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Organize the following terms into a flowchart
Organize the following terms into a flowchart
Natural Selection = only mechanism that gives consistent Adaptive
Natural Selection = only mechanism that gives consistent Adaptive
What are the 2 main causes of genetic variation
What are the 2 main causes of genetic variation
5 conditions of Hardy-Weinberg Equilibrium
5 conditions of Hardy-Weinberg Equilibrium
How we get the 2 equations
How we get the 2 equations
Essential knowledge 1.A.1: Natural selection is a major mechanism of
Essential knowledge 1.A.1: Natural selection is a major mechanism of
e. An adaptation is a genetic variation that is favored by selection
e. An adaptation is a genetic variation that is favored by selection
Learning Objectives
Learning Objectives
Organize the following terms into a flowchart
Organize the following terms into a flowchart
Essential knowledge 1.A.2: Natural selection acts on phenotypic
Essential knowledge 1.A.2: Natural selection acts on phenotypic
Peppered Moths, Variation, and the Industrial Revolution  Find the
Peppered Moths, Variation, and the Industrial Revolution Find the
Organize the following terms into a flowchart
Organize the following terms into a flowchart
c. Some phenotypic variations significantly increase or decrease
c. Some phenotypic variations significantly increase or decrease
Genetic variation preserved how
Genetic variation preserved how
Learning Objectives
Learning Objectives
Essential knowledge 1.A.3: Evolutionary change is also driven by
Essential knowledge 1.A.3: Evolutionary change is also driven by
What is genetic drift
What is genetic drift
Learning Objectives
Learning Objectives
List as many categories of Evidence of Evolution as you can
List as many categories of Evidence of Evolution as you can
Essential knowledge 1.A.4: Biological evolution is supported by
Essential knowledge 1.A.4: Biological evolution is supported by
2. Morphological homologies represent features shared by common
2. Morphological homologies represent features shared by common
How Rocks and Fossils Are Dated
How Rocks and Fossils Are Dated
Fraction of parent isotope remaining
Fraction of parent isotope remaining
Systematists use computer programs and mathematical tools when
Systematists use computer programs and mathematical tools when
Sorting Homology from Analogy
Sorting Homology from Analogy
Learning Objectives
Learning Objectives
L.O. 1.13
L.O. 1.13
Essential knowledge 1.B.1: Organisms share many conserved core
Essential knowledge 1.B.1: Organisms share many conserved core
b. Structural evidence supports the relatedness of all eukaryotes
b. Structural evidence supports the relatedness of all eukaryotes
Learning Objectives
Learning Objectives
L.O. 1.15
L.O. 1.15
Essential knowledge 1.B.2: Phylogenetic trees and cladograms are
Essential knowledge 1.B.2: Phylogenetic trees and cladograms are
Other even-toed ungulates
Other even-toed ungulates
c. Phylogenetic trees and cladograms can be constructed from
c. Phylogenetic trees and cladograms can be constructed from
Learning Objectives
Learning Objectives
Classification terms
Classification terms
Species: Panthera pardus
Species: Panthera pardus
A valid clade is monophyletic, signifying that it consists of the
A valid clade is monophyletic, signifying that it consists of the
Branch point: where lineages diverge
Branch point: where lineages diverge
L.O. 1.19
L.O. 1.19
Organize the following terms into a flowchart
Organize the following terms into a flowchart
Organize the following terms into a flowchart
Organize the following terms into a flowchart
Speciation  when does evolution result in a new species
Speciation when does evolution result in a new species
Figure 24
Figure 24
Prezygotic vs
Prezygotic vs
Allopatric vs
Allopatric vs
Hybrid Zones
Hybrid Zones
Fusion may lead to extinction of the polar bear
Fusion may lead to extinction of the polar bear
Speed of Speciation
Speed of Speciation
Essential knowledge 1.C.1: Speciation and extinction have occurred
Essential knowledge 1.C.1: Speciation and extinction have occurred
Learning Objectives
Learning Objectives
L.O. 1.21
L.O. 1.21
Essential knowledge 1.C.2: Speciation may occur when two populations
Essential knowledge 1.C.2: Speciation may occur when two populations
Learning Objectives
Learning Objectives
Essential knowledge 1.C.3: Populations of organisms continue to evolve
Essential knowledge 1.C.3: Populations of organisms continue to evolve
Learning Objectives
Learning Objectives
Essential knowledge 1.D.1: There are several hypotheses about the
Essential knowledge 1.D.1: There are several hypotheses about the
Learning Objectives
Learning Objectives
Concept 25
Concept 25
Early Earth
Early Earth
Abiotic synthesis of organic molecules is a testable hypothesis
Abiotic synthesis of organic molecules is a testable hypothesis
In 1953, Stanley Miller and Harold Urey tested the Oparin-Haldane
In 1953, Stanley Miller and Harold Urey tested the Oparin-Haldane
Organize the following terms into a flowchart
Organize the following terms into a flowchart
The Miller-Urey experiments still stimulate debate on the origin of
The Miller-Urey experiments still stimulate debate on the origin of
Laboratory simulations of early-Earth conditions have produced organic
Laboratory simulations of early-Earth conditions have produced organic
RNA may have been the first genetic material
RNA may have been the first genetic material
Short polymers of ribonucleotides can be synthesized abiotically in
Short polymers of ribonucleotides can be synthesized abiotically in
In the 1980s Thomas Cech discovered that RNA molecules are important
In the 1980s Thomas Cech discovered that RNA molecules are important
RNA-directed protein synthesis may have begun as weak binding of
RNA-directed protein synthesis may have begun as weak binding of
Protocells can form by self-assembly
Protocells can form by self-assembly
In the laboratory, droplets of abiotically produced organic compounds,
In the laboratory, droplets of abiotically produced organic compounds,
Liposomes behave dynamically, growing by engulfing smaller liposomes
Liposomes behave dynamically, growing by engulfing smaller liposomes
If enzymes are included among the ingredients, they are incorporated
If enzymes are included among the ingredients, they are incorporated
Natural section could refine protocells containing hereditary
Natural section could refine protocells containing hereditary
As an example: suppose that an RNA molecule ordered amino acids into a
As an example: suppose that an RNA molecule ordered amino acids into a
The most successful protocells would grow and split, distributing
The most successful protocells would grow and split, distributing
Evolution via differential reproductive success of varied individuals
Evolution via differential reproductive success of varied individuals
Essential knowledge 1.D.2: Scientific evidence from many different
Essential knowledge 1.D.2: Scientific evidence from many different
Animation: The Geologic Record Right-click slide / select Play
Animation: The Geologic Record Right-click slide / select Play
Present
Present
Continental drift has many effects on living organisms A continents
Continental drift has many effects on living organisms A continents
Mass Extinctions
Mass Extinctions
A number of factors might have contributed to these extinctions
A number of factors might have contributed to these extinctions
The Cretaceous mass extinction 65
The Cretaceous mass extinction 65
The presence of iridium in sedimentary rocks suggests a meteorite
The presence of iridium in sedimentary rocks suggests a meteorite
NORTH AMERICA
NORTH AMERICA
Is a Sixth Mass Extinction Under Way
Is a Sixth Mass Extinction Under Way
Adaptive Radiations
Adaptive Radiations
Worldwide Adaptive Radiations
Worldwide Adaptive Radiations
Clock analogy of History of Life
Clock analogy of History of Life
The First Single-Celled Organisms
The First Single-Celled Organisms
The First Eukaryotes
The First Eukaryotes
The prokaryotic ancestors of mitochondria and plastids probably gained
The prokaryotic ancestors of mitochondria and plastids probably gained
Plasma membrane
Plasma membrane
Key evidence supporting an endosymbiotic origin of mitochondria and
Key evidence supporting an endosymbiotic origin of mitochondria and
Plants, fungi, and animals colonized the land about 500 million years
Plants, fungi, and animals colonized the land about 500 million years
The gradual evolution from aquatic to terrestrial habitats required
The gradual evolution from aquatic to terrestrial habitats required
Plants created new opportunities for all life, including herbivorous
Plants created new opportunities for all life, including herbivorous
The terrestrial vertebrates, called tetrapods because of their four
The terrestrial vertebrates, called tetrapods because of their four
Learning Objectives
Learning Objectives
Essential knowledge 2.E.1: Timing and coordination of specific events
Essential knowledge 2.E.1: Timing and coordination of specific events
Concept 25
Concept 25
Changes in Rate and Timing
Changes in Rate and Timing
Changes in Spatial Pattern
Changes in Spatial Pattern
Hox genes are a class of homeotic genes that provide positional
Hox genes are a class of homeotic genes that provide positional
The Evolution of Development
The Evolution of Development
Changes in Genes
Changes in Genes
Hox gene 6
Hox gene 6
Changes in Gene Regulation
Changes in Gene Regulation
RESULTS
RESULTS
Learning Objectives
Learning Objectives
Essential knowledge 3.C.1: Changes in genotype can result in changes
Essential knowledge 3.C.1: Changes in genotype can result in changes
c. Errors in mitosis or meiosis can result in changes in phenotype
c. Errors in mitosis or meiosis can result in changes in phenotype
Learning Objectives
Learning Objectives
Concept 27
Concept 27
Essential knowledge 3.C.2: Biological systems have multiple processes
Essential knowledge 3.C.2: Biological systems have multiple processes
Learning Objectives
Learning Objectives
Essential knowledge 4.C.3: The level of variation in a population
Essential knowledge 4.C.3: The level of variation in a population
Bottleneck Effect
Bottleneck Effect
Case Study: Impact of Genetic Drift on the Greater Prairie Chicken
Case Study: Impact of Genetic Drift on the Greater Prairie Chicken
Figure 23
Figure 23
Researchers used DNA from museum specimens to compare genetic
Researchers used DNA from museum specimens to compare genetic
Effects of Genetic Drift: A Summary
Effects of Genetic Drift: A Summary
Learning Objectives
Learning Objectives
Essential knowledge 4.C.4: The diversity of species within an
Essential knowledge 4.C.4: The diversity of species within an
Learning Objectives
Learning Objectives

: . : DUSD. : .ppt. zip-: 7979 .

.ppt
1 Organize the following terms into a flowchart

Organize the following terms into a flowchart

Adaptation, Environmental Change, Natural Selection, Species Changes, Variation exists

2 Natural Selection = only mechanism that gives consistent Adaptive

Natural Selection = only mechanism that gives consistent Adaptive

Evolution

Relative fitness? 3 ways that it can affect phenotype distribution name and draw

3 What are the 2 main causes of genetic variation

What are the 2 main causes of genetic variation

Microevolution = Population =

4 5 conditions of Hardy-Weinberg Equilibrium

5 conditions of Hardy-Weinberg Equilibrium

Is it realistic?

5 How we get the 2 equations

How we get the 2 equations

6 Essential knowledge 1.A.1: Natural selection is a major mechanism of

Essential knowledge 1.A.1: Natural selection is a major mechanism of

evolution. a. According to Darwins theory of natural selection, competition for limited resources results in differential survival. Individuals with more favorable phenotypes are more likely to survive and produce more offspring, thus passing traits to subsequent generations. b. Evolutionary fitness is measured by reproductive success. c. Genetic variation and mutation play roles in natural selection. A diverse gene pool is important for the survival of a species in a changing environment. d. Environments can be more or less stable or fluctuating, and this affects evolutionary rate and direction; different genetic variations can be selected in each generation.

7 e. An adaptation is a genetic variation that is favored by selection

e. An adaptation is a genetic variation that is favored by selection

and is manifested as a trait that provides an advantage to an organism in a particular environment. f. In addition to natural selection, chance and random events can influence the evolutionary process, especially for small populations. g. Conditions for a population or an allele to be in Hardy-Weinberg equilibrium are: (1) a large population size, (2) absence of migration, (3) no net mutations, (4) random mating and (5) absence of selection. These conditions are seldom met. h. Mathematical approaches are used to calculate changes in allele frequency, providing evidence for the occurrence of evolution in a population. To foster student understanding of this concept, instructors can choose an illustrative example such as: Graphical analysis of allele frequencies in a population Application of the Hardy-Weinberg equilibrium equation

8 Learning Objectives

Learning Objectives

LO 1.1 The student is able to convert a data set from a table of numbers that reflect a change in the genetic makeup of a population over time and to apply mathematical methods and conceptual understandings to investigate the cause(s) and effect(s) of this change. [See SP 1.5, 2.2] LO 1.2 The student is able to evaluate evidence provided by data to qualitatively and quantitatively investigate the role of natural selection in evolution. [See SP 2.2, 5.3] LO 1.3 The student is able to apply mathematical methods to data from a real or simulated population to predict what will happen to the population in the future. [See SP 2.2]

9 Organize the following terms into a flowchart
10 Essential knowledge 1.A.2: Natural selection acts on phenotypic

Essential knowledge 1.A.2: Natural selection acts on phenotypic

variations in populations. a. Environments change and act as selective mechanism on populations. To foster student understanding of this concept, instructors can choose an illustrative example such as: Flowering time in relation to global climate change Peppered moth b. Phenotypic variations are not directed by the environment but occur through random changes in the DNA and through new gene combinations.

11 Peppered Moths, Variation, and the Industrial Revolution  Find the

Peppered Moths, Variation, and the Industrial Revolution Find the

moths in the pictures

Lets graph allele frequencies over time

12 Organize the following terms into a flowchart
13 c. Some phenotypic variations significantly increase or decrease

c. Some phenotypic variations significantly increase or decrease

fitness of the organism and the population. To foster student understanding of this concept, instructors can choose an illustrative example such as: Sickle cell anemia Peppered moth DDT resistance in insects d. Humans impact variation in other species. To foster student understanding of this concept, instructors can choose an illustrative example such as: Artificial selection Loss of genetic diversity within a crop species Overuse of antibiotics

14 Genetic variation preserved how

Genetic variation preserved how

Why not perfection?

15 Learning Objectives

Learning Objectives

LO 1.4 The student is able to evaluate data-based evidence that describes evolutionary changes in the genetic makeup of a population over time. [See SP 5.3] LO 1.5 The student is able to connect evolutionary changes in a population over time to a change in the environment.[See SP 7.1]

16 Essential knowledge 1.A.3: Evolutionary change is also driven by

Essential knowledge 1.A.3: Evolutionary change is also driven by

random processes. a. Genetic drift is a nonselective process occurring in small populations. b. Reduction of genetic variation within a given population can increase the differences between populations of the same species.

17 What is genetic drift

What is genetic drift

Give 2 examples

18 Learning Objectives

Learning Objectives

LO 1.6 The student is able to use data from mathematical models based on the Hardy-Weinberg equilibrium to analyze genetic drift and effects of selection in the evolution of specific populations. [See SP 1.4, 2.1] LO 1.7 The student is able to justify data from mathematical models based on the Hardy-Weinberg equilibrium to analyze genetic drift and the effects of selection in the evolution of specific populations. [See SP 2.1] LO 1.8 The student is able to make predictions about the effects of genetic drift, migration and artificial selection on the genetic makeup of a population. [See SP 6.4]

19 List as many categories of Evidence of Evolution as you can

List as many categories of Evidence of Evolution as you can

20 Essential knowledge 1.A.4: Biological evolution is supported by

Essential knowledge 1.A.4: Biological evolution is supported by

scientific evidence from many disciplines, including mathematics. a. Scientific evidence of biological evolution uses information from geographical, geological, physical, chemical and mathematical applications. b. Molecular, morphological and genetic information of existing and extinct organisms add to our understanding of evolution. Evidence of student learning is a demonstrated understanding of eachof the following: 1. Fossils can be dated by a variety of methods that provide evidence for evolution. These include the age of the rocks where a fossil is found, the rate of decay of isotopes including carbon-14, the relationships within phylogenetic trees, and the mathematical calculations that take into account information from chemical properties and/or geographical data. ?? The details of these methods are beyond the scope of this course and the AP Exam.

21 2. Morphological homologies represent features shared by common

2. Morphological homologies represent features shared by common

ancestry. Vestigial structures are remnants of functional structures, which can be compared to fossils and provide evidence for evolution. 3. Biochemical and genetic similarities, in particular DNA nucleotide and protein sequences, provide evidence for evolution and ancestry. 4. Mathematical models and simulations can be used to illustrate and support evolutionary concepts. To foster student understanding of this concept, instructors can choose an illustrative example such as: Graphical analyses of allele frequencies in a population Analysis of sequence data sets Analysis of phylogenetic trees Construction of phylogenetic trees based on sequence data

22 How Rocks and Fossils Are Dated

How Rocks and Fossils Are Dated

Sedimentary strata reveal the relative ages of fossils The absolute ages of fossils can be determined by radiometric dating A parent isotope decays to a daughter isotope at a constant rate Each isotope has a known half-life, the time required for half the parent isotope to decay Radiocarbon dating can be used to date fossils up to 75,000 years old For older fossils, some isotopes can be used to date sedimentary rock layers above and below the fossil

23 Fraction of parent isotope remaining

Fraction of parent isotope remaining

Remaining parent isotope

1 2 3 4

Time (half-lives)

Accumulating daughter isotope

Figure 25.5

1

2

1

4

1

8

1

16

24 Systematists use computer programs and mathematical tools when

Systematists use computer programs and mathematical tools when

analyzing comparable DNA segments from different organisms

1

1

2

Deletion

2

1

2

Insertion

3

1

2

4

1

2

Figure 26.8-4

25 Sorting Homology from Analogy

Sorting Homology from Analogy

When constructing a phylogeny, systematists need to distinguish whether a similarity is the result of homology or analogy Homology is similarity due to shared ancestry Analogy is similarity due to convergent evolution Convergent evolution occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages Bat and bird wings are homologous as forelimbs, but analogous as functional wings

26 Learning Objectives

Learning Objectives

LO 1.9 The student is able to evaluate evidence provided by data from many scientific disciplines that support biological evolution. [See SP 5.3] LO 1.10 The student is able to refine evidence based on data from many scientific disciplines that support biological evolution. [See SP 5.2] LO 1.11 The student is able to design a plan to answer scientific questions regarding how organisms have changed over time using information from morphology, biochemistry and geology. [See SP 4.2] LO 1.12 The student is able to connect scientific evidence from many scientific disciplines to support the modern concept of evolution. [See SP 7.1] LO 1.13 The student is able to construct and/or justify mathematical models, diagrams or simulations that represent processes of biological evolution. [See SP 1.1, 2.1]

27 L.O. 1.13

L.O. 1.13

28 Essential knowledge 1.B.1: Organisms share many conserved core

Essential knowledge 1.B.1: Organisms share many conserved core

processes and features that evolved and are widely distributed among organisms today. a. Structural and functional evidence supports the relatedness of all domains. Evidence of student learning is a demonstrated understanding of each of the following: 1. DNA and RNA are carriers of genetic information through transcription, translation and replication. [See also 3.A.1 ] 2. Major features of the genetic code are shared by all modern living systems. [See also 3.A.1] 3. Metabolic pathways are conserved across all currently recognized domains. [See also 3.D.1]

29 b. Structural evidence supports the relatedness of all eukaryotes

b. Structural evidence supports the relatedness of all eukaryotes

[See also 2.B.3, 4.A.2] To foster student understanding of this concept, instructors can choose an illustrative example such as: Cytoskeleton (a network of structural proteins that facilitate cell movement, morphological integrity and organelle transport) Membrane-bound organelles (mitochondria and/or chloroplasts) Linear chromosomes Endomembrane systems, including the nuclear envelope

30 Learning Objectives

Learning Objectives

LO 1.14 The student is able to pose scientific questions that correctly identify essential properties of shared, core life processes that provide insights into the history of life on Earth. [See SP 3.1] LO 1.15 The student is able to describe specific examples of conserved core biological processes and features shared by all domains or within one domain of life, and how these shared, conserved core processes and features support the concept of common ancestry for all organisms. [See SP 7.2] LO 1.16 The student is able to justify the scientific claim that organisms share many conserved core processes and features that evolved and are widely distributed among organisms today. [See SP 6.1]

31 L.O. 1.15

L.O. 1.15

32 Essential knowledge 1.B.2: Phylogenetic trees and cladograms are

Essential knowledge 1.B.2: Phylogenetic trees and cladograms are

graphical representations (models) of evolutionary history that can be tested. a. Phylogenetic trees and cladograms can represent traits that are either derived or lost due to evolution. To foster student understanding of this concept, instructors can choose an illustrative example such as: Number of heart chambers in animals Opposable thumbs Absence of legs in some sea mammals b. Phylogenetic trees and cladograms illustrate speciation that has occurred, in that relatedness of any two groups on the tree is shown by how recently two groups had a common ancestor.

33 Other even-toed ungulates

Other even-toed ungulates

Hippopotamuses

Pakicetus

Rodhocetus

Common ancestor of cetaceans

Dorudon

Living cetaceans

70

60

50

40

30

20

10

0

Pelvis

Tibia

Key

Millions of years ago

Femur

Foot

Figure 22.20

34 c. Phylogenetic trees and cladograms can be constructed from

c. Phylogenetic trees and cladograms can be constructed from

morphological similarities of living or fossil species, and from DNA and protein sequence similarities, by employing computer programs that have sophisticated ways of measuring and representing relatedness among organisms. d. Phylogenetic trees and cladograms are dynamic (i.e.,phylogenetic trees and cladograms are constantly being revised), based on the biological data used, new mathematical and computational ideas, and current and emerging knowledge.

35 Learning Objectives

Learning Objectives

LO 1.17 The student is able to pose scientific questions about a group of organisms whose relatedness is described by a phylogenetic tree or cladogram in order to (1) identify shared characteristics, (2) make inferences about the evolutionary history of the group, and (3) identify character data that could extend or improve the phylogenetic tree. [See SP 3.1] LO 1.18 The student is able to evaluate evidence provided by a data set in conjunction with a phylogenetic tree or a simple cladogram to determine evolutionary history and speciation. [See SP 5.3] LO 1.19 The student is able create a phylogenetic tree or simple cladogram that correctly represents evolutionary history and speciation from a provided data set. [See SP 1.1]

36 Classification terms

Classification terms

Phylogeny = Inferred from homologous structures and molecular data Systematics = Taxonomy = Binomial nomenclature DKPCOFGS look at table of 3 domains Taxon Phlyogenetic Tree Cladogram and clades

37 Species: Panthera pardus

Species: Panthera pardus

Genus: Panthera

Family: Felidae

Order: Carnivora

Class: Mammalia

Phylum: Chordata

Kingdom: Animalia

Domain: Bacteria

Domain: Archaea

Domain: Eukarya

Figure 26.3

38 A valid clade is monophyletic, signifying that it consists of the

A valid clade is monophyletic, signifying that it consists of the

ancestor species and all its descendants

Figure 26.10

(b) Paraphyletic group

(c) Polyphyletic group

(a) Monophyletic group (clade)

A

A

A

B

B

B

Group ?

Group ???

C

C

C

D

D

D

E

E

Group ??

E

F

F

F

G

G

G

39 Branch point: where lineages diverge

Branch point: where lineages diverge

Taxon A

Taxon B

Sister taxa

Taxon C

Taxon D

Taxon E

ANCESTRAL LINEAGE

Taxon F

Basal taxon

Taxon G

This branch point forms a polytomy: an unresolved pattern of divergence.

This branch point represents the common ancestor of taxa AG.

Figure 26.5

40 L.O. 1.19

L.O. 1.19

41 Organize the following terms into a flowchart
42 Organize the following terms into a flowchart
43 Speciation  when does evolution result in a new species

Speciation when does evolution result in a new species

Species defined = Macroevolution = What are 2 main types of reproductive isolation?

44 Figure 24

Figure 24

3_a

Prezygotic barriers

Postzygotic barriers

Gametic Isolation

Reduced Hybrid Viability

Reduced Hybrid Fertility

Hybrid Breakdown

Mechanical Isolation

Habitat Isolation

Temporal Isolation

Behavioral Isolation

(i)

(g)

(a)

(c)

(e)

(l)

(h)

(f)

(d)

(j)

(b)

(k)

Individuals of different species

VIABLE, FERTILE OFFSPRING

MATING ATTEMPT

FERTILIZATION

45 Prezygotic vs

Prezygotic vs

Postzygotic

Describe various methods of prezygotic: isolation: habitat, behavioral, temporal, mechanical, gametic Describe various methods of postzygotic: Reduced hybrid viability, Reduced hybrid fertility, Hybrid breakdown

46 Allopatric vs

Allopatric vs

Sympatric speciation has to do with geographic isolation

Allopatric: Sympatric:

47 Hybrid Zones

Hybrid Zones

Figure 24.14-4

Possible outcomes:

Isolated population diverges

Hybrid zone

Reinforcement

OR

Fusion

OR

Gene flow

Hybrid individual

Population

Barrier to gene flow

Stability

48 Fusion may lead to extinction of the polar bear

Fusion may lead to extinction of the polar bear

Figure 24.4

Grizzly bear (U. arctos)

Polar bear (U. maritimus)

Hybrid grolar bear

49 Speed of Speciation

Speed of Speciation

Gradualism Punctuated Equilibrium & Adaptive radiation

50 Essential knowledge 1.C.1: Speciation and extinction have occurred

Essential knowledge 1.C.1: Speciation and extinction have occurred

throughout the Earths history. Speciation rates can vary, especially when adaptive radiation occurs when new habitats become available. b. Species extinction rates are rapid at times of ecological stress. [See also 4.C.3] To foster student understanding of this concept, instructors can choose an illustrative example such as: Five major extinctions Human impact on ecosystems and species extinction rates ?? The names and dates of these extinctions are beyond the scope of this course and the AP Exam.

51 Learning Objectives

Learning Objectives

LO 1.20 The student is able to analyze data related to questions of speciation and extinction throughout the Earths history. [See SP 5.1] LO 1.21 The student is able to design a plan for collecting data to investigate the scientific claim that speciation and extinction have occurred throughout the Earths history. [See SP 4.2]

52 L.O. 1.21

L.O. 1.21

53 Essential knowledge 1.C.2: Speciation may occur when two populations

Essential knowledge 1.C.2: Speciation may occur when two populations

become reproductively isolated from each other. a. Speciation results in diversity of life forms. Species can be physically separated by a geographic barrier such as an ocean or a mountain range, or various pre-and post-zygotic mechanisms can maintain reproductive isolation and prevent gene flow. b. New species arise from reproductive isolation over time, which can involve scales of hundreds of thousands or even millions of years, or speciation can occur rapidly through mechanisms such as polyploidy in plants.

54 Learning Objectives

Learning Objectives

LO 1.22 The student is able to use data from a real or simulated population(s), based on graphs or models of types of selection, to predict what will happen to the population in the future. [See SP 6.4] LO 1.23 The student is able to justify the selection of data that address questions related to reproductive isolation and speciation. [See SP 4.1] LO 1.24 The student is able to describe speciation in an isolated population and connect it to change in gene frequency, change in environment, natural selection and/or genetic drift. [See SP 7.2]

55 Essential knowledge 1.C.3: Populations of organisms continue to evolve

Essential knowledge 1.C.3: Populations of organisms continue to evolve

a. Scientific evidence supports the idea that evolution has occurred in all species. b. Scientific evidence supports the idea that evolution continues to occur. To foster student understanding of this concept, instructors can choose an illustrative example such as: Chemical resistance (mutations for resistance to antibiotics, pesticides, herbicides or chemotherapy drugs occur in the absence of the chemical) Emergent diseases Observed directional phenotypic change in a population (Grants observations of Darwins finches in the Galapagos) A eukaryotic example that describes evolution of a structure or process such as heart chambers, limbs, the brain and the immune system

56 Learning Objectives

Learning Objectives

LO 1.25 The student is able to describe a model that represents evolution within a population. [See SP 1.2] LO 1.26 The student is able to evaluate given data sets that illustrate evolution as an ongoing process. [See SP 5.3]

57 Essential knowledge 1.D.1: There are several hypotheses about the

Essential knowledge 1.D.1: There are several hypotheses about the

natural origin of life on Earth, each with supporting scientific evidence. Scientific evidence supports the various models. Evidence of student learning is a demonstrated understanding of each of the following: Primitive Earth provided inorganic precursors from which organic molecules could have been synthesized due to the presence of available free energy and the absence of a significant quantity of oxygen. 2. In turn, these molecules served as monomers or building blocks for the formation of more complex molecules, including amino acids and nucleotides. [See also 4.A.1] 3. The joining of these monomers produced polymers with the ability to replicate, store and transfer information. 4. These complex reaction sets could have occurred in solution (organic soup model) or as reactions on solid reactive surfaces. [See also 2.B.1] 5. The RNA World hypothesis proposes that RNA could have been the earliest genetic material.

58 Learning Objectives

Learning Objectives

LO 1.27 The student is able to describe a scientific hypothesis about the origin of life on Earth. [See SP 1.2] LO 1.28 The student is able to evaluate scientific questions based on hypotheses about the origin of life on Earth. [See SP 3.3] LO 1.29 The student is able to describe the reasons for revisions of scientific hypotheses of the origin of life on Earth. [See SP 6.3] LO 1.30 The student is able to evaluate scientific hypotheses about the origin of life on Earth. [See SP 6.5] LO 1.31 The student is able to evaluate the accuracy and legitimacy of data to answer scientific questions about the origin of life on Earth. [See SP 4.4]

59 Concept 25

Concept 25

1: Conditions on early Earth made the origin of life possible

Chemical and physical processes on early Earth may have produced very simple cells through a sequence of stages: 1. Abiotic synthesis of small organic molecules 2. Joining of these small molecules into macromolecules 3. Packaging of molecules into protocells 4. Origin of self-replicating molecules

60 Early Earth

Early Earth

Spontaneous generation vs. biogenesis. Although there is no evidence that spontaneous generation occurs today, conditions on the early Earth were very different. There was very little atmospheric oxygen to attack complex molecules. Energy sources, such as lightning, volcanic activity, and ultraviolet sunlight, were more intense than what we experience today.

61 Abiotic synthesis of organic molecules is a testable hypothesis

Abiotic synthesis of organic molecules is a testable hypothesis

In the 1920s, A.I. Oparin and J.B.S. Haldane independently postulated that conditions on the early Earth favored the synthesis of organic compounds from inorganic precursors. They reasoned that this cannot happen today because high levels of oxygen in the atmosphere attack chemical bonds.

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62 In 1953, Stanley Miller and Harold Urey tested the Oparin-Haldane

In 1953, Stanley Miller and Harold Urey tested the Oparin-Haldane

hypothesis by creating, in the laboratory, the conditions that had been postulated for early Earth. They discharged sparks in an atmosphere of gases and water vapor.

Fig. 26.10

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63 Organize the following terms into a flowchart
64 The Miller-Urey experiments still stimulate debate on the origin of

The Miller-Urey experiments still stimulate debate on the origin of

Earths early stockpile of organic ingredients. Alternate sites proposed for the synthesis of organic molecules include submerged volcanoes and deep-sea vents where hot water and minerals gush into the deep ocean. Another possible source for organic monomers on Earth is from space, including via meteorites containing organic molecules that crashed to Earth. (Amino acids have been found in meteorites)

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65 Laboratory simulations of early-Earth conditions have produced organic

Laboratory simulations of early-Earth conditions have produced organic

polymers

The abiotic origin hypothesis predicts that monomers should link to form polymers without enzymes and other cellular equipment. Researchers have produced polymers, including polypeptides, after dripping solutions of monomers onto hot sand, clay, or rock. Similar conditions likely existed on the early Earth when dilute solutions of monomers splashed onto fresh lava or at deep-sea vents.

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66 RNA may have been the first genetic material

RNA may have been the first genetic material

Life is defined partly by inheritance. Today, cells store their genetic information as DNA, transcribe select sections into RNA, and translate the RNA messages into enzymes and other proteins. Many researchers have proposed that the first hereditary material was RNA, not DNA. RNA WORLD Because RNA can also function as an enzymes, it helps resolve the paradox of which came first, genes or enzymes.

67 Short polymers of ribonucleotides can be synthesized abiotically in

Short polymers of ribonucleotides can be synthesized abiotically in

the laboratory. If these polymers are added to a solution of ribonucleotide monomers, sequences up to 10 based long are copied from the template according to the base-pairing rules. If zinc is added, the copied sequences may reach 40 nucleotides with less than 1% error.

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Fig. 26.11

68 In the 1980s Thomas Cech discovered that RNA molecules are important

In the 1980s Thomas Cech discovered that RNA molecules are important

catalysts in modern cells. RNA catalysts, called ribozymes, remove introns from RNA. Ribozymes also help catalyze the synthesis of new RNA polymers. In the pre-biotic world, RNA molecules may have been fully capable of ribozyme-catalyzed replication.

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69 RNA-directed protein synthesis may have begun as weak binding of

RNA-directed protein synthesis may have begun as weak binding of

specific amino acids to bases along RNA molecules, which functioned as simple templates holding a few amino acids together long enough for them to be linked. This is one function of rRNA today in ribosomes. If RNA synthesized a short polypeptide that behaved as an enzyme helping RNA replication, then early chemical dynamics would include molecular cooperation as well as competition.

70 Protocells can form by self-assembly

Protocells can form by self-assembly

Living cells may have been preceded by protocells, aggregates of abiotically produced molecules. Protocells do not reproduce precisely, but they do maintain an internal chemical environment from their surroundings and may show some properties associated with life, metabolism, and excitability.

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71 In the laboratory, droplets of abiotically produced organic compounds,

In the laboratory, droplets of abiotically produced organic compounds,

called liposomes, form when lipids are included in the mix. The lipids form a molecular bilayer at the droplet surface, much like the lipid bilayer of a membrane. These droplets can undergo osmotic swelling or shrinking in different salt concentrations. They also store energy as a membrane potential, a voltage cross the surface.

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72 Liposomes behave dynamically, growing by engulfing smaller liposomes

Liposomes behave dynamically, growing by engulfing smaller liposomes

or giving birth to smaller liposomes.

Fig. 26.12a

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73 If enzymes are included among the ingredients, they are incorporated

If enzymes are included among the ingredients, they are incorporated

into the droplets. The protocells are then able to absorb substrates from their surroundings and release the products of the reactions catalyzed by the enzymes.

Fig. 26.12b

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74 Natural section could refine protocells containing hereditary

Natural section could refine protocells containing hereditary

information

Once primitive RNA genes and their polypeptide products were packaged within a membrane, the protocells could have evolved as units. Molecular cooperation could be refined because favorable components were concentrated together, rather than spread throughout the surroundings.

Fig. 26.13

75 As an example: suppose that an RNA molecule ordered amino acids into a

As an example: suppose that an RNA molecule ordered amino acids into a

primitive enzyme that extracted energy from inorganic sulfur compounds taken up from the surroundings This energy could be used for other reactions within the protobiont, including the replication of RNA. Natural selection would favor such a gene only if its products were kept close by, rather than being shared with competing RNA sequences in the environment.

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76 The most successful protocells would grow and split, distributing

The most successful protocells would grow and split, distributing

copies of their genes to offspring. Even if only one such protocell arose initially by the abiotic processes that have been described, its descendents would vary because of mutation, errors in copying RNA.

Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

77 Evolution via differential reproductive success of varied individuals

Evolution via differential reproductive success of varied individuals

presumably refined primitive metabolism and inheritance. One refinement was the replacement of RNA as the repository of genetic information by DNA, a more stable molecule. Once DNA appeared, RNA molecules would have begun to take on their modern roles as intermediates in translation of genetic programs.

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78 Essential knowledge 1.D.2: Scientific evidence from many different

Essential knowledge 1.D.2: Scientific evidence from many different

disciplines supports models of the origin of life. a. Geological evidence provides support for models of the origin of life on Earth. Evidence of student learning is a demonstrated understanding of each of the following: 1. The Earth formed approximately 4.6 billion years ago (bya), and the environment was too hostile for life until 3.9 bya, while the earliest fossil evidence for life dates to 3.5 bya. Taken together, this evidence provides a plausible range of dates when the origin of life could have occurred. 2. Chemical experiments have shown that it is possible to form complex organic molecules from inorganic molecules in the absence of life. b. Molecular and genetic evidence from extant and extinct organisms indicates that all organisms on Earth share a common ancestral origin of life. Evidence of student learning is a demonstrated understanding of each of the following: 1. Scientific evidence includes molecular building blocks that are common to all life forms. 2. Scientific evidence includes a common genetic code.

79 Animation: The Geologic Record Right-click slide / select Play

Animation: The Geologic Record Right-click slide / select Play

80 Present

Present

Cenozoic

65.5

135

Millions of years ago

Mesozoic

251

Paleozoic

Figure 25.14

Eurasia

North America

Africa

India

South America

Australia

Antarctica

Laurasia

Gondwana

Pangaea

Madagascar

81 Continental drift has many effects on living organisms A continents

Continental drift has many effects on living organisms A continents

climate can change as it moves north or south Separation of land masses can lead to allopatric speciation The distribution of fossils and living groups reflects the historic movement of continents For example, the similarity of fossils in parts of South America and Africa is consistent with the idea that these continents were formerly attached

82 Mass Extinctions

Mass Extinctions

The fossil record shows that most species that have ever lived are now extinct Extinction can be caused by changes to a species environment At times, the rate of extinction has increased dramatically and caused a mass extinction Mass extinction is the result of disruptive global environmental changes

83 A number of factors might have contributed to these extinctions

A number of factors might have contributed to these extinctions

Intense volcanism in what is now Siberia Global warming resulting from the emission of large amounts of CO2 from the volcanoes Reduced temperature gradient from equator to poles Oceanic anoxia from reduced mixing of ocean waters

84 The Cretaceous mass extinction 65

The Cretaceous mass extinction 65

5 million years ago separates the Mesozoic from the Cenozoic Organisms that went extinct include about half of all marine species and many terrestrial plants and animals, including most dinosaurs

85 The presence of iridium in sedimentary rocks suggests a meteorite

The presence of iridium in sedimentary rocks suggests a meteorite

impact about 65 million years ago Dust clouds caused by the impact would have blocked sunlight and disturbed global climate The Chicxulub crater off the coast of Mexico is evidence of a meteorite that dates to the same time

86 NORTH AMERICA

NORTH AMERICA

Chicxulub crater

Yucat?n Peninsula

Figure 25.16

87 Is a Sixth Mass Extinction Under Way

Is a Sixth Mass Extinction Under Way

Scientists estimate that the current rate of extinction is 100 to 1,000 times the typical background rate Extinction rates tend to increase when global temperatures increase Data suggest that a sixth, human-caused mass extinction is likely to occur unless dramatic action is taken

88 Adaptive Radiations

Adaptive Radiations

Adaptive radiation is the evolution of diversely adapted species from a common ancestor Adaptive radiations may follow Mass extinctions The evolution of novel characteristics The colonization of new regions

89 Worldwide Adaptive Radiations

Worldwide Adaptive Radiations

Mammals underwent an adaptive radiation after the extinction of terrestrial dinosaurs The disappearance of dinosaurs (except birds) allowed for the expansion of mammals in diversity and size Other notable radiations include photosynthetic prokaryotes, large predators in the Cambrian, land plants, insects, and tetrapods

90 Clock analogy of History of Life

Clock analogy of History of Life

Fig. 26.2

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91 The First Single-Celled Organisms

The First Single-Celled Organisms

The oldest known fossils are stromatolites, rocks formed by the accumulation of sedimentary layers on bacterial mats Stromatolites date back 3.5 billion years ago Prokaryotes were Earths sole inhabitants from 3.5 to about 2.1 billion years ago

92 The First Eukaryotes

The First Eukaryotes

The oldest fossils of eukaryotic cells date back 2.1 billion years Eukaryotic cells have a nuclear envelope, mitochondria, endoplasmic reticulum, and a cytoskeleton The endosymbiont theory proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells An endosymbiont is a cell that lives within a host cell

93 The prokaryotic ancestors of mitochondria and plastids probably gained

The prokaryotic ancestors of mitochondria and plastids probably gained

entry to the host cell as undigested prey or internal parasites In the process of becoming more interdependent, the host and endosymbionts would have become a single organism Serial endosymbiosis supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events

94 Plasma membrane

Plasma membrane

Cytoplasm

DNA

Ancestral prokaryote

Nucleus

Endoplasmic reticulum

Photosynthetic prokaryote

Mitochondrion

Nuclear envelope

Aerobic heterotrophic prokaryote

Mitochondrion

Plastid

Ancestral heterotrophic eukaryote

Ancestral photosynthetic eukaryote

Figure 25.9-3

95 Key evidence supporting an endosymbiotic origin of mitochondria and

Key evidence supporting an endosymbiotic origin of mitochondria and

plastids: Inner membranes are similar to plasma membranes of prokaryotes Division is similar in these organelles and some prokaryotes These organelles transcribe and translate their own DNA Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes

96 Plants, fungi, and animals colonized the land about 500 million years

Plants, fungi, and animals colonized the land about 500 million years

ago

The colonization of land was one of the pivotal milestones in the history of life. There is fossil evidence that cyanobacteria and other photosynthetic prokaryotes coated damp terrestrial surfaces well over a billion years ago. However, macroscopic life in the form of plants, fungi, and animals did not colonize land until about 500 million years ago, during the early Paleozoic era.

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97 The gradual evolution from aquatic to terrestrial habitats required

The gradual evolution from aquatic to terrestrial habitats required

adaptations to prevent dehydration and to reproduce on land. For example, plants evolved a waterproof coating of wax on the leaves to slow the loss of water. Plants colonized land in association with fungi. Fungi aid the absorption of water and nutrients from the soil. The fungi obtain organic nutrients from the plant. This ancient symbiotic association is evident in some of the oldest fossilized roots.

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98 Plants created new opportunities for all life, including herbivorous

Plants created new opportunities for all life, including herbivorous

(plant-eating) animals and their predators. The most widespread and diverse terrestrial animals are certain arthropods (including insects and spiders) and certain vertebrates (including amphibians, reptiles, birds, and mammals).

Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

99 The terrestrial vertebrates, called tetrapods because of their four

The terrestrial vertebrates, called tetrapods because of their four

walking limbs, evolved from fishes, based on an extensive fossil record. Reptiles evolved from amphibians, both birds and mammals evolved from reptiles. Most orders of modern mammals, including primates, appeared 50-60 million years ago. Humans diverged from other primates only 5 million years ago.

Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

100 Learning Objectives

Learning Objectives

LO 1.32 The student is able to justify the selection of geological, physical, and chemical data that reveal early Earth conditions. [See SP 4.1]

101 Essential knowledge 2.E.1: Timing and coordination of specific events

Essential knowledge 2.E.1: Timing and coordination of specific events

are necessary for the normal development of an organism, and these events are regulated by a variety of mechanisms. Observable cell differentiation results from the expression of genes for tissue-specific proteins. b. Induction of transcription factors during development results in sequential gene expression. Evidence of student learning is a demonstrated understanding of each of the following: 1. Homeotic genes are involved in developmental patterns and sequences. 2. Embryonic induction in development results in the correct timing of events. 3. Temperature and the availability of water determine seed germination in most plants. 4. Genetic mutations can result in abnormal development. 5. Genetic transplantation experiments support the link between gene expression and normal development. 6. Genetic regulation by microRNAs plays an important role in the development of organisms and the control of cellular functions.

102 Concept 25

Concept 25

5: Major changes in body form can result from changes in the sequences and regulation of developmental genes

Studying genetic mechanisms of change can provide insight into large-scale evolutionary change

103 Changes in Rate and Timing

Changes in Rate and Timing

Heterochrony is an evolutionary change in the rate or timing of developmental events It can have a significant impact on body shape The contrasting shapes of human and chimpanzee skulls are the result of small changes in relative growth rates

104 Changes in Spatial Pattern

Changes in Spatial Pattern

Substantial evolutionary change can also result from alterations in genes that control the placement and organization of body parts Homeotic genes determine such basic features as where wings and legs will develop on a bird or how a flowers parts are arranged

105 Hox genes are a class of homeotic genes that provide positional

Hox genes are a class of homeotic genes that provide positional

information during development If Hox genes are expressed in the wrong location, body parts can be produced in the wrong location For example, in crustaceans, a swimming appendage can be produced instead of a feeding appendage

106 The Evolution of Development

The Evolution of Development

The tremendous increase in diversity during the Cambrian explosion is a puzzle Developmental genes may play an especially important role Changes in developmental genes can result in new morphological forms

107 Changes in Genes

Changes in Genes

New morphological forms likely come from gene duplication events that produce new developmental genes A possible mechanism for the evolution of six-legged insects from a many-legged crustacean ancestor has been demonstrated in lab experiments Specific changes in the Ubx gene have been identified that can turn off leg development

108 Hox gene 6

Hox gene 6

Hox gene 7

Hox gene 8

Ubx

About 400 mya

Artemia

Drosophila

Figure 25.24

109 Changes in Gene Regulation

Changes in Gene Regulation

Changes in morphology likely result from changes in the regulation of developmental genes rather than changes in the sequence of developmental genes For example, threespine sticklebacks in lakes have fewer spines than their marine relatives The gene sequence remains the same, but the regulation of gene expression is different in the two groups of fish

110 RESULTS

RESULTS

Result: No

The 283 amino acids of the Pitx1 protein are identical.

Test of Hypothesis A: Differences in the coding sequence of the Pitx1 gene?

Pitx1 is expressed in the ventral spine and mouth regions of developing marine sticklebacks but only in the mouth region of developing lake sticklebacks.

Result: Yes

Test of Hypothesis B: Differences in the regulation of expression of Pitx1?

Marine stickleback embryo

Lake stickleback embryo

Close-up of mouth

Close-up of ventral surface

Figure 25.25b

111 Learning Objectives

Learning Objectives

LO 2.31 The student can connect concepts in and across domains to show that timing and coordination of specific events are necessary for normal development in an organism and that these events are regulated by multiple mechanisms. [See SP 7.2] LO 2.32 The student is able to use a graph or diagram to analyze situations or solve problems (quantitatively or qualitatively) that involve timing and coordination of events necessary for normal development in an organism. [See SP 1.4] LO 2.33 The student is able to justify scientific claims with scientific evidence to show that timing and coordination of several events are necessary for normal development in an organism and that these events are regulated by multiple mechanisms. [See SP 6.1] LO 2.34 The student is able to describe the role of programmed cell death in development and differentiation, the reuse of molecules, and the maintenance of dynamic homeostasis. [See SP 7.1]

112 Essential knowledge 3.C.1: Changes in genotype can result in changes

Essential knowledge 3.C.1: Changes in genotype can result in changes

in phenotype. Alterations in a DNA sequence can lead to changes in the type or amount of the protein produced and the consequent phenotype. [See also 3.A.1] Evidence of student learning is a demonstrated understanding of the following: DNA mutations can be positive, negative or neutral based on the effect or the lack of effect they have on the resulting nucleic acid or protein and the phenotypes that are conferred by the protein. b. Errors in DNA replication or DNA repair mechanisms, and external factors, including radiation and reactive chemicals, can cause random changes, e.g., mutations in the DNA. Evidence of student learning is a demonstrated understanding of the following: 1. Whether or not a mutation is detrimental, beneficial or neutral depends on the environmental context. Mutations are the primary source of genetic variation.

113 c. Errors in mitosis or meiosis can result in changes in phenotype

c. Errors in mitosis or meiosis can result in changes in phenotype

Evidence of student learning is a demonstrated understanding of each of the following: Changes in chromosome number often result in new phenotypes, including sterility caused by triploidy and increased vigor of other polyploids. [See also 3.A.2] 2. Changes in chromosome number often result in human disorders with developmental limitations, including Trisomy 21 (Down syndrome) and XO (Turner syndrome). [See also 3.A.2, 3.A.3] d. Changes in genotype may affect phenotypes that are subject to natural selection. Genetic changes that enhance survival and reproduction can be selected by environmental conditions. [See also 1.A.2, 1.C.3] To foster student understanding of this concept, instructors can choose an illustrative example such as: Antibiotic resistance mutations Pesticide resistance mutations Sickle cell disorder and heterozygote advantage Evidence of student learning is a demonstrated understanding of the following: 1. Selection results in evolutionary change.

114 Learning Objectives

Learning Objectives

LO 3.24 The student is able to predict how a change in genotype, when expressed as a phenotype, provides a variation that can be subject to natural selection. [See SP 6.4, 7.2] LO 3.25 The student can create a visual representation to illustrate how changes in a DNA nucleotide sequence can result in a change in the polypeptide produced. [See SP 1.1] LO 3.26 The student is able to explain the connection between genetic variations in organisms and phenotypic variations in populations. [See SP 7.2]

115 Concept 27

Concept 27

2: Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes

Prokaryotes have considerable genetic variation Three factors contribute to this genetic diversity: Rapid reproduction Mutation Genetic recombination

116 Essential knowledge 3.C.2: Biological systems have multiple processes

Essential knowledge 3.C.2: Biological systems have multiple processes

that increase genetic variation. The imperfect nature of DNA replication and repair increases variation. b. The horizontal acquisitions of genetic information primarily in prokaryotes via transformation (uptake of naked DNA), transduction (viral transmission of genetic information), conjugation (cell-to-cell transfer) and transposition (movement of DNA segments within and between DNA molecules) increase variation. [See also 1.B.3] ?? Details and specifics about the various processes are beyond the scope of the course and the AP Exam. c. Sexual reproduction in eukaryotes involving gamete formation, including crossing-over during meiosis and the random assortment of chromosomes during meiosis, and fertilization serve to increase variation. Reproduction processes that increase genetic variation are evolutionarily conserved and are shared by various organisms. [See also 1.B.1, 3.A.2, 4.C.2, 4. C3] ?? The details of sexual reproduction cycles in various plants and animals are beyond the scope of the course and the AP Exam. However, the similarities of the processes that provide for genetic variation are relevant and should be the focus of instruction.

117 Learning Objectives

Learning Objectives

LO 3.27 The student is able to compare and contrast processes by which genetic variation is produced and maintained in organisms from multiple domains. [See SP 7.2] LO 3.28 The student is able to construct an explanation of the multiple processes that increase variation within a population. [See SP 6.2]

118 Essential knowledge 4.C.3: The level of variation in a population

Essential knowledge 4.C.3: The level of variation in a population

affects population dynamics. a. Population ability to respond to changes in the environment is affected by genetic diversity. Species and populations with little genetic diversity are at risk for extinction. [See also 1.A.1, 1.A.2, 1.C.1] To foster student understanding of this concept, instructors can choose an illustrative example such as: California condors Black-footed ferrets Prairie chickens Potato blight causing the potato famine Corn rust affects on agricultural crops Tasmanian devils and infectious cancer b. Genetic diversity allows individuals in a population to respond differently to the same changes in environmental conditions. To foster student understanding of this concept, instructors can choose an illustrative example such as: Not all animals in a population stampede. Not all individuals in a population in a disease outbreak are equally affected; some may not show symptoms, some may have mild symptoms, or some may be naturally immune and resistant to the disease. c. Allelic variation within a population can be modeled by the Hardy- Weinberg equation(s). [See also 1.A.1]

119 Bottleneck Effect

Bottleneck Effect

Original population

Bottlenecking event

Surviving population

Figure 23.10-3

120 Case Study: Impact of Genetic Drift on the Greater Prairie Chicken

Case Study: Impact of Genetic Drift on the Greater Prairie Chicken

Loss of prairie habitat caused a severe reduction in the population of greater prairie chickens in Illinois The surviving birds had low levels of genetic variation, and only 50% of their eggs hatched

121 Figure 23

Figure 23

11

Post-bottleneck (Illinois, 1993)

Pre-bottleneck (Illinois, 1820)

Greater prairie chicken

Range of greater prairie chicken

(a)

Percentage of eggs hatched

Number of alleles per locus

Population size

Location

Illinois 19301960s 1993

5.2 3.7

1,00025,000 <50

93 <50

Kansas, 1998 (no bottleneck)

750,000

99

5.8

Nebraska, 1998 (no bottleneck)

75,000 200,000

5.8

96

(b)

122 Researchers used DNA from museum specimens to compare genetic

Researchers used DNA from museum specimens to compare genetic

variation in the population before and after the bottleneck The results showed a loss of alleles at several loci Researchers introduced greater prairie chickens from populations in other states and were successful in introducing new alleles and increasing the egg hatch rate to 90%

123 Effects of Genetic Drift: A Summary

Effects of Genetic Drift: A Summary

Genetic drift is significant in small populations Genetic drift causes allele frequencies to change at random Genetic drift can lead to a loss of genetic variation within populations Genetic drift can cause harmful alleles to become fixed

124 Learning Objectives

Learning Objectives

LO 4.25 The student is able to use evidence to justify a claim that a variety of phenotypic responses to a single environmental factor can result from different genotypes within the population. [See SP 6.1] LO 4.26 The student is able to use theories and models to make scientific claims and/or predictions about the effects of variation within populations on survival and fitness. [See SP 6.4]

125 Essential knowledge 4.C.4: The diversity of species within an

Essential knowledge 4.C.4: The diversity of species within an

ecosystem may influence the stability of the ecosystem. a. Natural and artificial ecosystems with fewer component parts and with little diversity among the parts are often less resilient to changes in the environment. [See also 1.C.1] b. Keystone species, producers, and essential abiotic and biotic factors contribute to maintaining the diversity of an ecosystem. The effects of keystone species on the ecosystem are disproportionate relative to their abundance in the ecosystem, and when they are removed from the ecosystem, the ecosystem often collapses.

126 Learning Objectives

Learning Objectives

LO 4.27 The student is able to make scientific claims and predictions about how species diversity within an ecosystem influences ecosystem stability. [See SP 6.4]

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