Grouping behavior and the evolution of animal migration: Difference between revisions

Latest revision as of 13:38, 26 June 2010

Participants

Andrew Hein
Ana Hocevar
Daniel Jones
Oana Carja
Kyla Dahlin

Project Summary

In the first week of the CSSS Ian Couzin presented models suggesting that migrating animal populations may evolve into sub-populations of individuals that are more informed and individuals that are more social (see an example [[1]]). However, his approach is far removed from the actual constraints that migrating animals experience. Starting from Couzin's model, we developed a framework that includes the amount of fuel animals can store and how that fuel is lost when the animals communicate or are force to travel at sub-optimal velocities to maintain a flock. As an initial model we have used data for migratory birds, assuming a small (N=300) population travelling 2000 km without stopping to refuel. We find that the added pressure to maintain fuel stores will drives the population to be more informed than was found in the Couzin papers.

Questions/ Objectives (current and future)

(1) How does limitation in fuel storage affect population viability?
(2) Is there a trade-off between time/distance taken to reach target and number of informed individuals?
(3) Is maximum group size related to the radius of socialization?
(4) Does varying the amount of mutation / selection algorithm change the results significantly?

Background Info

What is migration? (Dingle & Drake 2007)

Presentation Slides

Media:Evolution_Migration_Talk.pdf

@@ Line 1: / Line 1: @@
-==Meetings==
-''Next meeting is scheduled for Sunday the 11th at 5:00pm in the coffee shop''
 ==Participants==
 [[Andrew Hein]] <br/>
+[[Ana Hocevar]] <br/>
+[[Daniel Jones]] <br/>
+[[Oana Carja]] <br/>
 [[Kyla Dahlin]] <br/>
-[[Oana Carja]] <br/>
-[[Ana Hocevar]] <br/>
-[[Vanessa Weinberger]] <br/>
-[[Leif Karlstrom]] <br/>
 ==Project Summary==
-This project will start with some of the grouping behavior models that Ian Couzin showed us (see an example [[http://webscript.princeton.edu/~icouzin/website/wp-content/uploads/2010/05/couzin05.pdf]]). In addition to individuals evolving the ability to be 'informed' about the migratory route, I'd like to add another evolutionary trait: the ability to store fuel (e.g. fat). Increasing the amount of fuel stored is like increasing the amount of gas you put in your car. If you have some imperfect information about where you want to go, you are more likely to eventually get there without running out of gas if you start with more gas. In the case of migratory animals, increased fuel storage allows animals to search the landscape for a longer period of time. However, fuel storage comes at a great cost--individuals that store a lot of fuel experience drastically increased drag (fish, birds) and they must spend a lot of time gathering fuel before they migrate.
+In the first week of the CSSS Ian Couzin presented models suggesting that migrating animal populations may evolve into sub-populations of individuals that are more informed and individuals that are more social (see an example [[http://webscript.princeton.edu/~icouzin/website/wp-content/uploads/2010/05/couzin05.pdf]]). However, his approach is far removed from the actual constraints that migrating animals experience. Starting from Couzin's model, we developed a framework that includes the amount of fuel animals can store and how that fuel is lost when the animals communicate or are force to travel at sub-optimal velocities to maintain a flock. As an initial model we have used data for migratory birds, assuming a small (N=300) population travelling 2000 km without stopping to refuel. We find that the added pressure to maintain fuel stores will drives the population to be more informed than was found in the Couzin papers.
+<br/>
-The goal of this project would be to let individuals evolve BOTH the ability to store information about the migratory route at a cost as in Ian's models, and the ability to store more fuel at a cost. We'd like to see what types of trait combinations evolve over a number of generations.<br/>
+==Questions/ Objectives (current and future)==
-==Questions:==
+(1) How does limitation in fuel storage affect population viability? <br/>
+(2) Is there a trade-off between time/distance taken to reach target and number of informed individuals?<br/>
+(3) Is maximum group size related to the radius of socialization?<br/>
+(4) Does varying the amount of mutation / selection algorithm change the results significantly?<br/>
-(1) How does variation in fuel storage affect population viability? <br/>
+==Background Info==
-(2) Is there a trade-off between time/distance taken to reach target and group knowledge? <br/>
-==Models==
+[[Image:Power_curve.jpg|200px|thumb|left|This figure shows flight time for a 1kg bird as a function of flight velocity. The blue curve is a bird that is storing 50% of its body weight as fuel. The black curve is 25% and the red is 10%. Note the difference in optimal speed. This is an approximation but I think it gives the basic idea.]]<br/>
-At this point we are independently reading papers and working with code to implement Ian's migration model.
+[http://media.eurekalert.org/release_graphics/pdf/07%20February%20Article%20Drake.pdf What is migration? (Dingle & Drake 2007)]
-==Background Info==
+==Presentation Slides==
-[[Image:Power_curve.jpg|200px|thumb|left|This figure shows flight time for a 1kg bird as a function of flight velocity. The blue curve is a bird that is storing 50% of its body weight as fuel. The black curve is 25% and the red is 10%. Note the difference in optimal speed. This is an approximation but I think it gives the basic idea.]]
+[[Media:Evolution_Migration_Talk.pdf]]