The sympathetic nervous system is responsible for directing the involuntary actions and controls in the body one of the action is the maintenance of homeostasis.
Homeostasis is the ability of the body to regulate it's internal temperature, pH and internal body environment with respect to the changes occurring in the external environment surrounded by the body.
The sympathetic system helps in regulating the body temperature by directing the sweat glands to secrete sweat to obtain a cooling effect.
Whenever sudden change caused by human or natural disasters occurs in the environment leading to the reduction of organisms or biodiversity present to a lower size, such condition is referred to as BOTTLENECK EFFECT.
Although there is no context for this question, it would be safe to say that that population would have reached its carrying capacity, if not become overpopulated.
