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Back to anoles…

This text delves into the fascinating world of anoles and the broader phylum Chordata. It examines various anole species, including A. occultus from Puerto Rico and A. sagrei from Cuba, highlighting their adaptations and evolutionary constraints. Additionally, it explores the common characteristics that define chordates, such as notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, and endostyle. These features provide insight into the evolutionary history and diversity of chordates, including vertebrates, tunicates, and lancelets.

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Back to anoles…

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  1. Back to anoles…

  2. A. occultus – Puerto Rico A. sagrei – Cuba A. cristatellus – Puerto Rico A. lineatopus – Jamaica A. cybotes - Hispaniola A. sheplani – Hispaniola A. angusticeps – Cuba A. valencienni – Jamaica Trunk-ground anoles Twig anoles

  3. Evolutionary constraints • Change can only happen on … • Puts some limit on … • Main reason why adaptations are …

  4. Chordates – Phylum Chordata • Why study chordates? • We are chordates! • Many animals we see conspicuously are chordates • What is a chordate? • They are … • All chordates have a fluid-filled internal body cavity • Share 5 characteristics at some point in life

  5. Deuterostomes vs. Protostomes • Deuterostomes – • Echinoderms and chordates Fig. 2.3

  6. Deuterostomes vs. Protostomes • Protostomes – • Other animals Fig. 2.3

  7. Deuterostomes vs. Protostomes

  8. Chordate groups • Urochordates • Tunicates (sea squirts) • Cephalochordates • Amphioxus (lancelets) • Vertebrates • Largest chordate group by far • Incredible diversity within the group • Fossil record is good within this group Larvacea Pikaia

  9. Five characteristics of Chordates • All chordates display the following at some point during their life • Notochord • Dorsal Hollow Nerve Tube • Pharyngeal slits • Post-anal tail • Endostyle or Thyroid* Fig. 2.4

  10. Notochord • Originates from the … • Stiff, fluid-filled rod encased in fibrous sheath • Axially … • Laterally … • Largely replaced in function by the vertebral column in bony fishes and terrestrial vertebrates Fig. 2.5

  11. Notochord Fig. 2.5

  12. Dorsal Hollow Nerve Cord • Originates distinctively by invagination of the ectoderm Fig. 2.6

  13. Dorsal Hollow Nerve Cord Neural Plate Primitive Node Primitive Streak Neural Plate Notochord

  14. Dorsal Hollow Nerve Cord Neural Plate Neural Groove Neural Groove

  15. Dorsal Hollow Nerve Cord Neural Plate (Brain) Neural Fold Neural Tube

  16. Dorsal Hollow Nerve Cord Neural Plate (Brain) Neural Fold Neural Tube

  17. Dorsal Hollow Nerve Cord Neural tube formation and closure is complete by Day 24

  18. Pharyngeal Slits • Pharynx arises from endoderm immediately posterior to … • Punctuated by holes • Pharynx expands into pharyngeal basket (branchial basket) in … • Used for feeding and sometimes associated with … • How is this advantageous? Human: weeks 4-5

  19. Postanal Tail • Posterior elongation of the body past anus • Usually associated with …

  20. Endostyle • Endostyle = glandular groove in the floor of the pharynx; involved in ... • Thyroid = major endocrine gland; arises in development from the floor of … • Both metabolize iodine, suggesting common ancestry

  21. Chordate Phylogeny

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