Lec 7 Rhythms

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  • Lec 7 Rhythms

    1. 1. Lec 7: Rhythms <ul><li>HW2 </li></ul><ul><ul><li>In-class review and discussion of HW2 </li></ul></ul><ul><ul><li>Handout “Guidelines for answering short answer questions” </li></ul></ul><ul><ul><li>Lecture clarification sympatric speciation, character displacement </li></ul></ul><ul><li>Circadian Rhythms </li></ul>
    2. 2. Animal Behavior, Lec. 6, BIOL 4518 Sympatric speciation <ul><li>Create a species - > </li></ul><ul><ul><li>How? restrict gene flow </li></ul></ul><ul><ul><li>Who? Among members of the same population </li></ul></ul>
    3. 3. Sympatric Speciation <ul><ul><li>Sympatric speciation is a theory </li></ul></ul><ul><ul><ul><li>Does this happen in nature? </li></ul></ul></ul><ul><ul><ul><li>Why is it controversial? </li></ul></ul></ul><ul><ul><ul><li>Is instantaneous or gradual more likely to be a mechanism used? </li></ul></ul></ul>
    4. 4. Sympatric speciation <ul><li>Mechanisms for restricting gene flow in a population </li></ul><ul><ul><li>Polyploidy </li></ul></ul><ul><ul><ul><li>How does this work? </li></ul></ul></ul><ul><ul><ul><li>Is behavioral isolation involved? </li></ul></ul></ul>
    5. 5. Reproductive character displacement <ul><li>2 Components </li></ul><ul><ul><li>Female discrimination </li></ul></ul><ul><ul><ul><li>females are choosy! </li></ul></ul></ul><ul><ul><ul><li>Females choose among variation in male traits </li></ul></ul></ul><ul><ul><ul><li>“Receiver preference function” </li></ul></ul></ul><ul><ul><li>Male character divergence </li></ul></ul><ul><ul><ul><li>Over time key traits in males become more and more different </li></ul></ul></ul><ul><ul><ul><li>Bimodal distribution </li></ul></ul></ul>
    6. 6. Reproductive character displacement <ul><li>How would it work? </li></ul><ul><li>What is reinforcement? </li></ul><ul><ul><li>Is low hybrid fitness required? </li></ul></ul><ul><li>How do hybrid offspring have low fitness? </li></ul>
    7. 7. Reproductive character displacement <ul><li>Evidence supporting this theory </li></ul><ul><ul><li>Polyploid frogs </li></ul></ul><ul><ul><ul><li>Character: </li></ul></ul></ul><ul><ul><ul><li>Female discrimination: </li></ul></ul></ul><ul><ul><ul><li>Cause of low hybrid fitness: </li></ul></ul></ul>
    8. 8. Reproductive character displacement <ul><li>Evidence supporting this theory </li></ul><ul><ul><li>Polyploid frogs </li></ul></ul><ul><ul><ul><li>Character: vocalization </li></ul></ul></ul><ul><ul><ul><li>Value which females discriminate: frequency of pulses </li></ul></ul></ul><ul><ul><ul><li>Cause of low hybrid fitness: 3N are not viable </li></ul></ul></ul><ul><ul><li>Song bird </li></ul></ul>
    9. 9. Summary Reproductive Character Displacement and Sympatric Speciation <ul><li>Sympatric </li></ul><ul><ul><li>restrict gene flow within a pop. </li></ul></ul><ul><ul><li>Low hybrid fitness </li></ul></ul><ul><li>Mechanisms </li></ul><ul><ul><li>Instantaneous: Polyploidy </li></ul></ul><ul><ul><li>Gradual: Female discrimination and male character divergence </li></ul></ul><ul><li>Why controversial? </li></ul>
    10. 10. Geomagnetism: Earth's Magnetic Field Gary A. Glatzmaier
    11. 11. Geomagnetism: Earth's Magnetic Field Gary A. Glatzmaier <ul><li>Why does the Earth have a magnetic field </li></ul><ul><li>How is it generated? </li></ul><ul><ul><li>Poorly understood </li></ul></ul><ul><ul><li>Hypothesis: </li></ul></ul><ul><ul><ul><li>Iron-rich magma in the earth's crust rises with heat and sinks with cooling generating the field </li></ul></ul></ul>
    12. 12. Geomagnetism: Earth's Geomagnetism: Earth's Magnetic Field: Animal navigation <ul><li>Is it changing? </li></ul><ul><ul><li>Yes! </li></ul></ul><ul><ul><li>Polarity changes </li></ul></ul><ul><ul><ul><li>North and South magnetic poles reverse </li></ul></ul></ul><ul><ul><ul><li>Evidence in tectonic plates on sea floor that preserve the polarity as the new magma cools </li></ul></ul></ul><ul><ul><li>Field strengthens and weakens </li></ul></ul><ul><ul><ul><ul><li>the dipole moment will decay in about 1,300 years. </li></ul></ul></ul></ul><ul><li>How often does the magnetic field reverse? </li></ul><ul><ul><li>During the past 100 million years, the reversal rates vary (5 thousand years to 50 million years). </li></ul></ul><ul><ul><li>Last reversed 750,000 - 780,000 years ago. </li></ul></ul>
    13. 13. Geomagnetism: Pigeon navigation <ul><li>Pigeons navigate in overcast skies </li></ul><ul><li>Suggest they are using magnetic field </li></ul>
    14. 14. Geomagnetism: Pigeon navigation <ul><li>Pigeons navigate in overcast skies </li></ul><ul><li>Suggest they are using magnetic field </li></ul><ul><li>Evidence? </li></ul>
    15. 15. Geomagnetism: Pigeon navigation <ul><li>Pigeons navigate in overcast skies </li></ul><ul><li>Suggest they are using magnetic field </li></ul>
    16. 16. Geomagnetism: Pigeon navigation <ul><li>Pigeons navigate in overcast skies </li></ul><ul><li>Suggest they are using magnetic field </li></ul>
    17. 17. Electromagnetic Fields: Animals <ul><li>In addition to the use of the geomagnetic field for navigation, </li></ul><ul><li>Some animals generate their own electric field for example for prey detection </li></ul>
    18. 18. Summary Geomagnetism, Electromagnetic fields <ul><li>Geomagnetism </li></ul><ul><li>Electromagnetic fields generated by animals </li></ul>
    19. 19. Time – circadian rhythm <ul><li>Clock is affected by environmental cues </li></ul><ul><li>Clock is not affected by environmental cues </li></ul><ul><li>Evidence: </li></ul><ul><li>Conclusion – somewhere in the middle; free-running cycle updated with some environmental cues </li></ul>
    20. 20. Organization of clocks and behavior <ul><li>Chemical clock </li></ul><ul><li>Clock located in central place </li></ul><ul><li>Receives input and adjusts </li></ul><ul><li>Sends signals to other behaviors </li></ul>
    21. 21. Organization of clocks and behavior <ul><li>Chemical clock </li></ul><ul><ul><li>per PER, tau CKl e </li></ul></ul><ul><li>Clock located in central place </li></ul><ul><ul><li>Hypothalamus </li></ul></ul><ul><ul><ul><li>Suprachiasmic nucleus (SCN) </li></ul></ul></ul><ul><li>Receives input and adjusts </li></ul><ul><ul><li>e.g., light on retina </li></ul></ul><ul><li>Sends signals to other behaviors </li></ul><ul><ul><li>PK2 </li></ul></ul>
    22. 22. How is a clock made <ul><li>Endogenous </li></ul><ul><li>Pacemaker, master clock </li></ul><ul><li>Free-running cycle </li></ul><ul><li>Gene product feedback </li></ul>
    23. 23. How is a clock made
    24. 24. Cycles/Rhythms <ul><li>Single cycles </li></ul><ul><ul><li>Daily </li></ul></ul><ul><ul><li>Lunar </li></ul></ul><ul><ul><li>Tidal </li></ul></ul><ul><ul><li>Seasonal </li></ul></ul><ul><ul><li>Annual </li></ul></ul><ul><ul><li>Multiple years </li></ul></ul><ul><li>Combinations of cycles </li></ul>
    25. 25. Cycles/Rhythms
    26. 26. Circadian cycles <ul><li>Absence of cues </li></ul><ul><ul><li>Human sleep patterns </li></ul></ul>
    27. 27. Lunar Cycles <ul><li>Lunar cycles </li></ul>
    28. 28. Lunar cycles - cues <ul><li>Hydrostatic pressure </li></ul><ul><li>Temperature </li></ul><ul><li>Salinity </li></ul><ul><li>Turbulence </li></ul><ul><li>Vibrations </li></ul><ul><li>Immersion </li></ul>
    29. 29. Lunar Cycles - tides
    30. 30. Tidal cycles <ul><li>Intertidal pools of various heights </li></ul><ul><li>Protists </li></ul><ul><li>Encysted (18hr) and free swimming (6hr) </li></ul><ul><li>Cycle – remain in pools during flooding </li></ul><ul><li>Encyst for 2 high tides and one low tide </li></ul><ul><li>Faster rhythms and change in phase and duration on lower tide pools </li></ul>
    31. 31. Which cycle is the cue? <ul><li>Intertidal brown shrimp live in pools created at high tide </li></ul><ul><li>They are exposed to both diurnal and tidal cycles </li></ul><ul><li>What are cue are they using? </li></ul>
    32. 32. Which cycle is the cue?
    33. 33. Which cycle is the cue?
    34. 34. Which cycle is the cue?
    35. 35. Which cycle is the cue?
    36. 36. Seasonal Cycles <ul><li>Hibernation without external cues </li></ul>
    37. 37. Multiple Years <ul><li>Cicadas </li></ul><ul><li>Only in North America </li></ul><ul><li>Spend most of life in ground in larval stages </li></ul><ul><li>Emerge every 13 or 17 years </li></ul><ul><li>Co-occur every 221 years! </li></ul><ul><li>Emerge within a few days of each other </li></ul><ul><li>Several species identified </li></ul>
    38. 38. Multiple Years <ul><li>Can sympatric speciation occur by temporal displacement? </li></ul><ul><ul><li>Why would this be controversial, given what we have been discussing? </li></ul></ul><ul><li>What would you expect to observe if sympatric speciation occurred? </li></ul>
    39. 39. Multiple Years
    40. 40. Multiple Years <ul><li>Character divergence </li></ul>
    41. 41. Multiple Years
    42. 42. Multiple Years <ul><li>Suggests single gene change speciation event </li></ul>
    43. 43. Summary on cicadas <ul><li>Sympatric speciation through timing? </li></ul><ul><li>Character divergence </li></ul>
    44. 44. Combinations of cycles <ul><li>Ocean </li></ul><ul><ul><li>Tidal cycles </li></ul></ul>
    45. 45. Relative vs. absolute time
    46. 46. Clock shifts <ul><li>Clock shifted pigeons change </li></ul>

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