A natural population can't increase indefinitely for many reasons, they include, for example, the availability of space, and resources, such as food, and partner. Populations instead grow logistically, which means that they grow at different rates, with an individual growth limit known as carrying capacity, which refers to the maximum number of individuals of a population a habitat can support. This especially occurs in macro-organisms, such as animals and plants, in contrast, microorganisms such as bacteria can grow to a high amount of individuals when they are cultured under lab conditions where they have all their necessities supplied.