10.1: Early Ideas About EvolutionObjectives: Examine early ideas about evolution.

Identify three geological theories that influenced scientific debate over evolution.Warm Up: Have you ever heard the expression, “survival of fittest”? What doe sit suggest to you? With evolution, what is it that survives?Words to Know: Evolution, Species, Fossil, Catastrophism, Gradualism, Uniformitarianism.

Early Scientists Proposed Ideas about Evolution Evolution is the process of biological change by which descendants come to differ from their ancestors. The concept had been discussed for more than 100 years before Darwin proposed his theory.

Carolus Linnaeus (1700’s) Swedish botanist. Developed a classification system for all types of organisms known at the time. Did not believe that organisms were fixed and did not change. He proposed that they could change through hybridization. A Species is a group of organisms so similar to one another that they can reproduce and have fertile

offspring.Georges Louis Leclerc de Buffon (1700’s)

French naturalist in the 1700’s. He proposed that species shared ancestors instead of arising separately. He also suggested that the Earth was much older than the 6,000 years though by most.

Erasmus Darwin (1700’s) Charles Darwin’s grandfather. Respected English doctor and poet. Proposed all organisms evolved from a common ancestor and that more-complex forms of life arose from simpler

forms of life.Jean-Baptiste Lamarck (1800’s)

French Naturalist (1809) Proposed that all organisms evolved toward perfection and complexity. Proposed changes in an environment caused an organism’s behavior to change, leading to greater use or disuse of

a structure or organ. The structure would become larger or smaller as a result. The organism could then pass these changes on to its offspring. Called the Inheritance of Acquired characteristics. Ex: Giraffes had short necks They wanted to reach the leaves in the trees they stretched their necks long

enough to reach the leaves over time their necks stayed long they passed these traits onto their offspring. HE WAS WRONG!!!

What common ideas about organisms did these scientists share?Theories of Geologic Change Set the Stage for Darwin’s Theory

The early common view was that the Earth was about 6000 years old, and that neither the Earth or the species living on it had changed in that time.

Georges Cuvier (1800’s) Believed species could become extinct. Fossils are traces of organisms that existed in the past. He found that fossils in deeper layers of rock looked much different from those in the top layers. He explained is observations with the theory of Catastrophism. Catastrophism states that natural disasters such as floods and volcanic eruptions have happened often during

Earth’s long history. These event shape landforms and caused species to become extinct.

James Hutton (1700’s) Scottish Geologist. Proposed the idea of Gradualism which states that landforms resulted from slow changes over a long period of

time. Gradualism is a major component of evolutionary theory today.

Charles Lyell (1800’s)

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Published Principles of Geography in which he expanded on Hutton’s theory of gradualism into a theory of Uniformitarianism.

Uniformitarianism states that the geologic processes that shape Earth are uniform through time. This soon replaced catastrophism as the favored theory of geologic change.

What important concepts about Earth did Hutton and Lyell agree upon?

10.2: Darwin’s ObservationsObjectives: Describe how Darwin arrived at his idea about species variation.

Recognize how Darwin’s discoveries supported Lyell’s ancient-Earth theory.Warm Up: Thinking in terms of genetics, what is it about a cluster of islands that makes it a good laboratory for studying variation? What is it that the islands keep separate?Words to Know: The Origin of Species, Variation, Adaptation

Charles Darwin- the “Father of Evolution”• He went on a voyage from 1831 – 1836 on the H.M.S. Beagle as the ships naturalist. The voyage went around

the world and made a very important stop on the Galapagos Islands (a group of small islands off the west coast of South America). It was here that Darwin collected samples and observed the characteristics of many animals and plants varied noticeably among the different islands.

• Darwin began assembling his ideas upon his return from the voyage. However, he waited over twenty years (1859) before publishing his book On the Origin of Species. Because he was both stunned and disturbed by what he had observed/discovered as it challenged the fundamental scientific beliefs of that time (not to mention religious beliefs). Wallace, another scientist has similar ideas.

Darwin Observed Differences Among Island Species Darwin was struck by the variation in traits he observed on his travels. Variation is the difference in the physical traits of an individual from those of other individuals in the group to

which it belong. Ex: Different breeds of dogs. Darwin noted that the species found on one island looked different from those on nearby islands and that many of

the species looked different from those on the mainland. The most notable differences he discovered were on the Galapagos islands, an island chain off the coast of

Ecuador. Some difference seemed well suited to the animals’ environments and diets. Ex: Saddle-back Tortoises, which have long necks and legs, lived in areas with a lot of tall plants. Domed tortoises, with their shorter neck and legs, lived in wet areas rich with mosses and short

plants. Ex: He noticed finches with strong, thick beaks lived in areas with a lot of large, hard-shelled nuts,

while those species of finch with more delicate beaks were found where insects or fruit were widely available.

What he noticed was adaptations. An Adaptation is a feature that allows an organism to better survive in its environment. Adaptations can lead to genetic change in a population over time.

What adaptations did Darwin see in the finches of the Galapagos islands?Darwin Observed Fossil and Geologic Evidence Supporting an Ancient Earth.

Darwin found fossil evidence of species changing over time. He found large fossils in Argentina that looked like a larger version of current animals. He concluded that it must have taken a large amount of time in order for those changes to occur. Earth had to be more than 6000 years old. He also found marine fossils in the Andes mountains. He experienced an earthquake that showed him first hand how land underwater was forced above sea level.

What could account for fossils of marine organisms being found on top of modern-day mountain ranges?

10.3: Theory of Natural SelectionObjectives: Compare artificial selection to natural selection.

Examine the factors Darwin considered in forming his theory of natural selection. Summarize the four principles of natural selection.

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Warm Up: Why would Darwin turn to animal and plant breeders as a source of information in studying variation?Words to Know: Artificial Selection, Heritability, Natural Selection, List 4 Main Principles to the Theory of Natural Selection, Fitness

Several Key Insights Led to Darwin’s Ideas for Natural Selection.Artificial Selection

Artificial selection is the process by which humans change a species by breeding it for certain traits. Humans then determine which traits are favorable and then breed individuals that show those traits. Heritability is the ability of a trait to be passed down from one generation to the next. Darwin compared what he learned about breeding to his ideas on adaptation. He concluded that those traits that were not beneficial could be selected out. Darwin applied his views to the Theory of Natural Selection. Natural Selection is a mechanism by which individuals that have inherited beneficial adaptations produce more

offspring on average than do other individuals. In nature, the environment is the selecting agent.

Struggle for Survival Thomas Malthus proposed that resources such as food, water, and shelter were natural limits to population

growth. That is, human populations would grow geometrically if resources were unlimited. Instead disease and a limited food supply kept the population smaller. Darwin reasoned a similar situation took place in nature. Darwin proposed that these adaptations arose over many generations and called this process of evolution “descent

with modification”.How did Malthus’s economic theory influence Darwin?Natural Selection Explains how Evolution Can Occur

There are 4 main principles to the theory of natural selection:1. Variation The heritable differences that exist in every population are the basis for natural selection. The differences among individuals result from differences in the genetic material of the organisms, whether

inherited from a parent or resulting from a genetic mutation.2. Over-reproduction While having many offspring raises the chance that some will survive, it also result in competition between

offspring for resources.3. Adaptation Certain variations allow some individuals to survive better than others. More successful individuals are “naturally selected” to live longer and to produce more offspring that share those

adaptations for the environment.4. Descent with Modification Over time, natural selection will result in species with adaptations that re well suited for survival and reproduction

in an environment. More individuals will have the trait in every following generation, as long as the environmental conditions stay

the same. Examples: Jaguars 11,000 years ago, many species faced extinction. Jaguars faced a shortage of food due to climate change. Mammals were less available, but reptiles were

numerous. Jaguars with larger jaws and teeth were better able to survive and thus pass those traits onto their offspring. In Biology, the term Fitness is a measure of the ability to survive and produce more offspring relative to together

member of the population in a given environment.What are the similarities and differences between natural selection and artificial selection?Natural Selection Acts on Existing VariationChanging Environments

Ecologists observed an example of natural selection acting on existing traits within a population of medium ground finches on one of the Galapagos Islands.

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A drought in 1977 suddenly reduced the amount of small, soft seeds that the finches preferred. However there were still plenty of large, tough-shelled seeds. Because the large-beaked finches in the population were able to crack the large, tough seeds, they did not starve. The next year, they noticed a big increase in they number of large-beak hatchlings and most of the smaller beaked

birds died.Adaptations as Compromises

Not all adaptations result in individuals that are perfectly suited to their surroundings. Ex: Pandas have a structure in their wrist that acts like a thumb. The thumb is actually an enlarged wrist bone

that they use to help hold bamboo. It is not considered a true thumb though.Why is the panda’s “thumb” considered an adaptive compromise?

10.4: Evidence of EvolutionObjectives: Recognize the major sources of evidence for evolution.

Examine the pattern of features that reveal the history of a species.Warm Up: Why are the larger fossil organisms so different from the animals on Earth today?Words to Know: List all 9 Evidence of Evolution with definitions.

Evidence for Evolution in Darwin’s time Came from Several Sources1. Fossils

In the late 1700’s geologists wondered why certain types of fossils were found in some layers of rock and not others.

Later studies suggested that the fossil organisms in the bottom, or older, layers were more primitive than those in the upper or newer layers.

2. Biogeography Recall that Darwin saw that island plants and animals looked like, but were not identical to, species on the South

American continent... He hypothesized that at some point in the past, some individuals from the South American mainland had migrated

to the islands. Different ecosystems favored different traits and there speciation occurred. Biogeography is the study of the distribution of organisms around the world.

3. Comparative Embryology A study proposing a relationship between crabs, which can walk, and barnacles, which are fixed in one place as

adults, fascinated Darwin. He noticed that immature crabs and barnacles looked similar, but the adults were different. Comparative embryology now studies those similarities between organisms.

4. Homologous structures are features that are similar in structure but appear in different organisms and have different functions.

Ex: forelimbs of tetrapod vertebrates (human hand, bat wing and mole foot). The limbs look very similar even though they have different functions.

5.Analagous Structures are structures that perform a similar function but are not similar in origin. Ex: Bat wings and insect wings are both used for flight, but are NOT similar in structure.

Using the terms homologous and analogous, identify which group of structures provides evidence for a common ancestor? Explain.Structural Patterns are Clues to the History of a Species

Some organisms have structures or organs that seem to lack any useful function, or at least are no longer used for their original purpose.

6. Vestigial Structures are remnants of organs or structures that had a function in an early ancestor. Ex: Snakes share a common ancestor with lizards and dogs. The tiny pelvic bones and hind limbs in many

snakes are vestigial structures. Ex: The appendix in humans. It is a remnant of part of the large intestine and was used to help digest cellulose.

7.Comparative Biochemistry: Study of an organism on a biochemical level – for example: the similarities of amino acids in hemoglobin of the blood of various vertebrates.8.Genetic Evidence: for example: DNA similarities between people in certain parts of the world compared to people in other parts of the world.

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9.Direct Observations: observations of evolutionary changes that occur rapidly – for example: penicillin-resistant bacteriaWhat are vestigial structures, and how do they demonstrate common ancestry?10.5: Evolutionary Biology TodayObjectives: Summarize different types of evidence that support evolution.

Recognize the importance of evolution I unifying all branches of biological study.Warm Up: What was Darwin’s mechanism for explaining the diversity of life? Mendel’s mechanism?Words to Know: Paleontology

Fossils Provide a Record of Evolution Paleontology is the study of fossils or extinct organisms. The fossil record is not complete because most living things do not become fossils after they die. NO fossil evidence has ever contradicted evolution. Many transitional fossils have been discovered since Darwin’s work to help support his theories.

Why are fossils such as Basilosaurus isis considered transitional fossils?Molecular and Genetic Evidence Support Fossil and Anatomical Evidence.

Because all living things have DNA, they share the same genetic code and make most of the same proteins from the same 20 amino acids.

DNA or protein sequence comparisons can be used to show probable evolutionary relationships between species.DNA Sequence Analysis

The sequences of nucleotides in a gene change over time due to mutations. DNA sequence analysis depends on the fact that the more related two organisms are, the more similar their DNA

will be.Pseudogenes

Sequences of DNA nucleotides known as pseudogenes also provide evidence of evolution. Pseudogenes are like vestigial structures. They no longer function but still are carried with functional DNA.

Homeobox Genes Homeobox genes control the development of specific structures. These sequences are found in everything from fruit flies to humans.

Protein Comparisons Similarities among cell types across organisms can be revealed by comparing their proteins, a technique called

molecular fingerprinting. Cells from different species that have the same proteins most likely come from a common ancestor. Ex: light-sensitive cells from an ancient marine worm were found to closely resemble those of cells in the

vertebrate eye.How have protein comparisons helped determine ancestral relationships between organisms?Evolution Unites ALL Fields of Biology

Scientists are still actively studying evolution. The theory of evolution combined with genetics is sometimes called the Modern Synthesis of Evolutionary

Theory. The field of evolutionary biology is growing fast. The basic principles of evolution are used in fields such as medicine, geology, geography, chemistry, and ecology.

How can the idea of a common ancestor help us understand new diseases?Chapter 11: The Evolution of Populations11.1: Genetic Variation Within PopulationsObjectives: Describe the significance of genetic variation within a population.

Identify sources of genetic variation.Warm Up: What are the chances that you can put together a good team if just ten players try out? What about 30 players?Words to Know: Gene Pool, Allele Frequency, Phenotype, Gene, Allele, Meiosis, Gamete

Genetic Variation in a Population Increases the Chance that Some Individuals will Survive. Natural selection acts on different phenotypes in a population. In order to have different phenotypes (physical characteristic), a population must have genetic variation.

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A population with a lot of variation likely has a wide range of phenotypes. Genetic Variation is stored in a population’s Gene Pool – the combined alleles (genes) of all of the individuals in

a population. An Allele Frequency is a measure of how common a certain allele is in the population.

What is the relationship between allele frequencies and a gene pool?Genetic Variation Comes from Several Sources

There are two main sources of genetic variation:Mutation

A mutation is a random change in the DNA of a gene. This change can form a new allele. If these changes are in reproductive cells they can be passed on to new generations.

Recombination New allele combinations form in offspring through a process called recombination. Most recombination occurs during meiosis (producing 4 sex cells) in crossing over. This shuffling results in many new combinations of gametes (sex cells- sperm and egg)

Why aren’t mutations in nonreproductive cells sources of genetic variation?11.2: Natural Selection in PopulationsObjectives: Describe how natural selection acts on the distribution of traits in a population. Explain three ways natural selection can change the distribution of a trait in a population.Warm Up: When a drought caused more large- beaked ground finches to survive than small-beaked ground finches both of the same species, what was natural selection acting upon?

• Words to Know: Normal Distribution, Microevolution, List 3 Ways Natural Selection can change the Distribution of a trait (with definition) 1.Directional Selection, 2.Stabilizing Selection, 3.Disruptive Selection

Natural Selection Acts on Distributions of Traits If we were to line up a group of people on a football field by height, relatively few people would fall at the

extreme tall and short ends. A majority of people would fall in the middle range. When frequency is highest near the mean value (middle) and decreases towards each extreme, it is called a

Normal Distribution. The graphed result is a bell shaped curve.

What other types of data might follow a normal distribution?Natural Selection Can Change the Distribution of a Trait in One of Three Ways.

Microevolution is the observable change in the allele frequencies of a population over time. Microevolution occurs on a small scale, within a single population. This can result in one of three paths.

1. Directional Selection Directional Selection favors phenotypes at one extreme of a trait’s range. Ex: Drug Resistant Bacteria. This phenotype was selected Against when there were no antibiotics. Now that there are antibiotics, this phenotype is now more successful and selected for. Directional selections moves the curve on the graph left or right.

2. Stabilizing Selection In Stabilizing Selection the intermediate phenotype (median) is favored. Ex: Gall flies and their predators. Woodpeckers feed on larger gall fly larva. Parasitic wasps lay eggs on the smaller gall fly larva. Only the gall fly larva that are medium size have a chance to survive. Stabilizing Selection on a graph looks like Normal Selection.

3. Disruptive Selection Disruptive Selection occurs when both extreme phenotypes are favored, while individuals with intermediate

phenotypes are selected against by something in nature. Ex: Feather color in male lazuli buntings (a bird). Feathers range from dull brown to bright blue.

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Dull Brown and Bright blue feather buntings have a better chance of getting a mate than regular blue birds do.

The brown males are successful because the aggressive bright blue males do not see them as a threat. The regular blue birds are frequently attacked because they are seen as a threat. The graph in disruptive selection has two curves, one at each extreme.

If bluish brown coloring became advantageous for young males, what type of selection would likely occur in a lazuli bunting population?

11.3: Other Mechanisms of EvolutionObjectives: Explain how gene flow, genetic drift, and sexual selection can lead to the evolution of populations.Warm Up: What effect has immigration had on the genetic variation of the U.S. population?Words to Know: Gene Flow, Speciation, Genetic Drift, Bottleneck Effect, Founder Effect, Sexual Selection.

Gene Flow is the Movement of Alleles Between Populations. When an organism joins a new population and reproduces, its alleles become part of that population’s gene pool. At the same time its genes are removed from its previous population. The movement of alleles from one population to another is called Gene Flow. Gene flow increases genetic variation. A lack of gene flow can cause speciation.

How does gene flow affect neighboring populations?Genetic Drift is a Change in Allele Frequencies Due to Change

Genetic Drift is the change in allele frequencies due to chance. Two processes commonly cause populations to become small enough for genetic drift to occur.

Bottleneck Effect The Bottleneck Effect is genetic drift that occurs after an event greatly reduces the size of a population. Ex: Overhunting of northern elephant seals during the 1800’s. The population got reduced to about 20 seals that did not represent the genetic diversity of the original

population. Disasters such as earthquakes, floods, or fires may reduce the size of the pop. Drastically. The result is that a

small surviving pop. Is unlikely to be representative of the original pop.

Founder Effect The Founder Effect is genetic drift that occurs after a small number of individuals colonize a new area. The gene pools of these new populations are often very different from those of the larger population. Ex: The Amish of Lancaster Pennsylvania have a high rate of a rare form of Dwarfism. Because they are such a small community, this trait is common in the population.

Effects of Genetic Drift The population loses genetic variation. Less likely to have individuals to adapt. Alleles that are lethal can become more common.

What is genetic drift more likely to occur in smaller populations?Sexual Selection Occurs when Certain Traits Increase Mating Success

Mating has an important effect on the evolution of a population. Sexual Selection occurs when certain traits increase mating success. There are two types of sexual selection: 1. Intrasexual Selection involves competition among males. Whoever wins get the girl. 2. Intersexual Selection occurs when males display certain traits that attract the females, such as

peacock feathers.Male Irish elks, which are now extinct, had 12-foot-wide antlers. Describe how sexual selection could have caused such an exaggerated trait to evolve.11.3 Assessment p. 338 (1-5)

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Data Analysis: Patterns in Sexual Selection p. 33911.4: Hardy-Weinberg EquilibriumObjectives: Identify the conditions that define Hardy-Weinberg Equilibrium

Explain the predictive value of the Hardy-Weinberg equation.Warm Up: What does it mean to be in a state of equilibrium?Words to Know: Hardy-Weinberg Equilibrium.

Hardy-Weinberg equilibrium Describes Populations that are NOT Evolving Hardy and Weinberg showed that genotype frequencies in a population will stay the same over time as long as 5

conditions are met: 1. Must be a very Large Population (NO genetic drift). 2. No emigration or immigration (NO gene flow). 3. No mutations (NO new alleles). 4. Must have Random Mating (NO sexual selection allowed). 5. No Natural Selection (all traits must equally aid in survival). Real populations rarely meet all five requirements

How are models used by population biologists?The Hardy-Weinberg Equation is Used to predict Genotype Frequencies in a Population

For traits in a simple dominant-recessive systems, biologists can predict genotype frequencies using the Hardy-Weinberg equation.

P2 + 2pq + q2 = 1 p = frequency of the dominant allele q = frequency of the recessive allele. In Hardy-Weinberg Equilibrium, the equation ALWAYS equals 1. If the equation DOES NOT equal 1, evolution is occurring.

There are Five Factors that can Lead to Evolution 1. Genetic Drift – allele frequency can change due to chance alone. 2. Gene Flow – the movement of alleles from one place to another change the allele frequencies of the

population. 3. Mutation – new alleles can form through mutations, and these create the genetic variation needed for

evolution. 4. Sexual Selection – certain traits may improve mating success which cause an increase in that allele frequency. 5. Natural Selection – Certain traits may be an advantage for survival so alleles for these traits increase in

frequency.Why do real populations rarely reach Hardy-Weinberg equilibrium?11.5: Speciation Through IsolationObjectives: Explain how isolation of populations can lead to speciation.

Describe how populations can become isolated.Warm Up: How do we know that a three-foot-tall Irish wolfhound and a six-inch-high Chihuahua are the same species? At what point would the two breeds become separate species?Words to Know: List the 4 ways Speciation can Occur (with definition) 1. Reproductive Isolation 2. Behavioral Isolation 3. Geographic Isolation 4. Temporal Isolation.

The Isolation of Populations can lead to Speciation. If gene flow between two populations stops for any reason, the population are said to be isolated. As they adapt to their new environments, their gene pools may change.1. Reproductive Isolation occurs when member of different populations can no longer mate successfully with one

another. Speciation is the rise of two or more species from on existing species.

Why is reproductive isolation considered to be the final stage in speciation?Populations can become isolated in several ways.Behavioral Barriers

2. Behavioral Isolation is isolation caused by differences in courtship or mating behaviors. Ex: Fireflies. Male and female fireflies produce patterns of light flashes that attract only their own species.

Geographic Barriers3. Geographic Isolation involves physical barriers that divide a population into two or more groups.

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These can be rivers, mountains, and dried lakebeds. Ex: The isthmus of Panama separated many aquatic species that then evolved separately.

Temporal Barriers4. Temporal Isolation exists when timing prevents reproduction between populations. Some members of a population may show signs of courtship at different times. Ex: flowers bloom at different times of year.

What are the differences and similarities between behavioral isolation and temporal isolation?11.6: Patterns in EvolutionObjectives: Describe different types and rates of evolution.

Compare different types and rates of extinction.Warm Up: What are some different adaptations in plants and animals that seem to relate directly to features of their environment?Words to Know: Convergent Evolution, Divergent Evolution, Coevolution, Extinction, Punctuated Equilibrium, Adaptive Radiation

Evolution through Natural Selection is NOT Random. Natural Selection is NOT random. Individuals with traits that are better adapted for their environment have a better chance of surviving and

reproducing than do individuals without these traits. Natural selection always pushes traits in an advantageous direction. The environment controls the direction taken by natural selection.

Convergent Evolution Different species often must adapt to similar environments. Evolution toward similar characteristics in unrelated species is called Convergent Evolution. Ex: Shark and Dolphins are not related yet they have evolved similar tail fins.

Divergent Evolution When closely related species evolve in different directions, they become increasing different in Divergent

Evolution. Ex: Red Fox and Kit fox: though closely related they have developed different characteristics based on the

environment they live in.Are the shells of turtles and snails examples of convergent or divergent evolution? Explain.Species Can Shape each other over Time.Beneficial Relationships through Coevolution

Coevolution is the process in which two or more species evolve in response to changes in each other. Ex: Bees and flowers.

Evolutionary Arms Race Coevolution can also occur in competitive relationships. Ex: Many plants produce defense chemicals to discourage herbivores from eating them. Natural selection then favors the herbivores who can overcome the effect of the toxins. Ex: Thick shells and spines of murex snails are an adaptive response to predation by crabs. In turn, crabs have evolved strong claws.

What do you think will happen in future generations of crabs and snails?Species Can become Extinct

The elimination of a species from Earth is Extinction. There are two types of extinctions involved in evolution: 1. Background extinctions – occur continuously at a slow rate. (usually effect one or few

species in a small space). 2. Mass Extinctions – many species are destroyed suddenly. (ice age, meteors).

What are the differences and similarities between background extinctions and mass extinctions?Speciation Often Occurs in Patterns

There are repeating patterns in the history of life. The Theory of Punctuated Equilibrium states that episodes of speciation occur suddenly in geologic time and

are followed by long periods of little evolutionary change. This opposed Darwin’s theory of gradualism (slow, steady evolution). Adaptive Radiation the diversification of one ancestral species into many descendant species.

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Ex: Following the mass extinction at the end of the Cretaceous Period 65 million years ago, Adaptive radiation of mammals occurred.

The adaptive radiation of mammals followed the extinction of the dinosaurs. How do these events support the theory of punctuated equilibrium?Chapter 12: The History of Life12.1: The Fossil RecordObjectives: Describe the ways that fossils can form.

Identify the use of relative dating and absolute dating techniques.Warm Up: What are some of the ancient life forms you remember? Words to Know: Relative Dating, Radiometric Dating, Isotope, Half-Life, Radiocarbon Dating

Fossils Can form in Several Ways There are many processes that make fossils. 1. Permineralization – occurs when minerals carried by water are deposited around a hard

structure. 2. Natural Casts – form when flowing water removes all of the original bone or tissue, leaving just an

impression in sediment. This can be filled by minerals recreating the original shape of the organism. 3. Trace Fossils – record the activity of an organism. They include nests, burrows, imprint of leaves

and footprints. 4. Amber-preserved Fossils – organisms that become trapped in tree resin that hardens into amber

after the tree gets buried underground. 5. Preserved Remains – form when an entire organism becomes incased in material such as ice or

volcanic ash or immersed in bogs. Most fossils form in sedimentary rock, which is made by many layers of sediment or small rock particles. The environments for fossil creation are wetlands, bogs river mouths, lakebeds, and floodplains.

Why re so few complete fossils discovered?Radiometric Dating Provides an accurate Estimate of a Fossil’s Age.

Relative Dating estimates the time during which an organism lived by comparing the placement of fossils of the organism with the placement of fossils in other layers of rock.

Relative dating allows scientists to infer the order in which groups of species existed, but does NOT give actual ages.

Radiometric Dating is a technique that uses the natural decay rate of unstable isotopes found in material in order to calculate the age of that material.

Isotopes are atoms of an element that have the same number of protons, but a different number of neutrons. Ex: Carbon 14 is a common tool used for dating fossils. The decay rate of many radioactive isotopes has been measure and is expressed as the isotope’s half-life. A Half-Life is the amount of time it takes for half of the isotope in a sample to decay into a different element.

Radiocarbon Dating A fossil’s age can be estimated by comparing the ratio of stable isotope, such as Carbon 12, to the difference

between the amounts of Carbon 12 and Carbon 14 there will be.Determining Earth’s Age

Scientists have used radiometric dating to determine the age of Earth. Meteorites do not break down like rocks on Earth and are believed to have been on Earth from the beginning. Meteorites provide an unspoiled sample for radiometric dating. Scientists measure the Earth’s age at about 4.5 Billion years.

Why are meteorites helpful for determining the age of Earth?12.2: Geologic Time ScaleObjectives: Recognize the role of index fossils in determining the age of rocks.

Identify the major intervals of the geologic time scale.Warm Up: What are some reasons that species become extinct?Words to Know: Index Fossil, Geologic Time Scale, Era, Period, Epoch.

Index Fossils are Another tool to Determine the Age of Rock Layers Index fossils are fossils of organisms that existed only during specific spans of time over large geographic areas. Using index fossils for age estimates of rock layers is not a new idea (been around since the 1700’s).

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The best index fossils are common, easy to identify, found widely around the world, and only existed for a short period of time.

Ex: Fusulinids disappeared after a mass extinction and indicates that a rock layer must be between 248 million and 360 million years old.

Could a rock layer with fusulinid fossils be 100 million years old? Explain.The Geologic Time Scale Organizes Earth’s History.

The Geologic Time Scale is a representation of the history of Earth. It organizes Earth’s history by major changes or events that have occurred, using evidence from the fossil and

geologic records. The time scale is divided into units: 1. Eras – last tens to hundreds of millions of years and consist of two or more periods. 2. Periods – the most commonly used units of time on the geologic time scale, lasting tens of

millions of years. Each period is associated with a particular type of rock. 3. Epochs – the smallest units and last several million years.

Why do adaptive radiations often occur after mass extinctions?12.3: Origin of LifeObjectives: Describe the conditions on Earth Billions of years ago.

Summarize the main hypotheses of how life began on Earth.Warm Up: What scientific theories or ideas have you heard of that deal with the formation of Earth and the solar system?Words to Know: Nebula, What gases were on primitive Earth, Oparin and Haldane, Miller-Urey, Ribozyme

Earth was very Different Billions of Years ago. Most scientists agree on two points when it comes to the origin of the Earth: 1. Earth is billions of years old. 2. The conditions of the early planet and its atmosphere were very different from those of today. Today, the most widely accepted hypothesis of Earth’s origins suggests that the solar system was formed by a

condensing Nebula, a cloud of gas and dust in space. This idea is supported by research and suggests that the Earth is 4.6 Billion years old. Early Earth was violent and very hot for the first 700 million years. Hydrogen, Carbon Monoxide and Nitrogen gas were in the atmosphere. OXYGEN was NOT present. As the planet cooled, water vapor condensed and fell as rain that collected as pools. Once water was present, organic compounds could form.

Describe the nebular hypothesis of Earth’s origin.Several set of Hypotheses propose how Life Began on Earth:

1. Primordial Soup Model and the Bubble Model Hypothesis• In the 1920’s 2 Scientists Oparin and Haldane independently came to the same theory.• They theorize that life came from non-living matter under conditions that existed on primitive Earth, when the

atmosphere consisted of Gases- Hydrogen, Carbon Monoxide and Nitrogen gas.2. Organic Molecule Hypothesis

There are two general hypotheses about how life-supporting molecules appeared on early Earth. Miller-Urey Experiment tested this theory. In 1953, Miller and Urey designed an experiment to test a hypothesis first proposed in the 1920’s. Miller and Urey built a system to model early Earth. They demonstrated that organic compounds could be made by passing an electrical current through a

closed system of early gases. These gases were Methane, ammonia, hydrogen and water vapor.

3. Meteorite Hypothesis Analysis of a meteorite that fell in Australia in 1969 revealed that amino acids are present on

meteors. This evidence suggests that amino acids could have been present when Earth formed, or that these organic

molecules may have arrived on Earth through meteorite or asteroid impacts.

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Early Cell Structure Hypotheses4. Iron-Sulfide Hypothesis

Martin and Russel noted that hot iron sulfide rising from below the ocean floor combines with the cooler ocean water to form chimney-like structures made of many compartments.

They proposed that 4 billion years ago, biological molecules combined in the compartments of these chimneys.

5. Lipid Membrane Hypothesis Several scientists have proposed that the evolution of lipid membranes was a crucial step for the origin of

life. Lipid molecules spontaneously form membrane-enclosed spheres, call liposomes. In 1992, Harold Morowitz tested the idea that at some point liposomes were formed with a double, or

bilayer, lipid membrane. These liposomes could then form around a variety of organic molecules, such as amino acids, fatty acids,

sugars and nucleotides. The liposomes would act as membranes and would later give rise to the first true cells.

6. RNA as Early Genetic Material A hypothesis that has become much supported recently states that RNA, rather than DNA, was the genetic

material that stored information in living things on early Earth. In the 1980’s it was discovered that RNA can catalyze reactions. Ribozymes are RNA molecules that can catalyze specific chemical reactions. RNA can copy itself, chop itself into pieces, and from these pieces make even more RNA.

12.4: Early Single-Celled OrganismsObjectives: Recognize the role microbes played in shaping life on Earth.

Summarize the theory of Endosymbiosis. Relate increased biodiversity to sexual reproduction.

Warm Up: If you put photosynthetic organisms together with water what do you get?Words to Know: Cyanobacteria, Theory of Endosymbiosis

Microbes have Changed the Physical and Chemical Composition of Earth. Single-celled organisms changed Earth’s surface by depositing minerals. They changed the atmosphere by giving off oxygen as a by-product of photosynthesis. Before photosynthesis evolved, the first prokaryotes would have anaerobic, living without oxygen. Scientists have found evidence that photosynthetic life evolved more than 3.5 billion years ago. These fossils are of Cyanobacteria, which are bacteria that could carry out photosynthesis and release oxygen. Some cyanobacteria live in colonies. Higher oxygen levels in the atmosphere and ocean allowed the evolution of aerobic prokaryotes, which need

oxygen to live.How are stromatolites evidence of Earth’s early life?

Eukaryotic Cells may have Evolved through Endosymbiosis. The fossil record shows that eukaryotic organisms evolved 1.5 billion years ago. Eukaryotes have a nucleus and other membrane bound organelles. One hypothesis of eukaryotic evolution is the theory of endosymbiosis. Endosymbiosis is a relationship in which one organism lives within the body of another, and both benefit from

that relationship. The Theory of Endosymbiosis suggests that early mitochondria and chloroplasts were once simple prokaryotic

cells that were taken up by larger prokaryotes around 1.5 billion years ago. Instead of being digested, some of the smaller prokaryotes may have survived inside of the larger ones. If it the cell took in a prokaryote that acted like a mitochondria, the larger cell got the energy from ATP. If the cell took in a prokaryote that acted like a chloroplast, the larger cell got nutrients through photosynthesis. In exchange, the mitochondria and chloroplasts found a stable environment and nutrients. Support for this theory is based on the fact that both chloroplasts and mitochondria have their own DNA and are

the same size as prokaryotes.What evidence supports the theory of endosymbiosis?

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The Evolution of Sexual Reproduction led to Increased Diversity. The first prokaryotes and eukaryotes could only reproduce asexually. Sexual reproduction may have resulted in an increase in the rate of evolution by natural selection. Sexual reproduction creates more genetic variation. Sexual reproduction may have been the first step in the evolution of multicellular life.

How can mutations be beneficial to organisms?12.5: Radiation of Multicellular Life.Objectives: Summarize the key events in the Paleozoic, Mesozoic, and Cenozoic eras.

Identify how changes in environmental conditions affected the evolution and radiation of animal groups.

Warm Up: To what kind of habitat were dinosaurs and reptiles of the Mesozoic era adapted? Why aren’t there dinosaurs on Earth anymore?Words to Know: Paleozoic Era, Cambrian Explosion, Mesozoic Era, and Cenozoic Era.

Life Moved onto Land During the Paleozoic Era. One hypothesis suggests that it was an advantage for early one-celled organisms to increase in size by becoming

multicellular. Cells that cooperated could compete more effectively for limited resources. Multicellular organisms first appeared during the Paleozoic Era, which began 544 million years ago. Members of every major animal group evolved within only a few million years. The era ended 248 million years ago with a mass extinction. More than 90% of marine animal species and 70% of land animal species of that time became extinct. The earliest part of the Paleozoic Era, the Cambrian Period is often called the Cambrian Explosion. A huge diversity of animal species evolved. The middle of the Paleozoic Era was a time of great diversity as life moved onto land. The number and variety of plant groups greatly increased. Four-legged vertebrates, such as amphibians, became common.

Why is the Cambrian period also called the Cambrian Explosion?Reptiles Radiated During the Mesozoic Era

The Mesozoic Era began 248 million years ago and ended 65 million years ago. Called the Age of Reptiles because the dinosaurs roamed Earth during this era. The Mesozoic Era also feature birds and flowering plants. The oldest direct ancestor of mammals first appeared. The Mesozoic era is divided into three periods: Triassic, Jurassic and Cretaceous. Life took off slowly in the early Triassic. The Jurassic was marked by the dinosaurs. The peak in dinosaur diversity though is the Cretaceous. This era ended with the most famous mass extinction when it is believed a meteorite struck the Earth and blocked

the sun.How had life on earth changed from the beginning of the Paleozoic era to the end of the Mesozoic?Mammals Radiated during the Cenozoic Era.

The Cenozoic Era began 65 million years ago and continues today. It is divided into two periods: Tertiary and Quaternary. During the Tertiary Period, placental mammals and monotremes evolved and diversified. During the Tertiary period, birds, ray-finned fishes, and flowering plants also underwent dramatic radiations. The earliest ancestors of the modern humans evolved near the end of the Tertiary. However, homo sapiens anatomically modern humans, did not appear until about 100,000 years ago.

Why is the Cenozoic era sometimes referred to as the age of mammals?12.6: Primate Evolution Objectives: Examine the evolutionary relationships between humans and other primates.

Recognize the names and relative ages of extinct hominids. Summarize the events and forces that shaped human evolution.

Warm Up: What living primate species is the closest relative to our species?Words to Know: Primate, Prosimian, Anthropoid, Hominid, Bipedal

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Humans Share a Common Ancestor with other Primates The common ancestor of all primates probably arose before the mass extinction that closed the Cretaceous period

65 million years ago. Primates make up a category of mammals with flexible hands and feet, forward-looking eyes, and enlarged

brains relative to their body size. Primates also have arms that can rotate in a circle around their shoulder joint, and many primates have opposable

thumbs.Primate Evolution

The relationship of primate evolution forms a multi-branched tree. Prosimians are the oldest living primate group, and most are small and active at night. Ex: lemurs, lorises, and tarsiers. Anthropoids, the humanlike primates, are further subdivided into the New World monkeys, and hominoids. Many species have prehensile, or grasping, tails, that allows them to hang. They have larger brains and can manipulate objects. Hominids walk upright, have long lower limbs, thumbs that oppose, four other fingers and relatively large brains. This group includes ALL the human lineage, both modern and extinct.

Walking Upright Fossil discoveries have revealed that one trait had a huge impact on development – walking on 2 legs. Bipedal is an adjective that describes two-legged or upright walking.

What is another common animal that is bipedal?There are Many Fossils of Extinct Hominids

Most hominid species are classified into two group: the genus Australopithecus and the genus Homo The earliest member of the genus Homo was Homo habilis. (“handy man”). He lived 2.4-1.5 million years ago in what are now Kenya nd Tanzania. Made stone tools and more closely resembled the modern human brain in shape. H. neanderthalensis lived from 200,000 – 30,000 years ago, in Europe. Some evidence suggests that he existed with Homo sapiens (modern day humans).

What type of evidence could indicate that H. sapiens and H. neanderthalensis coexisted?Modern Humans Arose about 100,000 Years Ago.

Fossil evidence reveals that the first Homo sapiens (modern humans) appeared in Ethiopia.The Role of Culture

Human evolution is influenced by culture. Objects such as tools demonstrate a steady trend of increasing sophistication and usefulness.

Evolution of the Human Brain The human brain and skull size have both increased. These traits evolved much faster in human than in other hominids.

When might having an increasingly larger brain size no longer be a selective advantage?

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