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BIOL 4220 - Class Notes - Week 4

Created by: La-Teisha Allen Elite Notetaker

BIOL 4220 - Class Notes - Week 4

School: University of North Carolina at Pembroke
Department: Biology
Course: Evoloution
Professor: John Roe
Term: Fall 2016
Tags: evolution, darwin, and Evidence
Name: Evolution
Description: Evolution's Evidence
Uploaded: 09/19/2016
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background image Evolution Evidence  Indirect Evidence • Classification Systems • Comparative Morphology
• Biogeography
• Fossil record
• Comparative Embryology
• Molecular  Darwin’s Branching Tree of Life • Descent with modification from common ancestor – closely related species should share more common traits 
– reflected in Linnaean classification systems 
Comparative Morphology
Homology
• Homology – traits that share a common ancestry and development – may or may not share current common function • Bones in mammal appendages are homologs across species – same relative positions
– modified into different forms for different functions
The Panda’s Thumb • Thumb of Giant Panda is a modified (enlarged) radial sesamoid bone – homologous to very small bone in other mammals, NOT typical  “thumb” (1 st  digit) • Allows for prehensile gripping of bamboo stems – different solution for same challenge   Homology is  exactly what we expect to see if evolution proceeds as descent from common ancestor with modifications • Analogy – traits that look superficially similar and share common functions – do not share recent common ancestry or development • independent evolution • Wing structures among different flying animals – same function, but built on fundamentally different design  principles
background image Analogies are independent experiments in adaptation, showing multiple 
potential paths to achieving the same function…
exactly what we would  expect to see in distantly related groups.   • remnants of past structures that do not serve a current function • humans – appendix (vestige of cecum) – coccyx (vestige of tail) some snakes and whales have tiny hips and hind limb bones    Biogeography  • Species similarities decrease with increasing geographic distance – 11 species of Galapagos tortoises
– species on nearby islands genetically more similar than to distant
islands  – species in archipelago more similar to one another than to S.  American mainland • Placental vs. Marsupial mammals – geographically distant species that exploit same niches share  superficially similar traits – Diagnostic characteristics betray their evolutionary history  (e.g., marsupium pouch) Fossil Record • Demonstrates both extinctions and emergence of new species /  taxonomic groups • Okapi is giraffe’s closest living relative • Fossils of extinct S. major (7 MYA) reveal transitional anatomy • intermediate in neck length between two modern species • lengthening of vertebrae • Early embryonic stages of related species bear more common features • “Ontogeny recapitulates phylogeny” (Haeckel) – development of individual reveals ancestral sequence – organisms that share common ancestry use similar underlying  early building patterns ( conservation), but later develop into  different adult patterns ( modification) à descent with modification  Rapid Evolution  • Bacteria resistance to antibiotics

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School: University of North Carolina at Pembroke
Department: Biology
Course: Evoloution
Professor: John Roe
Term: Fall 2016
Tags: evolution, darwin, and Evidence
Name: Evolution
Description: Evolution's Evidence
Uploaded: 09/19/2016
3 Pages 14 Views 11 Unlocks
  • Better Grades Guarantee
  • 24/7 Homework help
  • Notes, Study Guides, Flashcards + More!
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