28.8
Competition
When organisms require the same limited resources within an environment, they may have to compete for them. Competition is a net-negative interaction.…
Ecosystems contain many organisms, but they have a limited amount of the resources needed for survival and reproduction.
Competition is an interaction between individuals that happens when resources like food, water, shelter, and mates are limited.
Competition can be categorized by the identity of the organisms involved—either intraspecific, within the same species, or interspecific, between different species. It can also be categorized as direct or indirect competition based on whether the organisms interact directly or indirectly.
Competition is more likely to happen when there is an overlap between ecological niches. Organisms with similar niches need many of the same resources, while those with very different niches may not compete at all.
Interspecific competition happens when individuals of different species, such as coyotes and wolves, compete for a common resource, such as prey or territory. In territories where gray wolf and coyote populations overlap, competition between the two species may limit the number of coyotes within those territories.
One possible consequence of interspecific competition is competitive exclusion. If two species compete for the same limiting resource over time, one species may outcompete the other.
The weaker competitor may need to adjust its behavior to use other resources within its niche. For example, coyotes may move to a new territory away from gray wolves or, over many generations, evolve to occupy a different niche. Otherwise, they may die out.
Intraspecific competition, on the other hand, happens between individuals of the same species. This type of competition is common because individuals occupy the same niche in the ecosystem and require the same resources.
Direct competition happens when individuals of the same or different species interact directly. For example, two male antelopes fight for the opportunity to mate with a female. In this mechanism, one individual prevents others from using a resource, in this case, a mate. Marking territory is another behavior that helps control access to a resource.
Indirect competition happens when individuals use up a shared resource, leaving less available for others. For example, elephants and other animals use a common water source, such as a pond. Elephants may drink more water, leaving less available for other animals.
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Q1: What is the difference between intraspecific and interspecific competition?
Intraspecific competition occurs between individuals of the same species, while interspecific competition happens between different species. Both types arise when organisms require the same limited resources. Intraspecific competition is common because individuals occupy the same ecological niche and need identical resources. Interspecific competition occurs when species like coyotes and wolves compete for prey or territory in overlapping habitats.
Q2: How does competitive exclusion affect species in an ecosystem?
Competitive exclusion occurs when two species compete for the same limiting resource, and one species outcompetes the other over time. The weaker competitor may die out, relocate to a new territory, or evolve to occupy a different ecological niche. This outcome demonstrates how competition shapes species distribution and survival in ecosystems with limited resources.
Q3: What is the difference between direct and indirect competition?
Direct competition involves organisms interacting to prevent others from accessing resources, such as two male antelopes fighting for a mate or marking territory. Indirect competition occurs when organisms use up shared resources, leaving less available for others, like elephants drinking more water from a pond than other animals. Both reduce overall fitness for competing individuals.
Q4: How does resource partitioning reduce competition between species?
Resource partitioning allows competing species to share limited resources by dividing them spatially or temporally. Caribbean anole lizards exemplify this by residing in different habitat locations and preying on insects entering their preferred territories. This spatial separation effectively divides available food sources, diminishing direct conflicts and competition between different species.
Q5: Why is intraspecific competition important for population regulation?
Intraspecific competition serves as a natural mechanism for regulating population size by preventing excessive growth. Stronger individuals outcompete weaker ones for resources, leading to reduced reproduction or death in weaker individuals. This keeps population size in check and prevents crowding and resource depletion within the same species.
Q6: What role does niche overlap play in determining competition intensity?
Competition is more likely when there is significant overlap between ecological niches. Organisms with similar niches require many of the same resources and compete intensely, while those with very different niches may not compete at all. The degree of niche overlap directly determines whether species will compete and how severe that competition becomes.
Q7: How does competition act as an evolutionary selection pressure?
Competition provides evolutionary selection pressure both within and between species when resources are limited, forcing organisms to adapt or risk extinction. Individuals better suited to compete survive and reproduce, passing advantageous traits to offspring. Over many generations, this pressure drives niche differentiation and behavioral adaptations that reduce competition intensity.