington Natl.Cemetery
Clarence Darrow
• Practiced law for another 13 years
• Died in Chicago in 1938, at age 80
• “Inherit the Wind” starring Spencer Tracy released in 1960 based on successful Broadway play received 4 academy nominations, however no Oscars were won
• Based on the trial with names changed