Answer:
Keystone Species: Kangaroo Rat Keystone species are species whose presence and role within an ecosystem has a disproportionate effect on other organisms within the system. Hawk (predator)/lizard (prey). scorpion (predator)/insect (prey). if their is no relationship between these two then the scorpions will die off and the insects will thrive.
Explanation:
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The parts wich are derived from these three areas include:the cerebellum,the brain stem of the brain stem consists of the parts:the midbrain,bridge brain,the medulla oblongata.other parts of the brain including the thalamus,hypothalamus and limbic device.
Natural selection is the correct answer