Unit 6: EVOLUTION

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63 Terms

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evolution

change in genetic make up of a population over time

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evolutionary fitness

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

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mutations

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

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sexual reproduction

mixing alleles, genetic recombination (new arrangement in offspring)

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what creates new phenotypes

new genetic recombinations

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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

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Lamackian view of evolution

adaptations were created by environmental necessity

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Darwin view of evolution

adaptations are inherited traits/genes

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Is natural selection random

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

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

a) directional selection

b) stabilizing selection

c) disruptive selection

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Heterozygote Advantage

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

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Artificial Selection

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

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Genetic Drift

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

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what is the founder effect

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

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what does bottleneck mean

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

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Human impact on: artificial selection/in-breeding

loss of alleles in gene pool

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Human impact on: loss of genetic diversity

reduces adaptability

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Human impact on: overuse of antibiotics/insecticides

resistance increased

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Hardy Weinberg Equilibrium

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

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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)

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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

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what is a species

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

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how do new species orginiate

when 2 populations become reproductively isolated from each other

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speciation model: allopatric

geographic separation

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speciation model: sympatric

still live in the same area

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Sympatric speciation example

disruptive selection can cause this or polyploidy events

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Pre-==zygotic== barriers

obstacle to mating or fertilization if mating occurs

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Pre-zygotic barriers: types of isolation

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

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Post-Zygotic Isolation

a) hybrid inviability - aborted fetus

b) hybrid sterility - offspring are infertile

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

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Divergent Evolution

2 or more species are separating from a common ancestor

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what is adaptive radiation in terms of divergent evolution

large number of species formed

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convergent evolution

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

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Evolution evidence: paleontology

fossils show change in a species over time

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Evolution evidence: biogeography

study of geographic distribution of species

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Evolution evidence: morphology

comparing structure

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Homologous structure

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

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Analogous structure

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

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Evolution evidence: biochemical or molecular (DNA)

similarities in gene sequences, protiens, DNA

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Vestigal Organs

remnants of structures that were functional in ancestral species

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Speed of Evolution: gradualism

species are slowly evolving (fossil evidence)

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speed of evolution: punctuated equilibrium

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

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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)

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Primitive Earth: Atmosphere

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

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Primitive Earth: Inorganic Precursors

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

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What were inorganic precursors used for

were used as the monomers for forming complex molecules

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Is it possible to form organic molecules from inorganic molecules

yes

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What is abiotic synthesis

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

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Key events in the origin of life: origin of cells

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

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Key events in the origin of life: origin of genetics

RNA is first genetic material

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what are the functions of RNA

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

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does natural selection work upon fitness of RNA or DNA

RNA

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Origin of Eukaryotes

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

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First Eukaryotes

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

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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

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an organism’s relative fitness is measured by its…

contribution to the gene pool of the next generation

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

selection

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geographic isolation

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

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mechanical isolation

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

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behavioral isolation

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

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gametic isolation

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

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directional selection graph

knowt flashcard image
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disruptive selection graph

knowt flashcard image
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stabilizing selection graph

knowt flashcard image