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Energy/Nutrient Relations (Ch. 7)

Energy/Nutrient Relations (Ch. 7). Lecture Outline. 1) Major methods of gaining energy 2) Limitations on energy gain Plants Animals. Plants. Light curve ….Photosynthetic rate vs. light (photon flux density). Note P max at I sat P max = max. rate

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Energy/Nutrient Relations (Ch. 7)

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  1. Energy/NutrientRelations (Ch. 7)

  2. Lecture Outline • 1) Major methods of gaining energy • 2) Limitations on energy gain • Plants • Animals

  3. Plants • Light curve….Photosynthetic rate vs. light (photon flux density). Note Pmax at Isat • Pmax = max. rate • Isat = light amt. when system saturated Fig. 7.20

  4. Plants Ps • Adiantum: fern in deep shade • Sciophyte: shade-adapted plant • Encelia: desert • Heliophyte: sun-adapted plant Lite

  5. Plants Fig. 7.21 • Sun/shade plant Pmax and Isat values • Highest Pmax? • Highest Isat?

  6. Lecture Outline • 1) Major methods of gaining energy • 2) Limitations on energy gain • Plants • Animals

  7. What limits animal food intake? Hi Food Intake Rate • Search time: find prey • Handling time: subdue & process prey Lo Hi Lo Prey Density

  8. Animal Functional Response Curves • Holling: 3 functional responses (how food intake varies with prey density) Fig. 7.22

  9. Animal Functional Response Curves • Type 1: Linear • Little search or handling time (rare) • Ex, filter feeders Fig. 7.22 Feather duster worm

  10. Animal Functional Response Curves • Type 2: Rate increases faster than density • Partially limited by search/handling time • Common! Fig. 7.22

  11. Animal Functional Response Curves • Ex, moose feeding Fig. 7.23

  12. Animal Functional Response Curves • Ex, wolf feeding Fig. 7.24

  13. Animal Functional Response Curves • Type 3: S-shaped curve (rare) • 1) Prey find safe sites at low density • Or, • 2) Predator needs to learn to handle prey efficiently

  14. Optimal Foraging • Principle: organisms cannot simultaneously maximize all life functions. • Choose prey to maximize energy gain

  15. Optimal Foraging

  16. Optimal Foraging Theory • Model: • Ne = number prey encountered per unit time • Cs = cost to search for prey • H = handling time • E = energy gained by consuming prey • Can calculate energy intake per unit time: E/T • E/T = (Ne1E1-Cs )/(1 + Ne1H1) • 1 refers to prey species 1 E: Energy gain minus Cost Time: reflects handling prey

  17. Optimal Foraging Theory • What if 2 prey? • E/T = (Ne1E1-Cs ) + (Ne2E2-Cs ) • 1 + Ne1H1 + Ne2H2 Ne = number prey encountered per unit time Cs = cost to search for prey H = handling time E = energy gained by consuming prey

  18. Optimal Foraging Theory • What if 2 prey? • E/T = (Ne1E1-Cs ) + (Ne2E2-Cs ) • 1 + Ne1H1 + Ne2H2 • If optimal foraging: prey choice maximizes E/T • Ex: if 2 prey, prey #2 eaten if E/T for both prey > E/T for prey #1 only

  19. Optimal Foraging Theory • Does it work? • Ex, bluegill sunfish

  20. Optimal Foraging Theory • Values calculated for prey in lab • Daphnia (water fleas), damselfly larvae, midge larvae damselfly midge water flea

  21. Optimal Foraging Theory • Prey abundance documented (top) • Equation predicts optimal prey size (mid) • Fish stomachs examined (bottom) • Does it work? • Yup...

  22. Optimal Foraging By Plants?

  23. Optimal Foraging By Plants? • Allocation to leaves, stems & roots • Principle of Allocation: Energy allocated to obtain resource in shortest supply • Do plants allocate to resource in shortest supply? • Where we see this before?

  24. Optimal Foraging By Plants? • Allocation to leaves, stems & roots • Principle of Allocation: Energy allocated to resource in shortest supply • Do plants allocate to resource in shortest supply? • Where we see this before?

  25. Optimal Foraging By Plants Fig. 7.26 • Ex, N in soil

  26. THE END (material for knowledge demo #1)

  27. Population Genetics &Natural Selection (Ch. 4) Who??

  28. Darwin • Proposed most important mechanism evolution: natural selection • Key points? (BIOL 1020)

  29. Natural Selection (BIOL 1020) • Organisms over-reproduce (competition). • Offspring vary. • Some differences heritable (transmitted between generations). • Higher chance survival/reproduction: pass favorable traits to offspring Define adaptation

  30. Natural Selection (BIOL 1020) • Organisms over-reproduce (competition). • Offspring vary. • Some differences heritable (transmitted between generations). • Higher chance survival/reproduction: pass favorable traits to offspring • Adaptation: Genetically determined trait with survival and/or reproductive advantages (improves “fitness”) • Key: Trait heritable

  31. Gregor Mendel • Discovered genes (heritable units). • Alternate forms: alleles. • Some (dominant alleles) prevent expression others (recessive alleles) Define….

  32. Evolution by Natural Selection • Adaptation: Genetically determined trait with survival/reproductive advantages (improves “fitness”) • Genotype: Alleles for trait • Phenotype: Expression of trait. May be affected by environment. • Phenotypic plasticity: ability phenotype to change based on environment

  33. Evolution by Natural Selection • Adaptation: Genetically determined trait with survival and/or reproductive advantages (improves “fitness”) • Depends on heritability (h2) trait (how “well” transmitted) h2 = VG / VP • VG: Variability due to genetic effect • VP: Total variability phenotype

  34. Evolution by Natural Selection • Heritability: h2 = VG / VP • VG: Variability due to genetic effect • VP: Total variability phenotype • Phenotype influenced by both genes and environment • Or, VP = VG + VE

  35. Evolution by Natural Selection • Modified equation: h2 = VG / (VG + VE) • h2 ranges 0-1 • If VG small, little heritability • If VE large (lots phenotypic plasticity), little heritability How measure?

  36. Measuring heritability • Linear Regression: Fits line to points • Equation line: Y = m X + b • m = slope (regression coefficient) • b = Y intercept • Regression coefficient: measures h2

  37. Variation Within Species • Many species’ populations differ • How much variation due VG vs. VE? • Clausen, Keck, Hiesey (CA plants) • How test VG vs. VE?

  38. Variation Within Species • Common garden experiment: Grow same location.

  39. Variation Within Species • Differences remain: genetic variation (VG) • Differences disappear: phenotypic plasticity (VE) Result?

  40. Variation Within Species • Found differences. • Populations form ecotypes: locally adapted to environment • Same species (can interbreed)

  41. Variation Within Species • Do animal populations vary locally? • Chuckwalla (Sauromalus obesus) • Herbivorous lizard (desert SW).

  42. Variation Within Species Found at different elevations Rainfall amount & variation changes Lizards bigger where more rain Due to better environment (VE) or genetic (VG)? How test?

  43. Variation Within Species • Chuckwalla “Common garden” expt. • Genetic differences!

  44. Variation Within Species • Genetic differences suggest adaptations • Experiments: can show natural selection in populations? Experiments: who am I?

  45. Adaptive Change in Lizards • Genus Anolis (anoles) • Hundreds species New World • Length hind leg reflects use vegetation • Perch diameter Anolis carolinensis

  46. Adaptive Change in Lizards • Experiment: lizards from 1 island (Staniel Cay) put on islands with different vegetation • Do they evolve (limb size changes)? Staniel Cay

  47. Adaptive Change in Lizards • Positive correlation (after 10-14 yr) between vegetation and change morphology • Is this natural selection in action?

  48. Adaptive Change in Lizards • Positive correlation (after 10-14 yr) between vegetation and change morphology • Is this natural selection in action? Probably. But genetic change not shown

  49. Adaptation by Soapberry Bugs • Soapberry Bug (Jadera haematoloma) feeds on seeds • Beak pierces fruit walls

  50. Soapberry Bugs • Feeds on native or introduced plants (fruit size varies) • Feed on bigger fruits: longer beaks • How test if differences genetic?

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