What is a density-dependent factor?

The density dependent factors are factors whose effects on the size or growth of the population vary with the population density. There are many types of density dependent limiting factors such as;

availability of food, predation, disease, and migration.  However the main factor is the availability of food.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands

your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.