How Glaciers Gave Us the Adorable, Handstanding Spotted Skunk
DNA tests suggest ancient changes in climate shaped the creatures’ evolution
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The western spotted skunk is as cute as a button, and pretty nifty too. Before spraying predators in the face with pungent chemicals, the little creature hops up onto its forelimbs and charges forward. This behavior is meant to intimidate foes, but if you aren’t on the receiving end of the skunk’s stinky ire, it’s delightful to watch.
Recently, scientists discovered that the hand-standing skunk evolved in an interesting way, Matt Simon reports for Wired. According to a study published in Ecology and Evolution, the species exists in three genetic sub-groups, or clades. Typically, clades develop when a species is separated by geological barriers, like drifting continents or rising mountains. Western spotted skunks do in fact live in a diverse range of habitats across North America. But the splintering of their DNA was driven by a different factor: ancient changes in climate.
By combining climate models and DNA information from 97 western spotted skunks, researchers determined that the animals diverged during the Pleistocene—a period of time spanning from 2.6 million years to 11,700 years ago. This divergence did not seem to have been driven solely by geographic barriers; populations separated by mountains, for instance, were genetically identical, according to a press release from the Field Museum. Instead, researchers traced changes in the skunks’ DNA to ancient climate regions.
When the skunks divided into clades approximately one million years ago, North America was covered with glaciers. Unlike the human-driven climate change of today, ancient temperatures fluctuated at a slow pace. Glaciers expanded and contracted over thousands of years, destroying some habitats that were suitable to the wood-dwelling skunks, and creating patches of land between the glaciers where the critters could survive.
“These regions are called climate refugia,” says Adam Ferguson, lead author of the study and a collections manager at The Field Museum in Chicago, in the press release. “When we analyzed the DNA of spotted skunks living today, we found three groups that correspond to three different climate refugia."
Shifting glaciers, in other words, isolated populations of skunks, allowing them to evolve genetic differences. The study suggests that skunks living in disparate regions today could belong to the same clade if their ancient ancestors once scurried around on the same patch of land, as Mary Beth Griggs points out in Popular Science.
By studying such changes in the past, scientists may be able to predict how skunks and other species will be affected by future changes in temperature. “You can make these general predictions of how climate change might affect an entire community—not just a single species," Ferguson tells Mindy Weisberger for Live Science.
Ferguson and his team opted to study skunks because the impact of climate change on small predators is not well known, but the creatures often made for challenging subjects. "[T]hey stink," Ferguson says in the release. “[E]ven their tissues stink, and you run the risk of getting sprayed.” No one wants to be assaulted by a skunk’s malodorous secretions—if even the adorable acrobat regales you with a handstand first.