Introduction to Ecology
Introduction to Ecology EVE 101
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This 3 page Class Notes was uploaded by Raven Connelly on Tuesday September 8, 2015. The Class Notes belongs to EVE 101 at University of California - Davis taught by Staff in Fall. Since its upload, it has received 19 views. For similar materials see /class/187322/eve-101-university-of-california-davis in Evolution And Ecology at University of California - Davis.
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Date Created: 09/08/15
EVE 101 7 W08 Lecture 4 Handout p 1 How to use optimal foraging theory to predict an animal s diet Molles Ch 6 151 2 Note your text uses different notation for basically the same the model on this page is explicit about search time and allows that to vary 1 The basic model based on a currency of energy includes both assumptions and fundamental properties 2pm CsTs diet Yt 2PM Ts diet Where Yt 2 amount of energy gained per unit time while foraging pi the proportion of food items that are type i e1 2 energy gained from one item of type i ti time to pursue handle and swallow a single type i item T5 mean search time per item of available food all types Cs 2 cost in energy per unit search time Example 61 kcal Food type Number pi e1 kcal ti sec E Rank 1 20 02 4 1 40 first 2 30 03 2 1 20 second 3 50 05 1 2 05 third Ni where C 01 kcalsec T 1 sec 39 S S P1 EN1 1 11 Predictions of the model A Which food types should be included in the forager39s diet Step 1 Compute Yt with only the firstranked prey most et per item 02 4 01 l Yt1 2058 kcalsec Step 2 Compute Yt with first and secondranked food types 024 032 011 Yt12 W 087 kcalsec Because Ytgg gt Yt1 include type 2 in the diet ie diet is the first and second ranked items Step 3 Compute Yt with first second and thirdranked food types 024 032 051 011 Yt123 0210310521 072kca1Sec Because Yt1yz3lt YKLZ exclude type 3 Prediction 1 Animals will eat types 1 and 2 and ignore type 3 whenever encountered even though type 3 is the most abundant General Whether a food type is included in the diet depends on the relative abundance of better items not on its own relative abundance B What if the abundance of all food types increased 10X That is the search time T5 will be reduced by 110 or T5 01 Step 1 Compute Yt with only the first ranked prey most et per item 02 4 01 01 Yt1 263 kcalsec Step 2 Compute Yt with first and second ranked food types 0 24 032 0 10 1 Yt12 W 232 kcalsec Because YKLZ lt Yta exclude type 2 from the diet ie diet is only the first ranked item Prediction When food abundance goes up lower ranked items are dropped from the diet even if they were acceptable before General When food density is increased foragers become more selective