lec 7 rhythms
TRANSCRIPT
- 1. Lec 7: Rhythms
- HW2
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- In-class review and discussion of HW2
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- Handout Guidelines for answering short answer questions
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- Lecture clarification sympatric speciation, character displacement
- Circadian Rhythms
2. Animal Behavior, Lec. 6, BIOL 4518 Sympatric speciation
- Create a species - >
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- How? restrict gene flow
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- Who? Among members of thesamepopulation
3. Sympatric Speciation
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- Sympatric speciation is a theory
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- Does this happen in nature?
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- Why is it controversial?
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- Is instantaneous or gradual more likely to be a mechanism used?
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4. Sympatric speciation
- Mechanisms for restricting gene flow in a population
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- Polyploidy
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- How does this work?
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- Is behavioral isolation involved?
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5. Reproductive character displacement
- 2 Components
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- Female discrimination
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- females are choosy!
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- Females choose among variation in male traits
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- Receiver preference function
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- Male character divergence
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- Over time key traits in males become more and more different
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- Bimodal distribution
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6. Reproductive character displacement
- How would it work?
- What is reinforcement?
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- Is low hybrid fitness required?
- How do hybrid offspring have low fitness?
7. Reproductive character displacement
- Evidence supporting this theory
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- Polyploid frogs
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- Character:
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- Female discrimination:
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- Cause of low hybrid fitness:
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8. Reproductive character displacement
- Evidence supporting this theory
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- Polyploid frogs
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- Character: vocalization
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- Value which females discriminate: frequency of pulses
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- Cause of low hybrid fitness: 3N are not viable
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- Song bird
9. Summary Reproductive Character Displacement and Sympatric Speciation
- Sympatric
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- restrict gene flow within a pop.
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- Low hybrid fitness
- Mechanisms
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- Instantaneous: Polyploidy
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- Gradual: Female discrimination and male character divergence
- Why controversial?
10. Geomagnetism: Earth's Magnetic Field Gary A. Glatzmaier 11. Geomagnetism: Earth's Magnetic Field Gary A. Glatzmaier
- Why does the Earth have a magnetic field
- How is it generated?
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- Poorly understood
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- Hypothesis:
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- Iron-rich magma in the earth's crust rises with heat and sinks with cooling generating the field
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12. Geomagnetism: Earth's Geomagnetism: Earth's Magnetic Field: Animal navigation
- Is it changing?
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- Yes!
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- Polarity changes
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- North and South magnetic poles reverse
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- Evidence in tectonic plates on sea floor that preserve the polarity as the new magma cools
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- Field strengthens and weakens
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- the dipole moment will decay in about 1,300 years.
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- How often does the magnetic field reverse?
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- During the past 100 million years, the reversal rates vary (5 thousand years to 50 million years).
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- Last reversed 750,000 - 780,000 years ago.
13. Geomagnetism: Pigeon navigation
- Pigeons navigate in overcast skies
- Suggest they are using magnetic field
14. Geomagnetism: Pigeon navigation
- Pigeons navigate in overcast skies
- Suggest they are using magnetic field
- Evidence?
15. Geomagnetism: Pigeon navigation
- Pigeons navigate in overcast skies
- Suggest they are using magnetic field
16. Geomagnetism: Pigeon navigation
- Pigeons navigate in overcast skies
- Suggest they are using magnetic field
17. Electromagnetic Fields: Animals
- In addition to the use of the geomagnetic field for navigation,
- Some animals generate their own electric field for example for prey detection
18. Summary Geomagnetism, Electromagnetic fields
- Geomagnetism
- Electromagnetic fields generated by animals
19. Time circadian rhythm
- Clock is affected by environmental cues
- Clock is not affected by environmental cues
- Evidence:
- Conclusion somewhere in the middle; free-running cycle updated with some environmental cues
20. Organization of clocks and behavior
- Chemical clock
- Clock located in central place
- Receives input and adjusts
- Sends signals to other behaviors
21. Organization of clocks and behavior
- Chemical clock
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- perPER,tauCKl e
- Clock located in central place
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- Hypothalamus
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- Suprachiasmic nucleus (SCN)
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- Receives input and adjusts
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- e.g., light on retina
- Sends signals to other behaviors
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- PK2
22. How is a clock made
- Endogenous
- Pacemaker, master clock
- Free-running cycle
- Gene product feedback
23. How is a clock made 24. Cycles/Rhythms
- Single cycles
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- Daily
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- Lunar
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- Tidal
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- Seasonal
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- Annual
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- Multiple years
- Combinations of cycles
25. Cycles/Rhythms 26. Circadian cycles
- Absence of cues
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- Human sleep patterns
27. Lunar Cycles
- Lunar cycles
28. Lunar cycles - cues
- Hydrostatic pressure
- Temperature
- Salinity
- Turbulence
- Vibrations
- Immersion
29. Lunar Cycles - tides 30. Tidal cycles
- Intertidal pools of various heights
- Protists
- Encysted (18hr) and free swimming (6hr)
- Cycle remain in pools during flooding
- Encyst for 2 high tides and one low tide
- Faster rhythms and change in phase and duration on lower tide pools
31. Which cycle is the cue?
- Intertidal brown shrimp live in pools created at high tide
- They are exposed to both diurnal and tidal cycles
- What are cue are they using?
32. Which cycle is the cue? 33. Which cycle is the cue? 34. Which cycle is the cue? 35. Which cycle is the cue? 36. Seasonal Cycles
- Hibernation without external cues
37. Multiple Years
- Cicadas
- Only in North America
- Spend most of life in ground in larval stages
- Emerge every 13 or 17 years
- Co-occur every 221 years!
- Emerge within a few days of each other
- Several species identified
38. Multiple Years
- Can sympatric speciation occur by temporal displacement?
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- Why would this be controversial, given what we have been discussing?
- What would you expect to observe if sympatric speciation occurred?
39. Multiple Years 40. Multiple Years
- Character divergence
41. Multiple Years 42. Multiple Years
- Suggests single gene change speciation event
43. Summary on cicadas
- Sympatric speciation through timing?
- Character divergence
44. Combinations of cycles
- Ocean
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- Tidal cycles
45. Relative vs. absolute time 46. Clock shifts
- Clock shifted pigeons change
47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64.