HELP HELP What is it called when organisms that were once the same species no longer interbreeds/mates?

Speciation

Explanation:

“ Speciation is a process of evolution that forms a distinct new species. It happens when two populations can no longer interbreed.”

Source: https://www.expii.com/t/what-is-speciation-definition-types-10263

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it is a learned trait

explanation:

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.