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77 Cards in this Set
- Front
- Back
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Alfred Russell Wallace
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Came up with ideas about evolution; recognized that Darwin deserved credit; Man who "discovered" evolution after Darwin because Darwin hadn't published.
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Homology
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similarity due to common ancestry
ex: limbs of humans, bats, cats, whales are all similar. Embryos look similar. amino acid %s. |
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Modern Synthesis
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1. Darwin's evolution and natural selection
2. Mendel's genetics 3. Math of genetics and population evolution. 4. Ideas about speciation |
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Population
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Individuals capable of interbreeding in a region, isolated or can overlap, no specific boundaries.
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Gene Pool
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all the alleles of the genes in a population
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Allele frequency
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% of all alleles of a gene that are of a particular type
ex: 500 total individuals->320 homozygous dominant, 160 heterozygous, 20 homozygous recessive |
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Hardy-Weinberg Theorem (equilibrium)
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describes populations that are not evolving (no change in allele frequency)
Assumptions: 1. Large population 2. No gene flow (immigration OR emigration) 3. No mutations 4. Random mating 5. No natural selection |
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Mutations
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Origin of variation, changes allele frequency, slim chance
(most variation from generation to generation is due to sexual recombination such as crossing over, independent assortment) |
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Genetic Drift
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any change in gene pool due to RANDOM EFFECTS of mating and recombination; more common in smaller populations (higher probability of deviation from expected, interbreeding)
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Genetic Drift: Bottleneck Effect
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large population goes through "bottleneck" until it is drastically reduced in size, surviving individuals may not be typical of the particular population
ex: cheetahs w/ feline leukemia |
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Genetic Drift: Founder Effect
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A few individuals are isolated from the main population (as few as 1 pregnant female), the alleles they carry start the new population--may not be typical of the original population
ex: albino monarch butterflies in Hawaii |
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Gene Flow
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Immigration or emigration, carries alleles--makes populations more similar until they eventually can become one population
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Polymorphism
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More than one phenotype/genotype in population (VERY common)
ex: males and females; Darwin's Galapagos finches |
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Continuous Variation
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multiple genes w/ a range of phenotypes
ex: skin color, height |
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Geographic Variation
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Isolated populations adapt to different environment-- may eventually lead to speciation, obvious break
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Clinal variation
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usually has genetic and environmental components
ex: height of plants on mountain (gradual change due to altitude); no obvious break |
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Fitness
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contribution an individual makes to the gene pool of the next generation's relative fitness: best adapted genotype has fitness of 1, others are relative to that individual (numbers between 0 and 1)
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Types of Selection:
Directional Selection |
Most Common; almost always continuous variation
ex: mice living in darker woods would slowly shift to darker colorings to camouflage |
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Types of Selection:
Disruptive selection |
Least common
Individuals are pushed to either extremes because the middle trait is not desired; non random mating |
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Types of Selection:
Stabilizing selection |
Somewhat common
ex: birth weight in babies- smaller is sickly, bigger is hard to birth |
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Maintaining Variation:
Diploidy |
Recessive genes are always preserved
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Maintaining Variation:
balancing selection |
heterozygous advantage
ex: sickle cell anemia w/ malaria |
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Maintaining Variation:
Frequency-dependent selection |
an evolutionary process where the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population
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Sexual Selection
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Natural selection for mating success (doesn't apply to most plants)
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Sexual Selection:
Intrasexual Selection |
Male/Male competition most common
ex: antlers, horns |
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Sexual Selection:
Intersexual selection |
Female choice most common
ex: male birds have bright colors |
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Speciation:
Microevolution |
changes in gene frequencies within populations
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Speciation:
Macroevolution |
process of speciation and divergence above the species level
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Speciation:
Anagenesis |
Change within a population over time
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Speciation:
Cladogenesis |
Splitting of a population into two over time
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Maintaining Variation:
Diploidy |
Recessive genes are always preserved
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Maintaining Variation:
balancing selection |
heterozygous advantage
ex: sickle cell anemia w/ malaria |
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Maintaining Variation:
Frequency-dependent selection |
an evolutionary process where the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population
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Sexual Selection
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Natural selection for mating success (doesn't apply to most plants)
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Sexual Selection:
Intrasexual Selection |
Male/Male competition most common
ex: antlers, horns |
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Sexual Selection:
Intersexual selection |
Female choice most common
ex: male birds have bright colors |
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Speciation:
Microevolution |
changes in gene frequencies within populations
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Speciation:
Macroevolution |
process of speciation and divergence above the species level
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Speciation:
Anagenesis |
Change within a population over time
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Speciation:
Cladogenesis |
Splitting of a population into two over time
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Maintaining Variation:
Diploidy |
Recessive genes are always preserved
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Maintaining Variation:
balancing selection |
heterozygous advantage
ex: sickle cell anemia w/ malaria |
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Maintaining Variation:
Frequency-dependent selection |
an evolutionary process where the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population
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Sexual Selection
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Natural selection for mating success (doesn't apply to most plants)
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Sexual Selection:
Intrasexual Selection |
Male/Male competition most common
ex: antlers, horns |
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Sexual Selection:
Intersexual selection |
Female choice most common
ex: male birds have bright colors |
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Speciation:
Microevolution |
changes in gene frequencies within populations
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Speciation:
Macroevolution |
process of speciation and divergence above the species level
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Speciation:
Anagenesis |
Change within a population over time
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Speciation:
Cladogenesis |
Splitting of a population into two over time
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Biological Species Concept
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grew out of Modern Synthesis; population or group of populations who have the potential to interbreed in nature and produce fertile offspring
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Morphological Species Concept
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based on structural features; doesn't work well w/ polymorphism
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Paleontological Species Concept
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based on structural features of fossils
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Ecological Species Concept
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based on ecological differences such as food use
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Reproductive Isolation
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factors that keep 2 populations from interbreeding, leading to speciation
prezygotic: before fertilization postzygotic: after fertilization ex: mule is non-fertile |
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Phylogenetic Species Concept
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set of organisms w/ a unique genetic history; everything since last branch
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Patterns of Speciation:
Allopatric Speciation |
Occurs when populations are separated by a geographic barrier and diverge genetically until they can no longer interbreed
ex: Galapagos finches |
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Patterns of Speciation:
Sympatric Speciation |
Occurs in geographically overlapping populations; may require chromosomal change; most common in plants ability to become polyploidy (many sets of chromosomes)
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Patterns of Speciation:
Autopolyploidy |
During meiosis 1 homologous pairs don't separate= diploid cell + empty cell
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Patterns of Speciation:
Allopolyploidy |
2 plants form new species, 1 plant w/ odd # of chromosomes mates w/ sterile plant
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Patterns of Speciation:
Adaptive Radiation |
Rapid speciation; species colonizes new environment and subpopulates quickly to adapt
Common on islands; may result in closely related genetically; founder effect |
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Tempo of Speciation
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1. gradualism- gradual change
2. punctuated equilibrium- stairsteps |
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Phylogeny
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evolutionary history of a species; evolutionary branching pattern
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Homology
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similarity due to common ancestry
ex: human, bat, cat, whale arms |
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Analogy
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Similarity due to similar adaptations to environment
ex: mole vs. marsupial |
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Sympleisomorphies
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(not informative)
Shared primitive characters ex: all mammals have 4 legs--doesn't tell us anything because so do many reptiles, insects, etc. |
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Synapomorphies
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(informative)
shared derived characteristics used to construct cladograms ex: all marsupials have pouches |
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Cladistic groups:
Monophyletic |
ancestor plus all of descendants
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Cladistic groups:
Paraphyletic |
ancestor plus some of descendants
ex: reptiles have separate group from birds even though birds evolved from reptiles |
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Cladistic groups:
Polyphyletic |
group w/ no common ancestor
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Phylograms
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lengths of branch reflects # of changes
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Ultrametric tree
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branches represent timing of divergence
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Taxonomy
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ordered classification of organisms based on characteristics
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Classification
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Category
ex: domain, kingdom, etc. |
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Taxon
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Any named group at any level of classification
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Evolution
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change in allele frequency of a population
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Natural Selection
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mechanism of evolutionary adaptation
Population selects favorable traits which become more frequent in gene pool. |
