Chapter 17: Population Genetics

Describe the Founder Effect

- A small group of individuals break off from a large population and colonize elsewhere - this new population can carry different allele frequencies

Describe Inbreeding

- breeding within "family" (same gene pool) - can increase risk of homozygous recessive disorders (more likely that both parents will be carriers when they come from the same family)

Describe Population

- individuals that interbred, live together, and experience same changes in natural selection - Smallest unit in which evolution can occur

Describe Gene flow

- migrating organisms introduces new alleles to a population - changes in gene frequencies accelerates the spread of alleles or if exchange between populations is frequent, separate populations can be maintains as 1 species reducing speciation

Describe natural selection

- some organisms are better suited for their environment, those alleles will increase in frequency over time -not based off chance as others are

Describe Mutation

- ultimate source of genetic variation - some are beneficial so they are favored by natural selection and slowly increase in frequency in gene pool

Describe Genetic Variation

- variation in gene pool creating polymorphic population - 2 or more alleles in a gene pool - large population have about .5% variation

Describe evolution

-Change in genetic material or allele frequencies over time - Any violation of Hardy Weinberg

What is selective breeding?

-Only allow certain individuals with the desired traits to breed -Causes a change in the population

Describe Twin Studies

-Study effects f genetics vs environment factors - twins have the same genes but may act/look different based on environmental factors

Describe population bottleneck

-large population may be drastically reduces due to a natural catastrophe - dramatic change in allele frequency (some alleles may be lost completely) - as the new small population breeds, allele frequencies can end up very different than original population

What is QTL mapping

-locating genes responsible for variation in quantitative traits using genetic markers and data gathered in crossing over - Genes that are located close to eachother cross over less

What does genetic equilibrium also need to have?

1. Diploid, sexually reproducing organisms 2. non-overlapping generations (parents die before offspring reproduce)

What is a gene pool?

All genes of a local population

What is the Hardy Weinberg theory?

Allele frequencies in a population will remain constant unless one or more factors cause frequencies to change

What is genetic equilibrium?

Allele frequencies remain constant= no evolution

What is Macroevolution?

Change in species over long time- can generate new species

What are two types of meiotic genetic recombination?

Crossing over and independent assortment (aka gene shuffling)

What is Microevolution?

Evolution within a species or population

What is inbreeding depression?

Fertility and survival decrease as homozygous recessive alleles appear causing harmful and lethal disorders

Why is the Hardy-Weinberg equation only good for one period of time?

Frequencies are always fluctuating

What is no migration?

Gene pool kept separate from other and kept together

What are the effects of inbreeding?

Inbreeding depression and once every individual is homozygous the population is in danger of extinction because there is no variation

What do the Hardy Weinberg conditions do?

Maintain genetic equilibrium

What are the three sources of variation?

Mutation, meiotic genetic recombination, random fusion of gametes (fertilization is a matter of chance)

What is allele frequencies?

Number of times an allele occurs in gene pool compared to other alleles

What can QTLs show?

QTLs show variation, proven by artificial sleection

What is QTL?

Quantitative trait loci are the genes that control these multifactoral traits

What is genetic drift?

Random changes in allele frequencies in small populations- major cause of microevolution

What are the five conditions for Hardy-Weinberg?

Random mating, large population, no migration, no mutation, and no natural selection

What are small populations more affected by?

Random variations

What is Population Genetics?

Study populations at the level of genes and alleles to discover how evolution works

What are quantitative traits?

aka Multifactoral, large variety of phenotypes

What is random mating?

equal chance of passing on alleles

What is large population?

genetic drift has little effect

What is the formula for allele frequency?

p + q = 1

What is the formula for genotype frequencies?

p2 + 2pq + q2 = 1

What does p and q equal?

p= frequency of dominant allele q= frequency of recessive allele

What can genetic drift result in?

the extinction of an allele or an entire population, or rapid evolution!