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Optimal strategies and information in foraging theory

Sernland, Emma LU (2005)
Abstract (Swedish)
Popular Abstract in Swedish

I den här avhandlingen presenterar jag ett antal empiriska och teoretiska arbeten där vi har studerat hur både människor och djur använder information. Vi har funnit att mängden information, och det sätt på vilket informationen presenteras, har betydelse för hur väl människans beslut anpassas till de förhållanden som råder. Vi har också funnit att människor verkar ha en inneboende uppfattning om hur en resurs är fördelad över ett område. Denna uppfattning verkar vara plastisk, såtillvida att den kan justeras m a p den information som tillkommer.



Med hjälp av matematiska modeller har vi studerat om tillgången till information från andra gruppmedlemmar kan vara en anledning till... (More)
Popular Abstract in Swedish

I den här avhandlingen presenterar jag ett antal empiriska och teoretiska arbeten där vi har studerat hur både människor och djur använder information. Vi har funnit att mängden information, och det sätt på vilket informationen presenteras, har betydelse för hur väl människans beslut anpassas till de förhållanden som råder. Vi har också funnit att människor verkar ha en inneboende uppfattning om hur en resurs är fördelad över ett område. Denna uppfattning verkar vara plastisk, såtillvida att den kan justeras m a p den information som tillkommer.



Med hjälp av matematiska modeller har vi studerat om tillgången till information från andra gruppmedlemmar kan vara en anledning till varför vissa arter lever i grupp. Vi har undersökt en situation där individerna strävar efter att maximera sin intagshastighet av föda. I en situation där gruppmedlemmarna delar lika på all information och på all föda som hittas, men där var och en, oavsett gruppstorlek, måste betala hela kostnaden i restid för att förflytta sig mellan platser, kommer intagshastigheten av föda att minska med ökad gruppstorlek. Individerna kommer spendera en större del av sin tid på att förflytta sig mellan födoplatser och en mindre del av sin tid på att äta ju större gruppen är. I ett sådant här scenario är alltså inte informationstillgången en anledning till att hålla ihop i grupp.



Vi har också med hjälp av matematiska modeller studerat hur informationsdynamiken i en grupp av födosökande djur kan se ut. I modellen har vi gett gruppmedlemmarna tre beteendeval: söka föda, söka efter information eller lämna födoplatsen för att förflytta sig till en ny plats. Individerna strävar efter att maximera sin överlevnad. Resultaten visar att valet av beteende beror på hur höga energireserver individen har. En individ med låga energireserver söker efter föda och lämnar födoplatsen om den bedömmer att den potentiella kvaliteten sjunker till en viss nivå, medan en individ med höga energireserver väljer att söka efter information. Vi har antagit att när en individ lämnar en födoplats så lämnar även resten av gruppen. Det innebär att det är de gruppmedlemmar som har låga energireserver som kommer fatta lämnabesluten för gruppen.



Som avslutning visar vi på en möjlig tillämpning av kunskaperna om informationens betydelse för beslutsfattande. Vi presenterar en ny typ av insatsbaserade fiskekvoter för en bättre skötsel av fiskbestånd: en effortbaserad dynamisk fiskekvot. Vi visar att genom att använda information från pågående fiske i kombination med fiskedata från tidigare år, kan vi nå en högre maximal hållbar skörd jämfört med att använda dagens system med en fast fiskekvot som sätts vid fiskets början. (Less)
Abstract
In this thesis, I present both theoretical and empirical work where we have studied how humans and animals use information in situations where they need to continually update their information on the density of a resource. We have found that the amount of information, and the way the information is presented, are important factors for how well decisions are adapted to current circumstances. In an empirical study on humans, we found that humans seem to have a default idea of the distribution of a resource. This default idea seems to be plastic, i.e. it is adjusted according to incoming information. The way additional information was presented, as well as the information content, was important for how well the default idea was adjusted to... (More)
In this thesis, I present both theoretical and empirical work where we have studied how humans and animals use information in situations where they need to continually update their information on the density of a resource. We have found that the amount of information, and the way the information is presented, are important factors for how well decisions are adapted to current circumstances. In an empirical study on humans, we found that humans seem to have a default idea of the distribution of a resource. This default idea seems to be plastic, i.e. it is adjusted according to incoming information. The way additional information was presented, as well as the information content, was important for how well the default idea was adjusted to current circumstances.



By using mathematical models, we have also studied whether access to information from group members, so called public information, is one of the reasons why some species live in groups. When group members aim to maximize its intake rate of food and share both information and food items found equally, and when each individual has to pay all the cost for travelling between foraging patches, the intake rate of food will decrease with increasing group size. The animals will spend a larger proportion of the time on travelling between patches and less time on foraging the larger the group size. In this case, information sharing on food density in patches is not a reason why animals live in groups.



We have also used mathematical models to study the information dynamics in a group of foraging animals that cannot both search for food and information at the same time. The animals aim to maximize their survival, and are given three behavioural choices in each time step: stay and search for food, stay and scan for information, or leave the current patch. The results show that the choice of behaviour depends on the energy reserves of the individual. An animal with low energy reserves searches for food and leaves the patch if its assessment of potential patch quality decreases to a certain level. An animal with high energy reserves chooses to stay in the patch and scan for information. In our model we assume that when one individual leaves the patch, the rest of the group also leaves. This means that it is those individuals that have low energy reserves that will make the leaving decisions for the group.



In the end, we use these theories on Bayesian foraging, information updating and decision-making in order to develop a new type of effort-based quota for sustainable fisheries management: an effort-based dynamic quota (EDQ). We show that by using information from ongoing fishing combined with fishing data from earlier years, we can reach a higher maximum sustainable yield compared to using a total allowable catch (TAC). (Less)
Please use this url to cite or link to this publication:
author
opponent
  • PhD Valone, Thomas, Department of Biology, St. Louis University, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
information use, Bayesian foraging, public information, prior information, negative binomial distribution, group foraging, decision-making, information updating, leaving strategy, Ecology, Ekologi
pages
104 pages
publisher
Department of Ecology, Lund University
defense location
Blå Hallen, Ekologihuset, Sölvegatan 37, Lund
defense date
2005-12-16 13:30
ISBN
91-7105-231-3
language
English
LU publication?
yes
id
02b6f713-7cb1-47ce-aabd-91277eb7e48a (old id 545834)
date added to LUP
2007-09-06 16:14:34
date last changed
2016-09-19 08:45:10
@misc{02b6f713-7cb1-47ce-aabd-91277eb7e48a,
  abstract     = {In this thesis, I present both theoretical and empirical work where we have studied how humans and animals use information in situations where they need to continually update their information on the density of a resource. We have found that the amount of information, and the way the information is presented, are important factors for how well decisions are adapted to current circumstances. In an empirical study on humans, we found that humans seem to have a default idea of the distribution of a resource. This default idea seems to be plastic, i.e. it is adjusted according to incoming information. The way additional information was presented, as well as the information content, was important for how well the default idea was adjusted to current circumstances.<br/><br>
<br/><br>
By using mathematical models, we have also studied whether access to information from group members, so called public information, is one of the reasons why some species live in groups. When group members aim to maximize its intake rate of food and share both information and food items found equally, and when each individual has to pay all the cost for travelling between foraging patches, the intake rate of food will decrease with increasing group size. The animals will spend a larger proportion of the time on travelling between patches and less time on foraging the larger the group size. In this case, information sharing on food density in patches is not a reason why animals live in groups.<br/><br>
<br/><br>
We have also used mathematical models to study the information dynamics in a group of foraging animals that cannot both search for food and information at the same time. The animals aim to maximize their survival, and are given three behavioural choices in each time step: stay and search for food, stay and scan for information, or leave the current patch. The results show that the choice of behaviour depends on the energy reserves of the individual. An animal with low energy reserves searches for food and leaves the patch if its assessment of potential patch quality decreases to a certain level. An animal with high energy reserves chooses to stay in the patch and scan for information. In our model we assume that when one individual leaves the patch, the rest of the group also leaves. This means that it is those individuals that have low energy reserves that will make the leaving decisions for the group.<br/><br>
<br/><br>
In the end, we use these theories on Bayesian foraging, information updating and decision-making in order to develop a new type of effort-based quota for sustainable fisheries management: an effort-based dynamic quota (EDQ). We show that by using information from ongoing fishing combined with fishing data from earlier years, we can reach a higher maximum sustainable yield compared to using a total allowable catch (TAC).},
  author       = {Sernland, Emma},
  isbn         = {91-7105-231-3},
  keyword      = {information use,Bayesian foraging,public information,prior information,negative binomial distribution,group foraging,decision-making,information updating,leaving strategy,Ecology,Ekologi},
  language     = {eng},
  pages        = {104},
  publisher    = {ARRAY(0x99ccd50)},
  title        = {Optimal strategies and information in foraging theory},
  year         = {2005},
}