Competition

• Organisms compete when a factor is in short supply (resources like food, light and space); it can have a big effect of population growth as completion increases, reproduction decreases and deaths increase
• Intraspecific: Same species; important in natural selection (best adapted individuals will survive to reproduce) and to limiting size in stationary phase (size increases, competition increases, size falls and same for size decrease)
• Interspecific: Different species, only if niches of two different species overlap
• Allelopathy: Plant competition; secrete chemicals into their habitats interfering with other plants metabolism (prevent their use of resources like light, space, and water), growth, seed germination, or mineral ion uptake