Biology 131 genetics & evolution exam

Meiosis functions

Meiosis functions

1. Reduces chromosomes from 2N (diploid) to N (monoploid) so that when they unite, they become 2N again

2. Independent assortment of genes to create genetic diversity

3. Synapses - creates genetic diversity, good and bad

Alleles

All the different genes that can occur in the same place on a chromosome.

Hardy Weinberg equation

P² + 2PQ + Q²

Darwin’s 3 observations in nature

1. Inheritable variation exists

2. Each generation is larger than the last

3. There exists a struggle for survival to keep this increase in check

Darwin’s theory of evolution

In the struggle for survival, individuals with valuable characteristics that increase chance of survival and have offspring will pass those characteristics to succeeding generations. Therefore, there should be an increase in individuals with valuable characteristics and a decrease of individuals with less valuable characteristics.

Theory of evolution vs. Evolution

Theory of evolution - used to interpret and coordinate data

Evolution - the actual process

Law of independent assortment

Assorting genes to go from 2N to N in sperm/egg cells

Synapses

The first meiotic division when chromosomes line up and intermix

Crossing over

homologous genes switching on chromosome pairs

Duplication

A piece of genetic material on a chromosome that duplicates (common in dogs)

Deletion

Loss of one or more segments of DNA on a chromosome

Inversion

The order of genes invert

Non-disjunction

When chromosomes intermix (like spaghetti), they fail to separate when pulled apart

Polyploidy

Total nondisjunction creates 4 chromosomes.

Mutation

A change in a gene’s phenotypic expression. Micro - may not be detected. Macro - appears phenotypically.

Genotype

Actual genetic makeup

Phenotype

How it looks

Genetic equilibrium

Allele or genotypic frequency in a population does not change across generations. Will always occur in populations with random mating.

Population (Genetic vs. ecological)

Genetic: The different alleles that can exist at one time

Ecological: All of one kind of organism

The conservative nature

Allows alleles to become incorporated in the population without regard to usefulness. Keeps the allele frequencies from being changed too quickly.

Forces that overcome genetic equilibrium

Mutation pressure - genes mutate spontaneously overtime.

Non-random mating - the chances in someone from one population mating with another population is low

Sexual selection - Females select males that carry a more desirable trait

Disruptive selection - disrupting the norm

Genetic drift

Chance fluctuations in allele frequency

Bottleneck effect

Drastic decrease in population size due to environmental effects (think pouring Orbeez out of a bottle with a narrow neck)

Founder effect

Loss of genetic variation when a new population is established by a small number of individuals from a larger population.

Punctuated evolution

Long periods of stabilization during which changes are made

Directional selection

As environment changes, the selective factors for a species change

Disruptive selection

As competition increases, there is selection for many desirable traits (Ex: Darwin’s finches beaks)

New species

A new group changes so much over time that when it encounters it’s parent species, it cannot reproduce with them

Species

A group of individuals that have the ability/potential to produce fertile offspring

Ecological species

Can occur together, but rarely breed (Ex: wolves, coyotes, and dogs)

Convergent evolution

When different species end up in the same environment and the environment selects for them (Ex: Coots)

Parallel evolution

Related species that stay in the same environment maintain traits necessary for that environment

Divergent evolution

Populations of species split into two groups due to geographical changes

Co-evolution

Species evolve together (Ex: Pollinators and flowers, humans and dogs)

Historical evidences of evolution

1. Fossils

2. Embryonic development

3. Biogeography

4. Molecular biology: DNA and the genetic code reflect shared ancestry

5. Homology: Species that have evolved to be different but share the same structures (Ex: Birds and bats wing structure)

Stabilizing

Evolution that occurs when climate is stable

Function of genetic equilibirum

If a trait that has been bred out becomes useful again, a small percent of the population still carry it. Prevents populations from evolving too fast.

Types of isolation

1. Behavioral: Whooping and sandhill cranes could mate but won’t because their mating dances are different

2. Ecological: Species live in same territory but different habitat (prairie vs. woodland deer mice)

3. Geographical: Physical barriers (pipelines, rivers, canyons, etc.)

4. Temporal: Flowers will bloom at different times to avoid pollen mixing

5. Climatic: when things get spread around through transportation, species may or may not survive

6. Reproductive isolation

Examples of mimic relationships

Flies that visit flowers selected to look like bees and wasps

Viceroy butterfly selected to look like monarch butterfly (poisonous to eat)

Speciation

1st part of name is Genus/Genus

2nd part of name is species/species

Allopatric speciation

various barriers must form to isolate portions of a population

Types of reproductive isolation

Pre-zygotic: Prevent fertilization

Post-zygotic: Occurs after zygotic formation. Either embryo dies or offspring is sterile (ex: mules)

Autopolyploidy

Organisms have more than two sets of chromosomes from the same species. All of the chromosomes go to the wrong side.