ap bio unit 3 ch19-25

disruptive selection

both of the extremes are favored

stabilizing selection

the majority is favored

hetero zygote advantage

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

genetic flow

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

genetic drift

chance that the frequency of an allele changes

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

creates new alleles, advantageous alleles will increase over generations

directional selection

one of the extremes are favored

divergent evolution

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

convergent evolution

2 species comeback together to create 1 species, usually due to environment changes

parallel evolution

2 species stay the same over time

Habitat (geographic) isolation

different environments (prezygotic)

behavioral isolation

different mating rituals (prezygotic)

temporal isolation

time of year of breeding (prezygotic)

mechanical isolation

reproductive parts do not fit (prezygotic)

gametic isolation

sperm can not fertilize egg (prezygotic)

hybrid inviability

offspring dies during development (postzygotic)

hybrid breakdown

offspring of the hybrid can not reproduce; sterile (postzygotic)

briefly explain what Darwin called "descent with modification"

favorable traits are passed on (natural selection)

how is the Darwinism view of life like a tree

all organisms have a common ancestor and from the ancestor evolution occurred and different species filled different niches

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

explain why an individual organism can not evolve

populations evolve because the changes have to be passed on through generations

explain how natural selection is more of an editing force than a creating force

it does not create favorable genes, it slowly edits out bad genes and keeps good genes in

explain what homologous structures are and give 2 examples

they are bones or aspects of an organism that are similar/the same in other organisms

the arm of a human and a wing of a bat

homologous structure

the flipper of a whale and a arm of a cat

homologous structure

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

No mutations, large population, random mating (no sexual selection), no immigration or emigration,  and no natural sleecti

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

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

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

1. structural evidence (homologous and analogous) structures,

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

3. fossils

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

allopatric speciation

new species is created due to geographic barriers

sympatric speciatin

new species is created within the orginial population

how can frequencies change

bottleneck effect, founder effect, genetic drift

differential reproductive success

natural selection acts on ___, not ____

populations not individuals

natural selection acts on frequencies

gene

Jean-Baptiste Lamarck’s theory of evolution

Use and disuse, inheritance of acquired traits, innate drive to become more complex

Use and disuse (Lamarck)

Parts of the body that are used extensively become larger and stronger, while those that are not used deteroriate

inheritance of acquired traits (Lamarck)

an organism could pass these modfications to their offspring

descent with modification

2 main ideas by Darwin

Evolution explains life’s unity & diversity and natural selection is a cause of adaptive evolution.

Darwin’s first observation

The more succesfful offspring, the more the population will increase

Darwin’s second obversation

populations tend to be stable in size, except for seasonal fluctuations

Darwin’s third observation

Resources are limited

Darwin’s fourth observation

Members of a population aren’t identical in appearance or characteristics

Darwin’s fifth observation

Much of this variation is heritable

Darwins first inference

Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving

Darwin’s second inference

Survival depends in part on inherited traits; individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals

Darwins third inference

This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations

What are phylogenetic trees?

it shows the evolutionary history with branch lengths representing evolutionary change or time,

What are cladograms?

show hypothetical evolutionary relationships (clades) based on shared derived characteristics.

shared derived characteristics

What are the effects physical barriers have on gene flow?

prevents interbreeding between populations, leading to genetic isolation and possibly speciation over time.

genetic isolation

barrier to gene flow isolates populations

speciation

Formation of new species

Example of physical barriers

Mountains, rivers, deserts, oceans, canyons. etc.

selection pressure

the environmental factors that favour certain phenotypes

sympatric species

species found in the same geographic area

allopatric species

Two closely related species that are geographically isolated from each other

How does selection pressure affect the isolated gene pool in terms of allele frequencies?

favors certain traits, causing advantageous alleles to increase and disadvantageous ones to decrease over time.

4 types of selection pressures

Predation, Competition for resources, Disease, Environmental changes (e.g., temperature or climate)

Polyploidy

condition in which an organism has extra sets of chromosomes

Hardy-Weinberg equation

p² + 2pq + q² = 1.