Term
| discribe the evidence for natural selection in darwin's finches |
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Definition
| average beak depth changed yare to year in sync with the annual rainfall |
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Term
| discribe the evidence for natural selection in peppered moths |
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Definition
-light colored moths in pristine habitats
-dark colored moths in polluted habitats |
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Term
| discribe the data which have led investigators to question the agent of selection in peppered moths |
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Definition
| they didnt factor in the changes in lichens |
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Term
| preserved remains of once-living organisms |
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Definition
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Term
| list the different types of fossils |
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Definition
-specimens preserved in amber
- siberian permafrost
-dry caves
- fossils preserved as rocks |
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Term
| list what must happen for an organism to form a rock fossil |
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Definition
- the organism must be buried in sediment
-the calcium in bone or other hard tissues must mineralize
-the surrounding sediment must harden into rock |
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Term
| discribe why fossils are so rare and why only a small percentage of species that once lived are represented in the fossil record |
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Definition
- usually animal or plant remains decay or are scavenged before the process may begin
-many fossils occur in rocks that are inaccessible to scientists, when they do become available, they are often destroyed by erosion and other natural processes before they can be collected. |
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Term
| discribe two of the most fascinating transitional fossils |
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Definition
-Archaeppteryx- intermediate between birds and dinosaurs
-tiktaalik- species that bridged the gap between fish and the first amphibions |
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Term
| discribe how the age of fossils is determined by radioactive decay of isotopes like U238 |
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Definition
| when a rock is formed, no additional radio active isotopes are added. therefore, by measuring the ratio of radioactive isotope to its derivative, "daughter" isotope, geologists can determine the age of the rock |
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Term
| structures with different appearances and functions that all derived from the same body part in a common ancestor |
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Definition
| homologuous structures (mammals) |
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Term
| explain how homologous structures illustrate natural selection |
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Definition
| natural selection has modified the same intial starting blocks to serve very different purposes |
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Term
| embryos of different types of vertebrates, often are similar early on, but become more different as they develop |
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Definition
| relict embryonic structures (vertebrates) |
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Term
| explain how relict embryonic structures illustrate natural selection |
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Definition
| early in their development, embryos possess pharyngeal pouches, which develop into different structures (humans- various glands and ducts, fish- gill slits) |
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Term
| natural selection can only influence the variation present in a population and becuase of this often results in workable but ___ |
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Definition
| imperfect structures (vetebrate eye) |
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Term
| have no apparent function, but resemble structures their ancestors possessed. |
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Definition
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Term
| may occur in distantly related species that are exposed to similar selective pressures |
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Definition
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Term
| discribe convergent evolution using marsupial and placental mammals |
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Definition
-marsupials are a group in which the young are born in a very immature condition and held in a pouch until mature enough to survive in the external environment
-placentals offspring are not born until they can safely survive in the external environment |
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Term
| is convergent evolution widespread or rare |
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Definition
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Term
| explain why island organisms are often lacking forms found on continents and are closely related to species on nearby continents, even though they may occupy different ecological niches |
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Definition
-island species usually are closely related to species on nearby continents even if environments are different.
-the species that occur there arrived by dispersing across the water, dispersal from nearby areas is more likely that than more distant sources, though long-distance colonization does occur occasionally |
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