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73 Cards in this Set
- Front
- Back
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Evolution
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The Change in allelic frequencies in a population
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Microevolution
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The changes in allelic frequencies in a single gene pool
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Macroevolution
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Appearance of a major evolutionary development of a new species
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Anagenesis
aka Phyletic Evolution |
When one species replaces another (a type of speciation)
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Cladogenesis
aka Branching Evolution |
A new species branches out from a parent species
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What does paleontology reveal when studying fossil records?
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The existence of species that have become extinct or have evolved into other species
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Earth's Approximate Age
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4.6 Billion Years
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What came first Prokaryotes or Eukaryotes?
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Prokaryotes- the first organisms to develop on earth and are the oldest fossils
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Homologous Structures
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Have the same internal bone structure but different functions- Have a common origin and reflect a common ancestor
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Analogous Structures
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Have similar functions but no internal similarities- reflects an adaptation to a similar environment but no common ancestor
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Vestigial Structures
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A structure that was once needed but has since been deemed unhelpful (ex. appendix)- These structures are evidence that evolution has taken place
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Comparative Biochem
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Organisms that have a common ancestor have a common biochemical pathway- The more closely related they are, the more similar the pathways
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Comparative Embryology
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Closely related organisms undergo similar stages in embryonic development
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Cytochrome C
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Aerobic cells contain polypeptide cytochrome c and a comparison of the aa sequence of cytochrome c in different organisms shows which organisms are most closely related
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Continental Drift
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A theory that about 200 million years ago the continents were one single supercontinent which slowly separated into the 7 continents over the course of about 150 million years
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Pangea
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The one single supercontinent that existed about 200 million years ago
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6 areas of study that confirm evolution
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Biogeography, Molecular Bio, Comparative Embryology, Comparative Biochem, Comparative Anatomy, Fossil Record
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Scala Natura
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Aristotle's theory that all organisms can be arranged on a ladder of increasing complexity - The species are permanent and do not evolve - Humans rest on the top of the ladder as the most complex species
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Taxonomy
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The branch of biology that is concerned with naming and classifying different forms of life
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Carolus Linnaeus
aka Carl von Linne |
Developed Binomial Nomenclature
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Binomial Nomenclature
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Genus name + Species name
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Cuvier
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Realized that each stratum of earth is characterized by different fossils- Believed that a series of catastrophes was responsible for the change in organisms on earth- Was also a strong OPPONENT of evolution
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James Hutton
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Theory of Gradualism= earth was molded by slow change (wind, weather, and water) not by catastrophe
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Lyell
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Wrote Principles of Geology- Believed that the earth was much older than they then thought (6000 yrs)- Also stated that geological change occurred from slow and continuous actions
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Lamarck
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His theory of evolution = individual organisms change in response to their environments (ie the giraffes with long necks) = inheritance of acquired characteristics & use and disuse
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Wallace
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A naturalist- published an essay discussing the process of natural selection (identical to Darwin's theory)
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Darwin's Theory of Natural Selection
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Populations tend to grow exponentially and then overpopulate and exceed resources (based on Malthus) - Overpopulation results in competition and a struggle for existence - In any population there is variation and an unequal ability of individuals to survive and reproduce (Medel's theory of genetics explains this) - Survival of the fittest - Evolution occurs as advantageous traits accumulate in a population
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Directional Selection
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A species has two different traits one is more advantageous than the other, the organisms possessing the more advantageous trait will survive while the other ones will die off, the surviving organisms breed quickly because there is no longer any competition, thus the entire population has the advantageous trait (ie insecticide resistance)
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5 Types of Selection
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Stabilizing, Diversifying, Directional, Sexual, and Artificial
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Stabilizing Selection
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Eliminated Extremes (ie really tiny or really large babies usually die) and favors the more common intermediate forms which weeds out many mutant forms
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Diversifying Selection
aka Disruptive Selection |
Increases the extremes of a population at the expense of the intermediate forms- over time this may result in two new species - usually caused by pressure from the environment (ie camoflage)
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Balanced Polymorphism
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One population developed into two distinct types - a result of diversifying selection
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Directional Selection
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One phenotype replaces another in a gene pool - caused by changing environmental conditions (ie industrial melanism in peppered moths = industrialization caused a darker environment which caused the darker moths to prosper and the previously dominant white moths to suffer) - Can produce rapid shifts in allelic freq.
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Sexual Selection
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Selection based on variation in secondary sexual characteristics related to competing for and attracting mates (ie males have horns and great strength etc.)
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Sexual Dimorphism
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Differences in appearance between males and females
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Artificial Selection
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Breeding - humans breed plants and animals with desired traits
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8 ways to preserve variation
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Balanced polymorphism, geographic variation, sexual reproduction, outbreeding, diploidy, heterozygote superiority, frequency dependent selection, & evolutionary neutral traits
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Balanced Polymorphism
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The presence of two or more phenotypically distinct forms of a trait in a single population of species ( ie banded snails vs unbanded snails - some places are better suited to each morph)
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Geographic Variation
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Variation due to different types of environments (ie north american rabbits)
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Cline
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A graded variation in the phenotype of an organism
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Sexual Reproduction ( as a means of variation)
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Provides variation due to the shuffling and recombination of alleles during meiosis and fertilization - independent assortment of chromosomes during metaphase I results in the recombination of unlinked genes- Crossing over <3 - Random fertilization of one ovum by one sperm of millions results in enormous variety among offspring
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Outbreeding
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the mating of organisms within one species that are not closely related
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Diploidy
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The 2n condition- maintains hidden pools of alleles that could potentially be helpful if conditions change
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Heterozygote superiority
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Preserves multiple alleles in a population- the heterozygote is selected bc it has greater reproductive success (ie sickle cell anemia)
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Frequency- Dependent Selection
aka Minority Advantage |
Decreases the frequency of the more common phenotypes and increases the frequency of the less common ones (predators will use their search image to determine the prey that has the highest frequency allele and eat that one) Eventually obviously the roles will reverse
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Evolutionary Neutral Traits
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Traits that seem to have no selective value (ie blood type and finger print variation)
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Factors That Cause Evolution
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Genetic drift, gene flow, mutations, nonrandom mating, & natural selection
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Genetic Drift
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Change in the gene pool due to chance- ex. = bottleneck effect and founder effect
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Bottleneck Effect
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Natural disasters reduce the size of a population unselectively resulting in less genetic variation - ex. Tay Sachs after the Holocaust or the hunting of the Northern Elephant seal in Cali are all from a single group of individuals
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Founder Effect
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When a small population breaks away from a larger one to colonize a new area- the population in the new area likely is not genetically representative of the original population (ex. polydactyl - multiple fingers or toes- in the amish community)
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Gene Flow
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The movement of alleles into or out of a population- can occur as a result of the migration of fertile individuals or gametes between populations
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Mutations
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Changes in genetic material and a re the raw material for evolutionary change- a single point mutation can introduce a whole new allele into a population - although mutations at one locus are rare and the cumulative effect of mutations at all loci in a population can be significant
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Conditions for a stable population according to the Hardy-Weinberg Equilibrium
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-Population Must Be Large (smallest populations are more affected by change)
- Must Be Isolated ( migration alters allelic frequencies) -Must be no mutations (mutations change allelic frequencies and can introduce a new allele) -Mating must be random (eliminates reproductive advantages and evolution) -No Natural Selection (causes change in allele frequencies) |
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Hardy- Weinberg Equation
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Calculates the frequencies of alleles in a population
(p^2)+2pq+(q^2)=1 p+q=1 |
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1-p
2-(p^2) |
1-Dominant allele in the Hardy- Weinberg Equation
2-Dominant homozygous |
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1-q
2-(q^2) |
1-The recessive allele in the Hardy-Weinberg Equation
2- Recessive homozygous |
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2pq
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Hybrid in Hardy- Weinberg equation
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Species
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A population whose members have the potential to interbreed in nature and produce viable and fertile offspring
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Reproductive Isolation
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One group of genes becomes isolated from another to begin a separate evolutionary history
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Allopatric Speciation
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Caused by geographic isolation
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Sympatric Speciation
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Speciation without geographic isolation
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Polyploidy
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A cell has more than two complete sets of chromosomes- common in plants- can occur naturally or through breeding- Nondisjunction during meiosis can result in gametes with the 2n chromosome number that when fertilized by a normal gamete produces a 3n daughter cell- plants that are polyploidy can only breed with other polyploidy plants
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Habitat Isolation
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2 organisms live in the same area but encounter each other rarely
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Behavioral Isolation
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If one mate fails in to respond in the appropriate manner or any part of the attraction does not go perfectly then the two do not mate
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Temporal Isolation
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Time that it takes to reach sexual maturity differs
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Reproductive Isolation
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Prezygotic and postzygotic variables are present
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Prezygotic Variable
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Something that prevents mating from occurring
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Postzygotic Variable
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Something that prevents the production of a fertile offspring once mating has occured
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Divergent Evolution
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A population becomes isolated, exposed to new selective pressure, and then evolves into a new species- both allopatric and sympatric speciation are divergent
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Convergent Evolution
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Unrelated species occupy the same environment and are thus subjected to similar selective pressures and then show similar adaptations (ie the whale and fish)
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Parallel Evolution
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Two related species that have made similar adaptations after divergence from a common ancestor (ie Marsupials in Australia and placental mammals in North America)
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Coevolution
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Reciprocal evolutionary set of adaptations of two interacting species like predators and prey
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Adaptive Radiation
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The emergence of numerous species from a common ancestor introduced into an environment- each form specializes to fill a niche (Darwin's finches)
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