What is a good example of reproductive isolation?

Reproductive isolation is the process to keep away two various species from mating with each other. An example is two fish species from the sticklebacks family. One species lives in fresh water all year while the other one lives in the sea during winter and goes to rivers to produce their offspring every spring and summer. This is specifically called temporal isolation.

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.