Study Guide: Parasites and Endangered Species

The article discusses the relationship between parasites and endangered species, using the example of the kakapo, a flightless parrot in New Zealand.
Author: Carl Zimmer, published on March 31, 2016.

Kakapo is a large, flightless parrot species that can potentially live for 95 years or longer.
Current Status: Endangered, with a population of fewer than 150 individuals remaining in New Zealand.
Conservation Efforts: Conservation biologists are vigorously working to prevent the extinction of the kakapo.
Incident: Discovery of tapeworm infections in a pair of captive kakapos led to their deworming.

Dr. Hamish G. Spencer, a geneticist at the University of Otago, proposes that deworming the kakapos could be detrimental.
Argument: Certain parasites may be beneficial for their hosts and that endangered species might need these parasites for survival.
Quote: “Some of these parasites may turn out to be quite good for their hosts.” - Dr. Spencer.

Common Perception: Species that live inside hosts are typically viewed as disease-causing enemies.
Medical Insights: Despite this perception, many studies have shown that humans have co-evolved with parasites, developing a nuanced relationship.

Evidence from 1968 by Brian M. Greenwood highlighted that Nigerians experienced lower levels of arthritis and other immune-related diseases compared to Britons, possibly due to chronic infections with parasites.
The concept of the hygiene hypothesis emerged, suggesting:
- Human immune systems evolved to tolerate low levels of infection.
- Parasites may contribute positively to immune system development.
- Balance is crucial; while parasites can aid the immune system, they can also pose risks.

Quote by Marlene Zuk, an evolutionary biologist: “Having worms can mean you have fewer allergies when you grow up, but it could also stunt your growth.”
The relationship with parasites is complex and does not always yield advantageous outcomes.

19th Century Changes: Improved sanitation, availability of clean food and water, and urbanization reduced human contact with parasites.
Consequences: Increased prevalence of allergies, asthma, Crohn's disease, and other immune-related disorders in industrialized nations.

Spencer and Zuk's View: The phenomena observed in humans may also apply to animals; treating wildlife against parasites could potentially be harmful.
- Wild animals often harbor numerous parasites that play a crucial role in their immune health.
- Conservation biologists often administer aggressive medications to captive animals to treat parasite infections.

While medication may save some animals' lives, it may also:
- Remove beneficial parasites that assist in immune system development.
- Leave animals unprepared to contend with diseases upon reintroduction to the wild.

Example: European colonization introduced smallpox and other diseases to populations that had no immunity, leading to severe consequences.
Risks with Conservation Efforts:
- Many organisms have parasites that are highly specialized and tied to their survival.
- Aggressive interventions could cause the extinction of species of parasites crucial for the host's adaptive immunity.

California Condor: In the 1980s, California biologists eradicated the feather louse species Colpocephalum californici during conservation efforts, demonstrating how human actions may lead to parasitic extinction.
Unknown Outcome: The specific species of tapeworm that infected the kakapos was never identified; aggressive treatment could have led to its extinction.

Spencer's Hypothesis: The absence of parasites could be a factor in the disappointing outcomes of some species restoration projects.
Need for Evolutionary Perspective: Conservation biologists should recognize the potential benefits of maintaining parasites in host populations.
Challenges: Changing established attitudes among conservation experts may be difficult.

Cautious Approach to Medicating Captive Animals:
- Encourages a reduction in aggressive medication before reintroduction into the wild.
- Argues against the common practice of rigorous pre-release treatments.
Research Needs:
- Further studies are essential to understand the role of parasites in wildlife health and conservation.

The article emphasizes the need for a paradigm shift in the conservation field to recognize that some parasites may be vital to the health and survival of endangered species. The deliberate management and understanding of parasite-host relationships could be crucial for species recovery efforts.