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How did the giraffe get its long neck?
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More offspring are produced that can possibly survive. BUT populations tend to remain stable AND there are limited resources Observation #1
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SO the inference is: There is a struggle for survival between individuals of a population and not all will survive Aphaenogaster tipunaAphaenogaster tipuna ants fighting over food
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Organisms display a lot of variety in their characteristics Much of this variety is inherited OBSERVATION #2
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Inference #2 : Those individuals whose inherited traits best fit them to their particular environment will leave more offspring
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Inference #3 : This unequal ability of individuals to survive and reproduce will cause a gradual change in the population Favorable characteristics will accumulate in the population over time
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Individuals DO NOT EVOLVE. Populations evolve Evolution is not caused by a NEED of an individual. Surviving does not contribute to evolution alone. There also has to be reproduction Acquired characteristics are not passed down to the next generation. Adaptations depend on the environment
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Fossils provide evidence of the change of life throughout time
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Comparative Anatomy
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Homologous structures: indicators of a common ancestor Anatomical Show divergent evolution
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vestigial structures Homologous structures with no or little function in organism
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Embryological homologies
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Molecular Homologies Compare DNA sequences or proteins (amino acid sequences) The more differences the longer ago the two species diverged from a common ancestor
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Generation to generation change in the frequencies of alleles in the gene pool Genetic Drift: changes in allele frequencies due to chance Causes: natural selection Gene flow immigration or emigration of individuals (and their genes) Mutation introduces new alleles
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Examples of Genetic Drift Bottleneck effect Natural disaster wipes out a portion of a population
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Fig. 13-11a-1 Original population
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Fig. 13-11a-2 Original population Bottlenecking event
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Fig. 13-11a-3 Original population Bottlenecking event Surviving population
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Example #2 Relatively few individuals start a new population in isolation founder effect
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A population that is not evolving is in equilibrium Hardy-Weinberg Equilibrium p=frequency of the dominant allele q=frequency of the recessive allele p+q=1 p 2 +2pq +q 2 =1 p 2 = frequency of homozygous dominants 2pq= frequency of heterozygotes q 2 = frequency of homozygous recessives
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Conditions required for a population to maintain Hardy-Weinberg equilibrium 1.Large population 2.Random mating 3.No natural selection 4.No mutation 5.No gene flow
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Analogous structures Evolved independently and don’t indicate close relationships
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A) Divergent evolution results in homologous structures B) Convergent evolution results in analogous structures
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Population or group of populations that have the potential to interbreed with each other in nature and produce viable offspring Key idea: reproductive isolation
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Fig. 14-3
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Fig. 14-3a Habitat isolation
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Fig. 14-3b Behavioral Isolation
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Fig. 14-3c Mechanical Isolation
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Fig. 14-3d Gametic Isolation
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Fig. 14-3e Postzygotic Barriers Hybrids do not develop into fertile adults
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National Geographic http://www.youtube.com/watch? v=1zOWYj59BXI http://www.youtube.com/watch? v=1zOWYj59BXI
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Speciation is the formation of a new species Often it comes about because of some kind of geographic barrier
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Adaptive radiation is a type of speciation One population evolves into several different species, each with different adaptive characteristics
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Phylogenetic trees
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Medium ground finch Cactus ground finch Small tree finch Large ground finch Small ground finch Large cactus ground finch Sharp-beaked ground finch Vegetarian finch Seed eaters Ground finches Cactus flower eaters Bud eaters Tree finches Insect eaters Medium tree finch Large tree finch Mangrove finch Woodpecker finch Green warbler finch Warbler finches Which finch is most closely related t the Green warbler finch? Is the medium ground finch more closely related to the small ground finch or to the large ground finch?
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Big eyes 3 toesLoss of tail
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Beastie Activity
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Fig. 15-16aa Iguana TAXA Long gestation Duck-billed platypus Kangaroo Beaver CHARACTERS Character Table 0 0 01 0 1 01 Gestation Hair, mammary glands 0 1 11
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Fig. 15-16ab Long gestation Gestation Hair, mammary glands Iguana Duck-billed platypus Kangaroo Beaver Phylogenetic Tree
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Big eyes 3 toesLoss of tail
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Figure 15.12A Pleistocene Pliocene Miocene Oligocene Brown bear Polar bear Asiatic black bear American black bear Sun bear Sloth bear Spectacled bear Giant panda Raccoon Lesser panda Ursidae Procyonidae Common ancestral carnivorans
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For several decades, scientists have classified life into five kingdoms Classification Figure 15.14A MONERAPROTISTAPLANTAEFUNGIANIMALIA Earliest organisms
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This system recognizes two basically distinctive groups of prokaryotes –The domain Bacteria –The domain Archaea A third domain, the Eukarya, includes all kingdoms of eukaryotes Figure 15.14B BACTERIAARCHAEAEUKARYA Earliest organisms A newer system is the 3 Domain system
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Organisms are grouped into progressively larger categories (taxons) Table 15.10
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CLASSIFICATION (TAXONOMY) DOMAIN KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIES (SMALLEST GROUP)
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NAMING OF ORGANISMS BINOMIAL NOMENCLATURE EX: Homo sapiens Pan troglodytes (chimpanzee) FIRST NAME IS GENUS NAME SECOND NAME IS SPECIES NAME
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5 KINGDOMS 1) MONERA 2) PROTISTA 3) FUNGI 4) PLANTAE 5) ANIMALIA
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http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Classification-Plants-Other-Organisms.topicArticleId-23791,articleId-23659.html
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