25.6-25.13 Selection and Altering Allele Frequency

Flashcard 1
Front: What are the two types of selection?

Back: Selection can be natural selection or artificial selection.

Flashcard 2
Front: What is stabilizing selection?

Back: Stabilizing selection occurs when the environment favors intermediate phenotypes, while extreme phenotypes are selected against. The population distribution narrows toward the mean.

Flashcard 3
Front: What is directional selection?

Back: Directional selection occurs when the environment favors one extreme phenotype, causing the population distribution to shift toward that extreme.

Flashcard 4
Front: What is disruptive selection?

Back: Disruptive selection occurs when the environment favors extreme phenotypes while intermediate phenotypes are selected against, causing the population distribution to diverge from the mean.

Flashcard 5
Front: What is sexual selection?

Back: Sexual selection is the process in which advantageous traits become more common due to differences in mating success.

Flashcard 6
Front: What is sexual dimorphism?

Back: Sexual dimorphism refers to large differences in appearance between males and females of the same species caused by sexual selection.

Flashcard 7
Front: What is intrasexual selection?

Back: Intrasexual selection occurs when individuals of the same sex compete with each other for mating opportunities (e.g., male deer fighting with antlers).

Flashcard 8
Front: What is intersexual selection?

Back: Intersexual selection occurs when individuals of one sex choose mates based on specific traits, usually physical traits (e.g., female birds selecting brightly colored males).

Flashcard 9
Front: Why is inheritance of traits necessary for evolution?

Back: Without trait inheritance, traits that improve survival and reproduction cannot be passed to future generations, so evolution would not occur.

Flashcard 10
Front: What is overproduction in natural selection?

Back: Overproduction means organisms produce more offspring than can survive to maturity due to limited resources.

Flashcard 11
Front: What is variation in natural selection?

Back: Variation means individuals within a population have different characteristics.

Flashcard 12
Front: What is selection in natural selection?

Back: Selection occurs when individuals with advantageous traits survive longer and reproduce more than others.

Flashcard 13
Front: What is adaptation in natural selection?

Back: Adaptation occurs when traits that increase survival and reproduction become more common in a population over time.

Flashcard 14
Front: What is artificial selection?

Back: Artificial selection is when humans selectively breed organisms to promote desirable traits or eliminate undesirable traits (e.g., dog breeding).

Flashcard 15
Front: What is evolution in terms of genetics?

Back: Evolution is defined as changes in allele frequencies within a population over time.

Flashcard 16
Front: What is a gene pool?

Back: A gene pool is all the copies of alleles that exist in a population.

Flashcard 17
Front: What is allele frequency?

Back: Allele frequency is how often a specific allele occurs in a population.

Flashcard 18
Front: What are the five mechanisms that drive evolution?

Back:

1. Natural selection

2. Gene flow

3. Genetic drift

4. Mutation

5. Sexual reproduction / genetic variation mechanisms

Flashcard 19
Front: How does natural selection affect allele frequencies?

Back: Alleles that increase fitness become more frequent in a population over time.

Flashcard 20
Front: What is gene flow?

Back: Gene flow is the transfer of alleles between populations through immigration or emigration.

Flashcard 21
Front: What is immigration?

Back: Immigration is when individuals enter a population and bring new alleles.

Flashcard 22
Front: What is emigration?

Back: Emigration is when individuals leave a population and remove alleles from that population.

Flashcard 23
Front: What is genetic drift?

Back: Genetic drift is a random change in allele frequencies due to chance events, especially in small populations.

Flashcard 24
Front: Why does genetic drift affect small populations more strongly?

Back: Because random events can significantly change allele frequencies when the population size is small.

Flashcard 25
Front: What is the founder effect?

Back: The founder effect occurs when a small group becomes isolated from a larger population, forming a new population with different allele frequencies.

Flashcard 26
Front: What is the bottleneck effect?

Back: The bottleneck effect occurs when a population is drastically reduced by a catastrophic event, leaving a smaller population with altered allele frequencies.

Flashcard 27
Front: What is genetic variation?

Back: Genetic variation refers to differences in genetic makeup among individuals in a population.

Flashcard 28
Front: Why is genetic variation important for evolution?

Back: Evolution occurs when selective pressures make one genetic variant more advantageous than another.

Flashcard 29
Front: What is mutation?

Back: Mutation is a change in the nucleotide sequence of DNA.

Flashcard 30
Front: How can mutations affect genes?

Back: Mutations can delete genes or alter gene number, position, or sequence.

Flashcard 31
Front: How do mutations contribute to evolution?

Back: Mutations introduce new alleles into a population, increasing genetic variation.

Flashcard 32
Front: Why do bacteria accumulate mutations quickly?

Back: Because they have rapid reproduction rates and limited DNA proofreading and repair mechanisms.

Flashcard 33
Front: How does sexual reproduction increase genetic variation?

Back: Through crossing over, independent assortment, and random fertilization, which produce unique allele combinations.

Flashcard 34
Front: What is diploidy?

Back: Diploidy means organisms have two copies of each gene, allowing offspring to inherit different allele combinations.

Flashcard 35
Front: How does diploidy increase genetic variation?

Back: Offspring may inherit either allele from each parent, creating variation.

Flashcard 36
Front: What is outbreeding?

Back: Outbreeding is mating between genetically unrelated individuals, increasing genetic diversity.

Flashcard 37
Front: What is hybrid vigor (heterosis)?

Back: Hybrid vigor occurs when offspring of genetically unrelated individuals show superior traits compared to parents (e.g., mules).

Flashcard 38
Front: What is inbreeding?

Back: Inbreeding is mating between closely related individuals, which increases homozygous genotypes and decreases genetic variation.

Flashcard 39
Front: What is balanced polymorphism?

Back: Balanced polymorphism occurs when multiple alleles are maintained in a population because they provide an advantage.

Flashcard 40
Front: What is heterozygous advantage?

Back: Heterozygous advantage occurs when heterozygotes have greater fitness than either homozygous genotype.

Flashcard 41
Front: What is frequency-dependent selection?

Back: Frequency-dependent selection occurs when the fitness of a phenotype depends on how common it is in a population.

Flashcard 42
Front: What is Hardy-Weinberg equilibrium?

Back: Hardy-Weinberg equilibrium is a hypothetical condition where allele frequencies remain constant across generations and no evolution occurs.

Flashcard 43
Front: What are the five requirements for Hardy-Weinberg equilibrium?

Back:

1. No mutations

2. Random mating

3. No natural selection

4. Large population size

5. No gene flow

Flashcard 44
Front: Why must populations be large for Hardy-Weinberg equilibrium?

Back: Large populations prevent genetic drift from altering allele frequencies.

Flashcard 45
Front: What happens if any Hardy-Weinberg condition is violated?

Back: The population is not in equilibrium and evolution can occur.

Flashcard 46
Front: What is the Hardy-Weinberg genotype equation?

Back: p² + 2pq + q² = 1

Flashcard 47
Front: What does p² represent in Hardy-Weinberg?

Back: Frequency of the homozygous dominant genotype (AA).

Flashcard 48
Front: What does q² represent in Hardy-Weinberg?

Back: Frequency of the homozygous recessive genotype (aa).

Flashcard 49
Front: What does 2pq represent in Hardy-Weinberg?

Back: Frequency of the heterozygous genotype (Aa).

Flashcard 50
Front: What is the Hardy-Weinberg allele equation?

Back: p + q = 1

Flashcard 51
Front: What does p represent in Hardy-Weinberg?

Back: Frequency of the dominant allele (A).

Flashcard 52
Front: What does q represent in Hardy-Weinberg?

Back: Frequency of the recessive allele (a).

Flashcard 53
Front: What is a species?

Back: A species is a group of organisms that is reproductively isolated.

Flashcard 54
Front: What is speciation?

Back: Speciation is the formation of a new species from a common ancestor.

Flashcard 55
Front: What is reproductive isolation?

Back: Reproductive isolation occurs when populations cannot produce viable, fertile offspring together.

Flashcard 56
Front: What is prezygotic isolation?

Back: Prezygotic isolation prevents fertilization and zygote formation.

Flashcard 57
Front: What is habitat isolation?

Back: Habitat isolation occurs when populations live in different geographic areas.

Flashcard 58
Front: What is temporal isolation?

Back: Temporal isolation occurs when populations reproduce or are active at different times.

Flashcard 59
Front: What is behavioral isolation?

Back: Behavioral isolation occurs when different mating behaviors prevent reproduction.

Flashcard 60
Front: What is mechanical isolation?

Back: Mechanical isolation occurs when reproductive structures are incompatible.

Flashcard 61
Front: What is gametic isolation?

Back: Gametic isolation occurs when sperm cannot fertilize the egg.

Flashcard 62
Front: What is postzygotic isolation?

Back: Postzygotic isolation occurs after fertilization and prevents successful reproduction.

Flashcard 63
Front: What is hybrid inviability?

Back: Hybrid inviability occurs when the zygote dies before reaching reproductive maturity.

Flashcard 64
Front: What is hybrid sterility?

Back: Hybrid sterility occurs when a hybrid survives but cannot reproduce (e.g., mule).

Flashcard 65
Front: What is hybrid breakdown?

Back: Hybrid breakdown occurs when hybrids reproduce but their offspring are weak or sterile.

Flashcard 66

Back: Allopatric speciation occurs when populations become separated by a geographic barrier.

Flashcard 67
Front: What happens if separated populations diverge genetically in allopatric speciation?

Back: They may no longer interbreed even if the geographic barrier disappears.

Flashcard 68
Front: What is sympatric speciation?

Back: Sympatric speciation occurs when new species form without geographic separation.

Flashcard 69
Front: What is habitat differentiation in sympatric speciation?

Back: Subpopulations occupy different habitats and experience different selective pressures.

Flashcard 70
Front: How can sexual selection cause sympatric speciation?

Back: Preferential mating within groups creates reproductive isolation.

Flashcard 71
Front: What is polyploidy?

Back: Polyploidy occurs when organisms have more than two sets of chromosomes, usually due to errors in meiosis.

Flashcard 72
Front: Why can polyploid plants form new species?

Back: They can only reproduce with other polyploid organisms, creating reproductive isolation.

Flashcard 73
Front: What is adaptive radiation?

Back: Adaptive radiation is the rapid evolution of many species from a common ancestor when new ecological niches become available.

Flashcard 74

Front: What classic example demonstrates adaptive radiation?
Back: Darwin’s finches.

Flashcard 75
Front: What is divergent evolution?

Back: Divergent evolution occurs when species evolve from a common ancestor and become increasingly different.

Flashcard 76
Front: What structures arise from divergent evolution?

Back: Homologous structures.

Flashcard 77
Front: What is convergent evolution?

Back: Convergent evolution occurs when unrelated species independently evolve similar traits due to similar environments.

Flashcard 78
Front: What structures arise from convergent evolution?

Back: Analogous structures.

Flashcard 79
Front: What is parallel evolution?

Back: Parallel evolution occurs when related species evolve in similar ways due to similar selective pressures.

Flashcard 80
Front: What is coevolution?

Back: Coevolution occurs when two species evolve in response to each other’s adaptations.

Flashcard 81
Front: Give an example of coevolution involving predators and prey.

Back: If predators evolve better hunting abilities, prey evolve better escape mechanisms

Flashcard 82
Front: How can predator-prey coevolution affect population sizes?

Back: It can cause cyclical population changes through negative feedback.

Flashcard 83
Front: What is an example of pollination coevolution?

Back: Hummingbirds and trumpet creeper flowers evolving longer beaks and floral tubes.

Flashcard 84
Front: What is a behavioral adaptation?

Back: An action performed by an organism to increase survival (e.g., migration).

Flashcard 85
Front: What is a structural adaptation?

Back: A physical feature that improves survival (e.g., horns).

Flashcard 86
Front: What is a physiological adaptation?

Back: A metabolic or internal process that improves survival (e.g., venom production).

Flashcard 87
Front: What are secondary compounds in plants?

Back: Toxic chemicals that deter herbivores (e.g., tannins and nicotine).

Flashcard 88
Front: What is cryptic coloration?

Back: Camouflage that allows organisms to blend into their environment.

Flashcard 89
Front: What is aposematic coloration?

Back: Bright warning colors indicating that an organism is toxic or dangerous.

Flashcard 90
Front: What is mimicry?

Back: When one species evolves to resemble another species to gain protection.

Flashcard 91
Front: What is Müllerian mimicry?

Back: When multiple dangerous species resemble each other and share the same defense (e.g., bees and wasps).

Flashcard 92
Front: What is Batesian mimicry?

Back: When a harmless species mimics a dangerous species (e.g., hoverflies mimicking wasps).

Flashcard 93
Front: What is metamorphosis in insects?

Back: Development through egg → larva → pupa → adult, allowing insects to use different habitats and resources.

Flashcard 94
Front:B How does metamorphosis reduce competition?

Back: Different life stages use different resources and habitats.

Flashcard 95
Front: Why is small size advantageous for insects?

Back: It reduces resource needs and allows insects to disperse into more environments.

Flashcard 96
Front: Why does a high reproductive rate benefit insects evolutionarily?

Back: It increases survival chances, mutation rates, and genetic recombination, allowing natural selection to occur faster.