An evolutionary game of Rock Papers Scissors.

 Introducing the common side blotched lizard (Uta stansburiana) from the coast range of California. This species has a very cool polymorphism among males. Polymorphism means that different males will have a different colours or body shape/size. In the population of side blotched lizards there are three types of male morphs:

Orange throat males:

 Larger and more aggressive than other male morphs. They can defend large territories and in direct male-male interaction will win. However, Orange males are not very observant of what its females are doing.

Blues throat males:

 Moderate size not as aggressive as orange males. They defend a moderate to small territory. Blue males are well connected and “know” each female in his group.
 Yellow throat males:
 Small, unaggressive and avoiding direct conflict. They do not defend any territory. Yellow males look like females and use this to sneak mates.

 Each one of these male morphs is heritable. The three types of males have their pros and cons, and the interaction of all three plays out in to a dynamic yet stable game of “rock, paper, scissors”. An orange male (rock) by using its superior strength can steals mates from blue males (scissors). However, an orange male will lose to a yellow “sneaker” male (paper), who thanks to the orange males inattention to his female. Yellow males infiltrate orange male’s territory, disguised as a female, and mates with the orange’s females. Yellow (paper) male’s strategy will fail when met by a blue (scissor) male. The blue males, with his smaller group of females which he “knows” individually, is attuned to when a yellow males tries to sneak to mate with his females and is able to scare off the smaller yellow male.

 

 This system was study for six years where researchers observed a fluctuating in the numbers of orange, blue, and yellow males in the population. The population of these lizards neatly demonstrate frequency-dependant selection. That is, as one morph becomes more prevalent it greatly increases the fitness of its counter male, and the counter male will increase its frequency. This new morph prevalence will favour the new morph’s counter male, and so the third morph will become dominate, which in turn will lose to the first morph.
 Even with a game like “rock, paper, scissors”, again we can see that nature thinks of things first.

Reference:
Sinervo, B. & Lively, C.M. 1996, "The rock-paper-scissors game and the evolution of alternative male strategies", Nature, vol. 380, no. 6571, pp. 240-243.