This is basically my dissertation, animated. LOL!!
What are you looking at?
Every pixel in that square is a genetic sequence. Some of those sequences confer a higher fitness advantage (the red colored peaks) or disadvantage (below the plane). The Blue color is neutral.
The grey dots are individual organisms within a population (the swarm of grey dots). The population does not explore every inch of the landscape at the same time (not every human alive right now represents all potential human DNA combinations). But there are populations of grey dots, who cluster together because they are genetically closely related to one another.
As generations of ‘dots’ go by, the genetic makeup of offspring changes due to random mutations, and the population of dots moves around the fitness landscape. The higher a dot is on a the plane, the more likely it will to produce ‘offspring’ dots.
Depending on how the environment/selective pressures change, depending on the mutation rate of the organism, lots of interesting things can happen.
EXAMPLE: 2:00-2:37 is like a Jack-In-The-Box for evilution junkies.
I started squealing, giggling, and clapping my hands at 2:37, like a goddamn delighted infant.
Then I thought about it later, and started laughing again.
When you think Darwin, you think “Survival of the Fittest!” “Onward and Upward!” Reach for the TOP of a fitness peak!…
Well, populations can reach a fitness peak… but then cant *stay* there. Random mutations occur, and they slip off the peak. Of course they could get back on again, after some more random mutations, but still– Even if populations reach the top, they cant stay there. How long they can stay there depends on their mutation rate.
Thats where HIV is different. Instead of discreet fitness peaks, HIV operates on a fitness plateau. A high-mutation rate organism like HIV has no use for high, narrow fitness peaks at all. Certainly one might evolve, here or there, but the second the virus multiplies it will introduce mutations, and the population will immediately fall off of the peak. Broad, flat plateaus, however, are ‘safe’ for high mutators. The populations can explore a *lot* of sequence space (reproduce a lot, make a lot of mutations), and still reproduce just fine.
Of course, ultimately, this topic is much more complex than this video conveys, but I think it is a *fantastic* video that gets the main ideas of fitness landscapes right, appropriate for a general audience AND not-so-evolution-and-population-dynamics-inclined scientists. I would have totally used this in my defense.
Edited to add: One of the animations creators, Bjørn Østman, has a blog!
And he recently did an AMA!