A) Calculate the conditions under which prey 3 should be added (or not added) to
ID: 259154 • Letter: A
Question
A) Calculate the conditions under which prey 3 should be added (or not added) to the diet.
B) Besides Ts, what term is missing from your final inequality? What does that tell you about the foraging rule used?
In class we considered an optimal foraging model where a forager chose between two prey types, labeled prey 1 and prey 2. NOw, suppose we have a forager with three prey types (prey 1, 2 and 3). Further suppose it is true that both prey 1 and prey 2 should both always be eaten. Let the handling time, encounter rate, and energy content of prey 1, 2 and 3 be equal to Prey 1 Prey 2 Prey 3 Handling time Encounter rate Energy content h1 L1 h2 L2 h3 L3Explanation / Answer
According to the optimal foraging strategy
E/h >= e1/(h1*L1) + e2/(h2+L2)
Where e1 and e2 are the energy contents that have to be obtained to pass on to the next generation by raising their reproducibility, h1 and h2 are the handling time of the current preys prey1 and prey2, and L1 and L2 are the search time for another prey to be added to the diet although whatever that is essential is already in the diet available. The above equation holds good, if the prey1 and prey2 are inevitable for the forage.
A) The conditions where the prey3 has to be added to the diet would be that the total energy content of the organism is not sufficient for its survival and reproduction (including activities like avoiding predators, foraging, mating, caring for young, etc.). If the energy content of e1+e2 is not sufficient after dividing by L1, h1 and h2, L2, then the organism has to opt for the third prey.
That is, when, E/h < e1/(h1*L1) + e2/(h2+L2)
B) The profitability of the prey item is determined usually by the energy content of the item (E)€ and the time required for handling the item (h). The profitability of the item is equal to E/h. If the animal goes not searching for next profitable item although it has profitable items in the diet, then the energy content that it is expecting is E/(s+h), where s is the searching time required for the next item that is expected to be profitable for the animal.
If the profitable item is sufficient, then the energy content obtained from it is sufficient for the animal to live well and reproduce well passing on all the traits to the next generation and make it fit for natural selection. In order to make the energy content obtained to be enough, it has to be divided by the searching time wasted for the next item and the handling time of the current prey. SO, the added term must be ‘s’.
In the part A) this ‘s’ is referred as L.
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