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DESCENT WITH MODIFICATIONA Darwinian View of LifeAP BIOLOGY Chapter 22
Kids Prefer Cheese Over Fried Green SpinachKings Play Chess On Fat Green StoolsKing Phillip Cried Oh For Goodness Sake! GENUS = group of closely related
species
GENUS = Ursus (Includes many kinds of bears)
SPECIES = unique to each kind of bearhttp://www.macecanada.com/images/bears/kodiak_bear. gifhttp://students.cs.byu.edu/~tole/Virtual%20Zoo/pola r-bear.jpghttp://en.wikipedia.org/wiki/Image:Black_bear_large .jpg
Ursusarctos
Ursusmaritimus
Ursusamericanis
Genus and species assignmentsprovide 2 part scientific name
Darwin collected 14 species of finches and hypothesized that the Galapagos had be colonized by organisms from the mainland that had then diversified on the various
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After Darwin returned to England in 1836, he spent years examining specimens he brought back from voyage and filling notebooks with his ideas.
He did not rush to publish his ideas because theydisagreed with the fundamental scientific views of hisday.
In 1844 he wrote an essay describing his ideas andasked his wife to publish it if he died.
http://www.elsie.brandeis.edu/images/journals.gif
Who Was Charles Darwin? In 1858 Alfred Russel Wallace, another
Isn’t evolution “just a theory”?In every day usage “theory” often refers to a hunch or a speculation. When people say, “I have a theory about what happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence.
The formal scientific definition of “theory” is quite different from the every day meaning.
It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.
http://evolution.berkeley.edu/evosite/evohome.htm
In Science a theory is a well supported, testable explanation of phenomena that have occurred in the natural world.
Example:Cell theoryAtomic theoryGravitational theory
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Lots of TRANSITIONAL FOSSILS have been found
Scientific American; Dec 2005; Vol 293; p100-107
GEOGRAPHIC DISTRIBUTION =BIOGEOGRAPHY
If Darwin’s theory is correct you would expect to find closely related yet different species living in a geographic region as they spread into nearby habitats and evolve.
That’s EXACTLY what we do see!
GALAPAGOS FINCHES
The beaks of Galapagos finches have adapted to eating a variety of foods
Tortoises adapted to different habitats as they spread from the mainland to the different islands.= DIVERGENT EVOLUTION = ADAPTIVE RADIATION
If Darwin’s theory is correct you would also expect to find different species living in far apart geographic regionsbut similar habitats becoming more alike as they adapt to similar environments.
That’s EXACTLY what we do see!
BOTH LIVE IN FOREST ECOSYSTEMS
Adapted to similar environments, but evolved independently from different ancestors.
SUGAR GLIDER in Australia is a marsupial more closely related to Kangaroos than North American FLYING SQUIRRELS becauseits ancestors were marsupials.
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Whales and sharks have a similar body designeven though they are very different organisms (one is a fish; the other, a mammal)because they have independently adapted to living in a similar environment.
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Same groups of undifferentiated cells develop in the same order to produce the same tissues and organs of all vertebrates, suggesting that they all evolved from a common ancestor.
HUMAN EMBRYO has a tail at 4 weeks which disappears at 8 weeks
Pharyngeal pouchesbecome gills in fish,parts of throat/ears
in humans
http://www.medicalgeo.com/images/appendix.gif
Nonfunctional legs in skinks
Why would an organism possess organs without function?
Why would an organism grow a part and then discard it?
If organisms evolved from ancestors in which that part functioned, the gene code to make the part would still be there even though it doesn’t work.If the organ is not vital to survival, then natural selection would not cause its elimination.
MOLECULAR HOMOLOGIES
• All life forms share same genetic machinery (DNA & RNA)
• Universal genetic code
• Important genes sharehighly conservedsequences
Similarities in protein sequencessuggests similarities in DNA
Similarities inDNA and protein sequencessuggestrelatedness
MOLECULAR HOMOLOGIES
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Similarities in karyotypessuggest an evolutionary relationship
Human: http://www.nationmaster.com/wikimir/images/upload.w ikimedia.org/wikipedia/en/thumb/1/18/300px-Human_ka ryogram.pngChimpanzee: Middle School Life Science , published by Kendall/Hunt.
Human- 46 chromosomes Chimpanzee- 48 chromosomes
If you take the two smaller chromosomes chimps have that we don’t, and place them end to end, the banding pattern is identical to the #2 human chromosome which we have and they don’t
http://www.evolutionpages.com/chromosome_2.htm
BANDING PATTERN MATCHES
Remember:
Protective TELOMEREsequences found at ends of chromosomes
http://joannenova.com.au/Speaking/Morslids.html
EVIDENCE CHROMOSOMES JOINED
Telomere sequences are found at ends and also in middle of human chromosome #2 suggesting it was made by joining two other chromosomes together.
http://www.evolutionpages.com/chromosome_2.htm
→
→
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Chromosome #2 has a second inactive centromereregion
http://www.evolutionpages.com/chromosome_2.htm
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EXTRA CENTROMERE Why don’t dogs and cats need to eat fresh fruit, but you do?
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Fish, amphibians, reptiles, and most mammals can make their own vitamin C, but humans can’t make vitamin C. Without fresh fruit, humans end up with scurvy.