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Name __________________________ Evolution 10.1 – Early Ideas About Evolution Key Concept: There were theories of biological and geologic change before Darwin. Early scientists proposed ideas about evolution. Evolution is the biological _______________________________. A species is a ___________________________________________________________________. Theories of geologic change set the stage for Darwin’s theory. There were three theories of geologic change: _________________________: natural disasters such as floods and volcanic eruptions have shaped landforms and caused species to become extinct. _________________________: changes in landforms resulted from slow changes over a long period of time _________________________: the geologic processes that shape Earth are uniform through time Uniformitarianism is the __________________________ of geologic change. 10.2 – Darwin’s Observations Key Concept: Darwin’s voyage provided insight on evolution. Charles Darwin Known as the __________________________ Traveled around the world on the HMS Beagle Observed _________________________________ and _______________________ in species Published findings in his book Origin of Species 1800’s Darwin observed differences among island species. Variation: ______________________________________ Galapagos tortoises that live in areas with tall plants have _____________________________ Galapagos tortoises that live in areas with low plants have _____________________________ Galapagos finches (Darwin’s finches) that live in areas with hard-shelled nuts have __________ Galapagos finches that live in areas with insects/fruit have ____________________________ Adaptation: feature that allows an organism to ____________________________________________ ___________________________________ to their environment Adaptations can lead to ___________________________________________ Darwin observed fossil and geologic evidence supporting an ancient Earth. Darwin found fossils of extinct animals that resemble ___________________________ Darwin found ______________________________ high up in the Andes _____________________ He saw land move from underwater to above sea level during an earthquake Darwin extended his observations to the evolution of organisms 10.3 – Theory of Natural Selection Key Concept: Darwin proposed natural selection as a mechanism for evolution. Several key insights led to Darwin’s idea for natural selection. Natural selection: mechanism by which _________________________________________________ ________________________________________________________________________________ Heritability: __________________________________________ There is a ____________________________________ due to overpopulation and limited resources Darwin proposed that adaptations arose over _______________________________ Natural selection explains how evolution can occur. Variation: heritable _______________________________________ are the basis for natural selection Overproduction: __________________________________________________________________ ________________________________________________________________________________ Adaptation: certain variation that _____________________________________________ than other individuals it competes against Descent with modification: Heritability of adaptations. _____________________________________ ________________________, as long as the environmental conditions remain beneficial for the trait Fitness: ________________________________________________________ Natural selection acts on existing variation. Natural selection can act only on ____________________________________. ________________________________________ in addition to their original function. 10.4 – Evidence of Evolution Key Concept: Evidence of common ancestry among species comes from many sources. Fossils & the Fossil Record ________________________________________________________________________________ Ways of dating fossils: Relative dating: __________________ the age of fossils by comparing fossil to others in the same layer of rock Pro: can be used _____________________________________________ of the fossil Con: ________________________________________________ (earthquakes, mudslides, etc.) and this can mess up estimate Radiometric dating: uses the ________________________________________________ (carbon-14 changes into carbon-12) Pro: can give an _________________________ Con: _________________________________________ (if all isotopes have decayed) Biogeography Island species most closely resemble nearest mainland species Populations can show ________________________________________ Example: _______________________________________ Embryology ______________________________, diverse organisms Identical larvae, diverse adult body forms __________________________________ as embryos Homologous Structures ____________________________________________ Evidence of a ______________________________ Example: __________________________________________________ (humans, cat legs, whale fins, bat wings) Vestigial Organs/Structures _________________________________________________________________________ in an early ancestor but have _______________________________________________ Evidence of ______________________________________ Examples: Human ______________________________________________ ______________________________________ (ostrich, penguins) Hindlimbs on __________________________________________ Molecular Biology _________________________________________ (A, T, C, & G) Similarities in _______________________________________________________________ Two closely related organisms will have similar ______________________________________ _____________________________________ will also be very close if the species are closely related 11.1 – Genetic Variation Within Populations Key Concept: A population shares a common gene pool. Genetic variation in a population increases the chance that some individuals will survive. Genetic variation leads to _________________________________ Necessary for ____________________________________ Genetic variation is stored in a population’s ______________________ Made up of _________________________________________ Allele combinations form when organisms have ___________________ Genetic variation comes from several sources. Mutations Can form a new allele Passed to offspring if in a gamete Recombination Usually occurs during meiosis Parents’ alleles rearranged during gamete formation 11.2 – Natural Selection in Populations Key Concept: Populations, not individuals, evolve. Microevolution Evolution _________________________________________ Observable change in allele frequencies Can _______________________________________________ Types: Directional selection, Stabilizing selection, Disruptive selection Directional Selection Favors phenotypes ___________________________ Stabilizing Selection Favors the ____________________________________ Disruptive Selection Favors _______________________________________ 11.3 – Other mechanisms of Evolution Key Concept: Natural selection is not the only mechanism through which populations evolve. Gene Flow _________________________________________________________________________ Occurs _________________________________________________________________________ Keeps neighboring populations ____________________ Low gene flow increases the chance that two populations will ________________________________ Genetic Drift Change in allele frequencies due to ______________ Causes a __________________________________________ Common in small populations _________________________ is genetic drift _____________________________________ Occurs when an ___________________________________________________ ___________________ is genetic drift that occurs ____________________________________ Occurs when ______________________________________________________ Sexual selection occurs when certain traits increase mating success. Sexual selection Occurs due to ____________________________________ Males produce sperm continuously Females are more limited in potential offspring each cycle Two types: Intrasexual selection: ____________________________ Intersexual selection: ____________________________ 11.6 – Patterns in Evolution Key Concept: Evolution occurs in patterns. Species can become extinct. Extinction: ______________________________________________ Background extinction Mass extinction Background Extinction Occur _______________, but at a _________________________ Usually affect only a _________________________ in a small area Can by caused by _____________________________________________ Mass Extinction ___________, but _________________________ Can operate at a __________________________ Caused by a _______________________________________ At least 5 mass extinctions in the last 600 million years Extinction Species go extinct because they _____________________________________ Fossil Record Biogeography Homologous Structures Embryology Bottleneck Effect Founder Effect