You are a CDC (Center for Disease Control) researcher studying malaria. Your goal is to understand the evolution of malaria in order to be able to possibly predict where a future outbreak may be. To do this you will be using information from the evolution of the pathogen, the host, and changes in the environment. Topics to think about include:
What is the evolutionary origin of human malaria? (hint: think about host-pathogen cospeciation or host shift)
What could you learn about adaptability of the malaria pathogen based on its reconstructed evolutionary history?
How does the information on the origin of human malaria affect your prediction for possible outbreaks? (hint: think what are the reservoirs for malaria pathogens)
What would happen if changes in climate affect the distribution of the malaria mosquito vector?
Discuss if and how patterns of malaria geographic distribution would change by considering also the effect that the presence/absence of the sickle cell anemia allele would play
How likely is it that human populations living in a geographic area without malaria will have high frequency of the sickle cell anemia allele?
The information that you have is:
Knowledge of the malaria cycle, which includes one host, primate (human, chimpanzee or gorilla), and one vector, mosquito. Malaria is prevalent in areas where the mosquitoes thrive (hot and humid).
Access to three different pathogens: Plasmodium falciparum (host: human), P. reichenowi (host: chimpanzee), Plasmodium sp. (host: gorilla). From these specimens, you can extract any type of information that you need (e.g., DNA)
Think about what type of information you would need to approach the problem above, how you would get that information, and once you have it, how would you interpret different patterns. Answer the questions with a series of "if-then" scenarios in which you explore different type of information you may get from the data and how you would interpret it.
Malaria life cycle
Questions
What type of information would you extract from the specimens to carry out your analysis?
Explain why and how you would get that information.
How could you distinguish between cospeciation and host shift?
If malaria and its hosts had been cospeciating, how ancient would the association of malaria and humans be?
If malaria had been shifting hosts, how ancient would the association with humans be?
What result would allow you to predict a pathogen reservoir in gorillas?
From an evolutionary point of view, is a pathogen more likely to cause new outbreaks if it has a long history of cospeciation with the host or if it can host shift easily? Explain.
If you wanted to prevent malaria infections, would you act on the pathogen, vector, and/or the host? Explain.
Due to climate change, it is predicted that temperature/humidity parameters will change in parts of the world. What do you think will happen to the geographic distribution of malaria after these changes take place?
Imagine that malaria were to expand into new geographic areas. What do you expect would happen, over long periods of time, to the allele frequency of sickle cell anemia in humans living in those newly affected areas?