Intraspecific Competition is the conflict between members of the same species for limited resources. This competition reduces the physical ability of both the individuals. The individuals may fight over sunlight, water, territory, mates or any other resources.
On the other hand interspecific competition takes place between individuals of different species for a common resource. Individuals of the same species require the same resources so the competition is more intense making it the stronger force. This competition is limiting factor for the population of many species. Due to this competition the members would receive limited resources when the population of the intraspecific competitors rises.
This competition is done over the resources which are required for survival. For the competition to arise the resource must be limited. If all the members of the species can acquire the required resources then this conflict would not occur and the population of the specie will increases exponentially. This situation is very rare and so every individual does not survive and intraspecific competition takes place for acquiring the necessary resources.
The conflict between the members may not involve direct interaction it also includes indirect interaction where the individual depletes the resources so that other members will not be able to acquire it.
Direct or Interference Competition
In this process the members of the same species directly compete with each other to acquire a shared resource. This competition can involve stealing, ritualised combating or fighting. Interference competition can involve animals claiming a territory and prevent other member of its species from entering. The animal debarred from the territory generally suffers a fitness loss due to the availability of reduced area and does not want to confront with the more dominant members of its species. In this process the organisms are directly encountering each other so they are able to develop behavioural strategies to out-perform their rivals.
Indirect or Exploitative Competition
The individuals can also compete with their own kind indirectly. This process includes organisms depleting a common resource and as a result both suffer from fitness loss. The organisms may not come in direct contact but they compete through the shared resource.
Partitioning of Resources
Aggressive competition can be harmful for the organisms as they may get injured or even die. Because of this reason many species have developed forms of ritualised combat to establish who survives the competition and gets access to the shared resource without having a dangerous encounter. In such scenarios the stronger male usually wins the competition. Contest competition relatively stables the population dynamics of the organism. Uneven distribution of necessary resources may result in some organisms dying off but also helps other members of the population to reproduce. Scramble competition on the other hand includes more equal distribution of resources when there is common resource pool.
Different species fight to breed and survive competition is a must in order to acquire resources to survive. It they are not able to compete then they will die the law of survival of the fittest is vey apt for this situation.