2Chapter 14 Vocabulary: 1. Fossil 2. Law of superposition 3. Radiometric dating4. Spontaneous generation5. Biogenesis6. endosymbiont theory
3SC.912.L.15.1Ch 14 Explain how the scientific theory of evolution is supported by the fossil record, comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary change.
4How Did Life Begin?The Earth formed about 4.6 billion years ago according to evidence obtained by radiometric dating.
5The age of the rocks and the fossils in them can be determined by the position and the amount of radioactive material in the rocks.Law of superposition
7½ lifeCompare it to the amount of time it takes for ½ of the carbonation in this bottle to leave… if we know how much time it takes, we could calculate the age of the bottle of soda based on how much carbonation was left in the container.
8Radiometric dating Gives a numerical age Places rocks and fossils in a time periodUses isotopes that decay at a constant rateUses isotopes that decay very slowly/ have a long ½ life.
9fossil A fossil is any preserved evidence of an organism. They form best in sedimentary rocksThey can be evidence or an organism, like foot prints or actual remains.
11What do fossils tell us and how do we know how old they are? The fossils in the bottom layer of rock are older
12Fossils show evidence of change in organisms, what types of organisms lived in each time period and that the complexity has increased over time.We know how old they are by relative positions and radiometric dating.
13Law of superposition! Youngest are on the top Oldest are on the bottom unless they have been disturbed!
14The geologic time scale is a model of the history of Earth showing the major events that occurred along the way.
15The longest units of time are eons and include the Precambrian time and Phanerozoic. The second largest unit of time is called an era and includes the Precambrian, Paleozoic, Mesozoic and Cenozoic.Each era can be divided into parts called periods and periods may be divided into the smallest parts called epochs.
16eon era period epoch age The history of the earth is broken up into a set of divisions for describing geologic time.the generally accepted divisions areeoneraperiodepochage
18PRECAMBRIAN SO LONG AGO… We know little due to deformation of rock layers.Large areas of Precambrian rock exposed are called shields. North America’s is called the Canadian shield.
19Precambrian life Fossils are rare Simple organisms with soft bodies Volcanic activity heat and pressure “erased” the fossil evidence.Stromatolites blue-green algae were common.
2014. Sum up what events occurred in Precambrian time 14. Sum up what events occurred in Precambrian time. Makes up almost 90% of Earth’s history, earth formed, first life appeared, autotrophs released oxygen into the atmosphere, Eukaryotes developed. At the end the first animals developed. Simple animals lived in the oceans
23Paleozoic Era: Life trilobites Brachiopods are marine animals that, upon first glance, look like clams
24Paleozoic Lots of fossils Trilobites index fossil Invertebrates, worms, jellyfish, snails vertebrates appearFish, amphibiansInsectsReptiles.
2515. Sum up the Paleozoic Era. Explosion of life 15. Sum up the Paleozoic Era. Explosion of life! Fish, land plants and insects appeared. First tetrapods or land vertebrates appeared reptiles arrived at the end of the Paleozoic
3417. Sum up the Mesozoic era. Mammals and dinosaurs appeared 17. Sum up the Mesozoic era. Mammals and dinosaurs appeared. Flowering plants, birds evolved from dinosaurs. The age of the reptiles
35Impact theory No dinosaurs found after the cretaceous- tertiary What happened?Possible impact hypothesis
3618. What makes scientists think a meteor hit the earth during the cretaceous time period? There is iridium found in the rock layers called the KT boundary. Iridium is found mostly in objects from space, like a meteor.
3719. How might a meteor impact cause a mass extinction 19. How might a meteor impact cause a mass extinction? The debris could cause global climate changes
3820. What other major geological event occurred during the Mesozoic era 20. What other major geological event occurred during the Mesozoic era? Pangaea the single land mass moved so that the continents were roughly in their current position by the end of the Mesozoic era.
49Hot, meteorites, volcanoes Hot, meteorites, volcanoes .Minerals in the oldest known rocks suggest that the earth’s atmosphere had little or no oxygen
50The primordial soup model and the bubble model propose explanations of the origin of the chemicals of life.Scientists think RNA formed before DNA or proteins formed.
51As the earth cooled from the liquid rock to the solid rock eventually the liquid water formed the oceans
52Francesco Redi performed a controlled experiment with flies and maggots to test this idea on the origin of life.He disproved spontaneous generation of maggots, by demonstrating absence of maggots on meat protected from flies.
53Spontaneous generation Some people believed that life could just develop from non life!
54In one of the first examples of a biological experiment with proper controls, Redi set up a series of flasks containing different meats, half of the flasks sealed, half open. He then repeated the experiment but, instead of sealing the flasks, covered half of them with gauze so that air could enter.
55Louis Pasteurdisproved this theory with pasteurization. He used the swan necked flask to do this
56biogenesisLife from life!Replaced the spontaneous generation idea!
57Scientists think that the first cells may have developed from microspheres. The development of heredity made it possible for organisms to pass traits to subsequent generations.
58Primordial soup Model of life or Chemical evolution Energy from sunlight and lightning allowed the first organic molecules to form.
59Miller and UreyOparin thought the Earth’s early atmosphere provided what was needed to make the first organic molecules.Who did an experiment to try to replicate the conditions of the early earth? Miller and Urey.6. What did they find in the mixture that they formed? Amino acids.
61Why did Miller and Urey do their experiment? To try to figure out how life might have originated on earth!Did they produce organic molecules from inorganic molecules?Yes!Did they produce life from non life?NO!
627. What do scientists believe was the first genetic code? RNA
63Order of eventsabiotic synthesis of amino acids and other organic molecules /synthesis of proteins /development of a genetic code /evolution of cells
64Complex Organisms Developed Prokaryotes are the oldest organisms and are divided into two groups, archaebacteria and eubacteria or Bacteria and ArcheaProkaryotes likely gave rise to eukaryotes through the process of endosymbiosis.
658. What evidence is there of life 3. 8 billion years ago on Earth 8. What evidence is there of life 3.8 billion years ago on Earth? Fossilized microbes in volcanic rock.9. What type of organisms were the first? Prokaryotic /archea
66Endosymbiont Theory Endosymbiosis Lynn Margulis proposed this idea to explain the origin or organelles such as the mitochondria and chloroplasts
68Mitochondria and chloroplasts are thought to have evolved through endosymbiosis. Multicellularity arose many times and resulted in many different groups of multicellular organisms.
6913. What is the endosymbiotic theory 13. What is the endosymbiotic theory? The ancestors of eukaryotic cells lived together in association with prokaryotic cells.
70Extinctions influenced the evolution of the species alive today Extinctions influenced the evolution of the species alive today. After mass extinctions there were increases in biodiversity that can be observed in the fossil records.These mark the changes from one era to the next!The new niches opened up by the extinction provided opportunities for the surviving species to expand and evolve!
71Life Invaded the LandAncient cyanobacteria produced oxygen, some of which became ozone. Ozone enabled organisms to live on land..
7310. Eventually cyanobacteria could perform photosynthesis and release what? Oxygen 11. With a layer of ozone in place over the earth, what type of organisms evolved next? Eukaryotic12. How long ago did eukaryotic cells evolve? 1.8 billion years
74Plants and fungi formed mycorrhizae and were the first multicellular organisms to live on land
78The first vertebrates to invade dry land were amphibians. tetrapods The extinction of many reptile species enabled birds and mammals to become the dominant vertebrates on land.
79The movement of the continents on the surface of the Earth has contributed to the geographic distribution of some species.
80The fossil record also provides an amazing amount of evidence concerning common ancestors. Fossilized remains of invertebrates (animals without an internal skeleton), vertebrates, and plants appear in the strata or layers of Earth's surface in the same order that the complexities of their anatomy suggest.
81The more evolutionarily distant organisms lie deeper, in the older layers, beneath the remains of the more recent organisms.Geologists are able to date rock strata with reasonable accuracy, and the age of a layer always correlates with the fossils discovered there.In other words, there would never be a stratum dating back 400 million years that contained fossils of mastodons, which evolved much later.
863. EvolutionCHANGE!Biologists use it to mean cumulative changes in organisms through time.Like the bacteria that as a population becomes resistant to the antibiotics….
87artificial selectionThe process of directed breeding to produce offspring with desired traits.
88Natural selection.Nature selects the traits best suited for survival based on the following criteria:1. organisms in a population are naturally different from each other.2. the differences are inherited from their parents and can be passed on to their offspring.3. Populations tend to overproduce, there is not enough food or resources for the number produced leading to competition4. Some of the variations provide an advantage to the ability to survive and reproduce more offspring compared to the others with out that variation.
89Natural selection is a way in which evolution can take place. It is an attempt to explain how the changes Darwin observed might have happened.Wallace and Darwin both wrote essays with almost the exact same conclusion.
90The Theory of Evolution by Natural Selection ● Based on years of observations during a trip Darwin wrote a book On the Origin of Species.
985. Vestigial structureStructures that are reduced in size and form, but are similar in structure to functioning structures in other organisms.Examples:
99Though their ancestors ceased to walk on four legs many millions of years ago, snakes still possess vestigial hind limbs as well as reduced hip and thigh bones.
1006. Analogous structure Superficially similar features. Such as wings of an insect and of a bird…no relationship in the structure exists!
101camouflageThe adaptation that allows an organism to blend in with their environment.
1028. MimicryOne species evolves to look like another.
1039. FitnessA measure of the relative contribution that an individual trait makes to the next generation.This is usually the number of reproductively viable offspring an organism makes in the next generation.Better fit means better able to survive and reproduce
104● Darwin proposed that natural selection favors individuals that are best able to survive and reproduce.● Under certain conditions, change within a species can lead to new species.
105Evidence of Evolution● Evidence of orderly change can be seen when fossils are arranged according to their age.● ● Similarities of structures in different vertebrates provide evidence that all vertebrates share a common ancestor.
106In some cases widely divergent organisms possess a common structure, adapted to their individual needs over countless generations yet reflective of a shared ancestor. A fascinating example of this is the pentadactyl limb, a five-digit appendage common to mammals and found, in modified form, among birds. The cat's paw, the dolphin's flipper, the bat's wing, and the human hand are all versions of the same original, an indication of a common four-footed ancestor that likewise had limbs with five digits at the end.
107The embryonic forms of animals also reflect common traits and shared evolutionary forebears. This is why most mammals look remarkably similar in early stages of development. In some cases animals in fetal form will manifest vestigial features reflective of what were once functional traits of their ancestors.
108Differences in amino acid sequences and DNA sequences are greater between species that are more distantly related than between species that are more closely related.
109Comparing DNA sequences is one way Biologists determine how closely related organisms are.
117Hardy Weinberg requirements No genetic drift,No gene flowno mutationsMating must be randomNo natural selection
11811. Genetic driftAny change in the allelic frequencies in a population that results from chance.Types of genetic driftFounder effect: an extreme example of genetic drift when a small group moves away from a population. The group carries a small sample of the larger groups alleles, if variations are present, they may start to show up more in the small sub set.Bottleneck: when a population declines to a very small number and then rebounds the genes in the small group are what are carried on.
119Genetic driftIt will randomly alter gene pools of small populations more than large ones!!!!
120Think Amish ! Extra fingers or toes! Polydactyly -- extra fingers or sometimes toes -- is one symptom of Ellis-van Creveld syndrome. The syndrome is commonly found among the Old Order Amish of Pennsylvania, a population that experiences the "founder effect." Genetically inherited diseases like Ellis-van Creveld are more concentrated among the Amish because they marry within their own community, which prevents new genetic variation from entering the population. Children are therefore more likely to inherit two copies of the particular recessive genes that lead to genetic disease.
121Gene flowOnly isolated populations have no gene flow! This is very rare.
122Non random MatingMost organism mate with others near them. This can lead to inbreeding and can change the allelic frequencies.
123mutationsMost mutations are random and will cause changes in the allelic frequencies so this will keep a population out of genetic equilibrium!
124Natural selection is one mechanism of evolution. How it happens…
125Natural selectionMost organisms are not equally adapted to their environment, so natural selection will occur.There are different types of Natural selection.Stabilizing selection is the most common and removes the extremes.Directional selection selects one phenotype over another.
126Disruptive selection selects the extreme. Sexual selection is based on the ability to attract a mate.
127Examples of Evolution● Individuals that have traits that enable them to survive in a given environment can reproduce and pass those traits to their offspring.●The moth example is directional selection
129Industrial Melanism and the Pepper Moth Both natural selection and mutation play a role in industrial melanism, a phenomenon whereby the processes of evolution can be witnessed within the scale of a human lifetime.Industrial melanism is the high level of occurrence of dark, or melanic, individuals from a particular species (usually insects) within a geographic region noted for its high levels of dark-colored industrial pollution.
130With so much pollution in the air, trees tend to be darkened, and thus a dark moth stands a much greater chance of surviving, because predators will be less able to see it.At the same time, there is a mutation that produces dark-colored moths, and in this particular situation, these melanic varieties are selected naturally.On the other hand, in a relatively unpolluted region, the lighter-colored individuals of the same species tend to have the advantage, and therefore natural selection does not favor the mutation.
131The best-known example of industrial melanism occurred in a species known as the pepper moth, or Biston betularia, which usually lives on trees covered with lichen.Prior to the beginnings of the Industrial Revolution in England during the late eighteenth century, the proportion of light-colored pepper moths was much higher than that of dark-colored ones, both of which were members of the same species differentiated only by appearance
133As the Industrial Revolution got into full swing during the 1800s, factory smokestacks put so much soot into the air in some parts of England that it killed the lichen on the trees, and by the 1950s, most pepper moths were dark-colored.It was at that point that Bernard Kettlewell ( ), a British geneticist and entomologist (a scientist who studies insects), formed the hypothesis that the pepper moths' coloration protected them from predators, namely birds.
134Kettlewell therefore reasoned that, before pollution appeared in mass quantities, light-colored moths had been the ones best equipped to protect themselves because they were camouflaged against the lichen on the trees.After the beginnings of the Industrial Revolution, however, the presence of soot on the trees meant that light-colored moths would stand out, and therefore it was best for a moth to be dark in color.This in turn meant that natural selection had favored the dark moths
135In making his hypothesis, Kettlewell predicted that he would find more dark moths than light moths in polluted areas, and more light than dark ones in places that were unpolluted by factory soot.As it turned out, dark moths outnumbered light moths two-to-one in industrialized areas, while the ratios were reversed in unpolluted regions, confirming his predictions.
137To further test his hypothesis, Kettlewell set up hidden cameras pointed at trees in both polluted and unpolluted areas.The resulting films showed birds preying on light moths in the polluted region, and dark moths in the unpolluted one—again, fitting Kettlewell's predictions
140Types of selection other than Natural selection●
141adaptive radiationOne common ancestor gives rise to many species based on the environments. A good example would be the birds of the Galapagos Islands
142allopatric speciation In allopatric speciation, an ancestral population is geographically isolated, resulting in the evolution of separate species largely due to genetic drift. The additive effect of differences due to genetic drift can eventually result in behavioral isolation (refusal to mate) if the two groups were to meet again in the future. If they refused to interbreed, they would be considered separate species.
143Allopatric speciation A physical barrier divides one population into two or more populations
145when the Colorado River cut open the Grand Canyon, separating groups of squirrels who lived in the high-altitude pine forest. Eventually, populations ceased to interbreed, and today the Kaibab squirrel of the northern rim and the Abert squirrel of the south are separate species.
146sympatric speciationSympatric speciation involves speciation without a geographic barrier. One example of sympatric speciation is polyploidy, found more often in plants. Polyploidy occurs when a failure of meiosis increases the number of chromosome sets to 3N or more. At this point, the two "cousin" species can no longer mate with each other.
147directional selection, When one extreme phenotype is favored by natural selection, the distribution of the phenotype shifts in that direction.
149disruptive selectionSelection that favors the extremes of a population trait is DISRUPTIVE SELECTION. An example of this would be the size of clams. Predators find it harder to locate smaller clams and are unable to pry open larger clams. Predators favor clams of a medium size.
150genetic driftGenetic drift - random events due to small population size. Random events have little effect on large populations. Consider a population of 1 million almond trees with a frequency of r at 10%. If a severe ice storm wiped out half, leaving 500,000, it is very likely that the r allele would still be present in the population. However, suppose the initial population size of almond trees were 10 (with the same frequency of r at 10%). It is likely that the same ice storm could wipe the r allele out of the small population.
151founder effect and bottle neck Reduction in genetic variability makes these species vulnerable to disease and environmental changes!
152gradualism Gradualism is the slow change from one form to another. The opposite of gradualism is:Punctuated equilibrium which implies long periods without appreciable change and short periods of rapid evolution. Volcanic eruptions and meteor impacts affecting evolution on Earth could cause these changes.
154sexual selectionSexual selection may produce elaborate characteristics, for example the feathers of a male peacock or the ornamental plumage of male birds of paradise. Other organisms such as elephant seals fight over territories.
155stabilizing selection Stabilizing selection occurs when the intermediate, or most common, phenotype is favored. This type of selection tends to narrow the variation in the phenotype over time. This is the most common type of selection because it is associated with the adaptation of an organism to the environment.
156Speciation begins as a population adapts to its environment. ● Reproductive isolation keeps newly forming species from breeding with one another.
157Speciation:the formation of a new species by splitting of an existing species.
159Write the term or phrase that best completes each statement Write the term or phrase that best completes each statement. Use these choices: adaptive radiation, allopatric speciation, directional selection, disruptive selection, founder effect, genetic drift, gradualism, sexual selection, stabilizing selection, sympatric speciation________________________ is a change in allelic frequencies in a population that is due to chance.________________________ removed individuals with average trait values, creating two populations with extreme traits.The most common form of selection, ___________________________, removes organisms with extreme expressions of a trait.When a small sample of the main population settles in a location separated from the main populations, the ___________________________ can occur.
160In _________________________, a species evolves into a new species without any barriers that separate the populations.__________________________ will shift populations toward a beneficial but extreme trait value.In __________________________, a population is divided by a barrier, each population evolves separately, and eventually the two populations cannot successful interbreed.__________________________ is a change in the size or frequency of a trait based on competition for mates.One species will sometimes diversify in a relatively short time into a number of different species in a pattern called ________________________________.The idea that evolution occurred in small steps over millions of years in a speciation model is currently known as ________________________________.
161Write the term or phrase that best completes each statement Write the term or phrase that best completes each statement. Use these choices: adaptive radiation, allopatric speciation, directional selection, disruptive selection, founder effect, genetic drift, gradualism, sexual selection, stabilizing selection, sympatric speciationgenetic drift is a change in allelic frequencies in a population that is due to chance.disruptive selection removed individuals with average trait values, creating two populations with extreme traits.The most common form of selection, stabilizing selection, removes organisms with extreme expressions of a trait.When a small sample of the main population settles in a location separated from the main populations, the founder effect can occur.In sympatric speciation , a species evolves into a new species without any barriers that separate the populations.directional selection will shift populations toward a beneficial but extreme trait value.In allopatric speciation , a population is divided by a barrier, each population evolves separately, and eventually the two populations cannot successful interbreed.sexual selection is a change in the size or frequency of a trait based on competition for mates.One species will sometimes diversify in a relatively short time into a number of different species in a pattern called adaptive radiation.The idea that evolution occurred in small steps over millions of years in a speciation model is currently known as gradualism .