Energy/Nutrient Relations (Ch. 7). Lecture Outline 1) Major methods of gaining energy 2) Limitations...
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Transcript of Energy/Nutrient Relations (Ch. 7). Lecture Outline 1) Major methods of gaining energy 2) Limitations...
Energy/NutrientRelations (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 Pmax at Isat
• Pmax = max. rate
• Isat = light amt. when system saturated
Fig. 7.20
Plants• Adiantum: fern in deep shade
– Sciophyte: shade-adapted plant
• Encelia: desert– Heliophyte: sun-adapted plant
Ps
Lite
Plants• Sun/shade plant Pmax and Isat values
• Highest Pmax?
• Highest Isat?Fig. 7.21
Lecture Outline• 1) Major methods of gaining energy• 2) Limitations on energy gain
– Plants– Animals
What limits animal food intake?• Search time: find prey
• Handling time: subdue & process prey
Prey Density
Food IntakeRate
LoLo Hi
Hi
Animal Functional Response Curves• Holling: 3 functional
responses (how food intake varies with prey density)
Fig. 7.22
Animal Functional Response Curves• Type 1: Linear
– Little search or handling time (rare)
– Ex, filter feeders
Feather duster worm Fig. 7.22
Animal Functional Response Curves• Type 2: Rate increases
faster than density– Partially limited by
search/handling time– Common!
Fig. 7.22
Animal Functional Response Curves• Ex, moose feeding
Fig. 7.23
Animal Functional Response Curves• Ex, wolf feeding
Fig. 7.24
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• Principle: organisms cannot simultaneously
maximize all life functions.– Choose prey to maximize energy gain
Optimal Foraging
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 CostTime: reflects handling prey
• What if 2 prey?• E/T = (Ne1E1-Cs ) + (Ne2E2-Cs )
• 1 + Ne1H1 + Ne2H2
Optimal Foraging Theory
Ne = number prey encountered per unit time
Cs = cost to search for preyH = handling timeE = energy gained by consuming prey
• 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 Theory
• Does it work?• Ex, bluegill sunfish
Optimal Foraging Theory
• Values calculated for prey in lab• Daphnia (water fleas), damselfly larvae, midge
larvae
Optimal Foraging Theory
midge
damselfly
water flea
• Prey abundance documented (top)
• Equation predicts optimal prey size (mid)
• Fish stomachs examined (bottom)
• Does it work?• Yup...
Optimal Foraging Theory
Optimal Foraging By Plants?
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 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 Plants• Ex, N in soil
Fig. 7.26
THE END (material for knowledge demo #1)
Population Genetics &Natural Selection (Ch. 4)
Who??
Darwin• Proposed most important mechanism
evolution: natural selection
• Key points? (BIOL 1020)
• Organisms over-reproduce (competition).• Offspring vary.
– Some differences heritable (transmitted between generations).
• Higher chance survival/reproduction: pass favorable traits to offspring
Natural Selection (BIOL 1020)
Define adaptation
• 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
Natural Selection (BIOL 1020)
Gregor Mendel• Discovered genes (heritable units).
– Alternate forms: alleles.– Some (dominant alleles) prevent
expression others (recessive alleles)
Define….
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 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 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 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• 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• Many species’ populations differ
• How much variation due VG vs. VE?– Clausen, Keck, Hiesey (CA plants)
How test VG vs. VE?
Variation Within Species• Common garden experiment: Grow same
location.
Variation Within Species– Differences remain: genetic variation (VG)
– Differences disappear: phenotypic plasticity (VE)
Result?
Variation Within Species• Found differences. • Populations form ecotypes: locally adapted to
environment– Same species (can interbreed)
Variation Within Species• Do animal populations vary locally?• Chuckwalla (Sauromalus obesus)
– Herbivorous lizard (desert SW).
Variation Within SpeciesFound at different elevationsRainfall amount & variation changes
Lizards biggerwhere more rain
Due to better environment (VE)or genetic (VG)? How test?
Variation Within Species• Chuckwalla “Common garden” expt.• Genetic differences!
Variation Within Species• Genetic differences suggest adaptations• Experiments: can show natural selection in populations?
Experiments: who am I?
Adaptive Change in Lizards• Genus Anolis (anoles)
• Hundreds species New World
• Length hind leg reflects use vegetation
• Perch diameter
Anolis carolinensis
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 Lizards• Positive correlation (after 10-14 yr) between
vegetation and change morphology• Is this natural selection in action?
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• Soapberry Bug (Jadera haematoloma) feeds on seeds• Beak pierces fruit walls
Soapberry Bugs• Feeds on native or introduced plants
(fruit size varies)• Feed on bigger fruits: longer beaks• How test if differences genetic?
Soapberry Bugs
• Raise bugs on common foods--beak length differences persisted
• Bugs adapted to different hosts: natural selection