Question

Contrast amensalism and competition. What do ecologists mean when they refer to amensalism as a form of asymmetrical competition?

Short answer

Answer: Amensalism is an ecological relationship between two species where one species is negatively affected, while the other species remains unaffected. Amensalism is considered a form of asymmetrical competition because one species has an inherent 'competitive advantage' over the negatively affected species, as there is no struggle for resources or harm to its growth, reproduction, or survival.

Step-by-step solution

Define Amensalism

Amensalism is an ecological relationship between two species where one species is negatively affected, while the other species remains unaffected. In this interaction, the unaffected species does not gain any benefit or suffer any harm from the relationship.

Define Competition

Competition is an ecological relationship between two or more species that struggle for the same limited resources such as food, water, space, or light. In competition, both species are negatively affected as they have to expend energy and resources to compete against each other, leading to reduced growth, reproduction, or survival.

Contrast Amensalism and Competition

The main difference between amensalism and competition lies in the impact on the interacting species. In amensalism, only one species is negatively affected while the other remains unaffected. In competition, both species involved are negatively affected due to the struggle for limited resources.

Define Asymmetrical Competition

Asymmetrical competition is a type of competition where one species has a significant advantage over the other in obtaining the limited resources. This advantage leads to unequal distribution of resources, causing the dominant species to grow and reproduce more efficiently than the weaker species.

Explain why Amensalism is considered to be a form of Asymmetrical Competition

Ecologists refer to amensalism as a form of asymmetrical competition because one species is negatively affected due to the presence of another species while the latter remains unaffected. Here, the unaffected species has an inherent 'competitive advantage' over the negatively affected species, as there is no struggle for resources or harm to its growth, reproduction, or survival.

Key concepts

Amensalism

Amensalism is an interesting ecological interaction where two species are involved. In this relationship, one species has a negative impact on the other, while remaining completely unaffected itself.

• The species causing the negative impact does not gain any advantage or benefit.
• The negatively affected species may experience inhibited growth, reduced reproduction, or even death.

This type of interaction is very one-sided, making it quite distinct from other ecological relationships. For example, when a large tree casts a shadow over smaller plants, the smaller plants may struggle due to limited sunlight, yet the tree remains unaffected by their struggle.
Amensalism shows that even without a struggle for resources, one species can still influence another.

Competition

In ecology, competition occurs when two or more species are in pursuit of the same limited resources. This struggle can have notable effects on the species involved.

• Both species expend energy trying to outcompete each other.
• Resources such as food, water, and space become points of contention.
• This often leads to decreased growth and reproductive rates for both competitors.

Unlike amensalism, where only one species is affected, competition results in negative effects on all parties involved.
For example, two plant species growing close to each other may both compete for sunlight and nutrients, which can result in reduced growth and vitality for both, illustrating the shared nature of their struggle.

Asymmetrical Competition

Asymmetrical competition is a special case of competition where one species has a distinct advantage over the other. This advantage can arise from various factors, like size, strength, or faster resource acquisition.

• One species captures more resources than its competitor.
• The stronger competitor can reproduce and grow more efficiently.
• The disadvantaged species may struggle to survive and reproduce.

Ecologists often view amensalism through the lens of asymmetrical competition because one species remains unaffected, effectively holding a competitive advantage.
This situation, although not a direct competition for resources, mirrors the influence seen in asymmetrical dynamics, where balance is not equal between species involved.