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Review— Evolution and Phylogeny

Review— Evolution and Phylogeny. Lecture 6b. Determining a Phylogenetic Tree—1. Based on shared characters (traits) Internal or external Major derived characters ( synapomorphies )—large scale relationships

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Review— Evolution and Phylogeny

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  1. Review—Evolution and Phylogeny Lecture 6b

  2. Determining a Phylogenetic Tree—1 • Based on shared characters (traits) • Internal or external • Major derived characters (synapomorphies)—large scale relationships • Examples: physostomus vs. physoclistous, ctenoid scales, thoracic pelvic fins

  3. Determining a Phylogenetic Tree—1 • Secondarily derived traits—fine scale relationships • Typically many traits are examined • Meristic counts and anatomical features

  4. Determining a Phylogenetic Tree—1

  5. Determining a Phylogenetic Tree—2 • Fossil record often used to determine ancestral origins of major lineages

  6. Determining a Phylogenetic Tree—3 • Gene sequencing and DNA fingerprinting commonly used to determine relationships • Molecular clocks—Genes used to determine when major branch points occur • Technique uses specific genes known to evolve at a constant rate • No selection pressure • Genetic drift

  7. Determining a Phylogenetic Tree—3 • Molecular clocks must be calibrated—example • Branching point for birds and mammals  310 mya • Extensive fossil record • Hypothesis: all mammals are equally different from any bird species, at this gene site

  8. The Amazing Teleosts

  9. Class Actinopterygii Class Sarcopterygii SublassNeopterygii SublassChondrostei Teleosts Order Lepisosteiformes Tetrapods Lungfish Coelacanth Gars Sturgeons

  10. Primitive Fishes Phylogeny Fish-like form Osmoregulation True teeth Jaws Swim bladder Teleosts Gars Lamprey Conodonts Placoderms Hagfish Chondrostei Sarcopterygii Tunicates Chondrichthyes First fishes

  11. Teleostei • Originated 215 mya • > 26,000 species • Adaptations of jaws, fins, swim bladder, & skeleton • All possess_____ or ______ scales,mobile maxilla bone, & ________ caudal fin • Scales overlap like shingles  greater flexibility

  12. Detached maxilla, cycloid/ctenoid scales, homocercal tail Phylogeny—teleostei Leptocephalus larvae Weberianossicles Physoclistous swim bladder Tetraodontiformes Perciformes Pleuronectiformes Atherinomorpha Gars Protacanthopterygii Ostariophysi Clupeomorpha Elopomorpha

  13. Cladogram—teleosteiJaws Protrusiblepremaxilla Tetraodontiformes Perciformes Pleuronectiformes Atherinomorpha Gars Protacanthopterygii Ostariophysi Clupeomorpha Elopomorpha

  14. Teleost Evolution: jaws & feeding Bowfin—non-teleost fish Premaxilla bone Maxilla bone

  15. Synapomorphy—jaw morphology #1 • Protrusible jaw • Posterior connection of maxilla bone freed • Swings forward • Benefits?

  16. Synapomorphy—jaw morphology #2 • Pipette mouth—premaxillary bone also freed • Structure slides along groove over skull • http://www.xromm.org/projects/fish-feeding

  17. Pipette mouth advantage • Increased suction power; more focused • Tradeoff  gape reduction • Ideal for small prey • Attack speed also  • Suction not always produced • LMB almost 2x Gape & protrusion (mm) Flow speed (m/s)

  18. Pharyngeal teeth • Protrusion of jaws has tradeoff • Maxillary bone not toothed in advanced forms • Pharyngeal teeth well developed in many teleosts • Gill arches, tongue, bones on roof of mouth

  19. Moray eel—pharyngeal jaws • Eels have weak suction power • Swallowing prey more difficult • Modified anterior gill arches • Project forward to draw prey in

  20. Moray eel—pharyngeal jaws

  21. Herbivorous teleosts • Almost all non-teleosts are carnivorous • Most herbivorous teleosts in freshwater or on coral reefs • Feed on algae or aquatic plants • Many temperate species are omnivorous

  22. Herbivorous teleosts • Plants  thick cell walls made of cellulose • How do mammals overcome this? • Herbivores have pharyngeal mills or gizzards • Highly acidic stomachs & long intestines • High intake, low assimilation

  23. Phylogeny—teleosteiPaired fin placement and function Pectoral fins placed higher Pelvic fins thoracic Tetraodontiformes Perciformes Pleuronectiformes Atherinomorpha Gars Protacanthopterygii Ostariophysi Clupeomorpha Elopomorpha

  24. Synapomorphies—paired fin placement More primitive  pectorals ventral to gills; horizontal • Paired fins for stabilization & braking, no spines • Derived pectorals behind gills &vertical; pelvics thoracic • Pectorals maneuvering & thurst • Pelvic fins  braking & stabilization • Defense

  25. Paired fin adaptations—more advanced teleosts

  26. Cladogram—teleosteiDorsal fin Two dorsal fins Tetraodontiformes Perciformes Pleuronectiformes Atherinomorpha Gars Protacanthopterygii Ostariophysi Clupeomorpha Elopomorpha

  27. Synapomorphy—Dorsal fin More primitive  single, only soft-rays, less articulating • Prevents rolling More advanced  Two fins • Anterior fin spinous and retractable • Function— • Posterior fin soft rays, articulating • Function—

  28. Dorsal fin adaptations—more advanced teleosts

  29. Bone reduction occurred throughout teleost evolution • Vertebrate reduction— > 60 in elopomorpha < 30 in advanced forms • Reduction in vertebral accessories (ribs) • Fewer bones in skull and tail • Scales reduced in size and thickness

  30. Phylogeny—teleostei Tetraodontiformes Perciformes Pleuronectiformes Atherinomorpha Gars Protacanthopterygii Ostariophysi Clupeomorpha Elopomorpha

  31. Tetraodontiformes—four teeth • Most derived and recently evolved group • Originated 65 mya • 360 living species—mostly marine

  32. Tetraodontiformes • Many bones fused or lost • 16 vertebrae • Premaxilla and maxillary fused • Pelvic fins lost • Scales modified into small spines or ossicles, or bony plates

  33. Tetraodontiformes Many have adapted to previously unoccupied niches • Diet of sponges, sea urchin, coral, jellyfish • Some eat benthic or pelagic invertebrates Fin swimmers—types?

  34. Tetraodontiformes—Leatherjackets Triggerfish and filefish—leatherjackets • Make noise grinding teeth or drumming swim bladder with pectoral spine-bone • Locking dorsal spine • Eyes move independent Humuhumu……….. “the fish that sews with a needle and grunts like a pig

  35. Tetraodontiformes—Puffers Puffers—fill stomach to puff up  3x volume • Stomach may  volume 100x • Causes spines to erect—diodontidae • Freshwater species • Viscera and eyes are toxic • 2nd most toxic vertebrate Fugu anyone?

  36. Tetraodontiformes—Mola Four species • Molamolaweigh > 4000 lbs. • > 300 million eggs in larger sunfishlow ________ • Highest among vertebrates • Much of skeleton cartilaginous—secondarily derived • Feed on abundant jellyfish • Common bycatch on driftnet and longline fisheries http://www.youtube.com/watch?v=U60obmWODLQ Slender Mola

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