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139 Cards in this Set
- Front
- Back
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What was wrong with lamarcks mechanism |
He said that the environment CAUSED the changes in the organism |
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What was Darwin’s mechanism |
The environment selects the organisms that will survive |
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Natural selection |
Individuals with certain inherited traits tend to survive and reproduce at higher rates (process of editing) |
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What 4 different types of evidence did Darwin use to explain evolution |
Direct observations, homology, fossil records, and biogeography |
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Direct observation of evolutionary change |
Evidence of evolutionary change we can see within a human lifetime -needs a sudden change in environment and rapid reproduction. -moths |
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Homology |
Similarities among different organisms arising from a common ancestry. |
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Fossil records |
Shows: -degree of relatedness between organisms -evolutionary change over time. -Past organisms differed from present day -Species become extinct - Life moved from water to land and vice versa. |
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Biogeography |
The geographic distribution of species Influenced by continental drift and islands close to mainland with endemic species |
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Endemic species |
Species not found anywhere else on the planet |
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How do some mutations become adaptations and some not |
If the mutation becomes beneficial to the survival of the species, the individuals with the mutations will reproduce more and pass it down to the next generation. |
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How do homologous structures give evidence for evolution |
Many organisms come from a similar ancestor but evolved into different variations |
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How do homologous structures give evidence for evolution |
Different organisms arise from a similar ancestor and evolved into different variations of organisms |
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Fossil records |
Shows: -degree of relatedness between organisms -evolutionary change over time. -Past organisms differed from present day -Species become extinct - Life moved from water to land and vice versa. |
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Biogeography |
The geographic distribution of species Influenced by continental drift and islands close to mainland with endemic species |
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Endemic species |
Species not found anywhere else on the planet |
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How do some mutations become adaptations and some not |
If the mutation becomes beneficial to the survival of the species, the individuals with the mutations will reproduce more and pass it down to the next generation. |
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How do homologous structures give evidence for evolution |
Many organisms come from a similar ancestor but evolved into different variations |
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How do homologous structures give evidence for evolution |
Different organisms arise from a similar ancestor and evolved into different variations of organisms |
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Convergent evolution |
When organisms with different ancestors adapt in similar ways to a similar environment |
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Macro-evolution |
Broad patterns of evolutionary change above the species level (takes millions of year) |
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Species |
A population whose members have the potential to interbreed in nature and produce viable FERTILE offspring |
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Speciation |
Isolating one group of genes from another (reproductive isolation) |
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Fossil records |
Shows: -degree of relatedness between organisms -evolutionary change over time. -Past organisms differed from present day -Species become extinct - Life moved from water to land and vice versa. |
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Biogeography |
The geographic distribution of species Influenced by continental drift and islands close to mainland with endemic species |
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Endemic species |
Species not found anywhere else on the planet |
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How do some mutations become adaptations and some not |
If the mutation becomes beneficial to the survival of the species, the individuals with the mutations will reproduce more and pass it down to the next generation. |
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How do homologous structures give evidence for evolution |
Many organisms come from a similar ancestor but evolved into different variations |
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How do homologous structures give evidence for evolution |
Different organisms arise from a similar ancestor and evolved into different variations of organisms |
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Macro-evolution |
Broad patterns of evolutionary change above the species level (takes millions of year) |
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Species |
A population whose members have the potential to interbreed in nature and produce viable FERTILE offspring |
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Speciation |
Isolating one group of genes from another (reproductive isolation) Each set of genes diverge genetically in different environments End result: two different species Explains similarities/differences in species + origin of new species |
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Darwin’s four observations |
Variations in traits exist These variations are heritable Species overproduce There is competition for resources, not all offspring survive. |
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Di |
Reduced hybrid viability: sperm and egg unite but offspring dies Reduced hybrid fertility: hybrid lives but is sterile Hybrid breakdown: first generation is fertile, 2nd generation is sterile |
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7 Patterns of evolution |
Divergent, convergent, parallel, coevolution, adaptive radiation, gradualism, and punctuated equilibrium |
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Divergent evolution |
A population becomes isolated from the rest of the species, becomes exposed to new selective pressures and evolves into a new species. |
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Convergent evolution |
Species occupy same environment, have similar selective pressures, show similar adaptations |
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Parallel evolution |
Two related species that have made similar evolutionary adaptations after their divergence from a common ancestor and have evolved in a similar environment. |
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Coevolution |
Two species evolve together by developing a reciprocal to evolutionary traits (bee and flower) |
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Adaptive radiation |
Numerous species emerge from a common ancestor (Darwin’s finches) (sympatric speciation) |
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Gradualism |
Species descended from a common ancestor, diverge more and more in morphology as they acquire unique adaptations (consistent change) |
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Punctuated equilibrium |
Periods of stability punctuated by sudden, rapid change |
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Allopatric speciation |
Population becomes divided geographically, interrupts gene flow Type of barrier depends on organisms ability to move Barrier exists-> gene pools diverge by mutations/natural selection/genetic drift -> reproductive isolation-> 2 new species emerge |
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Sympatric speciation |
No geographic isolation Reproductive barrier isolates gene pool (stops gene flow) |
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How sympatric speciation occurs |
Polyploidy, habitat differentiation, sexual selection, and reproductive isolation |
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Polyploidy |
nondisjunction occurs, causing a 2n gamete to fuse with another 2n gamete. The 4n organism can no longer reproduce with the 2n |
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Habitat differentiation |
The appearance of new ecological niches |
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Sexual selection |
Mates are chosen based on certain characteristics |
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Reproductive isolation and kinds |
Anything that prevents mating or production of a viable and fertile offspring Prezygotic barriers: prevents mating/fusion of egg and sperm Postzygotic: fertilization occurs, but does not develop into viable fertile adult types |
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Types of prezygotic barriers |
Habitat: physically separated. Genetic factor lets population exploit new habitat but gene pools cannot mix Behavioural: (sexual selection) species have unique mating behaviours, if not performed properly, mating won’t occur. Temporal: reproduce and different times Mechanism: morphological difference prevent mating Gametic: sperm cannot fertilize the egg (don’t match biochemically) |
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Microevolution |
A change in allelic frequencies in a population over generations |
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Three mechanisms of microevolution |
Natural selection, genetic drift and gene flow |
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Natural selection |
variety in heritable traits, the traits best suited to the environment allow the individual to survive to adulthood, reproduce, and pass on those traits. Only best fit individuals will survive |
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Five ways natural selection alters the frequency of alleles |
Directional- conditions favor one extreme phenotype (environment changes or pop. Migrates) Disruptive/diversifying: conditions favor both extremes of a phenotype Stabilizing: conditions favor intermediate phenotypes (reduces variation + removes outliers) Sexual: based on variation in sexual characteristics (sexual dimorphism, intra/intersexual selection Artificial: humans breed plants and animals |
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Genetic drift (2 types) |
Chance events cause allelic frequencies to fluctuate unpredictability. a) founder effect: few individuals become isolated from population. Takes some alleles b) bottleneck: most of the pop. is killed off. Remaining allelic frequencies are very different |
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Effects of genetic drift |
When original pop. is small, has greater impact Allelic frequencies change at random (unpredictable) loss of genetic variation Can cause harmful alleles to become fixed |
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Gene flow |
Immigration/emigration Transfer of alleles into or out of a population due to the movement of fertile individuals Increases diversity |
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2 types of genetic variation |
Discrete: variation consists of two choices only Quantitative: variation exists along a continuum (polygenic inheritance |
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Average heterozygosity |
Average percentage of loci that are heterozygous Shows if individuals with dominant phenotype have recessive allele |
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Sources of genetic variation |
1) mutation in the genes: rare it will help an organism 2) chromosomal changes: mostly harmfulrarely beneficial. |
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Microevolution |
A change in allelic frequencies in a population over generations |
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Factors that affect the rate of genetic variation |
Length of generation span (how many time they reproduce, how old?) and method of reproduction (asexual produces clones, no genetic variation) |
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Gene pool |
All possible genes within a population (gene pool of a popukau can be smaller than that of a species) |
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Fixed gene |
Only one allele for a gene is available. Everyone in a population is homozygous |
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Three mechanisms of microevolution |
Natural selection, genetic drift and gene flow |
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Natural selection |
variety in heritable traits, the traits best suited to the environment allow the individual to survive to adulthood, reproduce, and pass on those traits. Only best fit individuals will survive |
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Five ways natural selection alters the frequency of alleles |
Directional- conditions favor one extreme phenotype (environment changes or pop. Migrates) Disruptive/diversifying: conditions favor both extremes of a phenotype Stabilizing: conditions favor intermediate phenotypes (reduces variation + removes outliers) Sexual: based on variation in sexual characteristics (sexual dimorphism, intra/intersexual selection Artificial: humans breed plants and animals |
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Genetic drift (2 types) |
Chance events cause allelic frequencies to fluctuate unpredictability. a) founder effect: few individuals become isolated from population. Takes some alleles b) bottleneck: most of the pop. is killed off. Remaining allelic frequencies are very different |
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Effects of genetic drift |
When original pop. is small, has greater impact Allelic frequencies change at random (unpredictable) loss of genetic variation Can cause harmful alleles to become fixed |
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Gene flow |
Immigration/emigration Transfer of alleles into or out of a population due to the movement of fertile individuals Increases diversity |
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2 types of genetic variation |
Discrete: variation consists of two choices only Quantitative: variation exists along a continuum (polygenic inheritance |
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Average heterozygosity |
Average percentage of loci that are heterozygous Shows if individuals with dominant phenotype have recessive allele |
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Sources of genetic variation |
1) mutation in the genes: rare it will help an organism 2) chromosomal changes: mostly harmfulrarely beneficial. |
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Microevolution |
A change in allelic frequencies in a population over generations |
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Factors that affect the rate of genetic variation |
Length of generation span (how many time they reproduce, how old?) and method of reproduction (asexual produces clones, no genetic variation) |
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Gene pool 8 |
All possible genes within a population (gene pool of a popukau can be smaller than that of a species) |
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Fixed gene |
Only one allele for a gene is available. Everyone in a population is homozygous |
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8 mechanisms to preserve genetic variation |
balanced polymorphism, geographic variation, sexual reproduction, outbreeding , diploidy, heterozygous advantage, frequency-dependent selection, and evolutionary neutral traits |
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Balanced polymorphism |
two or more phenotypically distinct forms of a trait in a species. Each form is advantageous in different environments |
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Geographical variation |
Graded variation of phenotypes creating a cline (spectrum) |
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Sexual reproduction |
Shuffles or recombines alleles during meiosis and sexual reproduction (independent assortment, crossing-over, random fertilization) |
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Outbreeding |
Gene flow. Mating between members of same species that are not closely related |
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Diploidy |
2n genes allows alleles to remain hidden, may become advantageous when environment changes. |
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Three mechanisms of microevolution |
Natural selection, genetic drift and gene flow |
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Natural selection |
variety in heritable traits, the traits best suited to the environment allow the individual to survive to adulthood, reproduce, and pass on those traits. Only best fit individuals will survive |
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Five ways natural selection alters the frequency of alleles |
Directional- conditions favor one extreme phenotype (environment changes or pop. Migrates) Disruptive/diversifying: conditions favor both extremes of a phenotype Stabilizing: conditions favor intermediate phenotypes (reduces variation + removes outliers) Sexual: based on variation in sexual characteristics (sexual dimorphism, intra/intersexual selection Artificial: humans breed plants and animals |
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Genetic drift (2 types) |
Chance events cause allelic frequencies to fluctuate unpredictability. a) founder effect: few individuals become isolated from population. Takes some alleles b) bottleneck: most of the pop. is killed off. Remaining allelic frequencies are very different |
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Effects of genetic drift |
When original pop. is small, has greater impact Allelic frequencies change at random (unpredictable) loss of genetic variation Can cause harmful alleles to become fixed |
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Gene flow |
Immigration/emigration Transfer of alleles into or out of a population due to the movement of fertile individuals Increases diversity |
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2 types of genetic variation |
Discrete: variation consists of two choices only Quantitative: variation exists along a continuum (polygenic inheritance |
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Average heterozygosity |
Average percentage of loci that are heterozygous Shows if individuals with dominant phenotype have recessive allele |
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Sources of genetic variation |
1) mutation in the genes: rare it will help an organism 2) chromosomal changes: mostly harmfulrarely beneficial. |
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Microevolution |
A change in allelic frequencies in a population over generations |
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Factors that affect the rate of genetic variation |
Length of generation span (how many time they reproduce, how old?) and method of reproduction (asexual produces clones, no genetic variation) |
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Gene pool 8 |
All possible genes within a population (gene pool of a popukau can be smaller than that of a species) |
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Fixed gene |
Only one allele for a gene is available. Everyone in a population is homozygous |
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8 mechanisms to preserve genetic variation |
balanced polymorphism, geographic variation, sexual reproduction, outbreeding , diploidy, heterozygous advantage, frequency-dependent selection, and evolutionary neutral traits |
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Balanced polymorphism |
two or more phenotypically distinct forms of a trait in a species. Each form is advantageous in different environments |
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Geographical variation |
Graded variation of phenotypes creating a cline (spectrum) |
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Sexual reproduction |
Shuffles or recombines alleles during meiosis and sexual reproduction (independent assortment, crossing-over, random fertilization) |
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Outbreeding |
Gene flow. Mating between members of same species that are not closely related |
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Diploidy |
2n genes allows alleles to remain hidden, may become advantageous when environment changes. |
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Heterozygous advantage |
Preserves multiple alleles in a population Heterozygotes are sometimes |
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Gene pool |
All possible genes within a population (gene pool of a popukau can be smaller than that of a species) |
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Natural selection |
variety in heritable traits, the traits best suited to the environment allow the individual to survive to adulthood, reproduce, and pass on those traits. Only best fit individuals will survive |
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Five ways natural selection alters the frequency of alleles |
Directional- conditions favor one extreme phenotype (environment changes or pop. Migrates) Disruptive/diversifying: conditions favor both extremes of a phenotype Stabilizing: conditions favor intermediate phenotypes (reduces variation + removes outliers) Sexual: based on variation in sexual characteristics (sexual dimorphism, intra/intersexual selection Artificial: humans breed plants and animals |
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Genetic drift (2 types) |
Chance events cause allelic frequencies to fluctuate unpredictability. a) founder effect: few individuals become isolated from population. Takes some alleles b) bottleneck: most of the pop. is killed off. Remaining allelic frequencies are very different |
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Effects of genetic drift |
When original pop. is small, has greater impact Allelic frequencies change at random (unpredictable) loss of genetic variation Can cause harmful alleles to become fixed |
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Gene flow |
Immigration/emigration Transfer of alleles into or out of a population due to the movement of fertile individuals Increases diversity |
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Outbreeding |
Gene flow. Mating between members of same species that are not closely related Preserves genetic variation |
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Average heterozygosity |
Average percentage of loci that are heterozygous Shows if individuals with dominant phenotype have recessive allele |
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Heterozygous advantage |
Preserves multiple alleles in a population Heterozygotes are sometimes better adapted (sickle cell anemia) greater reproductive success |
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Frequency-dependent selection |
Minority advantage, sometimes minority genes have a survival advantage (so slow u don’t get chased) |
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Clade |
Group of species that includes and ancestral species and all of its descendants (monophyletic) |
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Para |
Hb |
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Evolutionary neutral traits |
Traits that seem to have no selective advantage No need to select against or for it Might become useful in future |
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Phylogeny |
The evolutionary history of a species of group of related species |
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A |
1)species (pardus) 2)genus (panthers) 3) family (felidae ) 4) order (carnivora) 5) class (mammalia) 6) phylum (chordata) 7) kingdom (animalia) 8) domain (eukarya, bacteria, archaea) |
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Binomial nomenclature |
Genes and species only Ex: panthera pardus |
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Rooted tree |
Includes a branch to represent the last common ancestor of all taxa in the tree |
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Sister taxa |
Groups that share an immediate common ancestor |
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Polytomy |
A branch from which more than two groups emerge |
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Paraphletic |
Grouping includes some but not all of its descendants |
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Polyphyletic |
Grouping that includes all of the descendants plus one or more species that are not |
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Shared ancestral characteristic |
A characteristic shared by members of a clade that originated from an ancestor that is not a member of that clade |
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Shared derived characteristic |
An evolutionary novelty that is unique to a particular clade |
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What do branch lengths represent |
The amount of evolutionary change or times particular events occurred |
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Maximum parsimony |
first investigate simplest explanation that is consistent with the facts |
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Maximum likelihood |
Take into account the hypothesis that reflects most likely sequence of evolutionary events |
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Polyphyletic |
Grouping that includes all of the descendants plus one or more species that are not |
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Lyell’s discovery |
Principle of uniformitarianism: mechanisms of change are constant over time |
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Shared ancestral characteristic |
A characteristic shared by members of a clade that originated from an ancestor that is not a member of that clade |
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Shared derived characteristic |
An evolutionary novelty that is unique to a particular clade |
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What do branch lengths represent |
The amount of evolutionary change or times particular events occurred |
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Maximum parsimony |
first investigate simplest explanation that is consistent with the facts |
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Maximum likelihood |
Take into account the hypothesis that reflects most likely sequence of evolutionary events |
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Linnaeus’ discovery |
Binomial classification system of genus species to name all organisms |
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Hutton’s discovery |
Theory of gradualism |
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Malthus’ discovery |
Populations will always overproduce their young and their survival rate is low Populations cannot grow exponentially |
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Cuvier’s discovery |
Extinctions Theory of catastrophism: events in past occurred suddenly caused by different mechanisms than today |
