London, April 5 : Unlike other mammals that concentrate on getting better during sickness and stop reproduction, mice divert energy into boosting the life chance of any babies they have before they die.
A study conducted by Lisa Schwanz, a researcher at Iowa State University in Ames, US, showed that deer mice infected with a schistosome parasite gave birth to young that were heavier than those of uninfected mothers.
The researcher surmised that the result might be due to the fact that the mice had evolved to respond to parasitic infection by allocating increased resources to their babies, making them bigger and more competitive in adulthood.
During the study, 30 female mice were infected with parasites, and 21 were kept healthy as controls. All of them were paired with males several weeks later, and they bred and gave birth in isolated cages.
Upon weighing the young after weaning them, the researchers observed that male offspring of infected mothers were, on average, two grams heavier than other mice.
They noted that the heavier young had better survival rates than lighter young, and kept their increased weight into adulthood.
According to the researchers, being heavier is a good predictor of sexual success for male deer mice in the wild.
"That a mother's (ill) health during pregnancy can have such a long-lasting effect on her offspring is remarkable, I am anxious to see if we can find this phenomenon in other mammals," New Scientist magazine quoted Schwanz as saying.