evidences for evolution - davis school district · 4 fossil record ... why would this be an...
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Darwin uses treesas a metaphor forpattern of
evolution.
• Hierarchical• Growing• Expansion/die-offs• Single common
ancestor (trunk)
TREE THINKING
The most reproductively successful individuals pass their traits to the next generation.
NATURAL SELECTION
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Fossil record provides snapshots of the past that can be assembled to illustrate a pattern of
evolutionary change over the last 4 billion years.
Mimicry https://www.youtube.com/watch?v=t-LTWFnGmegAn animal benefits due to its resemblance to another
organism.
http://www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html
Humans and chimps are 99% similar genetically.
But humans have 23 pairs of chromosomes and chimpanzees have 24
pairs. How can our chromosome pairs be
different when we share almost all the same
genes?
#24
1 2 3 4 5What features make these embryos look so
similar? Can you identify their species? chicken, fish, human, rabbit, salamander
The shading in these drawings indicates what significant fact about vertebrate forearms despite their extreme
differences in function and appearance?
ANALOGOUS STRUCTURES
• Bat wings have bones, insect wings do not
Evolved separately and not evidence of a
common ancestor
Why would this be an evidence for evolution?
When two different species live in an environment, they evolve the same way. Definitive example of how the environment causes natural selection.
Vestigial Structures
Structures or attributes that have lost most or all of their ancestral function in a given species, but have been retained during the process of evolution.
Can you think of 3?
Humans can have their appendix removed and still live a normal life. Where does the
appendix come from if it’s non-essential?
Wisdom Teeth
Anthropologists believe wisdom teeth, or the third set of molars, were the evolutionary answer to our ancestor's early diet of coarse, rough food – like leaves, roots, nuts and meats – which required more chewing power and resulted in excessive wear of the teeth.
Atavisms
Atavism is the tendency to revert to ancestral type, “evolutionary throwback”.
Traits reappearing which had disappeared generations before.
Shows that the ancestral genes are still a part of our DNA, even if they are not expressed.
How has this organism adapted to its environment? What kinds of selective pressure
could have led to this trait?
http://www.pbslearningmedia.org/resource/tdc02.sci.life.evo.camouflage/evolution-of-camouflage/
CAMOUFLAGE
Amazing Camoflauge https://www.youtube.com/watch?v=PmDTtkZlMwM
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