Lyme disease is caused by infections of the bacterium Borrelia burgdorferi (stained blue in the inset, among red blood cells), which is transferred to humans via blood-sucking bites from the tick, Ixodes scapularis. Lyme disease can cause flu-like symptoms in the short term and more serious illnesses in the long term if not treated.
Why is Lyme disease on the rise in eastern North America?
White-footed mice occupy a broad ecological niche—they occur in most communities regardless of habitat quality. Many other species, like the opossum, are absent from low-quality forest fragments. Based on this information and the data in Question 12, propose a hypothesis to explain the observed relationship between increased forest fragmentation and increased incidence of Lyme disease.

Verified step by step guidance

1. Understand the ecological context: Lyme disease is caused by Borrelia burgdorferi, which is transmitted to humans by ticks. The white-footed mouse is a key host for ticks, and its population thrives in fragmented forests, while other species like opossums, which may reduce tick populations, are absent in these areas.
2. Analyze the relationship between forest fragmentation and host species: Fragmented forests often lead to a decrease in biodiversity, favoring species like the white-footed mouse that can adapt to low-quality habitats. This increases the availability of hosts for ticks, potentially boosting tick populations.
3. Consider the role of biodiversity in disease regulation: Higher biodiversity in intact forests may include species that are less effective hosts for ticks or predators of ticks, such as opossums. Fragmentation reduces these beneficial species, disrupting natural checks on tick populations.
4. Formulate a hypothesis: Increased forest fragmentation leads to a rise in Lyme disease incidence because it creates environments that favor the proliferation of white-footed mice, which are effective hosts for ticks carrying Borrelia burgdorferi, while reducing species that help control tick populations.
5. Relate the hypothesis to broader ecological principles: This hypothesis aligns with the idea that reduced biodiversity in fragmented ecosystems can increase the prevalence of diseases by altering host-pathogen dynamics and disrupting ecological balances.

Key Concepts

Lyme Disease and Its Pathogen

Lyme disease is an infectious disease caused by the bacterium Borrelia burgdorferi, which is transmitted to humans through the bites of infected ticks, particularly Ixodes scapularis. Understanding the life cycle of this bacterium and its vectors is crucial for comprehending how the disease spreads and the factors contributing to its rise in certain areas.

Ecological Niche and Species Interactions

An ecological niche refers to the role and position a species has in its environment, including its habitat, resource use, and interactions with other organisms. The white-footed mouse, which thrives in various habitats, can serve as a reservoir for Borrelia burgdorferi, thus influencing the dynamics of Lyme disease transmission, especially in fragmented habitats where other species may be less prevalent.

Forest Fragmentation and Disease Ecology

Forest fragmentation refers to the process where large, continuous forests are divided into smaller, isolated patches, often due to human activities. This alteration of habitat can increase the incidence of Lyme disease by creating environments that favor the survival of tick populations and their hosts, such as the white-footed mouse, thereby enhancing the likelihood of disease transmission to humans.