When adult amphibian skin harbors populations of the bacterium, Janthinobacterium lividum (Jl), chytrid infection seems to be inhibited. Which of the following represents the best experimental design for conclusively determining whether this inhibition is real? A) Inoculate uninfected amphibians with Jl, and determine whether the amphibians continue to remain uninfected by chytrids. B) Inoculate infected amphibians with Jl, and determine whether the amphibians recover from infection by chytrids. C) Take infected amphibians and assign them to two populations. Leave one population alone; inoculate the other with Jl. Measure the rate at which infection proceeds in both populations. D) Take infected amphibians and assign them to two populations. Inoculate one population witha high dose of Jl; inoculate the other with a low dose of Jl. Measure the survival frequency in both populations.

To demonstrate that the inhibition by Janthinobacterium lividum on chytrid found in adult amphibian skin is real, the best experimental design would be take infected amphibians and assign them to two populations. Leave one population alone; inoculate the other with Jl. Measure the rate at which infection proceeds in both populations (option C).

Explanation:

Chytrids -Batrachochytrium dendrobatidis- are a species of pathogenic fungi with affinity for amphibian skin, causing alteration of keratin and damage to the animal body.

The verification that Janthinobacterium lividum is capable of inhibiting amphibian skin chytrids requires the design of an experimental model, the most appropriate being that of an infected amphibian population exposed to the bacteria, while the other (control) is not exposed to J. lividum.

In theory, amphibians in the population exposed to bacteria should decrease chytrid infection, whereas in the normal population the infection would remain the same.