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58 Cards in this Set
- Front
- Back
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evolution is the process of adaptation and change leading to genetic diversity and new life forms
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evolution may be accomplished through
1. natural selection 2. mutation 3. genetic drift 4. genetic shift |
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evolution is a THEORY
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lamarck's inheritance theory of acquired characteristics
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concept of use/disuse
-things used extensively(organs) would develop -those that were not used as much, would lead to atrophy |
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changes through time associated with use/disuse theory called acquired characteristics
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darwins natural selection theory
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1. organisms produce offspring, few to which survive to maturity
2. chance variations w/in individuals may be inheritable -if give slight advantage, deemed favorable |
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darwins natural selection theory contd
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3. individuals with more of these favorable variations are more likely to survive/reproduce
-process known as natural selection 4. over time, separation of traits will form new species |
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darwins natural selection theory contd
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fitness is defined as reproductive success of an individual
-reproductive success linked to relative genetic contribution of individual to next generation |
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lamarck was proven wrong in theory...
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natural selection is mechanism of evolution, not equivalent to evolution
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neodarwinism
-modern synthesis |
differential reproduction
-more favorable mutations passed on while less favorable ones are not |
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punctuated equilibrium
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suggests that changes in species occur in rapid bursts rather than evenly over time
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evidence of evolution comes from -paleontology
-biogeography -comparative anatomy -comparative embryology -molecular biology |
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paleontology
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use of radioactive dating of fossils
-help determine chronological succession of animals |
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biogeography
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migration
divergence(island species once on mainland, but separated over time,,,develop into new species) |
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comparative anatomy
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comparison of similar structures to determine relatedness
-homologous -analagous -vestigial |
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homologous structures
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similar in structure and share a common evolutionary origin even if they dont have a similar appearance, shape or form
ex) bats vs humans both have similar bone structures in wings/arms respectively |
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analagous structures
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structures that serve a common
purpose but evolved separately in each species ex) birds and insects...both can fly but developed ability to fly independent of one another aka NO COMMON ANCESTOR! |
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vestigial structures
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remnants of organs that have lost their ancestral function
ex) appendix -coccyx -things not necessary for life |
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comparative embryology
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analyze similarities between embryos of different species
-gills -tails etc |
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molecular embryology
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as species become distant taxonomically speaking, the amt of shared DNA will decrease
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when gene frequencies of population are not changing, the gene pool is stable and no evolution occurs..
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criteria for this to be true...
1. LARGE population 2. no mutations 3. random mating 4. no migration 5. genes in pool are equally successful at reproducing |
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hardy-weinberg EQ is when the following criteria mentioned is true
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no net evolution
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HW equation...
P^2 + 2PQ + Q^2 |
P + Q = 1
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5 agents of microevolution...
1. natural selection 2. mutation 3. assortive mating 4. genetic drift 5. gene flow |
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natural selection
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genotypes favorable are selected
-frequency of selected increases -more offspring with gene |
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mutation
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gene mutations change allele frequencies in population
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assortive mating
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when mates are selected
-non random mating -proximity/phenotype driven |
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genetic drift
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changes in the composition of the gene pool due to chance
-MORE PRONOUNCED IN SMALL POPULATIONS ----founder effect |
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founder effect = when small population of species finds itself isolated from other populations as a result of natural boundaries
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gene flow
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occurs from migration of individuals among populations
-loss/gain of genes -changes gene pool composition |
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natural selection is the ONLY method capable of generating stable evolutionary changes over long periods of time
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occurs through
-stabilizing selection -directional selection -disruptive selection |
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stabilizing selection
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elimination of the extremes
-uniform bell curve -ex) birth weights |
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directional selection
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leads to majority being of one of the extremes
-ex) bell-curve shifted to the right -EX) pathogen resistance |
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disruptive selection
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both extremes are favored
-ex) males and females...no middle sex |
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altruistic behavior
-selfless care for the concern of others.. |
ants have many workers who are sterile and benefit the community through their services
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kin selection
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suggests that organisms behave altruistically if they are closely related to successfully reproducing organisms
ex) workers are related to the queen ant |
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inclusive fitness
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the number of alleles that an individual passes on to the next generation, even if only indirectly through altruistic behavior
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speciation
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the emergence of a new species
defn: species -a group of individuals who can interbreed freely with one another but not with members of other species |
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reproductive isolation
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when two populations of same species isolated for long time to the point where they can breed with each other
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reproductive isolation can occur prezygotically or postzygotically
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prezygotic mechanisms...
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prevent formation of zygote completely
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postzygotic mechanisms...
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allow for gamete fusion, but yield sterile offspring..
horse + donkey = sterile mule |
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prezygotic isolating mechanisms
1. temporal isolation 2. ecological isolation 3. behavioral isolation 4. reproductive isolation 5. gametic isolation |
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temporal isolation
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time dependent
-species may breed during different times, seasons, day/night |
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ecological isolation
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live in same territory, but different habits
ex) top of tree vs ground level |
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behavioral isolation
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not sexually attracted due to pheromones, appearance, courtship etc
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reproductive isolation
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parts dont necessarily fit
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gametic isolation
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sex can occur, but fertilization can not
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postzygotic isolating mechanisms
1. hybrid inviability 2. hybrid sterility 3. hybrid breakdown |
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hybird inviability
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aborted hybrid, even if fertilized
-limited ability to mature to adult |
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hybrid sterility
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able to reach maturity, but not capable of reproduction since sterile
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hybrid breakdown
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1st generation hybrids are viable and fertile
2nd generation hybrid offspring are inviable or infertile -occurs when closely related but reproductively isolated species introduced --occurs in plants more than animals |
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adaptive radiation
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when a single ancestral species gives rise to a number of different species
each species diverges to the point that it is able to occupy a unique niche --this decreases competition among species for food/homes |
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3 evolutionary patterns exist
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1. divergent
2. parallel 3. convergent |
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convergent evolution
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independent development of similar characteristics in two or more lineages not sharing a common ancestor
ex) fish/dolphins both swim in water and look similar, yet have no ancestral connections |
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divergent evolution
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the independent development of dissimilar characteristics in two or more lineages sharing a common ancestor
ex)seals + cats belong to Carnivora, but have separate appearances/environments |
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parallel evolution
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process where related species evolve in similar ways for a long pd of time in response to analogous environmental selection pressures
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