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Key TermsBiogenesis:
All living things come from other living thingsMakes sense to us, but prior to the 17th
century they had other ideasSpontaneous Generation:
Living things could arise from nonliving things
Ideas from the PastFrancesco Redi (1626-1697):
Observed fundamental forms of flies Found that they form from maggots
Previously thought that flies spontaneously generated from rotten meat
Ideas from the PastDuring this time scientists using microscopes
thought that microorganisms arose spontaneously from a “vital force” in the air
Lazzaro Spallanzani (1729-1799): text p. 280Found that microorganisms come from other
microorganismsUsed broth: Control group & Experimental
GroupMany scientists did not accept his conclusions
Ideas from the PastMid-1800s, controversy over spontaneous
generation raged onPrize was offered to who ever could clear up
the issueLouis Pasteur (1822-1895):
Answered Spallanzani’s experimentUsed broth and curved-necked flask
Section 14.2
Earth’s HistoryFormation of the Earth
5 billion years ago our solar system formedAge of the earth is more than 4 billion years
Radiometric DatingDetermines the age of materialsUse radioactive isotopes and their rate of decay
Carbon 12 – STABLECarbon 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-LivesCarbon-14 = 5,730 yearsUranium-235 = 704,000,000 yearsPotassium-40 = 1,250,000,000 yearsUranium-238 = 4,500,000,000 years
Earth’s HistoryMiller-Urey Experiment: tested the
hypothesisSome 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 CellsLack evidence, and can only make
inferencesAnaerobic, heterotrophic prokaryotes
First EukaryotesFormed from prokaryotic cells that
formed a mutually beneficial relationshipEndosymbiosis: smaller aerobic
prokaryote was engulfed by and began to live and reproduce inside of a larger, anaerobic prokaryoteLater evolved into mitochondria and
chloroplastsEvidence for this: replicate independently,
circular DNA
Idea of EvolutionCharles Darwin (1809-1882)
Traveled the world & noticed similarities & differences among many organisms
Was convinced that organisms changed over time
Idea of EvolutionEvolution: development of new types of
organisms from preexisting types of organisms over timeHeritable change in characteristics w/in a pop.
from one generation to the nextDarwin’s Theory
Developed to explain how evolution occurs
Idea of EvolutionIdeas of Darwin’s Time
Species were permanent & unchangingEarth’s age only 1000’s of years old
Idea of EvolutionIdeas 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 EvolutionLamarck’s Ideas on Evolution
Supported DarwinIdea that simple organisms could arise from
nonliving matterLife developed from simple to complexAcquire traits during lifetime as a result of
experience or behavior––> offspring Inheritance of acquired characteristics
Darwin’s IdeasDarwin & Alfred Wallace formed new theory
on how evolution take’s placePresented to scientists in London after voyage
around the EarthPublished: On the Origin of Species by Means
of Natural Selection Evidence for evolution Explain variety & distribution of organisms
Darwin’s IdeasDescent 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 IdeasNatural 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 IdeasNatural Selection
Accounts for descent w/ modification, as species become better adapted to different environments
Nature changes species by selecting traitsFitness = measure of an individual’s hereditary
contribution to the next generation Ability to survive and reproduce
Evidence of Evolution
15-2 Questions1. The wing of a bat and the foreleg of an alligator are
A. Analogous features.B. Homologous featuresC. 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 Questions3. According to the principle of superposition, the lowest layer in a
cross section of a rock sequence A. Is the most recentB. Is the oldestC. Has the fewest fossilsD. 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 structuresB. Lack of transitional fossilsC. Lack of homologous structuresD. Presence of analogous structures
5. Fossils areA. Remains or traces of preexisting organisms B. All extinct organismsc. Deeply buried sedimentary rock strata D. From animals,
not plants
The Fossil RecordWhat is a fossil?
Remains or traces of an organism that died long ago
Formed under many different conditionsDifferent organisms, different times & placesSome of the most powerful evidence for
evolution
The Fossil RecordAge of Fossils
Nicolaus Steno (1638-1686) Principle of superposition: Rock strata at a location have not been disturbed, the
lowest stratum was formed before the strata above itGeologists 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 RecordAge 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 fossilsAbsolute 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 RecordThe 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 RecordTransitional 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
BiogeographyStudy of the locations of organisms around
the worldDarwin & 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 & EmbryologyAnatomy: study of the body structure of
organismsEmbryology: study of how organisms
developDescent w/ modification also predicts the
findings of anatomy & embryologyBones in the forelimbs of humans, penguins,
alligators, and batsExplanation: early ancestor shared by all these
organisms had a forelimb w/ a similar bone structure
Anatomy & EmbryologyWhat 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 & EmbryologyAnalogous Structures: closely related
functions but do not derive from the same ancestral structureEx: 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 organismsEx: human tailbone––animal tail; whale
pelvic bone; human appendix
Anatomy & EmbryologyDevelopment of Animal Embryos
Some stages of vertebrate embryo development are very alike
Similarities fade as development proceedsPossible answer––vertebrates share a common
ancestor
Biological MoleculesOrganisms that share many traits––>more
recent common ancestor than those that share fewer traitsDarwin predicted this through anatomyModern 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 TheoryHypotheses & 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 EquilibriumVariation of Traits w/in a Population
Population Genetics: genetic study of evolutionMicroevolution: evolution at the genetic level,
where a change in the collective genetic material of a population occurs
Vary in observable traits
Genetic EquilibriumVariation arises from:
MutationRecombinationRandom pairing of gametes
Genetic EquilibriumGene Pool: total genetic info available in a
populationAllele 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 EquilibriumHardy-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 EquilibriumMutations
Exposed to mutagens…increase mutationsCreates new alleles for a traitMost are harmful…some beneficial
Disruption of Genetic EquilibriumGene Flow
Size of population needs to remain constantImmigration: 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 EquilibriumGenetic Drift
Allele frequencies in a population change as a result of random events, or chance
Mechanism for evolution of a new speciesGraph page 322
Disruption of Genetic EquilibriumNonrandom Mating
Sexual Selection Females choose the males based on certain traits Ex: birds
Natural SelectionStabilizing Selection: average form of a trait
have the highest fitness – medium fishDisruptive Selection: either extreme variation
have greater fitness – very small/very large fishDirectional Selection: more extreme form has
greater fitness – very large fish
Question #1
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
)a )b )c )d
Question #3
)a )b )c )d
Question #4
)a )b )c )d
Question #5 )a )b )c )d
Question #6 )a )b )c )d
Question #7
)a )b )c )d
Question #8 According to Darwin, evolution occursa. In response to use or disuse of a
characteristicb. Because of catastrophic geologic eventsc. By natural selectiond. Within an individual’s lifetime
Question #9 The inference that evolution occurs
gradually over time,a. Is not supported by any fossil evidenceb. Is know as coevolutionc. Is supported by many transitional forms in
the fossil recordd. Was proposed by Lyell
Question #10 Natural selection causesa. Changes in the environmentb. Plants and animals to produce more
offspring than can survivec. Changes in the frequency of certain
adaptations in a populationd. Genetic variation w/in populations
Question #11 The similarity in the body shape of a
whale and of a fish is an example ofa. Divergent evolutionb. Convergent evolutionc. Coevolutiond. Vestigial structures
Question #12 Which of the following must exist in a
population in order for natural selection to act?
a. Genetic variationb. Overproductionc. Struggle to survived. All of the above
Question #13 The scientist who proposed that
individuals could pass on traits acquired during their lifetime was
a. Lamarckb. Darwinc. Cuvierd. Lyell
Question #14 Which of the following is an acquired
human characteristic?a. Number of bones in the handb. Eye colorc. The presence of a tailbone in humansd. 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 structuresb. Lack of transitional fossilsc. Lack of homologous structuresd. Presence of analogous structures