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DIVERSITY, CLASSIFICATION & EVOLUTION PART III

VERTEBRATE ZOOLOGY (VZ Lecture03 – Spring 2012 Althoff - reference PJH Chapters 1,2 & 7). DIVERSITY, CLASSIFICATION & EVOLUTION PART III. Two Embryonic Features that may account for difference between vertebrates and other chordates.

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DIVERSITY, CLASSIFICATION & EVOLUTION PART III

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  1. VERTEBRATE ZOOLOGY (VZ Lecture03 – Spring 2012 Althoff - reference PJH Chapters 1,2 & 7) DIVERSITY, CLASSIFICATION & EVOLUTIONPART III

  2. Two Embryonic Features that may account for difference betweenvertebrates and other chordates • In vertebrates: development of tissue called ______________. Forms many new structures found only in vertebrates • Duplication of the ______________________

  3. _______________ “migrating” to branchial arches 1 chicken embryo I – migrates to form mandible II—migrates to form hyoid apparatus III & IV—migrate to form outflow tract of heart

  4. 1 Neural Crest Cells • Originally thought that neural crest was derived from ectoderm germ layer • Recently (Hall 2000) proposed that neural crest actually is a truly “independent germ layer”—not part of ecto-, endo-, or mesoderm. If true…. • Vertebrates are the only animals that have __ germ layers making them ____________ • Helps explain significant advancement in variety of structures in “true” vertebrates

  5. 2 Hox gene complex • = Homeobox genes that characterize animals • Don’t code for specific features, but regulate expression of the hierarchy of other genes that control the shape of the body • Jellyfishes – 1 or 2 Hox genes Echinoderms & Nonvertebrate Chordates —7 up to 13 vs. Vertebrates which have undergone ___________ of entire Hox complex

  6. Hox gene complex…con’t • So, what is the minimum number of Hox genes in vertebrates? Likely ____ • Mammals appear to have ____ such genes • Bottomline: “More complex animals usually have a greater amount of genetic material…and it is thought that the ________ of this gene sequence at the _______ of vertebrate evolution made possible the evolution of a more complex type of animal” Pough, Janis, & Heiser 2005

  7. Early History & Vertebrate Evolution • Vertebrates first appeared in the early Paleozic, about 540 MYA….earth at the time was mostly water covered, extensive continental movements, and an O2 rich atmosphere formed as a result of ________________________ of autotrophs • Movement of land masses and climatic differences/changes resulted in major evolutionary effects on vertebrates. WHY?

  8. Early History: PALEOZOIC • Vertebrates first appeared in the early Paleozoic, about ~________….earth at the time was mostly water covered, extensive continental movements, and an O2 rich (in relative terms) atmosphere. • 490 MYA  443 MYA many shallow seas appeared, allowed for major radiation among marine animals, followed by first appearance of primitive vertebrates—primarily _____________, followed by _______________

  9. Early History: PALEOZOIC…con’t • 443  417 MYA vascular plants and arthropods just starting to appear, Jawless fishes continued to radiate and jawed fishes (including sharklike forms) appeared • 417  354 MYA major freshwater basins appeared with first tetrapods. End of this period marked by disappearance of ________________ ____________ (ostracoderms) • 354  290 MYA major glaciation. First appearance of ___________ and modern types of jawless fishes. Extensive radiation of non-amniote tetrapods. First __________ appeared.

  10. Early History: PALEOZOIC…con’t • 290  251 MYA Single continent (Pangea) formed near end of this period. -largest non-amniote tetrapods declined -amniotes radiated modern reptiles mammal-like reptiles first known ___________ tetrapods • Largest known ______________ event occurred at end of period—impacting both land and sea fauna: THE END OF THE PALEOZOIC

  11. MESOZOIC • 251  206 MYA Single continent high, few shallow seas, no evidence of glaciation mammal-like reptiles declined archosaurian reptiles (including dinosaur ancestors) diversified all large nonamniote tetrapods now aquatic forms true mammals appear dinosaurs, pterousaurs, marine reptiles, crocodiles, lepidosaurs, frog-like amphibians , and teleost fishes appear • 206  144 MYA Continent breakup. Modern sharks and rays appear. _________________________________

  12. 4 PALEOZOIC (late Carboniferous Period) 3 2 1 5 Aquatic nonamniote tetrapods Terrestrial nonamniote tetrapods Fig. 7-5 p165 PJH

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