UC Berkeley study finds parallel evolution in North American house mice

Photo of house mouse
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In a study published April 29, UC Berkeley researchers identified genes showing repeated patterns of parallel adaptive evolution in North American house mice.

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A group of strangers knock on your door and ask for permission to set mouse traps in your home. Resembling free pest control, these strangers are actually UC Berkeley researchers investigating the genetic basis of mammal adaptation to environments.

In a study published April 29, UC Berkeley researchers identified genes showing repeated patterns of parallel adaptive evolution in North American house mice, according to a Berkeley News article.

Campus researcher and Max Planck Institute for Developmental Biology postdoctoral researcher Taichi Suzuki said although house mice arrived in North America alongside humans two centuries prior, mice in colder climates have grown larger and build larger nests than mice in warmer climates.

“By bringing mice into the lab and rearing them over many generations in a common environment, we were able to discover that the traits that differ among populations have a genetic basis,” said Michael Nachman, lead researcher and campus professor of integrative biology, in an email.

Even when raised in similar conditions, mice from northern locations have always been larger than mice from southern locations, according to the article. Genomic scans revealed these traits have a genetic cause, with four of the five genes identified for body size showing strong signatures of natural selection in both eastern and western North American locations.

The genetic basis of adaptation for simple traits, which are those controlled by one or more genes, has been studied using insects and fish, Suzuki added. However, he noted that most evolutionary change involves complex traits controlled by many genes, making this particular study unique. 

Suzuki drove and camped across the West Coast, collecting house mice at farms and feed stores for the study. Other researchers in Nachman’s lab then conducted experiments and measured the phenotype and genotype of the mice along with analyzing data, according to Suzuki.

Additionally, Nachman said house mice are a “good model” when considering adaption in other mammals and in humans. Many of the adaptive differences seen in mice are also exhibited by humans globally, he added.

“Predicting evolution is a major challenge, but it is crucial in conservation biology given the current climate change and extinction rates,” Suzuki said in an email. “This study has implications in the prediction of mammalian evolution.”

The researchers have also sampled mice from South America and plan to extend their work to other environments, Nachman added.

Contact Serene Chang at [email protected] and follow her on Twitter at @_serenechang .