Spotted skunks can be considered one of the gymnasts of the animal world – venture too close to them and they will leap up into a handstand and amble around on their front paws.
The move may seem amusing but it is intended as a final warning before the animal lets off a blast of noxious musk to ward off predators.
Thanks to their stinky defence mechanism, and the fact that they are expert climbers, spotted skunks have been relatively under-studied compared to most North American mammals.
Now, a DNA analysis of more than 200 animals carried out by researchers in Chicago has found that there are seven distinct species of spotted skunk – three more than previously thought.
“North America is one of the most-studied continents in terms of mammals, and carnivores are one of the most-studied groups,” said study author and Negaunee collections manager of mammals at Chicago’s Field Museum Dr Adam Ferguson.
“Everyone thinks we know everything about mammalian carnivore systematics, so being able to redraw the skunk family tree is very exciting.”
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Spotted skunks were first identified by the so-called father of taxonomy Carl Linnaeus in 1758. Over the years scientists have recognised as many 14 distinct species, though they settled on there being just four several decades ago. However, due to the lack of genetic data, Ferguson suspected there may be more.
“We figured there had to be some surprises when it came to spotted skunk diversity, because the genus as a whole had never been properly analysed using genetic data,” he said.
“We made wanted posters that we distributed across Texas in case people trapped them or found them as roadkill. People recognize spotted skunks as something special, because you don’t see them every day, so they’re not the kind of roadkill that people just paint over.
“If we’re trying to tell the full story of skunk evolution we need as many samples as we can. For example, we didn’t have any modern tissues from Central America or the Yucatan. We were able to use museum collections to fill those holes.”
After amassing a collection of 203 specimens, the team took tissue samples and analysed the DNA. By comparing the DNA sequences they were able to determine that some skunks that were previously considered to belong to the same species had significantly different genomes.
They found that the Plains spotted skunk, an animal that has been in decline for the past century, was not a subspecies as previously thought but a separate species entirely – a key difference that may help with conservation efforts.
“If a subspecies is in trouble, there’s sometimes less emphasis on protecting it because it’s not as distinct an evolutionary lineage as a species,” said Ferguson.
“We’ve shown that the Plains spotted skunks are distinct at the species level, which means they’ve been evolving independently of the other skunks for a long time. Once something has a species name, it’s easier to conserve and protect.”