What type of isolation was occurring in the collared lizard population?

Dispersal

Explanation:

It should be understood that there was a point in time when the collard lizards were going into extinction. This is due to some certain human activities such as bush burning, which caused the death of this particular creature and others.

Therefore, this activity led to the dispersal of the remaining member of the population, which resulted to being isolated on a mountain.

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.