Problem 9 - Campbell Biology

Question

One factor favoring rapid population growth by an introduced species is the absence of the predators, parasites, and pathogens that controlled its population in the region where it evolved. In a short essay (100-150 words), explain how evolution by natural selection would influence the rate at which native predators, parasites, and pathogens attack an introduced species.

Step-by-Step Solution

Answer

Natural selection leads native predators, parasites, and pathogens to adapt to exploit the introduced species, thereby increasing their attack rate over time.

Step 1 - Understand Evolution by Natural Selection

Evolution by natural selection means that individuals with traits better suited to their environment are more likely to survive and reproduce. Over generations, these traits become more common in the population.

Step 2 - Introduce the Concept of Absence of Natural Enemies

An introduced species may initially face fewer challenges in a new environment because it lacks the natural predators, parasites, and pathogens that kept its population in check in its original habitat.

Step 3 - Discuss Adaptation of Native Species

Native predators, parasites, and pathogens that can exploit the introduced species are naturally selected over time. They may evolve to recognize the new species as a resource or prey.

Step 4 - Explain the Increase in Attack Rate

As native species adapt, the rate at which they attack the introduced species increases. The introduced species becomes a part of the local food web and faces new pressures.

Step 5 - Summarize the Role of Natural Selection

Natural selection leads to adaptations in native species, helping them target the introduced species. This process ultimately influences the dynamics of the ecosystem and the population growth of the introduced species.

Key Concepts

Evolution by Natural Selection

Evolution by natural selection is a fundamental concept in biology. It happens when individuals with advantageous traits are more likely to survive and reproduce. These traits become more common in the population over time. Imagine a group of animals where some can run faster. The fast runners are less likely to be caught by predators. Over generations, the population will have more fast runners. This is because the trait helps them survive and reproduce more successfully.
Natural selection is crucial in determining how species adapt to their environments and how populations grow or shrink. It’s a continuous and dynamic process, always at work in all ecosystems.

Population Growth

Population growth refers to the increase in the number of individuals in a species. Several factors can influence this, such as birth rates, death rates, immigration, and emigration. When a species is introduced to a new environment, it might experience rapid population growth if it finds suitable conditions and lacks natural enemies.
Without predators, parasites, or pathogens, the introduced species can reproduce freely and grow quickly. This rapid growth can lead to an imbalance in the ecosystem because the introduced species may outcompete native species for resources.
It's important to understand population growth dynamics to manage ecosystems and prevent problems like overpopulation or extinction.

Introduced Species

Introduced species are those that humans move from their native homeland to a new environment. Sometimes called invasive species, they can cause many ecological problems. These species don't naturally belong to the new ecosystem and often lack natural predators to keep their population in check.
Without predators, they can grow rapidly and become dominant. They might take over resources that native species need to survive.
For instance, an introduced plant species might outcompete native plants for sunlight, water, and space. Similarly, introduced animals might outcompete native wildlife for food or habitat, disrupting the balance of the ecosystem.

Native Predators

Native predators play a key role in controlling population sizes within an ecosystem. They are organisms that hunt and consume other organisms. This natural predation maintains balance because it regulates the number of prey species.
When an introduced species enters a new environment, native predators may not recognize it as food immediately. However, through natural selection, some predators might adapt and start feeding on the introduced species.
Over time, the adapted predators can help control the population of the introduced species. This interaction adds a new dynamic to the ecosystem, influencing which species thrive and which struggle to survive.

Ecosystem Dynamics

Ecosystem dynamics refer to the complex interactions and changes within an ecosystem. These include relationships between different species, such as predation, competition, and symbiosis.
Introduced species can disrupt these dynamics by introducing new elements into the food web. The absence of natural enemies for the introduced species can lead to their rapid growth, causing an ecosystem imbalance.
Adapting to their new circumstances, native species might evolve through natural selection to cope with the changes. These adaptations can bring the ecosystem back to a more balanced state over time. Understanding ecosystem dynamics helps us predict and manage the impact of introduced species.