Biological competition describes an interaction between organisms or species where the presence of one lowers the fitness of another due to shared limited resources. It is a fundamental aspect of life, shaping how living things interact within their environments. This interaction, while not always direct, consistently involves a struggle for necessities.
The Fundamental Drive for Resources
Competition arises from the universal principle that resources in any given environment are finite. Organisms must acquire these resources for basic survival, growth, and the ability to reproduce. This inherent need drives them to secure what is available.
An environment’s carrying capacity represents the maximum population size that it can sustainably support indefinitely. This capacity is determined by the availability of necessities like food, water, and habitat. When a population approaches or exceeds this carrying capacity, the demand for resources intensifies, making competition an unavoidable outcome.
Resources Organisms Compete For
Organisms compete for various essential resources. Food provides the energy and nutrients necessary for metabolic processes and growth. Water is also essential for all life processes, from cellular function to maintaining body temperature.
Plants, for instance, compete for sunlight, which is vital for photosynthesis. Space or territory is another commonly contested resource, providing areas for living, nesting, hunting, or growing. Animals may defend territories for exclusive access to food sources or breeding grounds. Mates are important for reproductive success, driving competition, especially within the same species. Finally, shelter or hiding spots offer protection from predators or adverse environmental conditions, leading to competition for safe havens.
How Competition Manifests
Competition manifests in different forms, depending on the organisms involved and the nature of their interaction. Intraspecific competition occurs among individuals of the same species, such as two male deer fighting for access to a mate during rutting season. This competition is intense due to identical resource requirements.
In contrast, interspecific competition involves individuals of different species vying for the same limited resources. Lions and hyenas, for example, compete for the same prey animals on the savanna. Both types can be direct or indirect.
Direct competition, also known as interference competition, involves organisms actively interfering with each other’s access to resources. This can include fighting, territorial defense, or even plants releasing chemicals to inhibit the growth of nearby competitors. Indirect competition, or exploitation competition, occurs when organisms consume or use shared resources, making them less available for others, without direct physical interaction. An example is when one species of insect-eating bird depletes the supply of insects, leaving less food for another species that preys on the same insects.
Impacts on Survival and Evolution
Competition impacts individual survival, population dynamics, and evolution. It acts as a powerful driver of natural selection, where individuals with traits better suited to acquiring resources or enduring competitive pressures are more likely to survive and reproduce. Those less adapted may not pass on their genes as effectively.
Competition limits population growth by influencing factors such as birth rates and survival rates, and it can also lead to population fluctuations. Over time, competition can also lead to resource partitioning, where species evolve to use different aspects of a shared resource, which reduces direct competition and allows for coexistence. In severe cases, intense competition can result in the local or even global extinction of less competitive species, especially when one species is significantly more efficient at resource acquisition.