Tsetse flies are parasites that live off fresh blood they obtain by biting their hosts in hot, humid areas in Africa.Their natural hosts are wild pig and bushbuck, a type of antelope, but they have a broad host range.A second parasite, Trypanosoma brucei, is a unicellular organism that spends part of its life cycle in the tsetse fly.This microorganism causes African sleeping sickness in humans and is transmitted into human blood through the bite of a tsetse fly.Humans are increasingly moving into regions where the tsetse fly lives.This has increased deforestation of the natural habitats of pigs and bushbucks, which has caused declines in their populations.Listed below are several possible outcomes of these changes.Evaluate the likelihood of each of the outcomes listed, and select the most likely outcome.

Question

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As humans continue to move into regions where the tsetse fly lives and deforestation occurs, the natural habitats of the wild pig and bushbuck are destroyed, causing a decline in their populations. This will force the tsetse fly to look for alternative hosts, and because it has a broad host range, the incidence of African sleeping sickness in humans and livestock will increase. Option A is unlikely because the decline in wild pig and bushbuck populations will not necessarily cause a decline in tsetse fly populations. Option B is also unlikely because the intensity and duration of African sleeping sickness symptoms are dependent on the stage of infection and not affected by changes in host availability. Option D is also unlikely because the tsetse fly and Trypanosoma brucei have a long-standing relationship, and evolutionarily, it is unlikely that the tsetse fly will lose its ability to transmit the parasite. Option E is also unlikely because Trypanosoma brucei has evolved to be dependent on the tsetse fly, and finding an alternative host would require a significant change in the parasite's biology.

Tsetse Flies Are Parasites That Live Off Fresh Blood They