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?
Researchers have measured a positive correlation between forest fragmentation and incidence of Lyme disease. According to the theory of island biogeography, how do you predict fragmentation will affect species richness?

Verified step by step guidance

1. Understand the context: Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted to humans by the tick Ixodes scapularis. The problem mentions a positive correlation between forest fragmentation and Lyme disease incidence, so we need to explore how forest fragmentation impacts species richness and disease dynamics.
2. Recall the theory of island biogeography: This theory explains how the size and isolation of habitats (like islands or fragmented forests) affect species richness. Smaller and more isolated habitats tend to support fewer species due to limited resources and reduced migration opportunities.
3. Apply the theory to forest fragmentation: When forests are fragmented, large continuous habitats are broken into smaller, isolated patches. This reduces overall species richness because smaller patches cannot support as many species, and isolated patches make it harder for species to migrate and maintain genetic diversity.
4. Connect species richness to Lyme disease: In fragmented forests, the loss of predators and competitors can lead to an increase in populations of certain species, such as white-footed mice, which are key hosts for Borrelia burgdorferi. This can increase the prevalence of infected ticks and, consequently, the incidence of Lyme disease.
5. Predict the outcome: Based on the theory of island biogeography, forest fragmentation is likely to decrease overall species richness while favoring species that thrive in disturbed or fragmented habitats. This ecological imbalance can contribute to the rise of Lyme disease in eastern North America.

Key Concepts

Lyme Disease and Its Transmission

Lyme disease is an infectious disease caused by the bacterium Borrelia burgdorferi, primarily transmitted to humans through the bites of infected ticks, particularly Ixodes scapularis. The disease manifests with flu-like symptoms initially and can lead to severe long-term health issues if untreated. Understanding its transmission is crucial for addressing the rising incidence of Lyme disease.

Forest Fragmentation

Forest fragmentation refers to the process where large, continuous forested areas are divided into smaller, isolated patches due to human activities such as urban development and agriculture. This fragmentation can disrupt ecosystems, alter species interactions, and increase the likelihood of disease transmission by creating favorable conditions for certain species, such as ticks, to thrive.

Island Biogeography Theory

The theory of island biogeography, proposed by Robert MacArthur and Edward O. Wilson, explains how the size and distance of an island (or habitat patch) affect species richness. Larger and closer habitats tend to support more species due to higher immigration rates and lower extinction rates. In the context of forest fragmentation, smaller patches may lead to reduced species diversity and increased dominance of certain species, potentially exacerbating the spread of Lyme disease.