How Mass Migration Might Have Evolved

[n2doc]

By Brandon Keim September 16, 2010 | 11:43 am | Categories: Animals


Just a few small changes in the social behaviors of even solitary animals may set in motion an evolutionary cascade ending in massive, globe-spanning migrations, suggests a study of migration’s origins.

Such migrations — caribou across the Arctic and wildebeest across the Serengeti, birds and butterflies over oceans — are among nature’s most beautiful and mystifying phenomena. Many models suggest how migration works now, in terms of individual actions producing collective behavior; but how it could have started in the first place is far harder to explain.

“Despite the ubiquity of collective migration, and the key function it plays in the ecology of many species, it is still unclear what role social interactions play in the evolution of migratory strategies,” wrote Princeton University evolutionary biologists Iain Couzin and Vishwesha Guttal in a study published Sept. 14 in the Proceedings of the National Academy of Sciences.

In their evolutionary model, Couzin and Guttal assumed two fundamental traits. First, the digital animals needed the ability to respond to a direction-linked environmental cue, of the sort provided in reality by temperature, geomagnetism, wind and chemical gradients. The second required trait was sociability, or an ability to be attracted toward moving neighbors and physically align with them.



Read More http://www.wired.com/wiredscience/2010/09/evolution-of-migration/

[Warpy]

1. What's always really puzzled me are schools of fish

They're incredibly beautiful to watch as they turn on a dime and in unison, but how in the hell do they coordinate it?

[foxfeet]

2. Twitter. It's a piscine flash mob.

[Warpy]

3. Or they're listening to a Michael Jackson song

genetically programmed into those little fishy brains and trying to redo the choreography aquatically.

[TheMadMonk]

4. Same way birds do.

1/2 inched from wiki entry on flocking behaviour.

Basic models of flocking behavior are controlled by three simple rules:

1. Separation - avoid crowding neighbors (short range repulsion)
   
2. Alignment - steer towards average heading of neighbors
   
3. Cohesion - steer towards average position of neighbors (long range attraction)

With these three simple rules, the flock moves in an extremely realistic way, creating complex motion and interaction that would be extremely hard to create otherwise.

[tinrobot]

5. You can simulate it in a computer fairly easily

All you have to do is supply the rules, start one moving, and the rest follow. It looks almost exactly like natural flocking behaviors.