# Intraspecific competition

Intraspecific competition (also intraspecific competition) is the ecological competition for space and resources within of populations , between several individuals of a kind . The intraspecific competition for regulating the population density and for adapting to changed living conditions ( evolution ) is important. In contrast, there is interspecific competition , which describes the competition between populations of different species.

Since individuals of one species have the same needs and behavior, they compete for the same resources. This leads to a lack of these resources in the course of growth. Individuals who suffer from a deficiency have a shorter lifespan, reproduction and growth. The deficiency arises either through

• Resource utilization of previous individuals at the same location, or
• Restriction of the habitat due to the repopulation of a habitat by another individual.

A common mathematical model for the temporal development of a population, taking intraspecific competition into account, is the logistic differential equation

${\ displaystyle {\ frac {dx} {dt}} = ax (1 - {\ frac {x} {K}})}$

where stands for the population density and for the capacity. ${\ displaystyle x}$${\ displaystyle K}$

The competitive pressure depends on the density of a population. If the number of animals in a certain habitat decreases, the death rate decreases and / or the birth rate increases (for example, a decrease in seed production in plants). Populations with fewer organisms can therefore grow over a longer period of time. A theoretical equilibrium of a stable population is called carrying capacity . A population is stable when the birth rate and death rate are in balance. The population density and size is also dependent on environmental conditions and predation (predators, feeding pressure). Therefore it is often subject to fluctuations - contrary to the theory.

If such an equilibrium is approximately established, self- thinning also regulates the population density as a negative feedback in plant stands in a restricted habitat . In self-thinning, weaker individuals are displaced by stronger ones; the number of individuals (population density) decreases while the biomass of the individual surviving individuals increases. The total biomass of the population remains the same. With the age of the individuals, their demands and their biomass grow. The intraspecific competition increases and the survival probability for the individual individual decreases.

## Individual evidence

1. ^ J. Murray: Mathematical Biology . Springer, 1989, ISBN 978-0-387-19460-8 .