Question

If you remove a species from a community, the population size of its main _____is likely to increase. a. parasite b. competitor c. predator

Short answer

The population size of its main competitor is likely to increase.

Step-by-step solution

Understanding the Impact of Removal

When a species is removed from a community, it's essential to consider its ecological role and interactions. Each species is part of a food chain or web, affecting others in its ecosystem.

Define Key Terms

Understand the terms provided: - **Parasite**: An organism that lives on or in a host organism and gets its food at the expense of its host. - **Competitor**: An organism that competes with other organisms (usually of the same or different species) for resources such as food and territory. - **Predator**: An organism that hunts, kills, and consumes other organisms for food.

Analyze the Effects of Species Removal

If a species is removed, its main interactions (parasitic, competitive, or predatory) are disrupted. Removing it means its influence on other organisms changes, potentially affecting those lower in the food chain or its competitors.

Identify Whose Population Will Increase

Removing a species typically reduces competition for resources. Therefore, the species that competes with it for the same resources will likely experience an increase in population due to less competition.

Select the Correct Option

Based on the analysis, the population size of the removed species' main competitor is likely to increase, as they will now have more access to resources that were previously limited.

Key concepts

Species Interactions

In community ecology, species interactions are crucial in shaping the dynamics and structure of ecosystems. These interactions occur in various forms, such as competition, predation, and parasitism. Each interaction can influence the survival and reproduction of the species involved. For instance, a predator-prey relationship ensures population control, as predators limit the number of prey, while prey may have adaptations to escape or avoid predators. The balance of these interactions helps maintain ecosystem stability. Beyond direct interactions, species indirectly affect each other through shared resources and environments, creating complex networks that can complicate ecological predictions. Recognizing and understanding these interactions allow ecologists to make informed predictions about how changes, like the removal of a species, can ripple through an ecosystem.

Competitive Exclusion

The principle of competitive exclusion states that when two species compete for the same limited resources, one is likely to outcompete the other, leading to the latter's local extinction. Essentially, two species cannot occupy the same niche simultaneously for a prolonged period if resources are scarce. This principle was famously demonstrated in experiments by G.F. Gause, illustrating how one species would dominate while the other declined when resources were limited.

This understanding is pivotal when considering species removal as it suggests that eliminating one competitor can lead directly to an increase in the population of its rival species. The reduced competition means that the surviving species can exploit available resources more effectively, thus potentially expanding its population size and altering the community structure.

Ecological Roles

Every species plays a unique role within its ecosystem, often referred to as its ecological or niche role. These roles encompass the resources a species uses, its interactions with other species, and its contribution to ecosystem functions, such as nutrient cycling or energy flow. For example, a species might serve as a primary producer, decomposer, or predator, each fulfilling indispensable ecosystem functions.

Understanding a species' ecological role is essential to predict the effects of its removal. If a species with a significant role, such as a keystone predator, is removed, the implications can be widespread and drastic. Keystone species maintain species diversity by controlling the populations of other species. Thus, their absence could lead to population booms in other species, which might outcompete others and ultimately reduce biodiversity. Considering these roles helps ecologists anticipate and mitigate potential negative consequences in ecosystem management.