BIO 117 Final Exam Lecture 1

Lecture 1

What is the modern synthesis?

The modern synthesis is the fusion of genetics with evolutionary biology

Five causes of Evolution

Natural Selection, Gene Flow, Mutation, Genetic Drift, and Nonrandom Mating

What is Evolution?

Change in the gene pool of a population over time

What is the gene pool?

All of the alleles of all the genes of a population

What is natural selection?

Differential survival and reproduction based on heritable traits

What is Gene Flow?

Genetic exchange with another population

What is immigration?

Introduces new alleles(genetic variation) to a population

What is emigration?

It removes alleles

What is mutation?

Permanent alteration in the DNA sequence of an organism acts as the primary source of genetic variation

What is genetic drift?

Any change in allele frequencies in a population due to chance, random with respect to fitness, is especially prevalent in small populations and can lead to loss and fixation of alleles

What is the founder effect?

When a new colony is founded by a small number of individuals

What is the Bottleneck effect?

Sharp reduction in population size caused by environmental disasters and human activities leading to reduced genetic diversity.

What is non-random mating+s selection

Inbreeding/outbreeding and choosing your mates

Nodes of Natural Selection

Natural selection of quantitative traits occur in a wide variety of patterns and modes

What is directional selection?

Changes the average phenotype in the population in one direction and tends to reduce the genetic diversity of populations

What is stabilizing selection?

Reduces both extremes in a population and reduces genetic variation in a trait, but does not change the average value of a trait over time

What is disruptive selection?

Intermediate phenotypes are selected against, and extreme phenotypes of a trait over time and increases variation in a trait

What is balancing selection?

When no single allele has a distinct advantage, and there is a balance among several alleles in terms of their fitness

What is the heterozygote advantage?

Heterozygous individuals have higher fitness than homozygous individuals do

What is frequency-dependent selection?

Certain alleles are favored when they are rare but not when they are common

How is a heterozygote advantage seen in sickle cell anemia?

Single nucleotide substitution in a hemoglobin protein

What is Evolution?

A change in the gene pool of a population over time, and allele frequencies

How can we measure evolution?

Hardy- Weinberg principle

What did the Hardy-Weinberg principle want to model?

Wanted to model what happened when all individuals in a population and thus all possible genotypes-mated

What is the Hardy-Weinburg Equilibrium?

Where no evolution is happening was their null hypothesis

What are the 5 assumptions of the Hardy-Weinberg Prinicple?

Random mating, no natural selection, no genetic drift, no gene flow and no mutation

What is random mating?

No male choice, gametes combine randomly

What is no natural selection?

All individuals contribute equally to gene pool

What is no genetic drift?

Alleles not picked by chance because population is large

What is no gene flow?

No alleles added or lost from the gene pool

What is no mutation?

No alleles introduced into the gene pool

What is p?

Frequency of dominant allele

What is q?

Frequency of recessive allele

What is p2?

frequency of homozygous dominant

What is 2pq?

Frequency is heterozygous

What is q2?

Frequency of homozygous recessive

How to calculate phenotype frequency?

Count individuals showing a trait divided by total population

How to calculate genotype frequency?

Number of genotype divided by total population

How to calculate allele frequency?

Count of alleles divided by total alleles in population

If genotype frequencies change over time

The population is evolving

If the HWE conditions hold

Allele frequencies stay constant, genotype frequencies remain predictable using so the next generation will have the same genetic structure

What are the mutation outcomes?

Neutral, Beneficial, and harmful

What is neutral?

No effect on fitness(common)

What is beneficial?

Increases survival or reproduction

What is harmful?

Reduces survival or reproduction

Are all mutations equally likely?

No most mutations are neutral and harmful, beneficial is rare

What is the interbreeding effect?

Increases homozygous, decreases heterozygous, and can increase the expression of harmful recessive alleles