Eye of newt and toe of frog: vital ingredients of the witches' potion in Shakespeare's Macbeth. But anyone attempting to concoct such a brew today might have trouble following the recipe: many amphibian species have become scarce or even extinct in recent years.
It is not clear why amphibian populations are declining in many areas of the world. But several lines of evidence implicate infectious disease. Interactions between climate and disease may also be important. For example, environmental temperatures determine the animals' body temperatures, and so may affect the rate of immune response to parasites.
Now Tom Raffel and collaborators have published field evidence suggesting that amphibians' ability to fight infections depends strongly on environmental temperature. Over a three-year period, the researchers measured immune cell production by red-spotted newts living in natural ponds. Their findings — which are consistent with previous laboratory studies — indicate that:
- As winter approaches, immune cell production declines
- In spring, the animals' immune system responds to increasing temperatures, but with a time lag
The researchers conclude that these changes could make the animals more susceptible to infection at times of rapid temperature change, particularly when environmental temperatures fall quickly.
Written By: T. R. Raffel, J. R. Rohr, J. M. Kiesecker, & P. J. Hudson
Journal: 20: 819-828
Journal Reference: 20: 819-828
Paper Id: 10.1111/j.1365-2435.2006.01159.x