Intraspecific competition

Intraspecific competition is a competition that occurs within the ranks of a species to eliminate overpopulation. Since an ecological niche will only support a specific number of healthy inhabitants, intraspecific competition is a natural way to maintain ecological balance and survival of the fittest. When the population density becomes too great within a territory, individuals of the same species struggle to survive and obtain a share of limited resources such as food, water, space, sunlight, or mates. It is considered a negative interaction because it reduces the fitness of an ecosystem’s flora and fauna, resulting in lower offspring production and population reduction through migration or death. Yet, it is a necessary process to return the niche to a healthy, stable, and vibrant ecological community.

In order for intraspecific competition to be identified as such, competition must occur between organisms of the same species vying for the same resources. It must also result in a lower birth rate and population reduction. Population is controlled by many factors, including competition between organisms of different species, disease, and natural disasters such as fire or weather. Intraspecific competition is the most essential process in maintaining sustainable population sizes and the balance of nature.

Humans have interfered both intentionally and unintentionally with the balance of nature, with both positive and negative effects. In addition, humans engage in intraspecific competition in several ways. As the density in cities rises, aggressive behavior and crimes increase as perpetrators attempt to obtain needed resources. During natural disasters, humans compete for scarcer resources. When conditions in a country produce poverty, hunger, and disease, crime can increase, and mass migration can occur. The ultimate intraspecific competition is war, as humans compete for control, territory, and resources.

Overview

Intraspecific competition can take many forms in the natural world. Each type is defined by the behavior of individual animals or humans as they seek the life-sustaining resources they need.

• Scramble competition occurs when all the individuals obtain a part of the declining resource. In this type of competition, the limited food, water, or living space is shared by all the individuals in a population. This results in individuals suffering from the effects of starvation and lower reproduction rates. Scramble competition is known as an indirect competition. For example, in the winter, deer populations feed on woody trees within a limited niche. Since all the deer are feeding on the same resource, they are indirectly competing for the food that they cannot keep for themselves. Another example would be cows grazing on grass in a meadow.
• Exploitative competition occurs between individuals who together exploit the same resource. This reduces the availability of the resource to others. Not all inhabitants will suffer, only those who are not successful in sharing the resource. The individuals can also share the same territory. An example of this type of competition is found on the Aldabra Islands in the Indian Ocean off the coast of Africa. On these islands, a species of feral goat feeds off the top part of a native shrub, and the Aldabra tortoise feeds off the lower leaves that can be reached by extending their necks.
• Interference (contest) competition occurs in species that have a designated hierarchy present with one or more individuals having a dominant position in the community. This position of dominance is usually obtained through aggressive behavior. By exercising power over subordinates, the dominant individual will limit or prevent access to the needed resource. Only the dominant individual or the keeper of the territory will increase their reproduction success. An example of interference competition can be seen in the aggression of male elephant seals. Because elephant seals mate with many females, the female seals are the limited resource. The males battle to the death to become the dominant male. Even if the seal survives the battle, he is prevented from mating. Mating privileges then go to the dominant male.

Results of Intraspecific Competition

The overall purpose of intraspecific competition is to provide a means by which an ecological niche can recover from overpopulation. For this to happen, several consequences can occur.

• Growth is suppressed. The number of young produced is reduced and the young already born will slow down growth. For example, a pond full of tadpoles will not be able to support normal tadpole growth as they metamorphize into frogs. In some species, juvenile animals will leave the habitat where they were born to increase their chances of accessing plentiful resources within a new territory with less competition. The consequences of this scattering can be deadly. New habitats may not provide the resources needed to propagate and individuals may succumb to new types of predators.
• Some individuals may develop social dominance over others by increasing aggression. Aggression is displayed through coloration, vocalization, and physical stances. Subordinate animals will yield to the aggressive actions and accept less food or shelter. An example of this type of social dominance occurs among primates when they bare their enlarged canine teeth or rise on their hind legs.
• Individual territories can be established within a habitat. Instead of dominating others, some individuals will protect a smaller area of habitat and claim all its resources. Both fighting and ritualistic posturing include mock fighting and scent markings that define boundaries. Adult gray seals partition their environmental niche. Juvenile seals only feed in the top layers of the water by making shallow dives, whereas adults dive deeply into the zone rich with food resources.

Significance of Intraspecific Competition

Intraspecific competition is nature’s way of keeping the natural world in balance and the population of a species in check. When the population exceeds a habitat’s ability to support the species with the resources it needs, growth slows and births are inhibited, causing the population growth to slow. Since fewer births occur and individuals' health declines, the population begins to recede. Eventually, the population size stabilizes. When the numbers are reduced to the point that the habitat can support the lower population, good health returns, offspring are born, and the population begins a growth pattern again. Intraspecific competition is a natural regulatory process for healthy ecosystems.

Some research indicates that intraspecific competition is critical for restoration projects in hardwood forests, demonstrating the value of the natural competition in nature. However, conservation efforts are hindered if an ecosystem is altered in a way that eliminates this competition.

Topic today

Since the advent of the industrial age, biological and social scientists have studied the effect humans have on the environment. The purposeful removal of the gray wolf from Yellowstone National Park in the 1920s is an example of an ecological disruption that has affected the park ecosystem for almost a century. Even after reinstating the wolves into the park in 1995, the ecosystem has not recovered. Since the living organisms in ecosystems are so closely dependent on each other, as demonstrated in the intraspecific competition process, environmental advocates have influenced economic and political organizations in ways to protect the delicate balance found in these ecosystems. It began in 1970 with the formation of the Environmental Protection Agency. The agency aims to protect all living organisms and the environment by maintaining nature's natural balance and life-sustaining processes.

Because of EPA research and advocacy, laws such as the Clean Air Act of 1970, the Clean Water Act of 1972, and the Toxic Substances Control Act have been passed by Congress. In addition, the EPA is responsible for developing regulations that outline the technical, operational, and legal aspects necessary to implement these laws. Another government agency, the National Wildlife Refuge System, targets and maintains specific ecosystems for protection and places threatened animals on the endangered list. Despite conservation efforts and climate protection laws of the late twentieth and early twenty-first centuries, climate change impacts on intraspecific competition and ecosystem diversity continued.

Intraspecific competition and climate change interact in complex ways. Increasing temperatures impact the intraspecific competition of native plants and trees, altering the region’s biodiversity. As the balance shifts, invasive species can more easily spread, taking vital nutrients that native flora need to survive and recover. As plant species that herbivores and omnivores in the region rely on become increasingly rare, intraspecific competition for that resource increases. This may lead to migration, adaptation, or species extinction. Sometimes, because of the changing landscape, invasive fauna may begin occupying the region, further threatening indigenous plants and animals.

Bibliography

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