Population genetic simulation … in Lego

Julien Yann Dutheil, of the Institut des Sciences de l’Évolution de Montpellier, has a long track record of work in population genetics and genomics methods, particularly in the C++ programming language. He recently posted a video to YouTube, though, which suggests he’s trying out a new simulation platform: Lego bricks.

The video shows a robot built using the Lego Mindstorms system, which connects a programmable computing unit to motors and sensors built into Lego bricks. The robot moves along a rack of colored balls representing a population of haploid, clonally reproducing individuals bearing one of two possible color genotypes. The robot randomly selects individuals to remove, simulating their deaths, and draws colored balls from two hoppers to replace dead individuals with ones “cloned” from one of the balls neighboring the empty space in the population. This is a physical model of Patrick Moran’s 1958 description of evolution by drift in a fixed, finite population, and while it’s not very computationally efficient, Dutheil speeds up the video to show how the random birth-death process eventually leads to the loss of diversity, and that this loss happens more quickly when the population is smaller. I’ll definitely be keeping this one in my pocket for my fall evolutionary biology class.

Hat tip to Will Shoemaker, who posted the video to Twitter.

Reference

Moran P. 1958. Random processes in genetics. Mathematical Proceedings of the Cambridge Philosophical Society, 54(1), 60-71. doi: 10.1017/S0305004100033193

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About Jeremy Yoder

Jeremy Yoder is an Assistant Professor of Biology at California State University, Northridge. He also blogs at Denim and Tweed, and tweets under the handle @jbyoder.
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