Intraspecific competition is competition between individuals of the same species for the same limited resources, such as food, water, space, shelter, light, territories and mates.Members of the same species have the same requirements, so they occupy the same niche and competition between them can be intense.Intraspecific competition regulates population size:1. When resources are plentiful, the population grows.
2. As the population increases, there are more individuals sharing the same resources, so competition increases.
3. Resources become limiting: fewer individuals get enough food or space, so fewer survive and reproduce. The population decreases.
4. With fewer individuals, there is less competition, more resources per individual, and the population increases again.This causes the population to fluctuate around the carrying capacity. Intraspecific competition is density-dependent: the more crowded the population, the stronger its effect.
Examples:• robins defend territories; birds that cannot hold a territory do not breed
• oak seedlings under a parent tree compete for light, water and minerals, and only a few grow into mature trees
• male red deer compete for access to females during the rut.Intraspecific competition is also a driving force of natural selection: individuals best adapted to obtaining the limited resources are more likely to survive, reproduce and pass on their alleles.
2. As the population increases, there are more individuals sharing the same resources, so competition increases.
3. Resources become limiting: fewer individuals get enough food or space, so fewer survive and reproduce. The population decreases.
4. With fewer individuals, there is less competition, more resources per individual, and the population increases again.This causes the population to fluctuate around the carrying capacity. Intraspecific competition is density-dependent: the more crowded the population, the stronger its effect.
Examples:• robins defend territories; birds that cannot hold a territory do not breed• oak seedlings under a parent tree compete for light, water and minerals, and only a few grow into mature trees
• male red deer compete for access to females during the rut.Intraspecific competition is also a driving force of natural selection: individuals best adapted to obtaining the limited resources are more likely to survive, reproduce and pass on their alleles.