Competition is a fundamental interaction across all biological systems, from microscopic bacteria to vast forest ecosystems. This force shapes individual organisms’ lives and influences the dynamics of populations and communities. Understanding competition provides insight into how life adapts and persists in a world of finite resources.
What is Biological Competition?
Biological competition occurs when two or more organisms require the same limited resources for survival, growth, or reproduction. These resources include food, water, light, space, or mates. When one organism uses a resource, its availability decreases for others, creating a negative interaction that can lower an organism’s fitness.
Different Forms of Competition
Competition manifests in distinct forms. Intraspecific competition occurs among individuals of the same species. For example, two oak trees growing close together compete for sunlight and soil nutrients. Male elephant seals also engage in battles for mating privileges.
Interspecific competition, conversely, involves individuals from different species vying for shared limited resources. Lions and hyenas, for instance, compete for the same prey in the African savanna. Different plant species in a forest also compete for sunlight, with taller trees often shading out smaller ones.
How Competition Plays Out
Competition operates through various mechanisms. Exploitative competition, also known as resource competition, involves organisms indirectly affecting each other by consuming or depleting shared resources. A plant absorbing water from the soil leaves less for neighboring plants, even if they never directly interact. Young spiders in a dense population indirectly compete for food, where fitter individuals consume more, leading to less available for others.
Interference competition, in contrast, involves direct physical or chemical interactions between competitors. An animal aggressively defending its territory from rivals, preventing them from accessing resources, is an example. Some plants also exhibit interference by releasing chemicals that inhibit the growth of nearby plants.
Ecological Outcomes of Competition
Competition impacts ecological systems, leading to several outcomes. The competitive exclusion principle, often referred to as Gause’s Law, states that two species cannot indefinitely coexist if they compete for the same limited resources in the same niche. Ultimately, one species will outcompete the other, leading to the local elimination or adaptation of the less competitive species.
To avoid such exclusion, species often develop resource partitioning strategies, allowing them to coexist by using different parts of a shared resource or using it at different times. For example, different bird species might feed on various parts of the same tree, or some species might be active at night while others forage during the day. Competition also influences population dynamics, limiting population growth and affecting the size and distribution of populations within an ecosystem. It is a driving force behind evolutionary adaptations, as organisms evolve traits that enhance their competitive ability or help them avoid direct competition.