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There Are Four Giraffe Species, Not Just One – DNA Reveals

The most basic thing you thought you knew about giraffes is wrong — in fact, there arefour species of giraffe, not one, scientists announced today: the southern giraffe, the Masai giraffe, the reticulated giraffe, and the northern giraffe. Genetically, they’re as distinct as brown bears are from polar bears. Today’s division has important implications for conservation because some of these newly discovered species are in grave danger, with just a few thousand individuals remaining in the wild.

The unexpected findings, described in a study published today in the journal Current Biology, show how little we know about one of the world’s most iconic animals. They’re also a vivid illustration of how much we still have left to do to ensure that giraffes won’t disappear because of poaching and habitat loss.

 Julian Fennessy
The reticulated giraffe

Giraffes are the tallest mammals on our planet. Until now, researchers had thought that all giraffes belonged to only one species, made up of up to nine subspecies that looked slightly different from each other. A few previous studies, including one in 2007, showed that giraffe groups have some genetic differences, but those studies fell short of recognizing that these genetic differences are deep enough to account for separate species. Today’s study was the first to conduct a thorough genetic analysis on all nine subspecies of giraffe, and the tests clearly showed that there are four genetically distinct species of the creature.

“We were very surprised ourselves. We didn’t expect to find species,” says Axel Janke, a professor at the Senckenberg Biodiversity and Climate Research Centre in Germany and one of the study’s authors.

 Julian Fennessy
The northern giraffe

The research began five years ago, when Janke was approached by Julian Fennessy, the co-director and co-founder of the Giraffe Conservation Foundation in Namibia. Fennessy wanted to run some genetic tests to learn how similar giraffes in distinct parts of Africa are to each other. The goal was to help Fennessy in a conservation effort where he relocates giraffes into parks or protected areas. So he wanted to know if he was mixing giraffes in ways he shouldn’t. (If genetically different giraffes interbreed, that would eventually lead to a giraffe population that’s less diverse — and biodiversity is key for a healthy environment.)

So Fennessy helped Janke collect tissue from 190 giraffes. The samples were collected with darts that are shot at the giraffes from a distance; after the dart hits the animal, it captures a small piece of giraffe tissue and then drops to the ground. Janke and other researchers then analyzed the samples’ DNA. They looked at both the mitochondrial DNA, which is the DNA passed down from mothers to their offspring, as well as seven specific genetic markers — pieces of genetic material that can indicate if populations belong to different species. The genetic differences led the researchers to declare four species, where before there had only been one.

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 Julian Fennessy
The Masai giraffe

These species live in different areas in Africa, but even in countries where they seem to live side by side, like Kenya, they don’t seem to interbreed, says Fennessy, who is one of the study’s authors. The species also look slightly different from each other: the Masai giraffe, for example, is noticeably darker, with patches separated by irregular, light brown lines all the way down to their legs. The reticulated giraffe has brown-orange patches separated by thick, bright white lines. Now, we need to understand whether the species behave differently, whether they have different mating systems, whether they’re adapted to different climates, and what else sets them apart, Janke says.

The study is particularly important for the conservation of the giraffe. All in all, there are as few as 80,000 giraffes remaining in Africa, 40 percent less than 15 years ago. Despite that, the giraffe is still listed as “least concern” on the IUCN Red List, which indicates the conservation status of plants and animals. A couple of months ago, a specialist group that works for the conservation of giraffes and their closest relatives, the okapi, asked for the giraffe to gain a “threatened” status on the list, in view of its dwindling population. (The “upgrade” is expected in December, Fennessy says.) But today’s study indicates that some of the giraffe species are not just threatened, they’re actually already endangered.

 Julian Fennessy
The southern giraffe

“This casts a very different light on what’s happening,” says Douglas Cavener, a geneticist and professor of biology at Penn State University, who was not involved in the study. “The decline in giraffe populations has been so dramatic that two or three of these species could disappear by the end of this century.”

For example, the northern giraffe has less than 4,750 individuals in the wild. The reticulated giraffe has less than 8,700 individuals. (The southern giraffe is the only one with numbers that are increasing.) The hope, Fennessy says, is that all four species will eventually be included on the IUCN Red List, with their own individual conservation status. “They need to be protected, otherwise we lose them, we lose their genetic identity,” Janke says. “If you lose one species … you can’t simply replace it.”

As to why we had to wait until 2016 to discover that there are four species of giraffes instead of just one, researchers say it shows how little scientific research has been conducted on this iconic animal. “It puts into perspective how little we know about giraffes,” Janke says. “They’re nice, big animals. You can hardly miss them, but they haven’t gained the interest of science.”

Source: theverge.com

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Written by PH

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