WHO INFLUENCED DARWIN’S THINKING Image from: AP BIOLOGY by Campbell and Reece Figure 22.2 Linnaeus (classification) Hutton (gradual geologic change) Lamarck (species can change) Malthus (population limits) Cuvier (fossils, extinction) Lyell (modern geology) Darwin (evolution, nutural selection) Mendel (inheritance) Wallace (evolution, natural selection) 1750 American RevolutionFrench Revolution U.S. Civil War Hutton proposes his theory of gradualism Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution Lyell publishes Principles of Geology. 1831–1836 Darwin travels around the world on HMS Beagle. Darwin begins his notebooks on the origin of species Darwin writes his essay on the origin of species Wallace sends his theory to Darwin The Origin of Species is published Mendel publishes inheritance papers. 1865
Aristotle- ( B.C.) Species are fixed (unchanging) BUT recognized similarities Image from: Arranged life forms on a scale of increasing complexity scala natura- “scale of nature”
Founder of TAXONOMY-1735 Science of grouping & naming Sought to discover order in the diversity of life “for the greater glory of God” Each creature was special- NO evolutionary link Devised classification system based on morphology (form and structure) ( ) Image from: Binomial Nomenclature: Naming system that gives organisms a two part scientific name- Genus species Still used today
LINNAEUS’S SYSTEM Nested hierarchy Taxon = classification unit to which organisms are assigned Ex: Panthera is a taxon at the genus level Mammalia is a taxon at the class level
Kidspiration by Riedell Image Sources: see end of show
Kingdom Phylum Class Order Family Genus Species Animalia Chordata Mammalia Carnivora Felidae Panthera leo Kids Prefer Cheese Over Fried Green Spinach Kings Play Chess On Fat Green Stools King Phillip Cried Oh For Goodness Sake!
GENUS = group of closely related species GENUS = Ursus (Includes many kinds of bears) SPECIES = unique to each kind of bear Ursus arctos Ursus maritimus Ursus americanis
Genus and species assignments provide 2 part scientific name Homo sapiens Image from:
Modern Taxonomy has added more Kingdoms AND more levels (DOMAINS) Linneaus only used 2 kingdoms (Plants & Animals) Domains are larger than Kingdoms and are based on the differences in ribosomal RNA
Ideas that shaped Darwin’s thinking: George Cuvier – Father of Paleontology Fossils are remains of extinct life forms “CATASTROPHISM” - boundaries represent floods, droughts, etc. that destroyed many species living at that time ANTI-EVOLUTONIST
Ideas that shaped Darwin’s thinking: 1795 –James Hutton “GRADUALISM” Profound changes can result from cumulative effect of slow but continuous processes Proposed that the Earth was shaped by geological forces occurring over very long periods of time, and is MILLIONS not THOUSANDS of years old.
Ideas that shaped Darwin’s thinking: 1833-Charles Lyell Incorporated Hutton’s ideas into “UNIFORMITARIANISM” Geological processes that shaped Earth are still operating at same rate. Darwin read his book on the Beagle voyage
Ideas that shaped Darwin’s thinking: Thomas Malthus (1798) wrote essay on population growth Human suffering (disease, famine, homelessness, and war) are consequences to human population increasing faster than food and other resources
Ideas that shaped Darwin’s thinking: Jean Baptiste Lamarck ( ) One of first scientists to recognize that living things changed over time and that all species were descended from other species Published his ideas about “Inheritance of Acquired Characteristics” the year Darwin was born
The male fiddler crab uses its front claw to attract mates and ward off predators. “USE or DISUSE” = Use it or lose it Through repeated use, the front claw becomes larger. The fiddler passes on this acquired characteristic to its offspring INHERITANCE OF ACQUIRED CHARACTERISTICS
What’s wrong with Lamarck’s hypothesis? Lamarck didn’t know about genes and how traits are inherited. Acquired traits are not passed on to offspring Or are they?... New field of EPIGENETICS is exploring this
What’s right with Lamarck’s hypothesis? Lamarck was first to develop a scientific hypothesis about evolution and recognize that organisms are adapted to their environment
Slide by Kim
In 1831, 22-year old Charles Darwin left England as naturalist aboard the HMS Beagle for 5 year voyage around the world. Mission: Chart the South American coastline Darwin noticed plants and animals were different from those he knew in Europe Wrote thousands of pages of observations and collected vast number of specimens Who Was Charles Darwin?
Who Was Charles Darwin? Although animals on Galapagos resemble species on the South American mainland, many species were found no where else in the world = ENDEMIC
DARWIN’S FINCHES Darwin collected 14 species of finches and hypothesized that the Galapagos had be colonized by organisms from the mainland that had then diversified on the various
After Darwin returned to England in 1836, he spent years examining specimens he brought back from voyage and filling notebooks with his ideas. He did not rush to publish his ideas because they disagreed with the fundamental scientific views of his day. In 1844 he wrote an essay describing his ideas and asked his wife to publish it if he died. Who Was Charles Darwin?
In 1858 Alfred Russel Wallace, another Naturalist working in the West Indies, wrote an essay describing his work that summarized the same ideas Darwin had been thinking about for 25 years!
Suddenly Darwin had incentive to publish the results of his work! In 1859 On the Origin of Species by Means of Natural Selection presented evidence and proposed a mechanism for evolution that he called NATURAL SELECTION
Isn’t evolution “just a theory”? In every day usage “theory” often refers to a hunch or a speculation. When people say, “I have a theory about what happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence. The formal scientific definition of “theory” is quite different from the every day meaning. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.
In Science a theory is a well supported, testable explanation of phenomena that have occurred in the natural world. Example: Cell theory Atomic theory Gravitational theory Isn’t evolution just a theory?
VOCAB ADAPTATION- Any inherited characteristic that increases an organism’s chance of survival
OVERPRODUCTION of OFFSPRING Capacity to over-reproduce seems characteristic of all species. WHAT IS DARWIN’S THEORY?
STRUGGLE FOR EXISTANCE means that members of each species must compete for food, space, and other resources.
WHAT IS DARWIN’S THEORY? GENETIC VARIATION is found naturally in all populations from
WHAT IS DARWIN’S THEORY? Some organisms in a population are less likely to survive.
VOCAB Ability of an individual to survive and reproduce in its specific environment = FITNESS
WHAT IS DARWIN’S THEORY? SURVIVAL OF THE FITTEST = Organisms which are better adapted to their environment tend to produce more offspring than organisms without those traits.
Over time, NATURAL SELECTION results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment. WHAT IS DARWIN’S THEORY? How Does Evolution Really Work?
POPULATIONS evolve NOT INDIVIDUALS. NATURAL SELECTION only works on heritable traits. A trait that is favorable in one environment may be useless or detrimental in another. IMPORTANT TO REMEMBER !
DESCENT WITH MODIFICATION suggests that each species has descended with changes from other species over time. This idea suggests that all living species are related to each other and that all species, living and extinct, share a common ancestor. WHAT IS DARWIN’S THEORY?
What do oranges, broccoli and Butterball turkeys have to do with EVOLUTION? (Answers to come in this slide show!) THINK ABOUT IT
EVIDENCE OF EVOLUTION: 1.________________ 2.________________ 3. _______________ 4. _______________ 5. _______________ 6. _________________ 7. _______________ Fossil record Geographic Distribution Anatomical homologies Embryology Molecular homologies Can see Natural selection happen Artificial selection
ARTIFICIAL SELECTION WORKS Nature provides the variation through mutation and sexual reproduction and humans select those traits that they find useful EX: We have selected for and bred cows to produce more milk, turkeys with more breast meat, etc.
WE’VE DONE IT WITH ANIMALS If humans can select for beneficial traits, why can’t nature? If artificial selection can achieve so much change in relatively short time, why can’t major changes happen over thousands of generations?
Now you know what broccoli and Butterball turkeys have to do with evolution! (Answers about oranges to come in this slide show!) THINK ABOUT IT
How Do We Know Evolution Happens? The Fossil Record provides evidence that organisms have changed over time.
If evolution has happened, we should be able to find evidence of evolution in the fossil record AND WE HAVE ! BBC Tiktaalik video
Lots of TRANSITIONAL FOSSILS have been found Scientific American; Dec 2005; Vol 293; p
TIK-TAALIK Intermediate between fish and early tetrapods Fins have basic wrist bones and simple fingers Earliest fish with a neck Discovered by Neil Shubin and Ted Daeschler in 2004
GEOGRAPHIC DISTRIBUTION = BIOGEOGRAPHY If Darwin’s theory is correct you would expect to find closely related yet different species living in a geographic region as they spread into nearby habitats and evolve. That’s EXACTLY what we do see!
GALAPAGOS FINCHES The beaks of Galapagos finches have adapted to eating a variety of foods
If Darwin’s theory is correct you would also expect to find different species living in far apart geographic regions but similar habitats becoming more alike as they adapt to similar environments. That’s EXACTLY what we do see!
BOTH LIVE IN FOREST ECOSYSTEMS Adapted to similar environments, but evolved independently from different ancestors. SUGAR GLIDER in Australia is a marsupial more closely related to Kangaroos than North American FLYING SQUIRRELS because its ancestors were marsupials.
Whales and sharks have a similar body design even though they are very different organisms (one is a fish; the other, a mammal) because they have independently adapted to living in a similar environment. = CONVERGENT EVOLUTION
TurtleAlligatorBirdMammal Ancient lobe-finned fish Section 15-3 EVOLUTION explains why certain characteristics in related species have an underlying similarity.
amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds, reptiles, and mammals, which lines the chorion and contains the fetus and the amniotic fluid
VESTIGIAL ORGANS Some homologous structures are vestigial and have no useful function even though they are still present. Examples: Hipbones and pelvis in whales and boa constrictors Cecum (appendix) in humans Skink legs
Most mammals have a pouch between their small and large intestine that contains bacteria to digest plants called a cecum. In humans the cecum is shrunken and unused. It is our appendix
EMBRYOLOGY Development of vertebrate embryos follows same path Image from:
Same groups of undifferentiated cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all evolved from a common ancestor. Image from:
Why grow a tail and then lose it? HUMAN EMBRYO has a tail at 4 weeks which disappears at 8 weeks Pharyngeal pouches become gills in fish, parts of throat/ears in humans
Nonfunctional legs in skinks Why would an organism possess organs without function? Why would an organism grow a part and then discard it? If organisms evolved from ancestors in which that part functioned, the gene code to make the part would still be there even though it doesn’t work. If the organ is not vital to survival, then natural selection would not cause its elimination.
MOLECULAR HOMOLOGIES All life forms share same genetic machinery (DNA & RNA) Universal genetic code Important genes share highly conserved sequences
Similarities in protein sequences suggests similarities in DNA Image from: Modern Biology by Holt, Rinehart, and Winston
Similarities in karyotypes suggest an evolutionary relationship Human: Chimpanzee: Middle School Life Science, published by Kendall/Hunt. Human- 46 chromosomesChimpanzee- 48 chromosomes
Even differences show relatedness Human: Chimpanzee: Middle School Life Science, published by Kendall/Hunt. Human- 46 chromosomes Chimpanzee- 48 chromosomes Chimpanzees have 2 smaller chromosome pairs we don’t have Humans have 1 larger chromosome pair (#2) they don’t have.
PSEUDOGENES are vestigial genes. EX: Humans have more than 99 different odor receptor genes, but more than 70% of them are nonfunctional.
Slide by Kim
EX: Changes in disease-causing microbes that produce new organisms and new diseases. _______ ___ __________________________ Can see Natural selection happen Bird flu Antibiotic-resistant tuberculosis HIV Why does evolution matter now?
Researchers have developed numerous drugs to combat HIV –But using these medications selects for viruses resistant to the drugs Graph from BIOLOGY by Campbell and Reece Patient No. 1 Patient No. 2 Patient No. 3 Percent of HIV resistant to 3TC Weeks