AP Biology Unit 7

Define natural selection.

A major mechanism of evolution

Define evolution.

The change in the genetic makeup of a population over time is supported by multiple lines of evidence

What are the requirements for evolution by natural selection?

-Limited resources

-Competition

Define variation.

Genetic differences within a population

Define adaptations.

Traits that provide an advantage in a particular environment

How is reproductive success measured?

By evolutionary fitness

Define fitness.

The ability of an organism to survive and produce fertile offspring

Define reproductive success.

Refers to the production of offspring

Define heritability.

Ability to pass on adaptations to successive generations

A stable environment results in ___ evolution.

Slow

An unstable environment results in ___ evolution.

Fast

Define genetic variation.

Genotypic and phenotypic differences in a population.

Define selective pressures.

Any biotic or abiotic factors influencing survivability

Define artificial selection.

Process by which humans select desirable traits in other species and selectively breed individuals with desirable traits

Define convergent evolution.

The process by which similar environmental conditions select similar traits in different populations or different species over time

Define analogous structures.

Structures evolved independently in different species due to similar environment/selective pressures

What is evolution driven by?

By random occurrances

Reduction of genetic variation can ___ the differences between populations of the same species.

Increase

Define genetic drift.

Random change in the frequency of a particular allele within a population

What size population does genetic drift/non-selective processes occur in?

Small population

Define bottleneck events.

Population sharply decreases due to a catastrophe

Define the founder's effect.

Refers to a random process that reduces genetic variation within a small population (Polydactyly)

What are examples of the founder's effect?

-Migration

-Geological events

Continued migration leads to ___ genetic diversity between populations over time

Less

Define null hypothesis.

Hypothesis which states experimental variables have no relationship and experimental observations are the result of chance

Define alternative hypothesis.

One of several hypotheses stating experimental variables have a relationship and the experimental observations are a result of nonrandom cause

Define Hardy-Weinberg Equilibrium.

A model for describing and predicting allele frequencies in a non evolving population

What are the 5 requirements to use the Hardy-Weinberg Equilibrium?

-Large population (no genetic drift)

-Absence of migration (no gene flow)

-No net mutation (no modified gene flow)

-Random mating (no sexual selection)

-Absence of selection (no natural selection)

Define gene flow.

The movement of individuals between populations causing an exchange of alleles between population

What is the equation to calculate genotype?

p^2 + 2pq + q^2=1

What is the equation to calculate an allele

p + q=1

What is p in the Hardy-Weinberg equation?

Dominant allele

What is q in the Hardy-Weinberg equation?

Recessive allele

When using the Hardy-Weinberg equation, do we calculate the dominate or recessive allele first?

Recessive

What evidence is used to indicate evolution?

-Geographical

-Geological

-Physical

-Biochemical

-Mathematical

Define geographical evidence.

Evidence based on characteristics of habitat or land area

Define geological evidence.

Evidence based on environmental features over the earth over time (fossils)

Define physical evidence.

Evidence based on phenotypes of species

Define biochemical evidence.

Evidence based on the chemical composition of living things (DNA)

Define mathematical evidence.

Evidence based on calculation and statistics

Define morphological homologies.

Modified traits shared among differential species

Define homologous structures.

Structure that is derived from a common ancestor (one bone, two bones, little bones, digits)

Define vestigial structures.

Reduced features that serve no purpose for an organism

When looking at DNA for evolution, the more amino acid difference the ___ time has passed between organisms' divergence.

More

What evidence supports common ancestry for all eukaryotes?

-Membrane bound organelles

-Linear chromosomes

-Genes that contain introns

What at the mechanisms of genetic change?

-Changes in DNA

-Cell division (crossing over)

-Environmental disruptions

Define phylogenetic/cladogram tree.

Changes over time and is a branch diagram showing the evolutionary relationships amongst species

Define the out-group.

Lineage that is least closely related to the remainder of the organisms

Define node.

Where 2 lines meet

Define derived character.

A trait in a recent species having evolved for an ancestral trait

Define speciation.

Occurs when organisms are reproductively isolated from each other and new species form

What do biological barriers prevent species from?

-Interbreeding

-Producing fertile offspring

How does reproductive isolation prevent gene flow?

-Prezygotic barriers

-Postzygotic barriers

What are prezygotic barriers?

-Habitat isolation

-Temporal isolation

-Behavioral isolation

-Mechanical isolation

-Gamete isolation

Define habitat isolation.

Different habitats

Define temporal isolation.

Species breed at different times

Define behavioral isolation.

Different mate/courtship preferences

Define mechanical isolation.

Reproductive structures prevent "baby making"

Define gamete isolation.

Sperm doesn't fertilize egg

What are postzygotic barriers?

-Hybrid inviability

-Hybrid sterility

-Hybrid breakdown

Define hybrid inviability.

Incompatibility stops development of zygote (miscarriage)

Define hybrid sterility.

Hybrid is healthy but sterile

Define hybrid breakdown.

First-generation hybrids are fertile, second-generation are sterile

Genetically diverse populations are ___ ___ to environmental change

More resilliant

Define extinction.

The disappearance of a species from Earth

Define niche.

An organism's role in an environment

Define deleterious.

Traits are those that reduce the chance of survival

Define adaptive.

Traits that increase the chance of survival

What is the RNA world hypothesis?

The hypothesis that RNA was the first nucleic acid to evolve and early life was based on RNA rather than DNA or proteins

Define allopatric speciation.

Evolution of new species due to individuals for the same species being geographically isolation

Define sympatric speciation.

Evolution of new species due to individuals being reproductively isolated from a surviving ancestral population

Define directional selection.

Favors individuals at one end of the phenotypic range

Define disruptive selection.

Favors individuals at both extremes of the phenotypic range

Define stabilizing selection.

Favors intermediate variants and acts against extreme phenotypes

Define microevolution.

Change in allele frequencies in a population over generations

Define survival of the fittest.

Individuals with certain heritable adaptive characteristics

Does natural selection create new traits?

No, it edits or selects for traits already present in the population.

When constructing a phylogeny, what is maximum parsimony?

The simplest explanation that is consistent with the facts

When constructing a phylogeny, what is maximum likelihood?

The one that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.

Define monophyletic group.

Consists of an ancestor and all of its descendants.

Define paraphyletic group.

Includes the most recent common ancestor of the group, but not all its descendants

Define polyphyletic group.

Does not have common ancestors for all decendents

Define endosymbiosis.

A process by which the mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger cells.

What was the Miller-Urey experiment?

An experiment to show if the hypothesis of lighting led to the formation of organic molecules from inorganic molecules present in the atmosphere of the early earth.