For instance, light stimulation, heat stimulation, chemical stimulation, sound stimulation, etc. -The stimulus that comes from within an organism is the internal stimulus. Humor stimuli and neural stimuli etc (release of hormones such as thyroxine).
What occurs when too much of a population rely on something?
This leads to overcrowding after which competition sets in and it would diminish the resources and death of the unfit organism while the fittest survives.
