Unit 6: EVOLUTION

AP BIO

evolution

evolution

change in genetic make up of a population over time

evolutionary fitness

favorable variations for survival and reproduction, populations can evolve not individuals

mutations

random changes to DNA, errors in mitosis/meiosism or in environmental change

sexual reproduction

mixing alleles, genetic recombination (new arrangement in offspring)

what creates new phenotypes

new genetic recombinations

dawrins idea of natural selection

a) variation exsists in populations

b) over-production of offspring (more than the environment can handle)

c) competition (food/mates/escape predators)

d) differential surival

e) differential reproduction (adaptations become more common

Lamackian view of evolution

adaptations were created by environmental necessity

Darwin view of evolution

adaptations are inherited traits/genes

Is natural selection random

NOT RANDOM, those with the most FIT traits are selected for SURVIVAL and reproduction

Changes in the average trait of a population (3 types)

a) directional selection

b) stabilizing selection

c) disruptive selection

Heterozygote Advantage

keeps the recessive alllele in the population (ex: sickle cell anemia)

Artificial Selection

hidden variations can be exposed through selections (ex: breeding dogs)

Genetic Drift

Chance events changing frequency of traits in a population (NOT adaptation to environmental conditions, not selection)

what is the founder effect

small group splinters off and starts new colony (random who joins new colony)

what does bottleneck mean

disaster reduces population to small # and then population recovers and expands again but from a limited gene pool

Human impact on: artificial selection/in-breeding

loss of alleles in gene pool

Human impact on: loss of genetic diversity

reduces adaptability

Human impact on: overuse of antibiotics/insecticides

resistance increased

Hardy Weinberg Equilibrium

created idea of hypothetical, non-evolving population (preserves allele frequencies), natural populations are NEVER in H-W equilibrium

H-W conditions that ocurs in non-evolving populations

a) very large population (no genetic drift)

b) no migration (no gene flow in or out)

c) no mutation (no genetic change)

d) random mating (no sexual selection)

e) no natural selection (everyone equal fit)

Populations and Gene pools

a) a population is a localized group of interbreeding individuals

b) gene pool is a collection of alleles in the population

c) allele frequency is how common is that allele in the population

what is a species

a population whose members can interbreed and produce viable, fertile offspring

how do new species orginiate

when 2 populations become reproductively isolated from each other

speciation model: allopatric

geographic separation

speciation model: sympatric

still live in the same area

Sympatric speciation example

disruptive selection can cause this or polyploidy events

Pre-zygotic barriers

obstacle to mating or fertilization if mating occurs

Pre-zygotic barriers: types of isolation

geographic, ecological, temporal isolation, behavioral, mechanical, gametic

Post-Zygotic Isolation

a) hybrid inviability - aborted fetus

b) hybrid sterility - offspring are infertile

c) hybrid breakdown - future generations have less fertility/viability

Divergent Evolution

2 or more species are separating from a common ancestor

what is adaptive radiation in terms of divergent evolution

large number of species formed

convergent evolution

2 or more species sharing similar traits but NO COMMON ANCESTRY (also analogus)

Evolution evidence: paleontology

fossils show change in a species over time

Evolution evidence: biogeography

study of geographic distribution of species

Evolution evidence: morphology

comparing structure

Homologous structure

body parts with similar structure but possible different function (shows common ancestry, divergent evolution)

Analogous structure

same function, different structure (different ancestry, convergent evolution)

Evolution evidence: biochemical or molecular (DNA)

similarities in gene sequences, protiens, DNA

Vestigal Organs

remnants of structures that were functional in ancestral species

Speed of Evolution: gradualism

species are slowly evolving (fossil evidence)

speed of evolution: punctuated equilibrium

short periods of fast evolution followed by periods with little to no change

Coevolution (2 living things in response to each other)

two or more species reciprocally affect each other’s evolution

a) predator-prey

b) competitive species

c) mutualism (pollinators and flowers)

Primitive Earth: Atmosphere

all chemicals/compounds necessary are thought to have originated on Earth

Primitive Earth: Inorganic Precursors

water vapor, nitrogen, carbon dioxide, small amounts of hydrogen and carbon monoxide

What were inorganic precursors used for

were used as the monomers for forming complex molecules

Is it possible to form organic molecules from inorganic molecules

yes

What is abiotic synthesis

1953 miller and urey tested the hypothesis: formed organic compounds (amino acids and adenine)

Key events in the origin of life: origin of cells

protocells, lipid bubbles →separate inside from outside → metabolism & reproduction

Key events in the origin of life: origin of genetics

RNA is first genetic material

what are the functions of RNA

encodes info, self-replicating, enzyme, regulatory molecule, transport molecule (tRNA, mRNA)

does natural selection work upon fitness of RNA or DNA

RNA

Origin of Eukaryotes

Endosymbiosis (symbiosis in which one of the symbiotic organisms lives inside the other)

First Eukaryotes

developent of internal memebranes, create internal micro-environments, advantage: specialization = increase efficiency (natural selection)

sequence of gentic varitation under the influence of natural selection

1. a change occurs in the environment

2. poorly adapted individuals do not survive

3. well adapted individuals leave more offspring

4. genetic frequencies within the population change

an organism’s relative fitness is measured by its…

contribution to the gene pool of the next generation

what is the only factor that can change allele frequencies in population to produce adaptive evolutionary change

selection

geographic isolation

occurs when two populations are separated by geographic barriers such as rivers, mountains, or bodies of water

mechanical isolation

a type of reproductive isolation where two species physically cannot undergo fertilization

behavioral isolation

occurs when members of a population diverge in their behaviors over time

gametic isolation

a type of prezygotic barrier where the gametes (egg and sperm) come into contact, but no fertilization takes place

directional selection graph

disruptive selection graph

stabilizing selection graph