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Chapters 22,23,24 (Chapter 22 (Darwin and Adaptation (Darwin beleived that…
Chapters 22,23,24
Chapter 22
Who was charles Darwin?
He was a 1800s english man that had just finished school and wanted to observe nature in the galapagos
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Darwin and Adaptation
Darwin beleived that the ancestors lived in various habitats and gradually accumulated diverse modificartions
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In his book, the origin of species he goes over 3 broad ideas, unity, diversity of life and how organisms are suited in life for that particular environment
Darwins explanation for adaptation was a big thing with NATURAL SELECTION, go hand in hand
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Natural selection, artificial selection, and adaptation
artificial
it's humans arttificially selecting what breeds with what, example is dog breeder
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adaptation
Goes hand in hand with artificial selection, new species can arise from gradual accumulation of adaptations to a diff environment
Natural selection
What it is ? individuals having certain traits tend to live longer and reproduce because of those special traits
when environment changes, natural selectrion results in adaptation to new conditions, sometimes new species arise
Homology
What is it ? similarities among organisms from common ancestry which are used ti help determine relationships
what are vestibular structures? They're remains of feautures that served a function in the organisms ancestors,
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Pre- Darwin
A French biologist, Jean-Baptiste de Lamarck, introduced how exactly life changes over time, a mechanism
introduced the use and disuse idea, essentially the thought that variation was introduced though inheritance of acquired characteristicts.
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Chapter 23
genetic variation
altering gene number
Chromosomal changes that change the loci are usually bad, in rare cases they could be good
key part in variation is DUPLICATION OF GENES DUE TO ERRORS IN MEIOSIS, unequal crossover
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rapid reproduction
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prokaryotes and viruse shave many more generations per unit of time however, so mutations can quickly generate more variation.
Formation of new alleles
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new alleles are possible through mutation, EX sickle cell
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some dont matter becuase they're not important EX, COLOR EYE GENE IN SKIN
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Genetic Variation
Even though Darwin observed that variation in heritable traits is needed fro evolution, he didn't know how it actually happened
After he wrote his book, mendel came out with a paper of inheritance , where organisms transfer genes to the offspring
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Chapter 24
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speciation, fast or slow, results from changes in a few or alot of genes
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we primarily look at fossil records to see relationships and determine the time, patterns in fossil records
speciation rates- natural selection could produce extensive genetic chanhes in hybrid poulations over time, EX sunflowers
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