8. Evolution + Flashcards
1
Q
Evolution
A
- chnages in pop, species, or group; changes in aallele (traits) frequencies in populations over time.
2
Q
Microevolution
A
- changes in allele frequencies within a population over time.
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Q
Macroevolution
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- patterns of changes in groups of related species over broad periods of time
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Q
Phylogeny
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- evolutionary relationships among species an groups of species.
5
Q
Lamarck Theory
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- use and disuse: unused parts weakened, used parts get stronger. ex. giraffe neck
- Inheritance of acquired characteristics: body features acquired during lifetime can be passed down to offspring (incorrect, only changes in genetic material is passed down).
- natural transformation of species: organisms produced offspring w/ changes, transforming each later generation slightly more complex (no extinction or splits into more species) => incorrect
6
Q
Natural Selection
A
- survival of fittest (Darwinism) => now called neo-Darwinism (synthetic theory of evolution) or modern synthesis.
7
Q
Evidence for Evolution
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- Palentology: fossils
- Biogeography: unrelated species in different parts of the world look like when found in similar environments
- Embryology: similar stages of development among related species. Gill slits and tails are found in fish, chicken, pig, and human embryos
- Comparative Anatomy: describe two kind of structures that contribute to identification of evolutionary relationships.
a. Homologous structure
b. Analogous Structure - Molecular biology: examine nucleotide and amino acid sequence of DNA and proteins from different species. more than 98% of nucleotide sequences in humans and chimpanzees are identical.
- Comparative Biochemistry: organisms w/ common ancestor = common biochemical pathway.
8
Q
Ontogeny
A
- similar stages of development.
- establish evolutionary relationships (phylogeny).
9
Q
Homologous Structures
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- similar parts in different species as a result of a shared common ancestor.
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Q
Analogous Structures
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- similar parts in different species as a result of independent adaptation to similar environments.
- No common ancestor
11
Q
Natural Selection
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- responsible for producing adaptations that increase fitness (more offspring).
12
Q
Darwin’s Theory Arguments
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- pop possess enormous reproductive potential
- pop size remain stable
- resources are limited
- individuals compete for survival
- there is variation among individ in a pop
- much variation is heritable
- only most fit survive
- evolution occurs as favorable traits accumulate in the population
13
Q
Stabilizing Selection
A
- bell curve
- ex. avg height in humans is middle, favors intermediate
14
Q
Directional Selection
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- favors traits that are at one extreme of a range of traits. traits at opposite extreme selected against.
- ex. industrial melanism: selection of dark-colored (melanic) varieties in various species of moths as a result of industrial pollution.
15
Q
Disruptive Selection
A
- environment favors extreme or unusual traits while selecting against common traits. ex. short and tall are favored while avg is selected against.
16
Q
Sexual Selection
A
- differential mating of males (or females) in a population
- female chooses superior males => incr fitness of offspring; they invest a lot of energy so they maximize quality.
- males incr fitness by maximizing # of mates. They invest little energy so they max quantity.
17
Q
Sexual Dimorphism
A
- differences in appearance of males and females => a form of disruptive selection.
- female choice leads to traits/behaviors in males that are favorable to female (colors, elaborate behavior) resulting in sexual dimorphism.
18
Q
Sources of Variation
A
- mutation: new alleles introduced
- sexual reproduction : crossing over, independent assortment, random joining of gametes
- diploidy: presence of 2 copies of each chromosome. in heterozygous condition, recessive allele is stored for later generations => more variation maintained in gene pool.
- outbreeding: mating unrelated partners
- blanaced polymorphism: maintenance of diff phenotypes in a pop
a. heterozygote advantage: heterozygous condition bears greater advantage than either homozygous conditions. ex. sickle cell heterozygotes (AS) have resis against malaria, and is common 14 % in Africa. heterozygotes (AS) are normal, homozygotes (SS) is fatal.
b. Hybrid vigor (heterosis): superior quality of offspring resulting from crosses between two different inbred strains of plants. ex. hybrid corn from 2 inbred species is more resistant to disease.
c. Frequency- dependent selection (minority advantage: least common phenotypes have a selective advantage. common phenotypes selected against (search image of common phenotype). Cycle: rare pheno increase, and is selected against, decre and becomes more advantag and increases again.
19
Q
Neutral Variation
A
- variation w/o selective value
- ex. fingerprints in humans
20
Q
Geographic Variation
A
- variation of a species dependent on climate or geographic conditions.
- a graded variation of phenotype due to this is known as a cline: variation from North/South environ is a north-south cline.
21
Q
Causes of Changes in Allele Frequencies
A
- natural selection
- gene flow - intro/removal of alleles due to emigration or immigration
- genetic drift - random incr/dec of allele by chance.
a. founder effect
b. bottlenck - nonradom mating: indivd choose mates based on partic traits (ex. nearby). sexual selection: females choose superior traits. inbreeding: mate w// relatives.
- mutations
22
Q
Hardy-Weinberg Equilibrium Conditions
A
- allele freq remain constant from gen to gen
- no mutations, all traits neutral (no natural selection), pop isolated (no gene flow), large pop (no genetic drift), random mating, no net migration.
23
Q
Speciaton
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- formation of new species
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Q
Species
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- group of individuals capable of interbreeding
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Allopatric Speciation
- pop divided by geographic barrier => interbreeding prevented => gene freq diverge due to natu selection/mutation/genetic drift. if gene pool sufficiently diverged => will not interbreed when barrier is removed => new species formed
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Sympatric Speciation
- formation of new species w/o presence of geographic barrier
- balanced polymorphism: natu selection due to polymorphism. ex. diff colors of an insect pop provide camouflage to diff substrate, forming subpopulations that only interbreed among each other, diverging over time
- polyploidy: more than normal 2 sets of chromosomes. nondisjunction results in diploid gametes that combine and form a tetraploid (4n) zygotes => reproduct isolated.
- hybridization: two distinctly diff forms of a species (or two closely related species) mate and produce along a geographic boundary called hybrid zone
- adaptive radiation: rapid evolution from single ancestor. occurs when ancestral species is intoduced to area with diverse geographic/ecological conditions. ex. galapagos finches
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Maintaining Reproductive Isolation
| Prezygotic Isolating Mechanism
- PREVENT FERTILIZATION
- habitat isolation
- temporal isolation: mate/flower in diff season/time
- behavioral isolation: diff courtship ritual
- mechanical isolation: genitalia not compatible
- gametic isolation: male gametes don't survive in environ of female gamete. gametes don't recognize others.
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Maintaining Reproductive Isolation
| Postzygotic Isolating Mechanism
- hybrid inviability: zygote dies before repro maturity
- hybrid sterility: hybrids become adults but can't repro
- hybrid breakdown: hybrid produces offspring that have reduced viability/fertility
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Divergent Evolution
- two or more species that originate from common ancestor and become increasingly diff over time (speciation)
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Convergent Evolution
- two unrelated species share similar traits due to similar environments (analogous traits)
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Parallel Evolution
- two related species made similar evo changes after divergence from common ancestor
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Coevolution
- evo of one species in response to evo in another (predator/prey)
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Macroevolution
| Phyletic Gradualism
- evo occurs by gradual accumulation of small changes
- unlikely to be valid bec intermediate stages of evo are missing (fossils)
- fossils only reveal major changes in groups of organisms
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Macroevolution
| Punctuated Equilibrium
- evo history consists of geologically long periods of stasis (stability) w/ little/no evo followd by short period of rapid evo.
- absence of fossils of intermediate stages of evo is considered data that confirms rapid evo events.
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Origin of Life
- Universe: 12-15 billion years old
- solar system: 4.6 billion years old
- Earth: 4.5 billion years old
- Prokaryote Fossils: 3.6 billion years old
- Photosynthetic bacteria: 2.3 billion
- Eukaryotes: 1.5 billion
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Steps that Led to First Primitive Cell
1. Earth and atmosphere form (volcanoes): CH4, NH3, CO, CO2, H2, N2, H2O, S, HCl, HCN, little/no O2
2. Primordial seas formation: earth cools => gases condense => sea w/ water and mineral
3. Complex molec synthesized: organic soup from inorganic, energy from UV, lighting, heat, radiation => acetic acid, formaldehyde, and amino acids
4. Polymers and Self-replication: monomer => polymer (dehydration condensation). Proteinoids are abiotically produced polypeptides
5. Organic molec conc/isolated into protobionts
6. primitive heterotrophic prokaryotes
7. primitive autotrophic prokaryotes: mutation, heterotroph gained ability to produce its own food => cyanobacteria
8. O2 and ozone layer + abiotic chemical evo ended: O2 from photosynthesis + UV => ozone =: no energy for abiotic synthesis => term of primitive cells
9. Eukaryotes formed: endosymbiotic theory => euk cells originated mutually among prok (mitochondria, chloroplast establish resident inside another prokaryote
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Oparin & Haldane Organic Soup Theory
- if there were O2 in early earth, no organ molec would have formed
- hypothesis: origin earth enviorn was reducing providing chemical requir to produce complex molec from simpler ones. In an oxidizing environ, you'd break complex molec apart.
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Stanley Miller
- tested theory of Oparin Haldane and produced organic molecules
- Miller and Urey used ammonia, methane, water, and hydrogen sealed + simulated lightning => several organic molec, AA's, starting material, nut no nucleic acids.
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Proteinoids
- abiotically produced polypeptides
| - amino acids dehydration on hot, dry substances confirm this.
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Protobionts
- precursor of cells, like cells metabolically active but unable to reproduce
- microspheres/liposomes and coacervates are experimentally (abiotcally) produced protobionts that have some selective permeable qualities.
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Evidence for Endosymbiotic Theory
- thylakoid membrane of chloroplasts resemble photosynthetic membrane of cyanobacteria
- mitochondria and chloroplasts have their own circ DNA not wrappd w/ histones (prok like)
- ribosomes of chloroplasts/mitochondria resemble those of bacteria
- reproduce independently via process similar to binary fission, two membranes.
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Modern Atmosphere Composition
- 78% N2
- 21% O2
- 1% Ar
- a lot of other less important gases
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Vestigial Structures
- appear useless but had ancestral functions
| - ex. humans (appendix and tail)
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Mullerian Mimicry
- two or more harmful species
- not closely related
- share one or more common predators
- mimic each other's warning signals
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Batesian Mimicry
- deceptive harmless species evolved to mimic warning signals of a harmful species directed at common predator
- Bait
- Poser
- Impostor
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Parapatric Speciation
- continuous population but doesn't mate randomly. individuals more likely to mate w/ geo neighbors, divergence may happen due to reduced gene flow
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Peripatric Speciation
- similar to allopatric speciation in that a pop is isolated and prevented from exchanging genes, but one pop is much smaller so subject to faster genetic drift
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Anagesis/phyletic evolution
- one species replaces another, straight path evo
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Cladogenesis/branching evolution
- new species branch out from parent species
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Clade
- a group of species that include a common ancestor and all of its descendents (aka monophylum)
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Sere
- a particular stage of an ecosystem
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Mold
- an organic matter leaves an impression in rock or inorganic matter, later the organic matter decays and leaves a negative impression
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Cast
- type of fossil formed when a mold is filled in
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Deme
- small local population
| - ex. all beavers along specific portion of a river
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Autotrophic Anaerobes
- chemosynthetic bacteria
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Autotrophic Aerobes
- green plants, photoplankton
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Heterotrophic Anaerobes
- yeast
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Heterotrophic Aerobes
- amobas, earthworm, humans
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Synapomorphies
- shared traits derived from an evo ancestor common to all members of a group
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Law of Parsimony
- simplest explanation is most likely correct (phylogenetic trees: fewest number of chnages w/ respect to synapomorphies)
