Most mammals can trace their origins to a single ancestral species. But in the Caribbean islands of the Lesser Antilles, there is a fruit bat with a far more complex family tree. Artibeus schwartzi’s genome is a hybrid mish-mash of DNA inherited from no less than three separate ancestors. One of these is probably extinct and the other two of which still live on the same island chain. It’s a fusion bat, a sort of fuzzy, winged spork.

The ancestry of A.schwartzi has puzzled scientists for almost three decades, and the idea that it’s a hybrid has been mooted before. Peter Larsen from Texas Tech University confirmed the bat’s unique ancestry by sequencing DNA from 237 individuals belonging to the seven fruit bat species of the Lesser Antilles. He found that A.schwartzi’s main genome is a cross between those of two other fruit bats, A. jamaicensis and A. planirostris, with a tiny minority of sequences that don’t match either genome.

Complicating matters, animal cells also have a separate smaller genome, housed in energy-providing structures called mitochondria. But A.schwartzi’s mitochondrial genome doesn’t resemble that of either of the two species that gave rise to it. These accessory genes must have come from yet another source – a third species of fruit bat that has either since gone extinct or that hasn’t been discovered yet.

A. jamaicensis and A.planirostris must have first hybridised fairly recently, for their ranges only overlapped around 30,000 years ago. Nonetheless, today, A.schwartzi is a distinct species in its own right. It has a stable population that can sustain itself without the need for the two ancestral species to continuously mate with each other.

Larsen thinks that its success stems from events that took place after the last Ice Age. Rising sea levels severely isolated the islands that it now lives on, particularly St Vincent. This separated the new hybrid from its parental species, cutting off the flow of genes that would otherwise dilute this unique lineage. Today, A.schwartzi is St Vincent’s dominant bat.

A.schwartzi is also a perfect example of a phenomenon that’s often seen in hybrids, called ‘transgressive segregation’. You might think that a hybrid would blend the features of its parents, leading to a body that’s half-way between the two. But not always – hybrids often do the opposite, developing extreme and overstated traits well beyond the natural variation of their parents. There are many possible explanations for this, including a clash between genes from the two parents or malfunctions in the way the hybrid develops. Either way, A.schwartzi is living proof of the effect – its skull is much bigger than those of either A.jamaicensis or A.planirostris, which are both roughly the same size.

A.schwartzi’s three-way chimeric genome is a rare find indeed. Some animal hybrids go on to establish new species, but such examples are rare, especially among mammals. Some scientists have suggested that the red wolf is a hybrid of the gray wolf and the coyote, but that’s been disputed of late. A couple of monkeys – the stump-tailed macaque and the kipunji – might also be hybrids, but the evidence for this is still uncertain. A.schwartzi is the clearest case study yet that hybridisation can give rise to new species of mammals.

Reference: PNAS http://dx.doi.org/10.1073/pnas.1000133107

Photo by Tobusaru; depicts A.jamaicensis

More on hybrids:

• Extra chromosomes allow all-female lizards to reproduce without males
• Drought drives toads to mate with other species
• New plant species arise from conflicts between immune system genes
• When bacteria merge – two species are turning into one
• And one that isn’t… The pink Galapagos iguana that Darwin never saw

This is a guest post from Vanessa Woods, author of the new book, Bonobo Handshake. Vanessa is a Research Scientist in Evolutionary Anthropology at Duke University and studies the cognition of chimpanzees and bonobos in Congo. The following is a modified excerpt from Bonobo Handshake. In 1988, a crane operator called Joe Honner was digging out telegraph poles on Darrell Tree’s farm in South Australia. Joe’s three-year-old son was sitting with him in the cabin while Joe maneuvered the crane. Suddenly, the crane swung into live telegraph wires. Over nineteen thousand volts of electricity shot through the broken wires into the crane, which, being made of metal, was a superb conductor. Joe jumped clear, but his son was stuck in the cabin. Joe rushed forward to get his son, but he was held back by the farmer, Darrell. The little boy was fine, Darrell said, as long as he didn’t move. The electricity wound around the crane, creating a perfect circuit, but the leather interior of the cabin was untouched. The boy was frightened and started to cry. As Darrell turned to get a rope to rescue him, Joe rushed forward. As soon as he touched the crane, he tapped into the circuit ...

Louise Bourgeois died yesterday. Perhaps at that very moment I was in the garden of the Leeum museum in Seoul being humbled by her sculpture, Maman. I had previously run into Maman at the Tate about a decade ago. She’s not someone you easily forget. At first all you notice is the immense, menacing, and tremendously unsettling spider. Then you notice that there’s a smaller spider nearby, perhaps a child. And then, much later, you notice that the larger spider has a sac at her belly, filled with eggs. She’s a mother (hence her name, which is french for the same). But this is not your canonical nurturing, soothing, swaddling mother figure.

The Leeum museum is outstanding: an oasis in the heart of Seoul. The museum is split into 3 buildings, each distinct and marvelous (both architecturally, and for their contents). One wing consists entirely of ancient art, with a beautiful collection of celadon (coming from someone that has always had trouble appreciating old pots and jars). One wing is an interactive space, encouraging you to be creative in various clever ways (and with lots to entertain children, who have no doubt suffered from hours of museum-going). The third wing is one of the most impressive small collections of contemporary art I have ever seen, including pieces by Warhol, Close, and a whole alcove devoted to Barney (with Cremaster 3 running on a loop). My favorites by far were two beautiful pieces by Richter: a photo-painting of two lit candles and a gorgeous abstract. As you leave the museum you wander into the garden, and confront the 3-story high mother in all her glory. There is something primal about the encounter, especially as the vast metropolis of Seoul stretches out in the distance below.

Although Bourgeois is now gone, her spiders will no doubt haunt generations to come.