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Lecture #2 - August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-204 1. A few more phylogenetic terms. 2. Bui

Lecture #2 - August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-204 1. A few more phylogenetic terms. 2. Building a tree a. synapomorphies & homologies b. swapping branches 3. Defining Characters of Cepahlopods, Myxiniformes, Petromyzontiformes, & Gnathostomata

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Lecture #2 - August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-204 1. A few more phylogenetic terms. 2. Bui

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  1. Lecture #2 - August 27, 2008Reading for Today: pgs. 10-14, 151-157,197-204 1. A few more phylogenetic terms. 2. Building a tree a. synapomorphies & homologies b. swapping branches 3. Defining Characters of Cepahlopods, Myxiniformes, Petromyzontiformes, & Gnathostomata notochord, cranium, 3-part brain, nephrons, lateral line, unpaired fins, paired fins, vertebrae, jaws, gill pouches 4. Details on hagfish 5. Details on lampreys 6. (time permitting) details on jawless fossil fishes

  2. Group Exercise - make a tree from these data, assume that taxa E is the outgroup. Also assume that all characters are informative.

  3. Cephalochordata important point in this picture is there is no brain and no cranium. The nerve cord just ends. Compare to picture of hagfish & lamprey.

  4. hagfish

  5. lamprey

  6. Lateral line in fishes A system of mechanoreptors that detect water movement or pressure change near fish’s body Neuromasts - made up of individual hair cells

  7. Gills: Agnatha 5-16 gill pouches 7 gill pouches hagfish lamprey

  8. Lamprey life cycle

  9. Lamprey life cycle Eggs hatch in 12-14 days Ammocoete stage

  10. Lamprey life cycle Eggs hatch in 12-14 days Ammocoete stage Free living species metamorph into adults and immediately return to spawning site to mate and then die

  11. Sea Lamprey, Petromyzon marinus • Anadromous species native to both sides of the • North Atlantic • Large parasitic species (up to 3’), can kill up to • 40 lbs. of prey in lifetime • Classic example of the deleterious effects of • an exotic species initiated by man-made habitat • alterations • But also one of the few examples of successful • control of exotic species

  12. Sea Lamprey, Petromyzon marinus First reported in 1890 but may be native

  13. Sea Lamprey, Petromyzon marinus First reported in 1890 but may be native Niagara Falls served as barrier to dispersal

  14. Welland Canal was built to allow ships to get around Niagara Falls

  15. Sea Lamprey, Petromyzon marinus First reported in 1890 but may be native 1946 Niagara Falls served as barrier to dispersal 1936 1921

  16. Sea Lamprey, Petromyzon marinus

  17. Sea Lamprey, Petromyzon marinus Control measures • Physical barriers to spawning streams • Releasing sterilized males • Application of a lampricide (TFM) - poured into streams • known to harbor ammocoetes, specific to ammocoetes

  18. lamprey video1

  19. Review Questions 1. Give the character states for notochord, cranium, 3-part brain, vertebrae, nephrons, gills/gill pouch, semi-circular canals, lateral line, jaws, paired fins, and unpaired fins for Cephalochordates, Myxiniformes, Petromyzontiformes, and Gnathostomata. Draw the phylogenetic tree and show the nodes of the tree where each character is informative. Be able to draw the same tree, but in multiple forms (i.e. rotate the branches). Be able to briefly describe each trait. 2. What evidence is there to suggest that lampreys are closely related to Cephalaspidiformes? (i.e. have you read pages 153-157) Who were the conodonts and what is their significance in the evolution of fishes? List 2 or 3 things. (see Box 11.1) Note: a possible paper topic is listed on pages 156-157 on “Later Evolution of Primitive Agnathous Fishes”.

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