Southern Grasshopper Mouse
Relative brain size in southern grasshopper mice tends to vary with food preferences as it’s smallest in folivores and largest in generalists.
Relative brain size in southern grasshopper mice tends to vary with food preferences. Brain size is usually smallest in folivores, larger in both granivores and insectivores, and largest in generalists.
Measurements of cranial volume of museum specimens of southern grasshopper mouse have shown that on average, females were heavier and longer than males, but their cranial volume was about 3% less than that of males. However, this was not a significant difference. This pattern of brain-body relationship can also be seen in northern grasshopper mice (Onychomys leucogaster).
On average, female southern grasshopper mice are able to deal with a larger body size without increasing their brain size, when compared to males. There is still not enough evidence to explain the difference in body size and brain between males and females. It is possible that there are different demands on both sexes, which might contribute to this difference. These studies were also only done in the laboratory, and there might be sex-specific stresses in their natural habitat that influence brain growth. However, sexual dimorphism is quite common and has been observed in the central nervous system of other mammals.