FUNCTIONAL RESPONSE

FUNCTIONAL RESPONSE

FUNCTIONAL RESPONSE

Fig. 7.20 in Molles 2008

Different Light Environments

Adiantum Encelia

Fig. 7.21 in Molles 2008

ForestUnderstory

Plants

Forest CanopyPlants

Functional Response

Fig. 7.22 in Molles 2008

Prey Density

Foo

d In

take

Prey Density

Fig. 7.23 in Molles 2008

Functional Response: Controlled Experiment

Fig. 7.24 in Molles 2008

Functional Response: Natural Environments

Predatory Water Bug

Prey: Mayfly Larva Prey: Isopod

vs.

How do Red-Winged Blackbirds Allocate Energy?1 2

3 4

How do Cacti Allocate Energy?

5 6

9

Optimal Foraging Theory(Derived from Economics)

• Energy Supplies are Limited

• Organisms cannot maximize all functions

• Allocation of Energy is a Compromise between Needs

Bluegill

How do Organisms Selecta Diet?

MODEL FOR ENERGY YIELD: ONE PREY ITEM

E

T=

Ne1E1 - Cs__________________

1 + Ne1H1

ET

=

Cs=

H1 =

Ne1

=

E

T=

(Ne1E1 – Cs)_____________________________________________

1 + Ne1H1 + Ne2H2

+ (Ne2E2 – Cs)

TWO PREY ITEMS

DIET CHOICE: Optimization

Ne1E1 - Cs__________________

1 + Ne1H1

(Ne1E1 – Cs)_____________________________________________

1 + Ne1H1 + Ne2H2

+ (Ne2E2 – Cs)

OR

ONE PREY ITEM

TWO PREY ITEMS

ET

=

ET =

Bluegill

?

Actual Food Availability in the Environment

Prey Length (mm)

Fig. 7.25 in Molles 2008

Bluegill Optimal Diet(Prediction from Theory)

Fig. 7.25 in Molles 2008

Bluegill Actual Diet

Prey Length (mm)

Fig. 7.25 in Molles 2008

Optimal Foraging Theory Observed

Bluegill Diet

Fig. 7.25 in Molles 2008

Optimal Foraging Theory Applied to Plants

LightLevel

Soil Fertility

Fig. 7.26 in Molles 2008

Energy Allocation to Roots

Fig. 7.27 in Molles 2008

Energy Allocation to Roots

1 http://www.coffeecreekwc.org/photos/birds/Red-Winged_Blackbird_(male).jpg

2 http://www.frw.ca/albums/Ponds-and-Wetlands/Projects_Ponds_and_wetlands_ Red_wing_blackbird_nest_in_c.jpg

3 http://www.migrationresearch.org/mbo/id/rwbl/id%20rwbl%20ahy%20f% 20566%20wing%20jul06.jpg

4 http://www.mikephoto.com/content/binary/blackbird-mobbing.jpg

5 http://www.desertusa.com/july96/IMG_0529.jpg

6 http://www.scienceaid.co.uk/biology/ecology/images/cactus.jpg

7 http://www1.istockphoto.com/file_thumbview_approve/3606144/2/istockphoto_ 3606144_saquaro_cactus_skeleton.jpg8 http://www.azcentral.com/help/reprints/pics/animal_1.jpg