Answer:
The hypothalamus plays ahuge role in the endocrine system. It is responsible for maintaining your body's internal balance of temperature.
When your hypothalamus senses that you're too hot, it sends signals to your sweat glands to make you sweat and cool your temperature.
When the hypothalamus senses that you're too cold, it sends signals to your muscles that make your shiver and create warmth, rising your temperature.
Well... if the predator would become extinct, the population of the hunted will grow and reproduce. There for it would increase.
Carbon dioxide is normally slightly warmer than oxygen so if there is a sudden increase, it would naturally increase the temperature.
Either the duodenum or the jejunum
