EVOLUTION EXAM 2 NOTES

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Questions and Answers

What is the primary role of mutation in evolution?

Preventing natural selection

Maintaining genetic equilibrium

Providing the raw material for evolution (correct)

Creating new species

How is the effect of mutation on Hardy-Weinberg equilibrium calculated?

p = p - mp & q = q + mp (correct)

p = p + mp & q = q - mp

p = q - up & q = p + mp

p = q + mp & q = p - mp

What does mutation selection balance refer to?

An absence of mutations in a population

An equilibrium in allele frequency due to mutation and natural selection (correct)

A decrease in allele frequency caused by migration

An increase in mutation rate due to selection pressure

What term describes the movement of alleles between populations?

Migration Signup and view all the answers

How does migration relate to gene flow?

Migration facilitates the movement of alleles between populations Signup and view all the answers

In the context of mutation in evolution, what do allele frequencies represent?

Frequency of occurrence of specific genes in a population Signup and view all the answers

How does genetic drift impact smaller populations compared to larger populations?

Genetic drift has a more pronounced effect on smaller populations Signup and view all the answers

What is the relationship between migration and selection in terms of preventing divergence?

Migration prevents divergence due to selection Signup and view all the answers

Why are smaller populations more susceptible to genetic drift?

Because chance events have a greater impact on allele frequencies Signup and view all the answers

In the context of genetic drift, what role does population size play?

Population size determines the rate of genetic drift Signup and view all the answers

What is the founder effect in relation to genetic drift?

It exemplifies genetic drift after a founder event Signup and view all the answers

How does the Hardy-Weinberg equilibrium need to be adjusted to account for drift?

By considering population size and genetic diversity Signup and view all the answers

What makes genetic drift more influential in smaller populations?

Random events having a greater impact in smaller populations Signup and view all the answers

Why does genetic drift have less influence in larger populations?

Larger populations have more individuals, reducing drift's impact Signup and view all the answers

What is the potential consequence of inbreeding on genotype frequencies?

Increase in homozygosity Signup and view all the answers

How does breeding depression relate to the Hardy-Weinberg equilibrium?

It is caused by a deviation from HW equilibrium Signup and view all the answers

What are delayed effects and how are they related to genetic outcomes?

Long-term impacts that may not be immediately noticeable Signup and view all the answers

What does fixation of an allele in a population mean?

All alleles at the locus have been eliminated except one Signup and view all the answers

How can genetic drift lead to fixation of alleles in a population?

Through random sampling leading to allele frequencies of 0 or 1 Signup and view all the answers

Which outcome is most likely to occur as a result of genetic drift?

Reduction in genetic diversity Signup and view all the answers

How does genetic drift impact the potential for adaptation in a population?

Reduces the potential for adaptation Signup and view all the answers

What is a consequence of genetic drift on the genetic differences between populations?

Increases genetic differences between populations Signup and view all the answers

How does genetic drift affect the prevalence of harmful alleles in a population?

Increases the prevalence of harmful alleles Signup and view all the answers

What is one potential long-term consequence of increased genetic differences between populations due to genetic drift?

Formation of new species over time Signup and view all the answers

How does genetic drift affect the level of heterozygosity within a population?

Decreases heterozygosity by making less common alleles more prevalent Signup and view all the answers

What insight does the fixation Index provide when studying genetic differentiation?

Extent of genetic diversity between populations Signup and view all the answers

What does effective population size represent in genetic studies?

Size of an ideal random mating population that loses genetic variation at the same rate as an actual population Signup and view all the answers

What is a quantitative trait based on the text provided?

A trait showing continuous variation due to genetics and environment Signup and view all the answers

How do small effect loci contribute to quantitative traits?

They have a significant impact on phenotype despite their small effect Signup and view all the answers

In the context of genetic drift, what can be inferred about populations that are genetically distinct?

They have evolved independently from each other Signup and view all the answers

How does genetic drift impact the genetic relationships between different groups of organisms?

It reveals hidden genetic similarities among organisms Signup and view all the answers

How do codominance and multiple alleles impact quantitative traits?

Increase phenotypic diversity Signup and view all the answers

What is the emphasis of nature in heritability?

Contribution of genetic factors Signup and view all the answers

What is the difference between broad-sense and narrow-sense heritability?

Broad-sense accounts for all genetic effects, narrow-sense only additive genetic effects Signup and view all the answers

Why do we typically use narrow-sense heritability in genetic studies?

It offers a more precise estimate of genetic variance inheritance Signup and view all the answers

Which term best describes broad-sense heritability?

Total phenotypic variance due to genetics Signup and view all the answers

In the context of heritability, what does 'nurture' refer to?

Environmental factors Signup and view all the answers

What does the use of narrow-sense heritability help us determine?

% of genetic variance passed down to offspring Signup and view all the answers

In quantitative genetics, why is narrow-sense heritability preferred over broad-sense heritability?

It specifically measures additive genetic effects. Signup and view all the answers

What does phenotypic plasticity refer to?

The ability of an organism to change its physical characteristics in response to environmental cues Signup and view all the answers

How is phenotypic plasticity described in the context of adaptation?

A flexible trait that helps an organism adjust to its surroundings for improved survival and reproduction Signup and view all the answers

What defines a trade-off in adaptation?

An unavoidable compromise between one trait and another Signup and view all the answers

How do constraints affect adaptation?

Constraints prevent populations from evolving optimal trait values Signup and view all the answers

In the context of adaptation, what is a lack of genetic variation indicative of?

Low potential for evolutionary responses to selective pressures Signup and view all the answers

Why is genetic variation crucial for adaptation?

To provide raw material for natural selection to act upon Signup and view all the answers

What role does environmental influence play in phenotypic plasticity?

It triggers changes in the physical characteristics of an organism Signup and view all the answers

What does behavioral thermoregulation involve?

Using various actions and behaviors to regulate body temperature within a certain range Signup and view all the answers

What defines sexual dimorphism?

A difference in the phenotypes of females versus males within a species Signup and view all the answers

Why does sexual dimorphism exist in some species?

To increase the chances of finding mates and reproducing successfully Signup and view all the answers

What is the primary difference between parental investment by males and females?

Females generally invest more heavily in parental care compared to males Signup and view all the answers

How does sexual selection impact mating success?

It enhances the average mating success of individuals with certain phenotypes Signup and view all the answers

What role do distinct physical characteristics play in enhancing reproductive success?

They increase the likelihood of finding mates and reproducing successfully Signup and view all the answers

In what way do environmental factors contribute to sexual dimorphism?

They impact the expression of genes related to reproductive success Signup and view all the answers

How does parental investment differ between males and females?

Females typically invest more heavily in parental care compared to males Signup and view all the answers

In the context of reproductive success limits, how does sexual selection influence individuals within a population?

By shaping the traits and behaviors individuals exhibit to enhance mating chances Signup and view all the answers

What factor often constrains female reproductive success limits in many species?

Availability of resources and ability to care for offspring Signup and view all the answers

How do reproductive success limits typically vary between males and females?

Males have higher potential reproductive success limits than females Signup and view all the answers

What defines mating success in individuals within a population?

Traits and behaviors that attract potential partners Signup and view all the answers

Why are reproductive success limits important in the context of evolutionary biology?

To study how individuals maximize their chances of passing on their genes Signup and view all the answers

What role do genetic constraints play in shaping reproductive success limits?

They impact the number of offspring an individual can produce Signup and view all the answers

How does sexual selection contribute to the evolution of traits and behaviors in a species?

By favoring traits that enhance mating success and reproduction Signup and view all the answers

What distinguishes mating success from reproductive success in individuals within a population?

The ability to attract potential partners vs. successful offspring production Signup and view all the answers

In which scenario would male-male competition most likely occur?

Males competing for mates during breeding season Signup and view all the answers

What is the main purpose of outright combat among male animals?

To establish dominance over females Signup and view all the answers

Which term describes the sneaker-males mating strategy?

Surreptitious fertilization Signup and view all the answers

What characterizes sperm competition among males?

Competing to fertilize the same female's eggs Signup and view all the answers

Which of the following best defines infanticide?

Killing of offspring by members of the same species Signup and view all the answers

What is the primary motivation for male-male competition during the breeding season?

Gaining access to mates to pass on genes Signup and view all the answers

Study Notes

Genetic Drift and Inbreeding

Inbreeding increases the likelihood of certain genotypes being passed down from one generation to the next, leading to an increase in homozygosity for certain alleles and affecting the overall genotype frequencies within the population.
Inbreeding can result in a reduction in genetic diversity and an increased prevalence of genetic disorders.

Breeding Depression

Breeding depression refers to reduced fitness in individuals or populations resulting from inbreeding.
It is a potential consequence of deviating from Hardy-Weinberg equilibrium.

Delayed Effects

Delayed effects refer to the impact or consequences of a certain action or event that are not immediately apparent, but become evident after a significant amount of time has passed.

Fixation

Fixation is the elimination from a population of all the alleles at a locus but one, leaving the one remaining allele at a frequency of 1.0.

Cumulative Effects of Genetic Drift

Genetic drift can lead to the fixation of certain alleles, reducing genetic diversity and increasing the prevalence of harmful genetic traits.
It can also lead to the loss of beneficial alleles, reducing the potential for adaptation and evolution within the population.

Mutation and Selection Balance

Mutation provides the raw material for evolution.
Mutation selection balance refers to an equilibrium in the frequency of an allele that occurs because new copies of the allele are created by mutation at exactly the same rate that old copies of the allele are eliminated by natural selection.

Migration and Gene Flow

Migration refers to the movement of alleles between populations.
Migration can prevent divergence due to selection.

Genetic Drift and Population Size

Genetic drift is more pronounced in small populations.
Smaller populations are more susceptible to genetic drift as chance events have a greater impact on allele frequencies.

Founder Effect

The founder effect is a specific type of genetic drift that occurs when a small group of individuals from a larger population establish a new population in a different area.
It is a change in allele frequencies that occurs after a founder event due to genetic drift.

Heterozygosity and Drift

Genetic drift can have a significant impact on the level of heterozygosity within a population.

Fixation Index

The fixation index is a measure of genetic differentiation within and between populations.
It provides insight into the genetic structure of populations and can help identify patterns of gene flow and migration.

Effective Population Size

The effective population size is the size of an ideal random mating population that would lose genetic variation via drift at the same rate as is observed in an actual population.

Quantitative Traits

Quantitative traits are determined by the combined influence of the environment and many loci of small effect.
Codominance and multiple alleles can have significant effects on quantitative traits by increasing the diversity of phenotypes within a population.

Nature vs. Nurture

Nature emphasizes the role of genetics, while nurture emphasizes the role of the environment in shaping heritable traits.

Heritability

Broad-sense heritability refers to the total genetic variance in a trait within a population.
Narrow-sense heritability specifically measures the proportion of genetic variance that is due to additive genetic effects.

Adaptation

Adaptation refers to the process by which an organism becomes better suited to its environment.

Phenotypic Plasticity

Phenotypic plasticity is the ability of an organism to change its physical characteristics in response to environmental cues.
It allows the organism to better survive and reproduce in different environmental conditions.

Trade-Offs and Constraints

Trade-offs and constraints create the conditions under which trade-offs must be made in order for an organism or system to successfully adapt to its environment.

Sexual Selection

Sexual selection refers to the differences in average mating success among individuals with different phenotypes.
It is a key driver of evolutionary change in many species.

Sexual Dimorphism

Sexual dimorphism refers to the differences between the phenotypes of females versus males within a species.
It can be influenced by environmental factors and social dynamics within a species.

Parental Investment

Parental investment refers to the expenditure of time and energy on the provision, protection, and care of an offspring.
Females typically invest more heavily in parental care compared to males.

Reproductive Success Limits

Reproductive success limits refer to the maximum number of offspring an individual can produce and successfully raise to adulthood.
Reproductive success limits vary between males and females due to differences in reproductive strategies and biological constraints.

Mating Success and Reproductive Success

Mating success refers to an individual's ability to attract and engage in mating behaviors with a potential partner.
Reproductive success refers to the actual production of offspring.

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Description

Week 4: Mutations, Drift, and Migration Week 5: Quantitative Genetics Week 6: Adaptation Week 7: Sexual Selection