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53 Cards in this Set
- Front
- Back
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What is evolution?
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Change over time
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What is a theory?
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A well-supported testable explanation of phenomena that have occurred in the natural world
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Who was Nils Stensen?
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An anatomist who dissected head of a shark and recognized similarity of shark teeth and other fossils he had found
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During his travels, Darwin made numerous observations and collected evidence that led him to propose what?
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A revolutionary theory that life changes over time
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What is the law of superposition?
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Stone was fluid, but become a solid; the earth is layered
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What are fossils?
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Preserved remains of ancient organisms
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What is the principle of original horizontality?
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Strata are either perpendicular to the horizon or inclined to the horizon were at one time parellel to the horizon
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What is the principle of lateral continuity?
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Similar layering in rocks
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What did William Smith do?
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He mapped a lot of England
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Where did Darwin do a lot of his research, and on what animal?
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Galapagos Islands in tortoises
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What is catastrophism?
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Changes on Earth happen in increments (idea about changes)
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What is uniformitarianism?
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Changes are gradual
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What two people believed in uniformitarianism?
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James Hutton and Steven Jay Gould
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What two observations did Darwin make about the Galapagos?
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-That only organisms that could reach the island could be found there
-Evolution can only transform those species that are avalible |
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What three people influenced Darwin?
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-Lyell's "Principle of Geology"
-Lemarck's theory of evolution -Thomas Malthus |
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What was Lemarck's theory of evolution?
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That by selective use and disuse of organs, organisms acquired of lost certain traits. These traits could than be passed to their offspring.
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What are Lemarck's three theories?
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-Tendency Toward Perfection=all organisms have an innate tendency to perfection
-Use and Disuse=that organisms could alter their apperance by using different parts of their bodies different ways -Inheritance of Acquired Traits=that acquired traits could be inherited |
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What did Malthus believe about population?
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That if human population continued to grow, sooner or later there would be insufficient living space and food.
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What is artificial selection?
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Nature provided variation and humans selected those variations that they found useful.
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What is struggle for existence?
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Members of each species compete regularly to get food
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What is fitness?
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The ability of an individual to survive and reproduce
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What is adaptation?
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Any inherited characteristic that increases an organism's chance of survival
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What is survival of the fittest?
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When individuals that are better suited for their environment (with adaptations that enable fitness) survive and reproduce
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What is natural selection?
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-More individuals born than the environment can support
-Individual variation w/in species is random -Variations can be inherited -Variant forms of a trait may be more of less adaptive under environment conditions |
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Over time, natural selection results in __________ in the inherited characteristics of a population.
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Changes
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What is descent with modification?
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That over long periods, natural selection produces organisms that have different structures have different niches and different habitats. As a result, species today look different from their ancestors
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What is Darwin's evidence?
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-Homologous body structures
-Geographical distribution of living species -Fossil record -Similarities in embryology |
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What are homologous structures?
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Structures that have different mature forms but develop from the same embryonic tissues
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What are vestigial organs?
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Traces of homologous organs
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What are three main elements of Darwin's evolution?
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-Variation
-Selection -Decent/heredity |
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What is a gene pool?
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A common group of genes
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What is relative frequency of an allele?
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The number of times that the allele occurs in a gene pool compared with the number of times other alleles for the same gene occur
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What are the two main sources of genetic variation?
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Gene mutations and gene shuffling
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The number of _________ produced for a give trait depends on how many ______ control the trait.
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Phenotypes, genes
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What is a single-gene trait?
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Ex. a widow's peak. A single gene that has two alleles
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What are polygenic traits?
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A trait controlled by two or more genes
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Natural selection on single-gene traits can lead to...
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Changes in allele frequencies and thus to evolution
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What is direction selection?
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When individuals at one end of the curve have higher fitness that individuals in the middle or at the end
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What is stabilizing selection?
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When individuals near the center of the curve have higher fitness than individuals at either end of the curve
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What is disruptive selection?
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When individuals at the upper and lower ends of the curve have higher fitness than those near the middle.
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What is genetic drift?
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A kind of random change in allele frequency
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In ______ populations individuals that carry a particular allele may leave more descendants than other individuals, just by chance. Over time a series of changes of this type can cause an allele to become _______ in a population
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Small, common
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What is the founder effect?
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A situation in which allele frequencies
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WHat is the Hardy-Weinberg principle?
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That allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change
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What is genetic equilibrium?
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When allele frequencies remain constant.
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What are the five conditions required to maintain genetic equilibrium from generation to generation?
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-There must be random mating
-The population must be very large -No movement -No mutation -No natural selection |
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What is speciation?
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The formation of new species
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As new species evolve, population become reproductively________ from each other
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Isolated
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What is reproductive isolation?
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When the members of two population cannot interbreed and produce fertile offspring
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What is behavioral isolation?
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When two populations are capable of interbreeding but have differences in courtship rituals or other reproductive stuff
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What is geographic isolation?
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When two populations are separated by geographic barriers
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What is temporal isolation?
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Two or more species reproduce at different times
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Speciation in the Galapagos finches occurred by what?
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A new population, geographic isolation, changes in the new population's gene pool, reproductive isolation, and ecological competition.
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