Competition in nature occurs when organisms need the same limited resource, such as food, water, space, light, or mates. When resources cannot satisfy everyone’s needs, individuals or species may interfere with one another or simply use resources that become unavailable to others. Competition can affect where organisms live, how many survive, how they reproduce, and which species persist in an ecosystem.
What is competition in nature?
Competition is a biological interaction in which organisms have overlapping needs for a resource that is limited. The resource might be something an organism consumes, such as food or water, or something it needs access to, such as nesting space, sunlight, or territory.
Competition does not always involve direct fighting. Two animals may compete for food without ever confronting each other. If one consumes enough of a limited food supply that less remains for another, both are competing. Likewise, plants can compete for sunlight, water, and minerals even though they cannot move toward or attack one another.
Competition is especially important when organisms require the same resource at the same time and place. If a resource is abundant, organisms may have little effect on one another through competition. As the resource becomes scarce, however, competition can become stronger.
Why resources become limiting
No environment provides unlimited supplies of everything organisms need. Food can become scarce, water can run short, and suitable shelter or nesting sites can be occupied. Plants may grow so densely that access to sunlight becomes limited. Animals living in the same area may depend on the same prey.
A resource can therefore be abundant in one environment but limiting in another. Seasonal changes can also alter competition. A food source that is plentiful during one part of the year may become scarce later, increasing competition among organisms that depend on it.
Population size matters as well. When many individuals depend on the same limited resource, each individual has access to a smaller share. This can intensify competition even when the environment itself has not changed.
Competition can occur within and between species
Competition can occur among members of the same species, called intraspecific competition, or between different species, called interspecific competition.
Intraspecific competition occurs when individuals have similar requirements because they belong to the same species. Deer, for example, may compete with other deer for food, water, territory, or mates. Because members of the same species generally have similar resource needs, competition among them can be particularly strong.
Interspecific competition occurs when different species depend on the same limited resource. Several species of herbivores may feed on the same plants, while different predators may depend on the same prey. Plants of different species can also compete for light, water, nutrients, and physical space.
How animals compete for resources
Animals compete for many resources, including food, water, shelter, territory, and reproductive opportunities.
Direct competition can involve aggressive behavior. An animal may defend a territory against members of its own species or another species, preventing rivals from accessing food or shelter within that area. Displays, calls, threats, and physical confrontations can all occur when individuals attempt to establish or maintain access to resources.
Competition does not have to be violent. An animal that reaches a food source first may consume it before another animal can use it. Individuals can also differ in their ability to find food, occupy shelter, or obtain mates. These differences can influence which organisms gain access to limited resources.
How plants compete without moving
Plants compete for resources even though they generally remain rooted in one place. Their main challenges include obtaining sufficient light, water, nutrients, and space.
Light can be especially important because plants use it to power photosynthesis. A taller plant may capture more light, leaving less available to plants growing beneath or nearby. Plants can respond to competition for light by changing their growth patterns, including directing shoots toward areas where more light is available.
Roots also compete underground. When plants grow close together, their roots may draw water and mineral nutrients from overlapping areas of soil. A plant with greater access to these resources may grow more successfully, while its neighbors receive less.
Competition can therefore shape the arrangement and growth of vegetation without any direct physical confrontation between plants.
Direct and indirect competition
Competition can take different forms depending on how organisms affect one another.
Direct competition occurs when organisms actively interfere with each other’s access to a resource. Territorial defense is one example. An individual may chase away a rival or prevent it from entering an area containing food, shelter, or nesting sites.
Indirect competition occurs when organisms affect one another by using up a shared resource. If two animals eat from the same limited food supply, one animal’s consumption reduces what remains for the other. Neither animal needs to confront the other for competition to occur.
Some organisms can also affect competitors by changing their surroundings. In plants, for example, growth can alter the availability of light, water, or nutrients for neighboring plants.
Competition influences where species live
Competition can help determine which species can survive in particular environments. A species may be able to tolerate a set of physical conditions but still struggle to persist if another species uses the same resources more effectively.
This does not mean that competition alone determines where a species lives. Temperature, moisture, predators, disease, food availability, and other environmental factors also influence distribution. Competition is one part of the set of pressures that shapes communities.
When closely related species have similar resource requirements, differences in behavior or resource use can sometimes reduce direct overlap. One species might feed in a different part of a habitat, use a different type of food, or be active at a different time. Such differences can allow species with overlapping needs to coexist.
Why competition can change over time
Competition is not fixed. The strength of competition can change as environmental conditions change.
A drought can reduce available water and increase competition among plants and animals. A decline in prey can intensify competition among predators. Seasonal changes can alter food supplies, while disturbances such as fire or storms can change the availability of shelter and space.
Competition can also change as populations grow or shrink. A resource that is sufficient for a small population may become limiting when the population increases. Conversely, when a population declines, the same resource may become less contested.
The role of competition in natural selection
Competition can influence evolution because individuals do not always have the same ability to obtain limited resources or survive difficult conditions.
Suppose individuals in a population differ in traits that affect their ability to find food, avoid competitors, defend territory, or tolerate resource shortages. If those differences affect survival or reproduction, individuals with advantageous traits may leave more offspring. Over many generations, natural selection can increase the frequency of traits that improve success under those conditions.
Competition is therefore not simply a struggle over immediate resources. It can also contribute to evolutionary change when differences among individuals affect their reproductive success.
Competition can shape entire communities
Competition helps determine which species are common, which are rare, and how organisms use available resources. It interacts with predation, disease, environmental conditions, and other ecological relationships to shape biological communities.
Two species that depend heavily on the same resource may experience strong competition when that resource is scarce. If they use resources differently enough, however, they may coexist. This division of resource use is often called resource partitioning.
Resource partitioning can occur in several ways. Species may use different foods, feed in different locations, occupy different parts of the same habitat, or use a resource at different times. By reducing overlap, these differences can lessen direct competition.
Competition in nature is therefore not simply a matter of organisms fighting. It is a fundamental ecological process that arises whenever organisms need the same limited resources. From plants competing for sunlight to predators sharing scarce prey, competition influences survival, reproduction, habitat use, population size, and the structure of ecosystems.
