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Chapter 10 Predation: 

Chapter 10 Predation Chapter 10 Predation

Introduction: 

Introduction Predation Traditional view: carnivory Differences from herbivory Herbivory is non-lethal Differences from parasitism In parasitism, one individual is utilized for the development of more than one parasite

Introduction: 

Introduction Predation (cont.) Predator-prey associations Figure 10.2

Slide4: 

Intimacy Low High Parasite Parasitoids Grazer Predator Lethality High Low

Antipredator Adaptations: 

Antipredator Adaptations Pages 151-155 in book

Predator-Prey Models: 

Predator-Prey Models Effects of predators on prey Depend on such things as prey and predator densities, and predator efficiency Graphical method to monitor relationship

Predator-Prey Models: 

Predator-Prey Models Graphical method to monitor relationship (cont.) Prey isoclines have characteristic hump shape Figure 10.4

Slide9: 

Prey increase i) Prey iscoline K N N N N K 1 1 1 2 2 2 ii) Predator iscoline Prey density Predator increases Predator decreases Predator density Predator density Prey density

Predator-Prey Models: 

Predator-Prey Models Superimpose prey and predator isoclines One stable point emerges: the intersection of the lines Three general cases Inefficient predators require high densities of prey (Figure 10.5a)

Slide11: 

Damped oscillations Prey isocline Predator isocline a) Predator Density Prey Density Time Population density

Predator-Prey Models: 

Predator-Prey Models Three general cases (cont.) A moderately efficient predator leads to stable oscillations of predator and prey populations (Figure 10.5b)

Slide13: 

Stable oscillations Population density Predator equilibrium density b) Prey Density Predator Density Time

Predator-Prey Models: 

Predator-Prey Models Three general cases (cont.) A highly efficient predator can exploit a prey nearly down to its limiting rareness (Figure 10.5c)

Slide15: 

Increasing oscillations Predator density Prey Density Time Population density

Predator-Prey Models: 

Predator-Prey Models All based on how efficient predator is Shift in isoclines Food enrichment (shift to right) (Figure 10.5d)

Predator-Prey Models: 

Predator-Prey Models Food enrichment (shift to right) (cont.) Carrying capacity changes Prey isocline changes, but predator isocline remains unchanged – “paradox enrichment” : Increases in nutrients or food destabilizes the system

Predator-Prey Models: 

Predator-Prey Models Functional response How an individual predator responds to prey density can affect how predators interact with prey (Figure 10.6)

Slide20: 

I II III Number of prey eaten per predator Prey density

Predator-Prey Models: 

Predator-Prey Models Functional response (cont.) Three types Type I: Individuals consume more prey as prey density increases Type II: Predators can become satiated and stop feeding.

Predator-Prey Models: 

Predator-Prey Models Three types (cont.) Type III: Feeding rate is similar to logistic curve; low at low prey densities, but increases quickly at high densities

Chapter 11 Hebivory: 

Chapter 11 Hebivory © 2002 by Prentice Hall, Inc. Upper Saddle River, NJ 07458

Slide24: 

Terrestrial vertebrate herbivores can have a big effect on terrestrial woody plant communities! Banta et al. (in press) PLANT COMMUNITIES GROWING ON BOULDERS IN THE ALLEGHENY NATIONAL FOREST: EVIDENCE FOR BOULDERS AS REFUGIA FROM DEER AND AS A BIOASSAY OF OVERBROWSING.

Slide25: 

Banta et al. (in press)

Slide26: 

Banta et al. (in press)

Slide27: 

Banta et al. (in press) Over browsing by deer can significantly reduce tree regeneration and diversity

Plant Defenses: 

Plant Defenses Example of plant chemical defenses Alkaloids Mustard oils Terpenoids

Effects of Herbivory on Plants: 

Effects of Herbivory on Plants Beneficial herbivory Review of herbivory (Bigger and Marvier, 1998) 60 comparsions demonstrated a reduction in plant size due to natural levels of herbivory

Effects of Herbivory on Plants: 

Effects of Herbivory on Plants Review of herbivory (Bigger and Marvier, 1998) (cont.). 10 comparisons demonstrated an increase in plant size Plants are stimulated to regrow after damage, and may overcompensate

Effects of Herbivory on Plants: 

Effects of Herbivory on Plants Beneficial herbivory (cont.). Benefits of root herbivory (Figure 11.12)

Slide32: 

Soil High- tide level A D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D A A A A A A A A A A

Effects of Herbivory on Plants: 

Effects of Herbivory on Plants Beneficial herbivory (cont.). Benefits of grazing and regrowth More flowers and fruits on grazed plants (Gronemeyer et al. 1997). Called “overcompensation”

Slide34: 

Un-browsed

Slide35: 

More likely to occur in perennials than annuals But overcompensation is most interesting in annuals and monocarps (perennials are usually not monocarpic) Beneficial herbivory (cont.).

Slide36: 

Also: High levels of tolerance can be observed in annuals too Arabidopsis thaliana

Slide37: 

Arabidopsis thaliana (cont.). Weinig et al. (2003) Significant genetic variation in tolerance to herbivory (overcompensation, as well as other responses, observed)

Slide38: 

Arabidopsis thaliana (cont.). Banta and Pigliucci (in prep.) Overall, simulated herbivory did not result in a decrease in fitness! Difference not significant (Error bars overlap)

Slide39: 

Arabidopsis thaliana (cont.). Banta and Pigliucci (in prep.) Bla-12 (a natural-collected genotype from Spain) Dashed line is simulated herbivory. Solid line is no herbivory

Slide40: 

Arabidopsis thaliana (cont.). Banta and Pigliucci (in prep.) Summary: In this study, the Arabidopsis thaliana genotypes studied were highly tolerant of browsing (although no overcompensation was observed)

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