Midterm Review

Question 1

How fast can artificial selection go?

Answer 1

depends on:

• genes
• genetic variation available
• how much of the phenotype is envionmental factors
• deleterious consequences

Question 1

How many kingdoms are there?

Answer 1

Linnaeus proposed just two kingdoms - plants and animals

• Five kingdom system
• domains

Question 1

What are the three domains?

Answer 1

• Bacteria
• Archaea
• Eukarya

Question 1

Genetic Correlation

Answer 1

selection favouring alleles for one trait causes a correlated bu suboptimal change in an allele for another trait

Question 1

Historical Constraints

Answer 1

present variation biases future possibilities - species evolve from ancesters

Question 1

Formal Constraints

Answer 1

laws of physics

Question 1

Temporal Constraints

Answer 1

Evolution occurs by mutation and it takes time for a series of useful mutations to occur - small phenotypic effect

Question 1

Genetic Correlation

Answer 1

changing one feature often affects multiple features ex. reduction in jaw size led to suboptimal tooth arrangement in humans.

Question 1

Fitness Trade-offs

Answer 1

• compromise between traits in terms of how the traits are adapted for the environment. ex. brain size and pelvis
  COMPROMISE

Question 1

The Hardy Weinberg principle

Answer 1

A null hypothesis that predicts what genotype frequencies should be given known allele frequencies.

Question 1

Allele frequency:

Answer 1

the frequency of each allele

*two pop. with the same allele frequencies can have different genotype frequencies. ex moths

Question 1

Genotype frequency:

Answer 1

the frequency of various allele populations

Question 1

Natural selection

Answer 1

increases or decreases the frequency of certain alleles

Question 1

Genetic Drift

Answer 1

Causes allele frequencies to change randomly (stochastically) over time

Question 1

Gene Flow

Answer 1

(migration) introduces alleles from another population
- homogenize gene frequencies
- tends to reduce genetic difference b/w pop.

Question 1

Mutation

Answer 1

Modifies allele frequencies by continually introducing new alleles, even deleterious ones.

Question 1

Gene pool

Answer 1

All of the gametes produced in each generation go into a single group and then combine

Question 1

The Hardy Weinberg principles that must hold true:

Answer 1

• no natural selection on fitness
• no genetic drift
• no gene flow
• no mutation
• no biased mating

Question 1

HLA and heterozygosity

Answer 1

T-shirt smelling experiment

Question 1

Is the HLA locus of Humans in Hardy-Weinberg Equilibrium?

Answer 1

• mutation, migration, and genetic drift are negligible in this case
  1) mating is biases with respect to the HLA genotype
  2) heterozygous individuals have higher fitness

Question 1

Heterozygous advantage:

Answer 1

Is a pattern of natural selection in which heterozygous individuals have higher fitness than homozygous individuals do. Must be co-dominant. ex. sickle cell anemia

Question 1

Directional Selection

Answer 1

When an extreme phenotype is favored by natural selection. Type of natural selection. ex. increased body size in swallow pop.

Question 1

Stabalizing Selection

Answer 1

Reduces the amount of variation in a trait. ex. Very large and very small newborns are less likely to survive.

Question 1

Disruptive Selection

Answer 1

increases the amount of variation in a trait ex. black bellied seedcrackers with either long or short beak. Castes of ants

Question 1

Negative Frequency Dependent Selection

Answer 1

Fitness is highest in rare phenotypes. ex. snakes

Question 1

Frequency dependent selection

Answer 1

fitness is highest in common phenotypes

Question 1

Impact of selection on phenotypic variance and allelic diversity

Answer 1

Different mechanisms can increase or decrease variance and diversity but most decrease.

Question 1

Genetic Drift

Answer 1

is any change in allele frequncies in a population due to chance
frequencies drift up and down randomly
unbiased with respect to fitness

Question 1

Indian Javan Rhino

Answer 1

Genetic drift

Question 1

Founder effect

Answer 1

Large population separates into a small isolated population, diversity is lost

Question 1

Bottlenecks

Answer 1

Populations go through a bottleneck. The longer and more sever the bottleneck the more diversity lost ex, cheetah can share skin grafts they are so genetically similar

Question 1

What is a population?

Answer 1

Groups of individuals with diff. allele frequencies

Question 1

Natural selection and genetic diversity

Answer 1

• cannot increase (could decrease) number of alleles in a population but it can increase (usually reduces) the diversity of alleles by influencing the frequency of pre-existing variation
• All other mechanisms decrease diversity

Question 1

Only mechanism to create new alleles

Answer 1

Mutation

Question 1

polymorphism

Answer 1

existing variation

Question 1

Nonrandom Mating

Answer 1

May not be random with respect to any particular gene in question

Question 1

Examples of biased mating

Answer 1

• inbreeding
• sexual selection
  (violate hardy-weinberg)

Question 1

Inbreeding

Answer 1

• increases the frequency of homozygotes and reduces the frequency of heterozygotes in each generation.
• does not change allele frequencies but does change genotype frequencies (increases homozygosity)

Question 1

Inbreeding Depression

Answer 1

a decline in average fitness that takes place when homozygosity increases and heterozygosity decreases in a population

Question 1

Causes of inbreeding depression?

Answer 1

• many deleterious mutations are recessive
• at some loci there is an advantage to being heterozygous
• Inbreeding increases homozygosity resulting in decreased fitness

Question 1

Advantages of inbreeding?

Answer 1

Purges your genetic load and removes deleterious alleles from the pop. Observed in plants.

Question 1

Allele frequency inbreeding vs inbreeding depression

Answer 1

Inbreeding: does not change allele frequencies it only changes genotype frequencies
Inbreeding depression: does not change allele frequencies either because homozygous deleterious recessives are more common in inbred individuals or because beneficial heterozygous genotypes are less common in inbred individuals

Question 1

Sexual selection

Answer 1

occurs when individuals within a population differ in their ability to attract mates. Favours those who can attract mates.

Question 1

The fundamental asymmetry of sex

Answer 1

-females invest more into their offspring than males therefore females should be choosy about mates

Question 1

Sexual Cannibalism

Answer 1

• Nutritional benefits
• mechanism of rejection
• mistaken identity
• prevent male monopolization

Question 1

sexual dimorphism

Answer 1

trait that differs between males and females of the same species

Question 1

How fast can artificial selection go?

Answer 1

depends on:

• genes
• genetic variation available
• how much of the phenotype is envionmental factors
• deleterious consequences

Question 1

Genetic drift

Answer 1

more pronounced in small populations than large ones

-Great concern to conservation biologists because endangered species are especially susceptible

Question 1

How many kingdoms are there?

Answer 1

Linnaeus proposed just two kingdoms - plants and animals

• Five kingdom system
• domains

Question 1

What are the three domains?

Answer 1

• Bacteria
• Archaea
• Eukarya

Question 1

Genetic Correlation

Answer 1

selection favouring alleles for one trait causes a correlated bu suboptimal change in an allele for another trait

Question 1

Historical Constraints

Answer 1

present variation biases future possibilities - species evolve from ancesters

Question 1

Formal Constraints

Answer 1

laws of physics

Question 1

Temporal Constraints

Answer 1

Evolution occurs by mutation and it takes time for a series of useful mutations to occur - small phenotypic effect

Question 1

Genetic Correlation

Answer 1

changing one feature often affects multiple features ex. reduction in jaw size led to suboptimal tooth arrangement in humans.

Question 1

Fitness Trade-offs

Answer 1

• compromise between traits in terms of how the traits are adapted for the environment. ex. brain size and pelvis
  COMPROMISE

Question 1

The Hardy Weinberg principle

Answer 1

A null hypothesis that predicts what genotype frequencies should be given known allele frequencies.

Question 1

Allele frequency:

Answer 1

the frequency of each allele

*two pop. with the same allele frequencies can have different genotype frequencies. ex moths

Question 1

Genotype frequency:

Answer 1

the frequency of various allele populations

Question 1

Natural selection

Answer 1

increases or decreases the frequency of certain alleles

Question 1

Genetic Drift

Answer 1

Causes allele frequencies to change randomly (stochastically) over time

Question 1

Gene Flow

Answer 1

(migration) introduces alleles from another population
- homogenize gene frequencies
- tends to reduce genetic difference b/w pop.

Question 1

Mutation

Answer 1

Modifies allele frequencies by continually introducing new alleles, even deleterious ones.

Question 1

Gene pool

Answer 1

All of the gametes produced in each generation go into a single group and then combine

Question 1

The Hardy Weinberg principles that must hold true:

Answer 1

• no natural selection on fitness
• no genetic drift
• no gene flow
• no mutation
• no biased mating

Question 1

HLA and heterozygosity

Answer 1

T-shirt smelling experiment

Question 1

Is the HLA locus of Humans in Hardy-Weinberg Equilibrium?

Answer 1

• mutation, migration, and genetic drift are negligible in this case
  1) mating is biases with respect to the HLA genotype
  2) heterozygous individuals have higher fitness

Question 1

Heterozygous advantage:

Answer 1

Is a pattern of natural selection in which heterozygous individuals have higher fitness than homozygous individuals do. Must be co-dominant. ex. sickle cell anemia

Question 1

Directional Selection

Answer 1

When an extreme phenotype is favored by natural selection. Type of natural selection. ex. increased body size in swallow pop.

Question 1

Stabalizing Selection

Answer 1

Reduces the amount of variation in a trait. ex. Very large and very small newborns are less likely to survive.

Question 1

Disruptive Selection

Answer 1

increases the amount of variation in a trait ex. black bellied seedcrackers with either long or short beak. Castes of ants

Question 1

Negative Frequency Dependent Selection

Answer 1

Fitness is highest in rare phenotypes. ex. snakes

Question 1

Frequency dependent selection

Answer 1

fitness is highest in common phenotypes

Question 1

Impact of selection on phenotypic variance and allelic diversity

Answer 1

Different mechanisms can increase or decrease variance and diversity but most decrease.

Question 1

What is a population?

Answer 1

Groups of individuals with diff. allele frequencies

Question 1

Natural selection and genetic diversity

Answer 1

• cannot increase (could decrease) number of alleles in a population but it can increase (usually reduces) the diversity of alleles by influencing the frequency of pre-existing variation
• All other mechanisms decrease diversity

Question 1

Only mechanism to create new alleles

Answer 1

Mutation

Question 1

polymorphism

Answer 1

existing variation

Question 1

Nonrandom Mating

Answer 1

May not be random with respect to any particular gene in question

Question 1

Examples of biased mating

Answer 1

• inbreeding
• sexual selection
  (violate hardy-weinberg)

Question 1

Inbreeding

Answer 1

• increases the frequency of homozygotes and reduces the frequency of heterozygotes in each generation.
• does not change allele frequencies but does change genotype frequencies (increases homozygosity)

Question 1

Inbreeding Depression

Answer 1

a decline in average fitness that takes place when homozygosity increases and heterozygosity decreases in a population

Question 1

Causes of inbreeding depression?

Answer 1

• many deleterious mutations are recessive
• at some loci there is an advantage to being heterozygous
• Inbreeding increases homozygosity resulting in decreased fitness

Question 1

Advantages of inbreeding?

Answer 1

Purges your genetic load and removes deleterious alleles from the pop. Observed in plants.

Question 1

Allele frequency inbreeding vs inbreeding depression

Answer 1

Inbreeding: does not change allele frequencies it only changes genotype frequencies
Inbreeding depression: does not change allele frequencies either because homozygous deleterious recessives are more common in inbred individuals or because beneficial heterozygous genotypes are less common in inbred individuals

Question 1

Sexual selection

Answer 1

occurs when individuals within a population differ in their ability to attract mates. Favours those who can attract mates.

Question 1

The fundamental asymmetry of sex

Answer 1

-females invest more into their offspring than males therefore females should be choosy about mates

Question 1

Sexual Cannibalism

Answer 1

• Nutritional benefits
• mechanism of rejection
• mistaken identity
• prevent male monopolization

Question 1

sexual dimorphism

Answer 1

trait that differs between males and females of the same species