AP Biology Unit Seven

directional selection

directional selection

one of the extremes are favored

disruptive selection

both of the extremes are favored

stabilizing selection

the majority is favored

heterozygote advantage

since you have both alleles, you can pass on the favorable one to your offspring so they will be successful

sexual selection

natural selection arising through preference by one sex for certain characteristics in individuals of the other sex

genetic flow

transfer of alleles or genes from one population to another, migration and emigration can causes this

genetic drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

bottleneck effect

some type of catastrophe wipes out a large segment of a population and survivors are not a representation of the original population

mutations

create new alleles, advantageous alleles will increase over generations

cline

there are different environments and the same species looks different because of it ex. black bears

deme

small, localized population

divergent evolution

one species goes 2 different way and becomes 2 different species, usually due to environment changes

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

parallel evolution

Two related species that have made similar evolutionary adaptations after their divergence from a common ancestor

Habitat (geographic) isolation

A type of reproductive isolation due to separation by an impassable geographic barrier such as a mountain range, body of water, etc.

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

mechanical isolation

reproductive parts do not fit

gametic isolation

A prezygotic (pre zygote) reproductive barrier where the sperm of one species may not be able to fertilize the eggs of another species

sterile offspring

reduced hybrid fertility (offspring cannot reproduce- postzygotic) i.e. mule

hybrid inviability

offspring dies during development (postzygotic)

hybrid breakdown

Some first-generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile

Hardy-Weinberg equilibrium

condition in which a population's allele frequencies for a given trait do not change from generation to generation

descent with modification

principle that each living species has descended, with changes, from other species over time

phylogenetic tree (cladogram)

a diagram that depicts the ancestral relationships between organisms

explain differential reproductive success as it relates to the struggle for existence

more successful you are at reproducing, the more you will pass on your genes and your offspring will be fit

Natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

explain what the statement "natural selection depends on time and place" means

what traits are passed on depends on the environment and it takes generations for natural selection to take effect

homologous structures

Structures in different species that are similar because of common ancestry. Same structure, different function

Analogous structures (convergent evolution)

various structures in different species having the same function but have evolved separately, thus do not share common ancestor

how are the founder effect and the bottleneck effect the same, yet different

the founder effect and the bottleneck effect are the same because the number of organism within a population changes and the frequency of a population changes but they are different because the founder effect happens when emigration or immigration occur and the bottleneck effect happens when a catastrophe wipes out a segment of a population

what 4 conditions must be met for a population to be in Hardy-Weinberg genetic equilibrium

1. no mutations

2. large population

3. random mating (no sexual selection)

4. no immigration or emigration

how can gene flow affect genetic equilibrium in a population

if more organisms come or more leave, then there can be more organisms or less organisms and can change the frequency of alleles and effect equilibrium

how can cline lead to speciation

a cline is when a species looks different because they live in different environments and this can lead to speciation because a new species can be created

what were Lamarck's 2 methods that organisms changed over time and was he correct

1. use and dis-use of characteristics (go away)

2. acquired characteristics

he was not correct because characteristics do not go away unless they are harmful and if an organism acquires a characteristics during its lifetime it will not pass it to its offspring

how does the term differential reproductive success relate to natural selection

if you are more successful at reproducing then natural selection will be successful and the offspring will be fit

describe how selection pressures can change allelic frequencies

if there is a catastrophe and you are only able to mate with an organism with certain genes, then the allelic frequencies will change because then there will be more of one gene and less of another

can an individual organism adapt to its environment

no because if an organism is not born with the genes then it can not make a gene in order to survive, only a population can adapt because mutations can occur and then will pass that gene along and then adaption will occur

why do vestigial structures disappear over time

because organisms that have that harmful structure will not mate and the structure will be lost

what are 4 types of evidence that can be used to determine common ancestry

1. structural evidence (homolgous and analogous) structures

2. molecular evidence (DNA sequencing, amino acid sequencing, and RNA types)

best way to determine common ancestry

3. embryological evidence

using darwins terms be able to explain the adaptive radiation of the finches and how they filled different niches

overproduction could have occurred and there was an abundance of food and the finches filled that niche

anagenesis

perfect species

cladogenesis

creates new species

allopatric speciation

new species is created due to geographic barriers

sympatric speciatin

new species is created within the orginial population

how can frequencies change over time

1. mutations

2. bottleneck effect

3. genetic drift

4. founder effect

5. genetic recombination

genetic recombination

sexual selection (mate choice and handicapping principle)

name 4 things that cladograms show

1. number of shared characteristics

2. all these species are alive today

3. how closely organisms are related to each other

4. when characteristics came about

how did Darwin explain the diversity of like on the Galapagos

1. overproduction

2. variation (Darwin could not explain)

3. speciation

4. heritability

5.adaptation

6. competition

differential reproductive success

what did darwin notice about the animals on the south american continent

-they looked like they should in the environment that they live in

-they looked different than european animals, but some looked similar

what did darwin notice about the organisms on the Galapagos

-some were similar to mainland organisms

-organisms were different on different islands

natural selection acts on ___________, not ____________

populations not individuals

natural selection acts on ______________ frequencies

gene

Hardy-Weinberg equation

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

Vistigual Structures

A structure that is no longer needed (i.e. hipbones in whales, wisdom teeth in humans, goosebumps in humans)