Lecture/ Chapter 2 Study Notes

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11 Dec 2010
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Department
Course
Lecture 2
What Darwin Saw: The Evidence for Evolution
Key Concepts/ Terms:
Biogeography
Homology
Adaptive Radiation
Convergent Evolution
1)The Fossil Record:
a.Provides lots of evidence for evolution through time
b.Fossils found in geological strata (layers of rock) are similar to each other, more distant
layers show differences, suggesting evolutionary change
c.Younger fossils similar to living organisms living in area while older are increasingly different
d.Since Darwin more evidence for transitional forms between species have been found: feathered
dinosaurs (evolution of birds from dinosaurs), detailed insights into whale evolution
Lessons from Geology:
1)The earth is very old, allows immense amount of time for biological evolution
2)Intermediate forms provide evidence for common ancestors linking features of living organisms
3)Fossils in younger strata increasingly resemble modern species in same region, while older strata
show increasing differences
4)Earth has to be old in order for these changes to exsist
2)Homology: (vestigial characters)
a.Descent with modification implies organisms should show similarities to each other to varying
amounts that reflect their common ancestry
b.Homology term is used to describe shared characteristics of organism that reflect shared
descent
c.This contrasts with features that evolved through convergent evolution
d.There is abundant evidence for hierarchical patterns of homology at many levels of biological
organization including:
i.Cellular
ii.Developmental
iii.Skeletal
e.Vestigial traits show evidence of homology but have no evidence for current function in
organism, provides good evidence
f.DNA evidence provides important means of examining homology
g.Homologous features provide basis for reconstructing relationships among organism using
phylogenetic methods
h.Amphibians and Human digits are similar- evidence
i. Approximately 500 genes are shared across all forms of life- evidence
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Document Summary

What da rwin saw: the evidence for evolution. Lessons from geology: the earth is very old, allows immense amount of time for biological evolution. 2: fossils in younger strata increasingly resemble modern species in same region, while older strata. Evidence from domestication: maize (sweet corn) and teosinte (ancestor) teosinte to sweet corn in matter of thousands of years, not that long a, early people crushed seeds and ate them, vast amounts of heritable variation found in species. 3: darwin didn"t exactly understand heritable variation this variation can be selected on, leading to dramatic changes over generations. Vestigial characters in humans: ear muscles- mammals move their eyes for sound, appendix- monkey uses it to break down leaves, tailbone-evolved from fish (humans have gills in the fetus, goosebumps-animals raise their fur when scared. Current evidence that darwin couldn"t know about is about our olfactory genes (sense of smell).

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