• BUN = 1
• BUB, BUD, BUG, BUM, BUR, BUS, BUT, BUY = 2 (Hereinafter referred to as the BUG mutation.)
• All other Genomes = 0

If the defender has the same or lower Power than the attacker, then the defender dies. BUGs kill anything they encounter, including other BUGs. 

The Founding Genome is BUN,,,,, (with commas used to pad the Genome up to the desired length). It begins with a Power of one. 

Each generation, surviving Killer Rabbits can spawn one Clone and one Mutant. The Mutant will have a single point-mutation, i.e. a single random letter substitution. 

Press ctrl-r to Run Killer Rabbits.  

I warned you.
You should have Run Away!

This is the Result.

The green cells are parameters available for experimentation.

• Genome is the length of the letter sequence. 
• Generations is how many turns of reproduction and killing you want. 
• Field is the crowding limit. It determines how often Killer Rabbits attack. The smaller the Field, the more crowded they are, and the more often they'll attack.
• Clone and Mutation represent the chance of producing offspring when the Field is crowded.  Clone is the chance of a Killer Rabbit producing an exact copy. Mutation is the chance of producing a mutant copy. With each value set to 100%, or when the Field is not crowded, a parent Killer Rabbit will always produce the maximum two offspring per Generation. 
• Toxicity is the chance that an attack will be successful assuming the attacker has at least as great a Power as the defender, otherwise the attack always fails.

Please note that if you set Toxicity to a low value without lowering the reproductive rate by adjusting Clone and Mutation, you may experience runaway Killer Rabbit population growth. 

Run away! Run away! You have been warned.

In orange cells, we have a summary of the results.

• Max Pop is the maximum number of surviving Killer Rabbits in any Generation. 
• Avr Pop is the average number of surviving Killer Rabbits in any Generation.
• Crash Pop is the minimum number of surviving Killer Rabbits in any Generation.
• Predominance is the first Generation in which at least half the surviving Population has a superior BUG mutation. 
• Purity is the percentage of the Genomes non-selectable letters (junk) across the Population that are still identical with the Founding Genome. The value shown is the Purity at Predominance. 

On the left of the screen are recorded the result of each Generation. It includes the surviving Population of Killer Rabbits, the percentage of the Population that has the BUG mutation (Power=2), and the Purity of the Population. Purity starts at 1.0 and can only decrease over Generations. 

The graphs give some idea of how the Killer Rabbits evolve over time. Population is the green line on the upper graph. On the lower graph, the blue line is the Power while the pink line is the Purity. 

Following is an example of results from the Field screen showing the actual Genomes. (each column is a Generation). The colors give some indication of the Power. The dead are grayed out. 

Notice all the various mutations that have been tried. But have since disappeared! 

Generation 2 3 4 5 6 7 8 9 10 Novelty L Y S J B X Q R A B* R! V W B D O K

Of all these, only the R! and D persist. Only a single change to the Junk Genome remains after 10 Generations. The rest were tried and discarded. Meanwhile, selection for fitness preserved the BUR strain.

Snippets of Code!  This function calculates the Power of a Genome.

Instead of bouncing fluffy bunnies around the screen, not-so-fluffy Killer Rabbits randomly encounter one another proportioned by how crowded they are in the Rabbit Field, numChildren/maxMembers. 

Some Results!

Following is the result with Genome = 200, Field = 100, Generations = 100. The pink line is Purity, that is, how much of the original sequence has been left untouched. Notice that Purity forms a nearly straight line. On the same graph is the proportion of the BUG mutation. Notice that once the BUG mutation occurs, it rapidly predominates in the Population. But because they still prey on one another, they never quite stabilize at 100% fixation. 

This scenario reached 50% BUG predominance on Generation = 13 with 97% Purity. 

This example is with a much smaller Genome and Field. The results are more chaotic and often results in Population crashes. The advent of the powerful BUG mutation varies considerably over a number of trials. The decline in Purity is not chaotic, though.

The following example is with a large Genome but a relatively small Field. Even with the very late onset of the BUG mutation, Purity is still very high. 

Genome = 1000, Field = 250, Generations = 100

These are some typical results from the moment when

The Purity is 93%. That means that out of 2000 letters, an average of 1863 letters will be the same as the Founding Genome. And this varies very little among the Population— a standard deviation only about 1½. Consequently, we can examine just a single sequence to determine how many Generations since it diverged from that Founding Genome. We have a statistically accurate monotonic Junk Genome Clock. 

Not only does this Population have great uniformity, but it will also have many areas of identity with other populations that diverged separately from the Founding Genome. Following are two divergent Populations. They each have 93% identity with the Founding Genome, and we can easily discern the family relationships within each Population and between the two Populations.  

(Keep in mind that the "," are just placeholders. They represent specific and decidedly non-random sequences of identity that have been inherited from the Founding Genome.)

Genome = 100, Generations =  150, Field = 100

The Empire of BUS is unusual because two mutations arose simultaneously; BUS and BUR. It took many Generations for BUS to become predominant; and because of the relatively large Population will probably remain so for many a Generation to come.  

The Land of BUN, Fjords of BUR, Kingdom of BUG and Isles of BUM each had their time, but then slipped into history.