Natural selection is a process that leads to evolution through changes in a species' genetic makeup over time.
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Topic 1: Introduction to Natural Selection
Learning Objectives
7.1.A: Describe the causes of natural selection.
7.1.B: Explain how natural selection affects populations.
Vocabulary/Review Questions
True or false: natural selection acts on genotypes.
True or false: organisms can adapt to their environments if they try to.
Fill in the blank: If an organism has a more favorable trait, then it will be more likely to and .
Natural selection only does what is best for the species. Do you agree with this statement? Why or why not?
Fill in the blank: Evolutionary fitness is measured by success.
Why is evolution a theory?
How is our general understanding of the phrase “survival of the fittest” misleading?
Essential Knowledge
7.1.A.1: Natural selection is a major mechanism of evolution.
7.1.A.2: According to Darwin’s 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.
7.1.B.1: Evolutionary fitness is measured by reproductive success.
7.1.B.2: Biotic and abiotic environments can be stable or fluctuating, which affects the rate and direction of evolution. Different genetic variations can be selected in each generation.
Topic 2: Natural Selection
Learning Objectives
7.2.A: Describe the importance of phenotypic variation in a population.
7.2.B: Explain how variation in molecules within cells connects to the fitness of an organism.
Vocabulary/Review Questions
Can an organism’s physical environment influence evolutionary change? Why or why not?
Research an example of natural selection and identify the selective pressure.
Organisms of the same species with different genotypes will always have different phenotypes. Do you agree with this statement? Why or why not?
Essential Knowledge
7.2.A.1: Natural selection acts on phenotypic variations in populations.
7.2.A.2: Environments change and apply selective pressures to populations.
7.2.A.3: Some phenotypic variations significantly increase or decrease the fitness of the organism in particular environments.
7.2.B.1: Variation in the number and types of molecules within cells can provide populations a greater ability to survive and reproduce in different environments.
Topic 3: Artificial Selection
Learning Objectives
7.3.A: Explain how humans can affect diversity within a population.
Vocabulary/Review Questions
How does artificial selection differ from natural selection?
How did artificial selection influence Darwin’s thinking?
Essential Knowledge
7.3.A.1: Through artificial selection, humans affect variation in other species.
Topic 4: Population Genetics
Learning Objectives
7.4.A: Explain how random occurrences affect the genetic makeup of a population.
7.4.B: Describe the role of random processes in the evolution of specific populations.
7.4.C: Describe the change in the genetic makeup of a population over time.
Vocabulary/Review Questions
What factors contribute to phenotypic variation in a population?
What does the phrase “non-selective pressures” mean?
Why is genetic variation important to survival?
Research the bottleneck effect on cheetahs.
a. What has happened to their population?
b. How has this affected their genetic diversity?
c. If a new disease were to be introduced into the cheetah population, what effect could it have? Why? Be specific.
True or false: mutations can lead to new alleles.
Draw a diagram for directional, stabilizing, and disruptive selection.
How is sexual selection similar to directional selection?
Essential Knowledge
7.4.A.1: Evolution is driven by random occurrences.
i. Mutation is a random process that adds new genetic variation to a population.
ii. Genetic drift is a change in allele frequencies attributable to a non-selective process occurring in small populations.
iii. The bottleneck effect is a type of genetic drift that occurs when a population size is reduced to a small number of individuals for at least one generation.
iv. The founder effect is a type of genetic drift that occurs when a population is separated from its rest and it results in a gene pool that differs from the original population.
v. Migration can result in gene flow, which is the addition or removal of alleles from a population.
7.4.B.1: Random processes can lead to changes in allele frequencies in a population.
i. Mutations result in genetic variation, which provides phenotypes on which natural selection acts.
ii. Genetic drift can allow a small population to diverge from other populations of the same species.
iii. Gene flow between two populations prevents them from diverging into separate species.
7.4.C.1: Changes in allele frequencies provide evidence for the occurrence of evolution in a population.
Topic 5: Hardy-Weinberg Equilibrium
Learning Objectives
7.5.A: Describe the conditions under which allele and genotype frequencies will change in populations.
Vocabulary/Review Questions
What is the difference between genotype frequencies and phenotype frequencies in a population?
Is the Hardy-Weinberg model realistic?
What are the five conditions that must be met for a population to be in Hardy-Weinberg equilibrium?
The frequency of individuals who express a recessive disease in a population is 5%. What variable in the Hardy-Weinberg equations does the 5% refer to? Why?
No dimples (D) is dominant to dimples (d). If there are 350 people with no dimples in a population of 500 people. What are the predicted frequencies for heterozygotes?
White fur color (w) is recessive to black fur color (W) in mice. 22 mice have a white coat in a population of 200. Knowing this, calculate the frequency of the r allele.
Essential Knowledge
7.5.A.1: The Hardy-Weinberg model describes and predicts allele frequencies in a non-evolving population and serves as a valuable null hypothesis.
Conditions:
Large population size.
No migration.
No new mutations.
Random mating.
No natural selection.
7.5.A.2: Allele frequencies in a non-evolving population can be calculated from genotype frequencies.
Hardy-Weinberg Equation: p^2 + 2pq + q^2 = 1
Where:
p = frequency of allele 1 in the population
q = frequency of allele 2 in the population
p + q = 1
Topic 6: Evidence of Evolution
Learning Objectives
7.6.A: Describe the types of data that provide evidence for evolution.
7.6.B: Explain how morphological, biochemical, and geological data provide evidence that organisms have changed over time.
Vocabulary/Review Questions
In what ways is evolution supported (i.e., what are some evidences of evolution?)
From the evidences you listed in question #1, which would give scientists the most accurate information?
Does the fossil record provide a complete picture of life in the past? Why or why not?
Why might species that live in different geographical areas sometimes resemble each other?
How do homologous structures differ from analogous structures?
What are some vestigial structures in humans? Describe what these structures/features may have been useful for in the past.
How is it possible for two species that look similar, to be less related than two species who look completely different?
What does it mean if a trait is “highly conserved”?
When comparing DNA sequences of two closely related species what would you expect to find? What about between two distantly related species?
Essential Knowledge
7.6.A.1: Evolution is supported by scientific evidence from many disciplines.
7.6.B.1: Molecular, morphological, and genetic evidence from extant and extinct organisms adds to our understanding of evolution.
i. Fossils can be dated by:
The age of the rocks where a fossil is found.
The rate of decay of isotopes including carbon-14.
Geographical data.
ii. Morphological homologies, including vestigial structures, represent features shared by common ancestry.
7.6.B.2: A comparison of DNA nucleotide sequences and/or protein amino acid sequences provides evidence for evolution and common ancestry.
Topic 7: Common Ancestry
Learning Objectives
7.7.A: Describe structural and functional evidence on cellular and molecular levels that provides evidence for the common ancestry of all eukaryotes.
Vocabulary/Review Questions
How does the idea of descent with modification explain the unity and diversity of life?
Essential Knowledge
7.7.A.1: Structural and functional evidence indicates common ancestry of all eukaryotes, including:
a. Membrane-bound organelles
b. Linear chromosomes
c. Genes that contain introns
Topic 8: Continuing Evolution
Learning Objectives
7.8.A: Explain how evolution is an ongoing process in all living organisms.
Vocabulary/Review Questions
Explain how evolution is an ongoing process in all living organisms.
What evidence supports your explanation to problem #1?
What are “emergent diseases”? How do they come about?
Due to the over-prescription of antibiotics, many strains of bacteria are developing resistance. Can this resistance evolve? Explain your reasoning.
Think back to unit 6, where are genes that code for antibiotic resistance found in bacteria?
Essential Knowledge
7.8.A.1: All species have evolved and continue to evolve.
Examples include:
i. Genomic changes over time.
ii. Continuous change in the fossil record.
iii. Evolution of resistance to antibiotics, pesticides, herbicides, or chemotherapy drugs.
iv. Pathogens evolve and cause emergent diseases.
Topic 9: Phylogeny
Learning Objectives
7.9.A: Describe the types of evidence that can be used to infer an evolutionary relationship.
7.9.B: Explain how phylogenetic trees and cladograms can be used to infer evolutionary relatedness.
Vocabulary/Review Questions
What is the main difference between phylogenetic trees and cladograms?
List at least 3 items, or pieces of “evidence” that can be used to create a cladogram/phylogenetic tree.
Most species of butterflies have six walking legs, while some species have four walking legs and two non-walking legs. How does the comparison to the non-butterfly outgroup help identify derived and ancestral characters?
How can the principle of parsimony be applied to phylogenetics?
Why might analyzing DNA sequences be more accurate than analyzing amino acid sequences when creating a phylogenetic tree?
Draw three basic cladograms to demonstrate the difference between monophyletic, paraphyletic, and polyphyletic groups.
Fill in the blank: Nodes represent ___.
Essential Knowledge
7.9.A.1: Phylogenetic trees and cladograms show hypothetical evolutionary relationships among lineages that can be tested.
7.9.A.2: Phylogenetic trees show the amount of change over time calibrated by fossils or a molecular clock, whereas cladograms do not show time scale or the evolutionary difference between groups.
7.9.A.3: Traits that are either gained or lost during evolution can be used to construct phylogenetic trees and cladograms. The out-group represents the lineage that is least closely related to others in the tree.
i. Shared derived characters can be present in more than one lineage and indicate common ancestry.
ii. Molecular data typically provide more accurate and reliable evidence than morphological traits.
7.9.B.1: Phylogenetic trees and cladograms can illustrate speciation that has occurred and represent the most recent common ancestor.
7.9.B.2: Can be constructed from morphological similarities and from DNA and protein sequence similarities.
7.9.B.3: Represent hypotheses that are constantly being revised.
Topic 10: Speciation
Learning Objectives
7.10.A: Describe the conditions under which new species may arise.
7.10.B: Describe the rate of evolution and speciation under different ecological conditions.
7.10.C: Explain the processes and mechanisms that drive speciation.
Vocabulary/Review Questions
True or False: a species can diverge while living in the same geographical area.
In general, how are prezygotic and postzygotic barriers similar? In general, how are they different?
If the Vogelkop Superb Bird-of-Paradise performs its unique courtship dance in a different area, what would you expect to happen? Why?
How can natural selection promote reproductive isolation in allopatric and sympatric speciation?
Essential Knowledge
7.10.A.1: Speciation may occur when two populations become reproductively isolated.
7.10.A.2: The biological species concept defines species as groups that can interbreed and produce viable, fertile offspring.
7.10.B.1: Punctuated equilibrium means rapid evolution after long periods of stasis. Gradualism means slow evolution over long periods.
7.10.B.2: Divergent evolution happens through adaptation. Rapid speciation can occur during adaptive radiation.
7.10.B.3: Convergent evolution results in similar adaptations due to similar selective pressures.
7.10.C.1: Sympatric speciation occurs with geographic overlap, while allopatric speciation occurs with geographic isolation.
7.10.C.2: Prezygotic and postzygotic mechanisms can maintain reproductive isolation and prevent gene flow.
Topic 11: Variations in Populations
Learning Objectives
7.11.A: Explain how the genetic diversity of a species or population affects its ability to withstand environmental pressures.
Vocabulary/Review Questions
How does species diversity correlate to the survival of the species?
Research an endangered species.
a. Identify the species.
b. How many individuals are currently living?
c. What caused the species to become endangered?
d. How does the low number affect genetic diversity?
e. Why are low-number species at higher risk of extinction?
f. How does genetic diversity affect species' survival against environmental pressures?
Essential Knowledge
7.11.A.1: The level of variation in a population affects dynamics:
i. A population's ability to respond to environmental changes is influenced by genetic diversity.
ii. Populations with little diversity are at risk of decline/extinction.
iii. Genetically diverse populations are more resilient to changes and likely to survive.
iv. Adaptive traits in one environment may be harmful in another due to selective pressures.
Topic 12: Origins of Life on Earth
Learning Objectives
7.12.A: Describe the scientific evidence that supports models of the origin of life on Earth.
Vocabulary/Review Questions
When did early Earth form?
What is the earliest known fossil?
Describe the Miller Urey experiment.
How does the RNA World Hypothesis explain a pre-cellular stage of life?
What evidence supports the endosymbiotic theory?
Essential Knowledge
7.12.A.1: Life's origins on Earth are supported by scientific evidence, which includes:
i. Geological evidence reinforces origin models.
ii. Earth formed ~4.6 billion years ago, and earliest life dates to ~3.5 billion years ago.
7.12.A.2: The RNA World Hypothesis proposes that RNA was the earliest genetic material.
Assumptions:
Genetic continuity assured by RNA replication.
Base-pairing necessary for replication.
Catalysts did not involve genetically encoded proteins.
Additional Points
Charles Darwin
Notable research at the Galapagos Islands focusing on species variation.
Suggested that organisms left the mainland, colonized the islands, and gradually evolved into new species.
Evolutionary Theories and True/False Game
Explored misconceptions about natural selection, adaptation, and evolutionary change.
Natural Selection Mechanisms
Defined natural selection as a process involving differential survival and reproduction based on advantageous traits.
Genetic Diversity and Population Dynamics
Explained that greater genetic diversity enables populations to adapt better to environmental changes.
Evolutionary Changes and Speciation
Described mechanisms of speciation, including reproductive isolation and types of barriers.
Origins and Experiments
Discussed early Earth conditions and experiments demonstrating possible origins of life.
Illustrated the RNA World Hypothesis as a foundational theory for understanding life's beginnings.