One interesting symbiosis relationship we talked about at the ROM is the one between the snowshoe hare and the lynx. This predator-prey (+/-) relationship is particularly interesting as the habitat of these two species does not have a lot of other relationships. For this reason the predator-prey boom-and-bust cycle is especially distinct between the two.
The population of the lynx lags slightly behind the population of hares. As the hare population increases, more food is available to the lynx and hence its population also increases. However, as the lynx population increases, it consumes a greater number of hares. This causes the hare population to decrease, diminishing the food supply for the lynx, in turn causing the lynx population to decline. The cycle repeats itself.

Of course, besides predator-prey population control, each species is limited by the density-dependent limiting factors, as both are K-selected species.