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

plants1
Plants

Ps

  • Adiantum: fern in deep shade
    • Sciophyte: shade-adapted plant
  • Encelia: desert
    • Heliophyte: sun-adapted plant

Lite

plants2
Plants

Fig. 7.21

  • Sun/shade plant Pmax and Isat values
  • Highest Pmax?
  • Highest Isat?
lecture outline1
Lecture Outline
  • 1) Major methods of gaining energy
  • 2) Limitations on energy gain
    • Plants
    • Animals
what limits animal food intake
What limits animal food intake?

Hi

Food

Intake

Rate

  • Search time: find prey
  • Handling time: subdue & process prey

Lo

Hi

Lo

Prey Density

animal functional response curves
Animal Functional Response Curves
  • Holling: 3 functional responses (how food intake varies with prey density)

Fig. 7.22

animal functional response curves1
Animal Functional Response Curves
  • Type 1: Linear
    • Little search or handling time (rare)
    • Ex, filter feeders

Fig. 7.22

Feather duster worm

animal functional response curves2
Animal Functional Response Curves
  • Type 2: Rate increases faster than density
    • Partially limited by search/handling time
    • Common!

Fig. 7.22

animal functional response curves3
Animal Functional Response Curves
  • Ex, moose feeding

Fig. 7.23

animal functional response curves4
Animal Functional Response Curves
  • Ex, wolf feeding

Fig. 7.24

animal functional response curves5
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
optimal foraging
Optimal Foraging
  • Principle: organisms cannot simultaneously maximize all life functions.
  • Choose prey to maximize energy gain
optimal foraging theory
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

optimal foraging theory1
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

optimal foraging theory2
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
optimal foraging theory3
Optimal Foraging Theory
  • Does it work?
  • Ex, bluegill sunfish
optimal foraging theory4
Optimal Foraging Theory
  • Values calculated for prey in lab
  • Daphnia (water fleas), damselfly larvae, midge larvae

damselfly

midge

water flea

optimal foraging theory5
Optimal Foraging Theory
  • Prey abundance documented (top)
  • Equation predicts optimal prey size (mid)
  • Fish stomachs examined (bottom)
  • Does it work?
  • Yup...
optimal foraging by plants1
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?
optimal foraging by plants2
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?
optimal foraging by plants3
Optimal Foraging By Plants

Fig. 7.26

  • Ex, N in soil
darwin
Darwin
  • Proposed most important mechanism evolution: natural selection
  • Key points? (BIOL 1020)
natural selection biol 1020
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

natural selection biol 10201
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
gregor mendel
Gregor Mendel
  • Discovered genes (heritable units).
    • Alternate forms: alleles.
    • Some (dominant alleles) prevent expression others (recessive alleles)

Define….

evolution by natural selection
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
evolution by natural selection1
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
evolution by natural selection2
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
evolution by natural selection3
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?

measuring heritability
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
variation within species
Variation Within Species
    • Many species’ populations differ
  • How much variation due VG vs. VE?
    • Clausen, Keck, Hiesey (CA plants)
  • How test VG vs. VE?
variation within species1
Variation Within Species
  • Common garden experiment: Grow same location.
variation within species2
Variation Within Species
  • Differences remain: genetic variation (VG)
  • Differences disappear: phenotypic plasticity (VE)

Result?

variation within species3
Variation Within Species
  • Found differences.
  • Populations form ecotypes: locally adapted to environment
    • Same species (can interbreed)
variation within species4
Variation Within Species
  • Do animal populations vary locally?
  • Chuckwalla (Sauromalus obesus)
    • Herbivorous lizard (desert SW).
variation within species5
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?

variation within species6
Variation Within Species
  • Chuckwalla “Common garden” expt.
  • Genetic differences!
variation within species7
Variation Within Species
  • Genetic differences suggest adaptations
  • Experiments: can show natural selection in populations?

Experiments: who am I?

adaptive change in lizards
Adaptive Change in Lizards
  • Genus Anolis (anoles)
      • Hundreds species New World
      • Length hind leg reflects use vegetation
      • Perch diameter

Anolis carolinensis

adaptive change in lizards1
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

adaptive change in lizards2
Adaptive Change in Lizards
  • Positive correlation (after 10-14 yr) between vegetation and change morphology
  • Is this natural selection in action?
adaptive change in lizards3
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
adaptation by soapberry bugs
Adaptation by Soapberry Bugs
  • Soapberry Bug (Jadera haematoloma) feeds on seeds
  • Beak pierces fruit walls
soapberry bugs
Soapberry Bugs
  • Feeds on native or introduced plants (fruit size varies)
  • Feed on bigger fruits: longer beaks
  • How test if differences genetic?
soapberry bugs1
Soapberry Bugs
  • Raise bugs on common foods--beak length differences persisted
  • Bugs adapted to different hosts: natural selection