Key Terms Biogenesis: All living things come from other living things Makes sense to us, but prior to the 17th century they had other ideas Spontaneous Generation: Living things could arise from nonliving things

Ideas from the Past Francesco Redi ( ): Observed fundamental forms of flies Found that they form from maggots Previously thought that flies spontaneously generated from rotten meat

Ideas from the Past During this time scientists using microscopes thought that microorganisms arose spontaneously from a “vital force” in the air Lazzaro Spallanzani ( ): text p. 280 Found that microorganisms come from other microorganisms Used broth: Control group & Experimental Group Many scientists did not accept his conclusions

Ideas from the Past Mid-1800s, controversy over spontaneous generation raged on Prize was offered to who ever could clear up the issue Louis Pasteur ( ): Answered Spallanzani’s experiment Used broth and curved-necked flask

Section 14.2

Earth’s History Formation of the Earth 5 billion years ago our solar system formed Age of the earth is more than 4 billion years

Radiometric Dating Determines the age of materials Use radioactive isotopes and their rate of decay Carbon 12 – STABLE Carbon 14 – UNSTABLE – decays at a certain rate Half-life = length of time it takes for one-half of any size sample of an isotope to decay to a stable form Measured against the amount of another stable substance (Carbon – 12) How? When an organism dies, its uptake of carbon stops Carbon-14 decay continues & Carbon-12 remains constant

Radiometric Dating & Half-Lives Carbon-14 = 5,730 years Uranium-235 = 704,000,000 years Potassium-40 = 1,250,000,000 years Uranium-238 = 4,500,000,000 years

Earth’s History Miller-Urey Experiment: tested the hypothesis Some molecules, including amino acids, did form However: now know that the early atmosphere was CO2, N, water vapor, & high O2…this prevents organic molecule production

First Cells Lack evidence, and can only make inferences Anaerobic, heterotrophic prokaryotes

First Eukaryotes Formed from prokaryotic cells that formed a mutually beneficial relationship Endosymbiosis: smaller aerobic prokaryote was engulfed by and began to live and reproduce inside of a larger, anaerobic prokaryote Later evolved into mitochondria and chloroplasts Evidence for this: replicate independently, circular DNA

Idea of Evolution Charles Darwin ( ) Traveled the world & noticed similarities & differences among many organisms Was convinced that organisms changed over time

Idea of Evolution Evolution: development of new types of organisms from preexisting types of organisms over time Heritable change in characteristics w/in a pop. from one generation to the next Darwin’s Theory Developed to explain how evolution occurs

Idea of Evolution Ideas of Darwin’s Time Species were permanent & unchanging Earth’s age only 1000’s of years old

Idea of Evolution Ideas About Geology Studied Strata, or rock layers Lower strata=older rock/ Higher strata=younger Different strata holds different organisms Georges Cuvier: Catastrophism, idea that sudden geologic catastrophes caused extinctions Charles Lyell: Uniformitarianism, processes that have changed the shape of the Earth’s surface in the past continue to work

Sedimentary Rock

Idea of Evolution Lamarck’s Ideas on Evolution Supported Darwin Idea that simple organisms could arise from nonliving matter Life developed from simple to complex Acquire traits during lifetime as a result of experience or behavior––> offspring Inheritance of acquired characteristics

Darwin’s Ideas Darwin & Alfred Wallace formed new theory on how evolution take’s place Presented to scientists in London after voyage around the Earth Published: On the Origin of Species by Means of Natural Selection Evidence for evolution Explain variety & distribution of organisms

Darwin’s Ideas Descent w/ Modification Species descend by reproduction from preexisting species Argued that ALL species had descended from only ONE or a FEW original kinds of life Example: Galapagos Islands Finches: 13 species descended from 1 common ancestor

Darwin’s Ideas Natural Selection 4 Main Parts of Darwin’s Reasoning Overproduction: More offspring produced than survive Thomas Malthus: environment limits populations Genetic Variation: Individuals have different traits Occasionally new traits may appear in a population Struggle to Survive: individuals compete to survive & reproduce Variations improve or reduce chances Adaptation = trait that makes an individual successful Differential Reproduction: Best adaptations = survival Adaptations become more frequent & populations differ

Darwin’s Ideas Natural Selection Accounts for descent w/ modification, as species become better adapted to different environments Nature changes species by selecting traits Fitness = measure of an individual’s hereditary contribution to the next generation Ability to survive and reproduce

Evidence of Evolution

15-2 Questions 1. The wing of a bat and the foreleg of an alligator are A. Analogous features. B. Homologous features C. Vestigial features. D. Artificially selected features. 2. Features that were useful to an ancestral organism but are not useful to a modern organisms that inherited them are said to be? A. Analogous. B. Homologous. C. Vestigial. D. Artificially selected.

15-2 Questions 3. According to the principle of superposition, the lowest layer in a cross section of a rock sequence A. Is the most recent B. Is the oldest C. Has the fewest fossils D. Contains only the fossils of burrowing animals 4. Which of the following is an impediment to understanding the evolutionary history of all organisms? A. Presence of vestigial structures B. Lack of transitional fossils C. Lack of homologous structures D. Presence of analogous structures 5. Fossils are A. Remains or traces of preexisting organisms B. All extinct organisms c. Deeply buried sedimentary rock strata D. From animals, not plants

The Fossil Record What is a fossil? Remains or traces of an organism that died long ago Formed under many different conditions Different organisms, different times & places Some of the most powerful evidence for evolution

The Fossil Record Age of Fossils Nicolaus Steno ( ) Principle of superposition: Rock strata at a location have not been disturbed, the lowest stratum was formed before the strata above it Geologists in 1700s & 1800s compared strata from different places & compared fossils found in different strata Put together the geologic time scale – timeline for the order of organisms

The Fossil Record Age of Fossils Fossil’s relative age: age compared to that of other fossils Determined by referring to the geologic time scale and to records of known fossils Absolute age: time since the formation of the rock Determined by radiometric dating Use relative and absolute dating to make the history of life on earth as precise as possible Fossil record is incomplete––not ALL organisms have left fossil evidence, only form by rare events

The Fossil Record The Distribution of Fossils 4 Inferences that can be made Different organisms lived at different times Today’s organisms are different from those in past Fossils found in adjacent layers are more similar than fossils found higher or lower in strata By comparing fossils from all over the world, we can infer when and where organisms existed

The Fossil Record Transitional Species Infer that species have differed in a gradual sequence of forms over time Based on Transitional Species, which have features that are intermediate b/w those of hypothesized ancestors and later descendent species Hypothesis of whale evolution is an example Other groups of organisms for which no transitional species have been found as fossils

Biogeography Study of the locations of organisms around the world Darwin & Wallace saw evidence of evolution in distribution of organisms Closely related organisms, but occupied different habitats Unrelated organisms, but had similar adaptations in similar environments that were far apart Example: Australian Mammals

Anatomy & Embryology Anatomy: study of the body structure of organisms Embryology: study of how organisms develop Descent w/ modification also predicts the findings of anatomy & embryology Bones in the forelimbs of humans, penguins, alligators, and bats Explanation: early ancestor shared by all these organisms had a forelimb w/ a similar bone structure

Anatomy & Embryology What happened? Generations passed, & diff. populations of descendents adapted to diff. envirn. Bones inherited from ancestors became modified for different tasks Homologous Structures: anatomical structures that occur in diff. species & that originated by heredity from the most recent common ancestor

Anatomy & Embryology Analogous Structures: closely related functions but do not derive from the same ancestral structure Ex: birds, bats and moths have wings, but they have very diff. underlying structures Wings evolved independently in these animals Vestigial Structures: structures that seem to serve no function, but that resemble structures w/ functional roles in related organisms Ex: human tailbone––animal tail; whale pelvic bone; human appendix

Anatomy & Embryology Development of Animal Embryos Some stages of vertebrate embryo development are very alike Similarities fade as development proceeds Possible answer––vertebrates share a common ancestor

Biological Molecules Organisms that share many traits––>more recent common ancestor than those that share fewer traits Darwin predicted this through anatomy Modern studies of biological molecules support this DNA & RNA are molecular basis for inheritance of traits DNA affects traits encoding the amino acid sequences that form proteins

Developing Theory Hypotheses & theories of evolution are continually being formed, challenged, and revised Many aspects are poorly understood & some observations remain unexplained Can never be “proven”, but is widely accepted & applied by scientists b/c it explains the broadest range of observations & makes useful predictions

Convergent Evolution

Divergent Evolution

Artificial Selection

Chapter 16

Genetic Equilibrium Variation of Traits w/in a Population Population Genetics: genetic study of evolution Microevolution: evolution at the genetic level, where a change in the collective genetic material of a population occurs Vary in observable traits

Genetic Equilibrium Variation arises from: Mutation Recombination Random pairing of gametes

Genetic Equilibrium Gene Pool: total genetic info available in a population Allele frequency: how often an allele will show up Certain allele number / total number of alleles Phenotype frequency: how often a phenotype shows Number of indiv. w/ phenotype / total number of indiv. in the population

Genetic Equilibrium Hardy-Weinberg Genetic Equilibrium Genotype frequencies in a population tend to remain the same from generation to generation UNLESS acted on by outside influences No mutations No individuals enter or leave the population Large population Random mating Natural selection does not occur

Disruption of Genetic Equilibrium Mutations Exposed to mutagens…increase mutations Creates new alleles for a trait Most are harmful…some beneficial

Disruption of Genetic Equilibrium Gene Flow Size of population needs to remain constant Immigration: movement into a pop. Emigration: movement out of a pop. Process of genes moving from one population to another Migration, dispersal of seeds/spores

Disruption of Genetic Equilibrium Genetic Drift Allele frequencies in a population change as a result of random events, or chance Mechanism for evolution of a new species Graph page 322

Disruption of Genetic Equilibrium Nonrandom Mating Sexual Selection Females choose the males based on certain traits Ex: birds Natural Selection Stabilizing Selection: average form of a trait have the highest fitness – medium fish Disruptive Selection: either extreme variation have greater fitness – very small/very large fish Directional Selection: more extreme form has greater fitness – very large fish

Question #1 Scientists have estimated the age of Earth to be a. about 10 billion years old. b. 100,000 years old. c. about 4.6 billion years old. d. about 4.6 million years old.

Question #2 What theory proposes a method for the evolution of photosynthetic eukaryotic organisms from prokaryotes? a) Chemosynthesis b) RNA replication c) radioactive decay d) endosymbiosis

Question #3 What is the idea developed by Charles Lyell stating that the geologic processes that shaped the Earth in the past continue to operate today? a) Catastrophism b) uniformitarianism c) inheritance of acquired characteristics d) descent with modification

Question #4 What is the process called by which different species evolve similar traits? a) adaptive radiation b) divergent evolution c) Coevolution d) convergent evolution

Question #5 Strong evidence for evolution comes from: a) phylogenetic trees. b) nuclear physics. c) the fossil record. d) works of philosophy.

Question #6 Eukaryotes may have evolved from: a) prokaryotes and engulfed small anaerobic prokaryotes. b) eukaryotes and engulfed small aerobic prokaryotes. c) cyanobacteria. d) none of the above.

Question #7 The evolutionary pattern illustrated by the finch species on the Galapagos Islands is an example of: a) coevolution. b) convergent evolution. c) divergent evolution. d) artificial selection.

Question #8 According to Darwin, evolution occurs a. In response to use or disuse of a characteristic b. Because of catastrophic geologic events c. By natural selection d. Within an individual’s lifetime

Question #9 The inference that evolution occurs gradually over time, a. Is not supported by any fossil evidence b. Is know as coevolution c. Is supported by many transitional forms in the fossil record d. Was proposed by Lyell

Question #10 Natural selection causes a. Changes in the environment b. Plants and animals to produce more offspring than can survive c. Changes in the frequency of certain adaptations in a population d. Genetic variation w/in populations

Question #11 The similarity in the body shape of a whale and of a fish is an example of a. Divergent evolution b. Convergent evolution c. Coevolution d. Vestigial structures

Question #12 Which of the following must exist in a population in order for natural selection to act? a. Genetic variation b. Overproduction c. Struggle to survive d. All of the above

Question #13 The scientist who proposed that individuals could pass on traits acquired during their lifetime was a. Lamarck b. Darwin c. Cuvier d. Lyell

Question #14 Which of the following is an acquired human characteristic? a. Number of bones in the hand b. Eye color c. The presence of a tailbone in humans d. Large muscles from weight lifting

Question #15 Which of the following is an impediment to understanding the evolutionary history of all organisms? a. Presence of vestigial structures b. Lack of transitional fossils c. Lack of homologous structures d. Presence of analogous structures