Topic 6 Review Name: Key
1.
Briefly describe the influential thinkers below. Describe how they were influential to Darwin. Tell whether not they believed in evolution?
Thinkers Contribution to Darwin / Importance Believe in
Evolution?
Aristotle 
Aristotle opposed any concept of evolution

Viewed species as fixed and
No unchanging

All living forms could be arranged on a ladder of increasing complexity with each perfect, permanent species having its own rung

Strict belief in the Book of Genesis and
Carolus LInnaeus
George Cuvier creation
--developed hierarchy of taxonomic categories based morphology and anatomy
--did not believe in evolution
--taxonomic system became the focal point of
Darwin’s arguments for evolution

French anatomist and paleontologist and father of paleontology (study of fossils)

Based on fossils found in sedimentary rock strata

Idea that the boundaries between strata were due to local catastrophic events (fires, floods, volcano eruptions, droughts) that destroyed the species then present

Cuvier proposed the theory of catastrophism to reconcile fossil
No
No evidence and his anti-evolutionary background
 Proposed that catastrophes were localized and regions were repopulated by species immigrating from unaffected areas
 Opposed idea of gradual evolutionary change
Charles Lyell

Expansion on gradualism

Geological processes had not changed throughout Earth’s history

Topic 6 Review Name: Key
Jean Baptiste Lamarck Mechanism:
1. Use and Disuse
--body organs used become stronger/larger
--those not used deteriorated
2. Inheritance of Acquired Characteristics
--changes acquired during a lifetime are passed on to offspring
Yes
2.
What is binomial nomenclature? What does each word stand for?
Two-part naming system that includes the organism’s genus and species
3.
List the taxonomic levels in order from largest to smallest.
Dear King Phillip Come Over for
Domain Kingdom Phylum Class Order Family
Good Spaghetti
Genus Species
4.
What is catastrophism? Who proposed this principle? What does it explain?
Proposed that catastrophes were localized and regions were repopulated by species immigrating from unaffected areas. Cuvier
5.
What is uniformitarianism?
Idea that geological processes that have shaped the planet have not changed over ht course of Earth’s history - Lyell
6.
What is the theory of use and disuse? This includes the Inheritance of Acquired characteristics- What does this state?
1. Use and Disuse- Lamarck
--body organs used become stronger/larger
--those not used deteriorated
2. Inheritance of Acquired Characteristics
--changes acquired during a lifetime are passed on to offspring
7.
Briefly describe Darwin’s voyage on the HMS Beagle. i.
Sailed from England in December of 1831 to chart South American coastline ii.
Darwin Noted:
1. Geographical distribution of species

Topic 6 Review Name: Key
2. On the Galapagos Islands he collected several different kinds of finches that were similar but seem to be different species
8.
What is Darwin’s mechanism for evolution? Describe it.
Both papers (Darwin and Wallace) presented by Lyell to Linnaean Society of London on
July 1, 1858
Darwin published Origin of the Species in 1859
Two main ideas of the book: a. Species evolved from ancestral species; not specially created b. Mechanism for evolutionary change— natural selection
1.
In the 1st edition, he used term “descent with modification” instead of evolution.
2.
Modifications occur as organisms moved into new habitats or as habitats changed
3.
Viewed history of life as a tree with most branches evolutionary dead ends
4.
Common ancestors at each fork
9.
What is Artificial Selection? i.
Striking differences can occur in a very short time if one selects which organisms reproduce.
10.
List and briefly describe the Four Evidences for evolution.
1 . Artificial Selection

Striking differences can occur in a very short time if one selects which organisms reproduce.
2. Biogeography

Geographical distribution of species

Pangaea

Endemic species
3. Fossil Record

Missing links gradually being filled in
 Shows chronological appearance of vertebrates (fish, amphibians, reptiles, birds, mammals)
4. Taxonomy
 Linnaeus’ taxonomic scheme reflected the genealogy of the tree of life
5. Comparative Anatomy

Topic 6 Review Name: Key a. Anatomical similarities between species in same taxonomic group show evidence of common descent b. Based on homologous and vestigial structures
 homologous structures-represent variations on a structural theme that was present in their common ancestor
-Ex: skeleton elements of mammalian forelimbs
 vestigial organs-remnants of structures that served important functions in the organism’s ancestors
-Ex: pelvic and leg bones in snakes; human appendix
6. Comparative Embryology
 Defined as the comparison of early stages of animal development
 Closely related organisms go through similar stages

Ex: all vertebrate embryos have pharyngeal pouches and a tail at some time

“Ontogeny recapitulates phylogeny.” Embryonic development
(ontogeny) is a replay of the evolutionary history of the species
(phylogeny).
11.
What is the smallest level of biological organization that can evolve?population
12.
What is homology? a.
Similarity resulting from common ancestry.
13.
What are the differences between homologous structures, analogous structures and vestigial structures? Give an example of each.
 Analogous – structures that represent a similar function that is not due to common ancestry. they have similar functions but not common ancestry
 Sugar glider and flying squirrel
 homologous structures-represent variations on a structural theme that was present in their common ancestor
-Ex: skeleton elements of mammalian forelimbs
 vestigial organs-remnants of structures that served important functions in the organism’s ancestors
-Ex: pelvic and leg bones in snakes; human appendix
14.
What are the differences between molecular and embryonic homologies?
Molecular homologies – shared characteristics on the molecular level
Ex. All life forms use the same genetic language of DNA and RNA
Embryonic homologies – Comparison of early stages of animal development reveals many anatomical homologies in embryos that are not visible in adult organisms
- Ex. All vertebrate embryos have a post-anal tail and pharyngeal pouches

Topic 6 Review Name: Key
15.
What is convergent evolution?
 convergent evolution—refers to the development of structures which have a similar function but develop differently and appear unrelated
16.
What is continental drift? How is this related to Pangaea?
- continental drift – movement of the continents relative to each other by appearing to drift across the ocean bed. It has been proposed along with the theory of plate tectonics.
Pangaea was the supercontinent that existed- eventually began breaking apart and those pieces moved to form the continents of today.
17.
What is microevolution? - defined as a change in allele frequencies in a population over time and represents evolutionary change on its smallest scale .
18.
What are mutations? What are the two types of mutations?
Mutations - the only source of new genes and new alleles. Only those produced in cel lines can be passed to offspring. Defined as a change in the nucleotide sequence of DNA
Base-pair substitutions
Base-pair insertions or deletions
19.
Sexual reproduction rearranges alleles into new combinations using three mechanisms. What are they? List and briefly describe them.
Three mechanisms that contribute to the unique combinations of alleles are: a. Crossing over b. Independent assortment of chromosomes c. Fertilization
20.
What is a population?
A population is a group of individuals that belong to the same species, live in the same area, and interbreed to produce fertile offspring
 Individuals near the population’s center are, on average, more closely related to one another than to those individuals on the periphery
21.
What is population genetics? – study of how populations change genetically over time
22.
When will an allele become fixed in a population?- . A locus is fixed if all individuals in a population are homozygous for the same allele

Topic 6 Review Name: Key
23.
What is the Hardy-Weinberg principle?
Describes the gene pool of a population that is not evolving
2. If a population does not meet the criteria of the Hardy-Weinberg principle, it can be concluded that the population is evolving
3. The Hardy-Weinberg principle states that frequencies of alleles and genotypes in a population remain constant from generation to generation unless acted upon by agents other than Mendelian segregation and recombination of alleles
4. Such a gene pool is said to be in Hardy-Weinberg equilibrium
24.
What five conditions must be met in order for a population to be in Hardy-
Weinberg equilibrium?
.The five conditions for nonevolving populations are rarely met in nature:
 No mutations
 Random mating
 No natural selection
 Extremely large population size
 No gene flow (migration)
25.
What is the Hardy-Weinberg Equation? What do the following symbols represent: p and q
If p and q represent the relative frequencies of the only two possible alleles in a population at a particular locus, then p 2 + 2pq + q 2 = 1
AA Aa aa where p 2 and q 2 represent the frequencies of the homozygous genotypes and
2pq represents the frequency of the heterozygous genotype
This equation can be used to determine the frequencies of the possible genotypes if we know the frequencies of alleles, or we can calculate the frequencies of alleles in a gene pool if we know the frequencies of genotypes. evolutionary change.
Three major factors that alter allele frequencies and bring about evolutionary change are:
26.
Be able to work Hardy-Weinberg equilibrium problems.
27.
Describe the three factors that alter allele frequencies and bring about most a.
Natural selection (adaptive) i.
Differential success in reproduction results in certain alleles being passed to the next generation in greater proportions b.
Genetic drift (nonadaptive) i.
Defined as changes in the gene pool (allele frequencies) of a small population due to chance

Topic 6 Review Name: Key ii.
The smaller a sample, the greater the chance of deviation from a predicted result iii.
Genetic drift tends to reduce genetic variation through losses of alleles iv.
May occur in small populations (less than 100) as the result of two situations: v.
Bottleneck effect vi.
Founder effect
1.
Bottleneck effect a.
Defined as a sudden reduction in population size due to a change in the environment (Ex: disaster) b.
Alleles may be lost c.
New gene pool may differ drastically from original
2.
Founder effect a.
Occurs when a few individuals colonize a new habitat or become isolated from a larger population b.
Allele frequencies in the small founder population can be different from those in the larger parent population vii.
Effects of Genetic Drift Summary a. Genetic drift is significant in small populations b. Genetic drift causes allele frequencies to change at random c. Genetic drift can lead to a loss of genetic variation within populations d. Genetic drift can cause harmful alleles to become fixed
3. Gene flow (nonadaptive)
1.
Defined as the transfer of alleles among populations due to the migration of fertile individuals or gametes (pollen)
2.
Tends to reduce differences between populations over time
3.
More likely than mutation to alter allele frequencies directly
4.
Can increase or decrease the fit between organism and environment
5.
Can introduce new alleles into a population
28.
What is relative fitness? a.
Defined as the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals b.
Natural selection acts on the genotype indirectly by how the genotype affects the phenotype c.
How an organism benefits from a particular allele depends on the genetic and environmental contexts in which it is expressed

Topic 6 Review Name: Key
29.
Describe the ways in which natural selection acts on the phenotype (and therefore indirectly on genotype).

Depends on which phenotypes in a population are favored.
1. Directional Selection
 Favors phenotype of one extreme
 Most common when species migrate to new and different habitats or during major environmental change
2. Disruptive Selection
 Favors individuals at both extremes of the phenotypic range
3. Stabilizing Selection
 Favors intermediate variants and acts against extreme phenotypes

Topic 6 Review Name: Key
30.
Given a passage be able to identify the type of selection.
31.
What is sexual selection? What can it lead to?
-Defined as natural selection for mating success
-Can result in sexual dimorphism (marked differences between the sexes in secondary sexual characteristics not directly associated with reproduction)
-Intrasexual selection is competition among individuals of one sex (often males) for mates of the opposite sex
-Intersexual selection, often called mate choice, occurs when individuals of one sex
(usually females) are choosy in selecting their mates
32.
What are the two ways in which genetic variation is preserved in a population?
1. Diploidy
 Maintains genetic variation in the form of hidden recessive alleles
2. Balancing selection
 Occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population (polymorphism)
 Two mechanisms that help maintain balanced polymorphism a. Heterozygote advantage
--Occurs when heterozygotes have a higher fitness than do both homozygotes
--Natural selection will tend to maintain two or more alleles at that locus
--The sickle-cell allele causes mutations in hemoglobin but also confers malaria resistance
--Defined in terms of the genotype, not the phenotype b. Frequency-dependent selection
--the fitness of a phenotype declines if it becomes too common in the population
--Selection can favor whichever phenotype is less common in a population c. Neutral Variation
--genetic variation that appears to confer no selective advantage or disadvantage
33.
What is the process by which new species arise called?
Speciation
• Is defined as the origin of new species (process by which one species splits into two or more species)
• Is at the focal point of evolutionary theory which must explain how new species originate and how populations evolve
34.
What is the difference between microevolution and macroevolution?
A.Microevolution
• Consists of adaptations that evolve within a population, confined to one gene pool
• Mechanisms—mutation, natural selection, genetic drift, and gene flow
B.Macroevolution
• Refers to evolutionary change above the species level

Topic 6 Review Name: Key
• Deals with the appearance of evolutionary novelties that can be used to define high taxa
35.
What is the biological species concept?
Biological Species Concept
1. Proposed by Ernst Mayr in 1942
2. A species is defined as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but who cannot produce viable, fertile offspring with other such populations
36.
List and briefly describe the 5 prezygotic barriers
1. Habitat Isolation
 Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers
2. Behavioral Isolation

Species use unique and elaborate courtship behavior to attract mates
3. Temporal Isolation

Two species that breed during different times of day, different seasons, or different years cannot mix gametes
4. Mechanical Isolation

Closely related species may attempt to mate but fail because they are anatomically incompatible and transfer of sperm is not possible
5. Gametic Isolation

Gametes of one species may not be able to fertilize eggs of another species
37.
List and briefly describe the 3 postzygotic barriers.
1.Reduced Hybrid Viability
- Genetic incompatibility between the two species may stop the development of the hybrid at some embryonic stage or produce frail offspring
2. Reduced Hybrid Fertility

Even though hybrid offspring survives, it may be sterile
3. Hybrid Breakdown
 Some first-generation hybrids are viable and fertile, but when they mate with another species or with either parent species, the offspring of the next generation are sterile or feeble
38.
Given a passage be able to identify the type of pre- or postzygotic barrier.
39.
What is the difference between allopatric and sympatric speciation? Provide and example of each.
1. Allopatric Speciation

Topic 6 Review Name: Key
• Occurs when geographic separation of populations restricts gene flow
• Geological process can fragment a population into two or more isolated populations.
• Definition of barrier depends on the ability of a population to disperse
• Separate populations may evolve independently through mutation, natural selection, and genetic drift
• Evidence of allopatric speciation can be seen in regions with many geographic barriers typically having more species than do regions with few barriers
• Reproductive isolation between populations generally increases as the distance between them increases
2. Sympatric Speciation
• New species arise within the range of the parent population
• Occurs when reproductive barriers evolve between sympatric populations
• May occur rapidly
• Types: Polyploidy, habitat differentiation, sexual selection
•
40.
What is autopolyploidy? a.
Polyploidy i.
Defined as the presence of extra sets of chromosomes due to accidents during cell division ii.
An autopolyploid is an individual with more than two chromosome sets, derived from one species iii.
An allopolyploid is a species with multiple sets of chromosomes derived from different species (more common) iv.
Polyploidy is more common in plants than animals
41.
What is adaptive radiation?
Adaptive Radiation
• Occurs when many new species arise from a single common ancestor
• Typically occurs when a few organisms make their way to new, distant areas or when environmental changes cause extinctions thus opening up niches for survivors
• Ex: Darwin’s finches
42.
What is the difference between gradualism and punctuated equilibrium?
A. Gradual—proposes that species descended from a common ancestor and gradually diverge more and more in morphology as they acquire unique adapations
-difficult to prove with fossils

Topic 6 Review Name: Key
B. Punctuated—spurts of rapid change rather than gradual divergence
-based on fossils that suddenly appear and disappear
-proposed by Eldredge and Gould
Punctuated equilibrium - periods of apparent stasis punctuated by sudden change observed in the fossil record
43.
What are the 4 main stages of the current theory about how life arose?
1. Abiotic synthesis of small organic molecules (monomers)
2. Joining of monomers to form macromolecules
3. Packaging of macromolecules into “protobionts,” droplets with membranes that maintained a distinct internal chemistry
4. Origin of self-replicating molecules that eventually made inheritance possible.
44.
Who hypothesized that the early atmosphere could have formed organic compounds? i.
In the 1920’s, A. I Oparin (Russian) and J. B. S. Haldane (British) independently postulated that the conditions on early Earth
(reducing environment) favored the synthesis of organic compounds from simple molecules. ii.
Energy possibly from lightning and UV radiation
45.
Who tested the hypothesis above and produced a variety of amino acids? i.
In 1953, Stanley Miller and Harold Urey tested the Oparin-
Haldane hypothesis ii.
They conducted lab experiments that showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possible iii.
Atmosphere of primitive Earth: water vapor hydrogen gas methane ammonia iv.
Used electrical sparks as source of energy
46.
What is hypothesized to be the first genetic material? - RNA i.
First genetic material was probably RNA, not DNA ii.
RNA molecules called ribozymes can catalyze many different reactions iii.
Has been demonstrated that RNA sequences can evolve under abiotic condition
47.
What is the endosymbiotic hypothesis? What evidence supports this hypothesis?
Endosymbiosis

Topic 6 Review Name: Key
• Proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells
• Endosymbiont—a cell that lives within a host cell
• Prokaryotic ancestors of mitochondria and plastids probably gained entry to the host cell as undigested prey or internal parasites
Eventually host and endosymbionts would have become a single organism
 Serial endosymbiosis supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
Evidence to support an endosymbiotic origin of mitochondria and plastids: a. Similarities in inner membrane structures and functions b. Division is similar in those organelles and some prokaryotes c. Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes d. Circular DNA
48.
Relative dating uses the order of rock strata to determine the relative age of fossils. Radiometric dating uses the decay of radioactive isotopes to determine the age of rocks or fossils.
49.
The earliest living organisms were prokaryotes .
50.
About 2.7 billion years ago, oxygen began to accumulate in Earth’s atmosphere as a result of photosynthesis.

Topic 6 Review Name: Key
51.
.
Eukaryotes appeared about 2.1 billion years ago.
52.
Multicellular eukaryotes evolved about 1 .2 billion years ago.
53.
The colonization of land occurred about 500 million years ago, when plants, fungi, and animals began to appear on Earth.