Problem 11 - Biology: The Unity and Diversity of Life

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

Step-by-Step Solution

Answer

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

Step 1: Understanding the Problem

The question asks what happens to the population size of another group or organism if a certain species is removed. Specifically, it examines an ecological interaction where removing a species affects the population size of its main ecological interaction partner, such as a parasite, competitor, or predator.

Step 2: Identifying Ecological Interactions

Let’s break down the ecological interactions mentioned: - Parasite: An organism that lives on or in a host organism, getting its nutrients at the host's expense. - Competitor: A species that competes with another for the same resources in an ecosystem. - Predator: An organism that hunts and feeds on another organism. Understanding these interactions is essential to predict the population changes if one interaction partner is removed.

Step 3: Analyzing Each Option

- If a parasite is removed, the host population might increase since there is no parasitic impact, not another species increasing. - If a competitor is removed, the other competitor species now has access to more resources and fewer challenges, potentially increasing in population size. - If a predator is removed, the prey population (not the predator's) typically increases. This analysis indicates the competitor would be the species whose population size is likely to increase.

Step 4: Drawing Conclusions

Considering the interactions, the most plausible answer is that the population size of a species' main competitor will likely increase if that species is removed. This is because the removal of a competitor decreases competition for resources, allowing the other competitor to thrive more easily.

Key Concepts

Species Removal

When discussing ecological interactions, understanding the effects of species removal is crucial. Each species plays a unique role within its ecosystem, often interacting in complex ways with other species. Removing even a single species can lead to significant changes in the ecosystem's dynamics.

• The removal affects not only the removed species but also those depending on or competing with it.
• The absence of one species can cause drastic shifts in resource availability and population sizes of other species.
• For example, if a predator is removed, its prey may experience a population boom due to reduced predation.

Understanding these changes requires considering the specific relationships between species, such as competition, predation, and parasitism.

Population Dynamics

Population dynamics refers to the study of how and why the numbers of individuals in a population change over time. This field considers various biological and environmental factors that influence population size and composition.

• The removal of species can lead to changes in birth rates, death rates, immigration, and emigration.
• For example, removing a competitor species may lead to an increase in the population of the remaining competitors.
• These dynamics are influenced by available resources and the overall ecosystem balance.

By examining these factors, ecologists can predict how populations will respond to changes, such as the removal of a species. This helps in both conservation and managing natural resources.

Competition

Competition is a fundamental ecological interaction where species vie for the same resources, such as food, space, or light. It can occur both within a single species—known as intraspecific competition—and between different species—known as interspecific competition.

• In the case of interspecific competition, the removal of one species can significantly affect the competing species.
• This is because more resources become available, leading to potential increases in the population of the remaining competitors.
• Changes in competition can disrupt the balance of an ecosystem, leading to shifts in species composition and abundance.

Understanding this concept is key to predicting the ecological outcomes of changes, such as the removal of a species. It highlights the intricate balance ecosystems maintain and the cascading effects one change can initiate.