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Darwinian Evolution (ch 23. (The genes of a species evolves, an individual…
Darwinian Evolution
ch 23.
The genes of a species evolves, an individual does NOT.
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Genetic variation- differences among individuals in the composition of their genes are or other DNA sequences'
Genetic variation is important to evolution b/c it introduces new alleles and helps to change gene frequency
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The speed of reproduction affects the rate of evolution because there are more genes being produced meaning more of a chance of mutation
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Meiosis is important to sexual reproduction because it ensures genetic variation and genetic variation is important to evolution.
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population- a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring
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genotype- the genetic makeup, or set of alleles, of an organism
phenotype- The observable physical and physiological traits of an organism, which are determined by it's genetic makeup
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genetic drift- process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next
founder effect- genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of the original population
bottleneck effect- genetic drift that occurs when the size of a population is reduced as by a natural disaster or human actions
directional selection- natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other idividuals
disruptive selection- natural selection in which individuals on both extremes of a successfully than do individuals with intermediate phenotypes
intrasexual selection- a form of natural selection in which there is direct competition among individuals of one sex for mates of the opposite sex
intersexual selection-a form of natural selection in which individuals of one sex (usually the females)are choosy in selecting their mates from the other sex; also calls mate choice
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frequency-dependent selection- selection in which the fitness of a phenotype depends on how common the phenotype is in a population
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Ch.22
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Charles Darwin was a rich kid who was looking for his passion in life and his research on the HMS Beagle paved his way to being remembered as the father of evolution
Lyell published the principles of of geology in 1830, helping Darwin to realize his theory of gradual evolution over time through natural selection.
On the HMS Beagle Darwin was a naturalist which is what helped him discover the ideas of "Descent with modification" and natural selection etc. through his study of the finches on the Galapagos islands.
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natural selection- individuals who have certain traits tend to survive and reproduce at a higher rate than those that don't.
artificial selection- modifying species over many generations by selecting and breeding individuals that posses
macroevolution- the broad pattern of evolution above the species level ex- origin of new group of organisms
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homology- development of different species based upon their descent from a common evolutionary ancestor
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homologous structures- similar structure, different function
Convergence- animals change to fit their environment and come to look like others in its environment. ex: finger bones in whale flipper
analogous structure- similar structures that evolved independently in two living organisms to serve the same purpose.
CH. 24
prezygotic barrieres block fertilization by: impeding members of different species from mating, unsuccessful mating, hindering fertilization
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mechanical isolation- the parts don't line up, so they can't mate
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post-zygotic barriers may reduce survival among hybrid embryos; problems after birth may cause hybrids to be infertile or not to live long enough to produce
reduced hybrid fertility- an offspring can be produced but offspring cannot produce their own offspring
hybrid break down- some first generation hybrids can have offspring but it affects later generations
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reproductive isolation- barriers that impede memebers of two species from interbreeding and producing an offspring
limitations of biological species concept are: no way to evaluate reproducttive isolation of fossils; does not apply to organisms that reproduce asexually most of the time; gene flow is not always absent
biological species concept- a species is a group of populations whose members have the same potential to interbreed in nature and produce a fertile offspring
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ecological species concept- defines a specids in terms of its ecological niche the sum of how members if the species interact w the non-living and living parts of the enviornment
geographic isolation- a population that are seperated from exchanging genetic material w other organisms of the same species
allopatric speciation- the formation of new species in populations that are geographically isolated from one another
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hybrid zone- a region in which members of different species meet and mate producing at least some offspring of mixed ancestry
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