Which neurotransmitter regulates sleep, mood, attention, and learning, and too little of this neurotransmitter can cause depressed mood?

In some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. the production of sterile male ligers is an example of read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. the production of sterile male ligers is an example of a postzygotic barrier the founder effect sympatric speciation a prezygotic barrier

Which of the following was not a result of early humans increasing proficiency at finding food

When pay is made public, people evaluate how equitable their pay is in light of the pay other people are receiving. the problem in this case is that dwight and guillermo have found out that others are getting paid more than they do for the same work. what are they likely to do under these circumstances