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