New research suggests that the commonly used ‘lab mouse’ may display behaviors entirely distinct from their wild-derived counterparts, prompting new considerations for the future of animal-based research.
Mice are the most commonly used specimen in mammalian research because of their high reproduction rate, ease of maintenance and handling and ancestral similarities with humans. Inbred mice are ideal research subjects for many scientific disciplines because they are essentially genetically identical, which enables better stability and reproducibility in results
The most commonly used inbred strain of mice — C57BL/6J — inspired this study. After observing that C57 lab mice acted in a much more docile manner than their wild-derived counterparts, Caleb Vogt grad, a researcher in the Cornell Laboratory for Animal Social Evolution and Recognition, sought to investigate this difference.
Vogt set up his study using a garden design, placing wild-derived and C57 mice in large outdoor enclosures. He was the first to examine the social and behavioral patterns of C57 mice in these pseudo-natural environments.
These garden environments were created in contrast to the mice’s typical lab environment, which Principal Investigator Prof. Micheal Sheehan, neurobiology and behavior, characterized as “a very socially cramped space.” Neither Sheehan nor Vogt anticipated what they would find out about mice behavioral patterns when female C57 mice were placed in a more open environment.
“The male results were not very surprising,” Vogt said. “We were not expecting what we found in females.”
The female C57 mice demonstrated completely distinct social behavior from their wild-derived counterparts, with more interconnected social structures and less bias towards familiar social partners.
The C57 females spent only 18 percent of their time alone, as opposed to the 83 percent that wild-derived females spent alone, and more readily explored their enclosure. Additionally, the C57 females did not show preferential interactions with their sister mice and interacted freely with all of the other females.
The male C57 mice demonstrated similar but muted territorial behaviors to their wild-derived counterparts. When they were first placed into the enclosures, both the C57 and wild-derived mice shared space with their cage mates. Over time, the territorial overlap decreased as they began to establish their own spaces.
It took an average of 54 minutes for the territorial overlap to collapse in wild-derived mice, compared to 590 minutes in C57 mice. The reduced urgency of establishing clear spatial boundaries highlights the dampened sense of territoriality in lab mice compared to wild-derived mice.
The results of this study have implications extending beyond mouse behavior — they will add “context to the way we interpret the biomedical model,” Vogt said.
“All of our biology is influenced by our environment, and the lab is but one environment,” Sheehan said.
According to Sheehan, an animal’s biology cannot be separated from their behavioral tendencies and preferences, which are likewise influenced by their environment. This raises the question of how manipulating environmental factors can affect health and fitness outcomes for individuals. Sheehan is particularly excited by the prospect of “marrying sociobiology and socioecology with tools available in biomedical mouse models” moving forward.
There is “a lot of work to be done using this approach,” said Vogt, who hopes that this integrated approach “can supercharge the way that we study social relationships [in the animal world].”
Maggie Walsh can be reached at [email protected].