Why might a sudden shift to a high-moisture diet be problematic for a jerboa?

Answer

Their system is optimized for extracting water from low-moisture seeds and might struggle with the new energy-to-water ratio.

An animal whose system is finely tuned to extract every molecule of water from low-moisture, high-energy seeds might struggle to process a new diet lacking that specific energy-to-water ratio.

Why might a sudden shift to a high-moisture diet be problematic for a jerboa?
mammaldrinkdesertrodentJerboa