Climate change is having a significant impact on the morphology of animals. Some birds are losing their luster, others are changing the size of their beaks to adapt to rising temperatures, while bees living in the Rocky Mountains in the US are losing body mass due to early snowmelt.

New research provides a similar window onto this phenomenon. This time, it concerns shaggy soft-haired mice, which are found in the Andes Mountains.

After examining 450 skulls of mice of this species from museum collections in Argentina, Chile and the United States, the scientists came to a strange conclusion: the mice living in the western part of the mountain range were larger than those on the eastern side, despite being of the same species.

The researchers hypothesized that these differences could be explained by significant variations in rainfall levels on both sides of the Andes. Compared to the eastern side, the western part receives more rainwater, which could mean that food is more abundant for mice.

As such, the study states that, to some extent, climate patterns are important in determining the morphology of mice through the resources they can find for sustenance.

“With climate change, we know we’re going to see dramatic changes in temperature throughout the year, and changes in precipitation.

“While they might not be the most important variables affecting the mice’s well-being, they are important in determining available food sources,” explains Noé de la Sancha, a research associate at Chicago’s Field Museum, an assistant professor of Environmental Science and Studies at DePaul University, and the paper’s corresponding author.

The scientist goes on to stress the importance of studying the evolution of animal species such as these mice, as they may represent “good indicators of long-term changes in our environment.”