Welcome Wendiceratops, Dinosauria’s Newest Horned Face

If you’re a dinosaur fan now, you’re spoiled. There’s no denying it. Just look at the horned dinosaurs. Back when I was a young whippersnapper, Triceratops – old “three horned face” – was the main game in town. If you wanted variety you could go “Ooh” and “Aah” over the skulls of Centrosaurus, Styracosaurus, Pentaceratops, and Chasmosaurus, but that’s most of what we had to gawk at. And we were thankful. It wasn’t like today, when there are new species bristling with weird horns popping out of the rock like crazy. So make sure you fully appreciate the beauty that is Wendiceratops pinhornensis.

Where Wendiceratops was discovered. From Evans and Ryan, 2015.
Where Wendiceratops was discovered. From Evans and Ryan, 2015.

The new dinosaur comes to us thanks to legendary fossil hunter Wendy Sloboda. In the summer of 2010, while walking the 79 million year old rock of Canada’s Oldman Formation, when she spotted a chunk of a horned dinosaur’s skull. That was just the first piece of what ended up becoming a bonebed containing over 200 bones of several individuals that required moving tons of rock to exhume. Now, in PLOS ONE, paleontologists David Evans and Michael Ryan have dubbed the dinosaur Wendiceratops in Sloboda’s honor and given the ancient herbivore a place in the ceratopsid family tree.

Ceratopsid dinosaurs basically came in two flavors. There were the centrosaurines – like Centrosaurus itself and Styracosaurus – and the chasmosaurines, such as Chasmosaurus and Triceratops. In the past, differences in ornamentation seemed to separate the two – the chasmosaurines had long brow horns, while centrosaurines had short brow nubs and long nose horns – but in recent years those patterns have broken down. Wendiceratops continues the trend by being a centrosaurine that looks like it’s doing a rough impression of a chasmosaurine called Kosmoceratops.

A reconstruction of Wendiceratops. Known bones are in blue. From Evans and Ryan, 2015.
A reconstruction of Wendiceratops. Known bones are in blue. From Evans and Ryan, 2015.

Not all of the Wendiceratops skull has been found yet. But enough has turned up to allow Evans and Ryan to reconstruct this dinosaur with a thin, blade-like nasal horn and a row of short frill horns that look like evolution put this dinosaur on tight rollers for a bit. (The long brow horns are a hypothesis based on the fact that early centrosaurines had such extended ornaments, too.) This not only showed Evans and Ryan that this dinosaur was new to science, but identified Wendiceratops as the oldest ceratopsid yet found with a nasal horn. It puts a minimum date on when the centrosaurine lineage, at the very least, evolved when one of the flashiest parts of their ornamentation.

But aside from what it can tell us about horned dinosaur evolution, Wendiceratops is a testament how scientific curiosity and dedication is turning up more dinosaurs than ever before. At the dinosaur’s public unveiling earlier this year, Evans recounted how many paleontologists thought Canada’s Oldman Formation wasn’t worth prospecting because the fossils seemed few and far between. There were other places that offered a greater osteological return for the effort. This created a gap in our understanding of the Cretaceous world – a span from about 90 to 77 million years ago from which relatively few of North America’s dinosaurs have been found.

True to other researchers’ frustrated accounts, Evans explained, early fieldwork was difficult and sometimes demoralizing work. The dinosaurs did not give themselves up easily. But Evans, Ryan, Sloboda, and all the others who went out into the desert kept trying, and gradually the dinosaurs began to emerge. Persistence made the difference, and promises to yield even more strange species. The same story is being played out in other places and rock units, where explorers target the parts of the paleontological map that still whisper “Here be dragons”.


Evans, D., Ryan, M. 2015. Cranial anatomy of Wendiceratops pinhornensis gen. et. sp. nov., a centrosaurine ceratopsid (Dinosauria: Ornithischia) from the Oldman Formation (Campanian), Alberta, Canada, and the evolution of ceratopsid nasal ornamentation. PLOS ONE. doi: 10.1371/journal.pone.0130007

Why an Ichthyosaur Looks Like a Dolphin

Textbooks aren’t known for their originality. They build on the basics, and often include the same standard examples from one generation of students to the next. (I haven’t checked, but I wouldn’t be surprised if the fox terrier clone is still creeping somewhere.) That’s why ichthyosaurs are a textbook staple.

Mesozoic “fish lizards”, ichthyosaurs were marine reptiles that independently became adapted to a life at sea around 200 million years before dolphins. Despite their distance from the oceanic mammals in both time and evolutionary history, though, ichthyosaurs look enough like dolphins for the two to be practically inseparable in textbooks. They’re a striking example of convergent evolution – two lineages independently evolving extremely similar anatomy from different starting points.

A Jurassic ichthyosaur on display at the Royal Ontario Museum. Photo by Brian Switek.
A Jurassic ichthyosaur on display at the Royal Ontario Museum. Photo by Brian Switek.

But how similar are the two, exactly? An Opthalmosaurus looks kind of like a bottlenose dolphin, sure, but stopping at superficial similarities isn’t very scientific. Here’s where a new Biology Letters study by National Museum of Natural History paleontologist Neil Kelley and U.C. Davis’ Ryosuke Motani offers an opportunity to see whether such resemblances are only skin deep.

Kelley and Motani focused on skulls of marine tetrapods – descendants of the four-legged vertebrates that crawled out of the swamps over 360 million years ago. They’re an ideal group for such comparisons because all of them – from seals to turtles to whales – had terrestrial ancestors that eventually took on life in the seas. By combining skull, jaw, and tooth measurements from 69 living species with data on what they actually eat, Kelley and Motani were able to pick out how form relates to feeding.

How skull (top) and tooth (bottom) shapes group marine tetrapods together. From Kelley and Motani, 2015.
How skull (top) and tooth (bottom) shapes group marine tetrapods together. From Kelley and Motani, 2015.

As it turns out, skull anatomy is a fairly good predictor of feeding style regardless of ancestry. For example, herbivores like the marine iguana, green sea turtle have short skulls with larger areas of attachment for powerful jaws muscles to crop and crush vegetation. Species that snatch up fish and squid, on the other hand, tend to have longer, toothier snouts better-suited to “snap feeding” and swallowing prey whole. Apex predators such as the saltwater crocodile, leopard seal, and orca fell in-between, characterized by elongated jaws and relatively deep skulls that give them the power to tear apart larger prey.

Despite diverging far back in the prehistoric past, creatures as distantly-related as iguanas and dugongs have evolved similar skull shapes to cope with similar diets. And with this proof-of-concept in place, the same technique can be applied to the fossil record. Paleontologists will able to investigate the similarities, and differences, between ichthyosaurs and dolphins, and perhaps even gauge how marine reptiles like different species of mosasaur may have been able to coexist by picking different items off the marine menu. There are plenty of prehistoric secrets embodied by evolution’s greatest hits.


Kelley, N., Motani, R. 2015. Trophic convergence drives morphological convergence in marine tetrapods. Biology Letters. doi: 10.1098/rsbl.2014.0709

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The Silence of the Crickets, The Silence of the Crickets

In 2003, Marlene Zuk travelled to the Hawaiian island of Kauai and heard something very strange—nothing. A disquieting quiet. An absence of chirping. A silence of the crickets.

Zuk had been studying crickets in Kauai since 1991, back when the insects were both noisy and plentiful. But every time she went back, she heard fewer and fewer of them. In 2001, she heard a single calling male. By 2003, the silence was complete.

The crickets hadn’t disappeared. Zuk would go for nighttime walks and see multitudes of the insects in the light of her headlamp. If anything, there were more of them than before. They just weren’t calling out. When she dissected them, Zuk found out why.

Male crickets call with two structures on the backs of their wings—a vein with several evenly spaced teeth (the file) and a raised ridge (the scraper). When the cricket rubs these together, the effect is like running your nail along the teeth of a comb—you get a thrrrrrrrrrrrp sound. But on all the silent Kauai crickets, the file was growing at a weird angle and had all but disappeared. Their wings were flat.

This change hobbled their courtship songs, but likely saved their lives. In the 1990s, Zuk’s team discovered that the crickets were targeted by a parasitic fly, whose larvae burrow inside them and devour them alive. The flies finds the crickets by listening out for their songs and they’re so effective that, in the early 90s, they had parasitised a third of the males. In 2002, the cricket population had fallen dramatically, and Zuk thought that they were done for.

But the silent males escaped the attention of the fly. As they bred and spread, they carried the flatwing mutation with them. By 2003, the cricket population had rebounded. And in fewer than 20 generations, they had gone from almost all-singing to almost all-silent. The crickets have become a classic textbook example of rapid evolution.

Then, a few years later, the team found that exactly the same thing had happened on the neighbouring island of Oahu! In 2005, for the first time, they found four flatwing males on the island. By 2007, half the males were flatwings.

At first, they thought that the flatwing mutation arose once on Kauai before spreading to Oahu. That made sense: with just 70 miles between the islands, it seemed possible—likely, even—that boats or strong winds carried the flatwing males across to Oahu. When they arrived, they bred with the locals, and their beneficial mutation spread.

But that’s not what happened.

In a new study, Sonia Pascoal from the University of St Andrews has found that this case of evolutionary déjà entendu is actually an example of convergence. The two populations of crickets, threatened by the same eavesdropping parasite, independently evolved similar flattened wings, at pretty much the same time, in just a handful of years.

Normal wings versus flatwings. Credit: Nathan Bailey.
Normal wings versus flatwings. Credit: Nathan Bailey.

Pascoal’s first clue was that the wings of the silent Kauai crickets look different on those of the silent Oahu ones. You can even tell the two groups apart by eye.

Genetic tests revealed even bigger differences. On both islands, the flatwings are caused by a mutation on a single gene, somewhere on the X chromosome. But both mutations arose independently!

Pascoal’s team looked for genetic markers that flank the flatwing mutation and are inherited together with it. They found more than 7,000 of these, but only 22 were common to both populations. This strongly suggests that the two flatwing mutations arose independently of one another. They seem to have arisen on different versions of the X chromosome. They may even have arisen on different genes or on different parts of the same gene.

“It was quite a surprise!” says Nathan Bailey who led the new study (which Zuk is also part of).  “There is solid evidence that evolution can act in the proverbial blink of an eye, but the bulk of this comes from laboratory studies where it is much easier to control conditions. What’s unique about these crickets is the nearly simultaneous appearance of the mutations on two islands.”

The team still have to identify the mutations (or gene) responsible for the flat wings. They also want to know why they arose and what they do. Did the two populations have different starting conditions, that influenced the mutations they eventually gained? Is there a hotspot in the cricket genome where mutations that shape the wings can easily emerge? And do the mutations lead to flat wings in the same way?

The answers will come in time. Just as Zuk’s discovery of the silent crickets gave us a great example of rapid evolution to study, this new discovery provides an excellent opportunity to look at convergent evolution in its earliest stages.

“Many studies that examine convergent evolution are faced with the difficulty that the appearance of mutations that cause similar adaptations in different populations may have occurred very long ago,” says Bailey. “That makes it difficult to tell whether traits with similar functions were derived independently, or whether they share a common ancestry.” I wrote about one such example last week: scientists only recently realised that large, flightless birds like ostriches, emus and rheas evolved their grounded, giant bodies independently of one another.

But on Kauai and Oahu, Zuk and her colleagues have found an example of convergent evolution, happening in real-time. “It’s an extraordinary opportunity,” says Bailey.

Reference: Pascoal, Cezard, Eik-Nes, Gharbi, Majewska, Payne, Ritchie, Zuk & Bailey. 2014. Rapid Convergent Evolution in Wild Crickets. Current Biology. http://dx.doi.org/10.1016/j.cub.2014.04.053

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The Surprising Closest Relative of the Huge Elephant Birds

The largest birds that ever lived—the now-extinct elephant birds—looked a lot like super-sized ostriches. They were fast-running and flightless, just like ostriches are. And their island home of Madagascar was just a short distance from mainland Africa, where ostriches live.

If you had to put money on the identity of the elephant birds’ closest living relative, the ostrich would be a safe bet. It would also be a spectacularly wrong one.

Elephant birds have been extinct for centuries, but many of their skeletons reside in museums around the world. By extracting DNA from these specimens and comparing it to DNA from living birds, Kieren Mitchell from the Australian Centre for Ancient DNA has discovered that the elephant birds’ closest living relative is… the kiwi.

“That blew us away completely,” says Alan Cooper, who led the study. “You have to try pretty hard to get a more disparate pair.”

He’s not exaggerating. Elephant birds probably plucked fruit from trees, while kiwis rummage through leaf litter for grubs and worms. Elephant birds lived in Madagascar, around 7,000 miles away from the kiwi’s home in New Zealand. The biggest elephant birds great up to 3 metres tall and weighed up to 275 kilograms; kiwis would bump against your shins and smaller species could fit inside an elephant bird’s gargantuan egg.

“Geographically, it didn’t make any sense. Morphologically, it didn’t make sense. Ecologically, it didn’t make any sense,” says Cooper. “We tested it pretty exhaustively because we were so surprised, but there’s no doubt in the genetic data.”

All the scientists I contacted agreed that the result is surprising. But it actually fits with a new narrative about the origin of ostriches, kiwis and their kin, which has been gaining support over the last few decades.

Aepyornis maximus, the elephant bird.
Aepyornis maximus, the elephant bird.

The elephant bird and kiwi belong to a group of birds called the ratites. These include the ostrich from Africa, the rhea from South America, the emu and cassowary from Australia, and the extinct moas of New Zealand.

Kiwis aside, these species are all big and flightless. Many scientists (quite reasonably) assumed that evolved from a common ancestor that was itself already big and flightless. This ancestral ratite probably lived at a time when all the southern continents were fused into a single land mass called Gondwana, and diverged into separate forms when the super-continent broke apart.

This ‘rafting’ story seems intuitive but it has crumbled in the face of genetic evidence.

As scientists compared ratite DNA, they found that geographical neighbours aren’t necessarily evolutionary neighbours. The moas and kiwis, for example, both hail from New Zealand. But when Cooper sequenced moa DNA in 1992, he found that kiwis are closer to the Australian emus and cassowaries than to their island neighbours. These birds arose after Australia and New Zealand had split so if they all evolved from an already flightless ancestor, the kiwis must have somehow rafted over a huge stretch of Pacific.

The ratites aren’t all flightless either. Genetic studies revealed that a group of flying, South American birds called tinamous are part of the ratite group. Stranger still, the closest relatives of the small, partridge-like tinamous are the huge, towering moas—a fact that Allan Baker from the Royal Ontario Museum confirmed earlier this month.

Cooper’s discovery mirrors the moa-tinamou relationship. Two groups of giant birds (moas and elephant birds) are more closely related to small, chicken-sized ones (tinamous and kiwis) from the other side of the world, than to similarly large neighbours (ostrich and rhea). Time and again, physique and geography have proved to be poor guides to ratite evolution.

There’s only one plausible explanation: the ratites evolved from small, flying birds that flapped their way between continents and independently lost the ability to fly on at least six separate occasions.

A) The break-up of Gondwana into separate continents. B) The ratite family tree, as you'd predict from the rafting hypothesis. C) The actual ratite family tree. Credit: Mitchell et al, 2014.
A) The break-up of Gondwana into separate continents. B) The ratite family tree, as you’d predict from the rafting hypothesis. C) The actual ratite family tree. Credit: Mitchell et al, 2014.

The rafting hypothesis is dead, and the kiwi-elephant bird is the “final nail in the coffin”, says Michael Bunce from Curtin University, who studies ancient DNA. “A number of text-books need to be re-written.”

Indeed, in his 2004 book The Ancestor’s Tale, Richard Dawkins writes, “I take delight in the power of natural selection, and it would have given me satisfaction to report that the ratites evolved their flightlessness separately in different parts of the world… Alas, this is not so.” Cheer up, Richard. It is so.

The ratites are an incredible example of convergent evolution—the process where living things turn up to life’s party wearing the same clothes. “They all started as these small, flighted, partridge-like things and most of them became these large, giant forms that were so close that everyone assumed they must have started off like that,” says Cooper.

Cooper thinks that the rise of the ratites took place shortly after the extinction event that wiped out most of the dinosaurs. Their absence created an ecological vacuum—there were lots of plants around and no big animals to eat them. The ratites filled those niches. Time and again, they evolved into big plant-eaters, losing the ability to fly in the process.

After around 10 million years, the mammals started doing the same thing, and their success stopped other birds from following in the ratites’ footsteps. “The window of opportunity had gone,” says Cooper. “No bird after that point could try and become big and flightless again, or they’d get eaten. The ratites survived by running like hell.”

This idea also explains why the kiwis and tinamous stayed small. Cooper thinks that they diversified in places that already had large flightless ratites—the moas and rhea. “These guys turned up after someone else had taken up the big and flightless niche, forcing them to do something alternative,” he says. “The kiwis became small, nocturnal insectivore. The tinamous kept flying.”

The discovery raises other puzzles about kiwi evolution. Some scientists believed that kiwis lay disproportionately huge eggs because they evolved from a much larger ancestor. “This new paper proposes that kiwis have always been small, suggesting that egg size independently became large in kiwis even when body size did not,” says Rebecca Kimball from the University of Florida. “That may stimulate some new and interesting research.”

If there’s a crack in this story, it’s that Cooper’s result is based on mitochondrial genomes—small, secondary sets of DNA within our cells. In the past, scientists have had to revise conclusions based on mitochondrial DNA after getting their hands on the main nuclear genome.  “The mitochondria only give us part of the picture,” says Bunce. “The next challenge is to peek into the nuclear genome.”

“We’re working on that,” says Cooper. It’s not easy. Elephant birds tend to die in hot, humid, swampy conditions, which are awful at preserving DNA. Cooper’s team struggled for years to get enough material to sequence, before finally recovering enough from specimens stored in a New Zealand museum. It’ll be even harder to sequence the nuclear genome of these titans. Cooper adds, “The nuclear DNA from the other ratites, including the moa, confirms what we see from the mitochondria, so we’re not expecting too many surprises.”

Reference: Mitchell, Llamas, Soubrier, Rawlence, Worthy, Wood, Lee & Cooper. 2014. Ancient DNA reveals elephant birds and kiwi are sister taxa and clarifies ratite bird evolution. Science http://dx.doi.org/10.1126/science.1251981


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On Dolphins, Big Brains, Shared Genes and Logical Leaps

In 2012, a team of Chinese scientists showed that a gene called ASPM has gone through bouts of accelerated evolution in two very different groups of animals—whales and dolphins, and ourselves.

The discovery made a lot of sense. Many earlier studies had already shown that ASPM is one of several genes that affect brain size in primates. Since our ancestors split apart from chimps, our version of ASPM has changed with incredible speed and shows signs of intense adaptive evolution. And people with faults in the gene develop microcephaly—a developmental disorder characterised by having a very small brain. Perhaps this gene played an important role in the evolution of our big brains.

It seems plausible that it did something similar in whales and dolphins (cetaceans). They’re also very intelligent, and their brains are very big. Compared to a typical animal of the same size, dolphin brains are 4-5 times bigger than expected, and ours are 7 times bigger than expected. The Chinese team, led by Shixia Xu, concluded that “convergent evolution might underlie the observation of similar selective pressures acting on the ASPM gene in the cetaceans and primates”.

It made for a seductive story. I was certainly seduced. In my uncritical coverage of the study, I wrote: “It seems that both primates and cetaceans—the intellectual heavyweights of the animal world—could owe our bulging brains to changes in the same gene.”

Many other scientists were sceptical—check out the comments in my original post—and it seems they were right to be. Three British researchers—Stephen Montgomery, Nicholas Mundy and Robert Barton—have now published a response to Xu’s analysis, and found it wanting. “It’s a completely plausible hypothesis but they didn’t test it very well,” says Montgomery.

In the original paper, Xu’s team looked at how ASPM has changed in 14 species of cetaceans and 18 other mammals, including primates and hippos. ASPM encodes a protein, and some changes in the gene don’t affect the structure of the protein. These “synonymous mutations” are effectively silent. Other “non-synonymous mutations” do change the protein and can lead to dramatic effects (like microcephaly). The Chinese team claimed that a few cetacean families had a high ratio of non-synonymous to synonymous mutations in ASPM—a telltale sign of adaptive evolution.

But Montgomery’s team had two problems with this conclusion. First, it’s statistically weak. Second, it’s not unique to cetaceans. Xu’s team largely looked at brainy groups like cetaceans and primates, but the British trio found exactly the same signature of selection in other mammals, including those with average-sized brains. “It looks like ASPM evolved adaptively in all mammals,” says Montgomery. “It could be that ASPM is a general target of selection in episodes of brain evolution and isn’t specific to large brains.”

Xu’s team also failed to check if the changes they found in ASPM were actually related to differences in cetacean brains. If the gene is changing quickly under the auspices of natural selection, does that translate to equally fast changes in brain size? The Chinese team never explicitly addressed that question. Montgomery’s team did, and their answer was a resounding no.

“We felt a little bad picking on them because it’s quite a common problem,” says Montgomery. “People pick a gene to analyse because it’s linked to something interesting. They find that it’s got this pattern of evolution, and they infer that it’s doing what they thought it was doing. It’s a circular argument. “

“These analyses need to be followed up with experimental work (if that is possible) or treated with caution if not,” says Graham Coop from University of California, Davis. “At best, such studies can only act to generate hypotheses about the role of a particular gene in phenotypic evolution”. That’s because most genes do many jobs, “and we are profoundly ignorant of many of these roles and how they differ across organisms.”

ASPM, for example, isn’t a “brain gene”. It creates molecular structures that help cells to divide evenly. It’s activated in the embryonic cells that make neurons, so if it’s not working properly, fewer neurons are made and individuals end up with small brains. But ASPM is also activated in other parts of the body.

As Vincent Lynch pointed out in a comment to my earlier post, ASPM affects the development of the testes:

“This brain-testis connection was described by Svante Pääbo’s lab. They swapped the mouse and human ASPM genes, I assume hoping to breed a super-intelligent strain of mice, and surprisingly found that nothing happened. Bummer… But rather than uncovering a role for ASPM as a casual agent of increased brain size in the human lineage, these authors found ASPM was required for male fertility (yes, the jokes are obvious) and suggested that the signal of selection observed in humans and other primates is likely related to role in testis. It is on old observation that many testis expressed genes evolve rapidly, many under some form of positive selection.”

So, maybe ASPM’s fast evolution in primates is more a story about nuts than noggins. Then again, Montgomery’s team have indeed found that changes in primate ASPM are related to differences in the size of their brains but not their testes.

These conflicting results illustrate just how important it is to test hypotheses carefully, rather than finding bits of evidence that look nice together, and uniting them through conjecture. It’s a valuable cautionary note to both scientists and journalists alike.

Reference: Montgomery, Mundy & Barton. 2013. ASPM and mammalian brain evolution: a case study in the difficulty in making macroevolutionary inferences about gene–phenotype associations. Proceedings of the Royal Society B http://dx.doi.org/10.1098/rspb.2013.1743

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Same gene linked to bigger brains of dolphins and primates

Every whale and dolphin evolved from a deer-like animal with slender, hoofed legs, which lived between 53 and 56 million years ago. Over time, these ancestral creatures became more streamlined, and their tails widened into flukes. They lost their hind limbs, and their front ones became paddles. And they became smarter. Today, whales and dolphins – collectively known as cetaceans – are among the most intelligent of mammals, with smarts that rival our own primate relatives.

Now, Shixia Xu from Nanjing Normal University has found that a gene called ASPM seems to have played an important role in the evolution of cetacean brains. The gene shows clear signatures of adaptive change at two points in history, when the brains of some cetaceans ballooned in size. But ASPM has also been linked to the evolution of bigger brains in another branch of the mammal family tree – ours. It went through similar bursts of accelerated evolution in the great apes, and especially in our own ancestors after they split away from chimpanzees.

It seems that both primates and cetaceans—the intellectual heavyweights of the animal world—could owe our bulging brains to changes in the same gene. “It’s a significant result,” says Michael McGowen, who studies the genetic evolution of whales at Wayne State University. “The work on ASPM shows clear evidence of adaptive evolution, and adds to the growing evidence of convergence between primates and cetaceans from a molecular perspective.”


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Geckos evolved sticky feet many times

Geckos are superb wall-crawlers. These lizards can scuttle up sheer surfaces and cling to ceilings with effortless grace, thanks to toes that are covered in microscopic hairs. Each of these hairs, known as setae, finishes in hundreds of even finer spatula-shaped split-ends. These ends make intimate contact with the microscopic bumps and troughs of a given surface, and stick using the same forces that bind individual molecules together. These forces are weak, but summed up over millions of hairs, they’re enough to latch a lizard to a wall.

Many geckos have these super-toes, but not all of them. There are around 1,450 species of geckos, and around 40 per cent have non-stick feet. A small number are legless, and have no feet at all. Initially, scientists assumed that the sticky toes evolved once in the common ancestor of all the wall-crawling species. That’s a reasonable assumption given that the toes look superficially similar. It’s also wrong.

Tony Gamble from the University of Minnesota has traced the evolutionary relationships of almost all gecko groups, and shown that these lizards have evolved their wall-crawling acumen many times over. In the gecko family tree, eleven branches evolved sticky toes independently of each other, while nine branches lost these innovations.


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Stickleback genome reveals detail of evolution’s repeated experiment

Apathy, weary sighs, and fatigue: these are the symptoms of the psychological malaise that Carl Zimmer calls Yet Another Genome Syndrome. It is caused by the fast-flowing stream of publications, announcing the sequencing of another complete genome.

News reports about such publications tend to follow the same pattern. Scientists have deciphered the full genome of Animal X, which is known for Traits Y and Z, which could include commercial importance, social behaviour, being closely related to us, or just being exceptionally weird. By understanding X’s collection of As, Gs, Cs and Ts, we may gain insights into the genetic basis of Y and Z, which will be terribly important and there will be parties and cake.

Note the future tense. The value in sequencing yet another genome is almost never in the act itself, but in enabling an entire line of subsequent research. It’s the harbinger of news; it’s rarely news itself.

But there are exceptions. This week, there’s a paper about a new animal genome that goes the extra mile. It includes not just one full sequence, but twenty-one. It doesn’t just spell out the creature’s DNA, but also uses it to address some big questions in evolutionary biology. And its protagonist is a small, unassuming fish – the three-spined stickleback.


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A lack of taste – how dolphins, cats and other meat-eaters lost their sweet tooth

Imagine a world without sweetness, where you couldn’t taste the sugary rapture of cakes, ice cream or candy. This is what it’s like to be a cat. Our feline friends carry broken versions of the genes that build sugar detectors on the tongue. As such, they’re completely oblivious to the taste of sweet things.

So are Asian otters. And spotted hyenas. Sea lions and dolphins too. In fact, Peihua Jiang from the University of Zurich has found that a wide variety of meat-eating animals can’t taste sugars. The genomes of these carnivores are wastelands of broken taste genes.


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How the sawfish wields its saw… like a swordsman

If you ever saw a sawfish, you might wonder if someone had taped a chainsaw to the body of a shark. The seven species of sawfish are some of the wackier results of evolution. They all wield a distinctive saw or ‘rostrum’, lined with two rows of sharp, outward-pointing ‘teeth’. But what’s the saw for?

Barbara Wueringer has an answer: the saws are both trackers and weapons. They’re studded with small pores that allow the sawfish to sense the minute electrical fields produced by living things. Even in murky water, their prey cannot hide. Once the sawfish has found its target, it uses the ‘saw’ like a swordsman. It slashes at its victim with fast sideways swipes, either stunning it or impaling it upon the teeth. Sometimes, the slashes are powerful enough to cut a fish in half. Even less dramatic blows can knock a fish to the sea floor, and the sawfish pins it in place with its saw.


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Sociable wasps have an eye for faces

At first glance, we might think that all wasps look the same. But if you look closer at the face of a paper wasp Polistes fuscatus, you’ll see a variety of distinctive markings. Each face has its own characteristic splashes of red, black, ochre and yellow, and it’s reasonably easy to tell individuals apart. And that’s exactly what the wasps can do.

Michael Sheehan and Elizabeth Tibbetts have shown that these sociable insects have evolved the special ability to recognise each others’ faces. They can learn the difference between different faces more quickly than between other images, or between faces whose features have been rearranged. It’s an adaptation to a social life, and one that a close but solitary relative – Polistes metricus – does not share.


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How vampire bats tuned their thermometers to evolve a heat-seeking face

Mythology imbues the vampire bat with supernatural powers, but its real abilities are no less extraordinary. Aside from its surprising gallop and its anti-clotting saliva, the bat also has a heat-seeking face. From 20 centimetres away, it can sense the infrared radiation given off by its warm-blooded prey. It uses this ability to find hotspots where blood flows closest to the skin, and can be easily liberated by a bite. Now, Elena Gracheva and Julio Cordero-Morales from the University of California, San Francisco have discovered the gene behind this ability.

Among the back-boned vertebrates, there are only four groups that can sense infrared radiation. Vampire bats are one, and the other three are all snakes – boas, pythons, and pit vipers like rattlesnakes. Last year, Gracheva and Cordero-Morales showed that the serpents’ sixth-sense depends on a gene called TRPA1, the same one that tells us about the pungent smells of mustard or wasabi. Boas, pythons and vipers have independently repurposed this irritant detector into a thermometer.

Vampire bats evolved their ability in a similar way, but they have tweaked a different protein called TRPV1 that was already sensitive to heat. Like TRPA1, TRPV1 also alerts animals to harmful substances. It reacts to capsaicin, the chemical that makes chillies hot and allyl isothiocyanate, the pungent compound that gives mustard and wasabi their kick. In humans, it also responds to any temperature over 43 degrees Celsius. The vampire has simply tuned it to respond to lower temperatures, such as those of mammal blood.


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Moth and plant hit on the same ways of making cyanide

If “cyanide two-ways” sounds like an unappetising dish, you’d do well to stay clear of the bird’s-foot trefoil. This common plant flowers throughout Europe, Asia and Africa, and its leaves are loaded with cyanide. The plants are also often crawling with the caterpillars of the burnet moth, which also contain a toxic dose of cyanide

The poisons in the insect are chemically identical to those of the plant, and they are produced in exactly the same way. But both species evolved their cyanide-making abilities separately, by tweaking a very similar trinity of genes. This discovery, from Niels Bjerg Jensen at the University of Copenhagen, is one of the finest examples of convergent evolution – the process where two species turn up for life’s party accidentally wearing the same clothes.

Recently, several studies have shown that the convergence runs very deep. Many animals have hit upon the same adaptations by altering the same genes. Rattlesnakes and boas evolved the ability to sense body heat by tweaking the same gene. Three desert lizards evolve white skins through different mutations to the same gene. The literally shocking abilities of two groups of electric fish have the same genetic basis.

These cases are perhaps understandable, since the species in question aren’t too distantly related from one another. It’s perhaps more surprising to learn that bats and whales evolved sonar via changes to the same gene, or that venomous shrews and lizards evolved toxic proteins in the same way. But the cyanide-making genes of the trefoil and the moth take these disparities to a whole new level. Here is a case of convergent evolution between entirely different kingdoms of life!


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Sleepless in Mexico – three cavefish groups independently evolved to lose sleep

Caves are dark, sheltered and often quiet. They’re seemingly ideal places for a bit of a nap. But for a small Mexican fish, they have done exactly the opposite. As a result of life in dark caves, the blind cavefish has evolved sleeplessness, on at least three separate occasions. They don’t go entirely without sleep, but they doze far less than their surface-dwelling relatives.

The blind cavefish (Astyanax mexicanus) is a sightless version of a popular aquarium species, the Mexican tetra. They live in 29 deep caves scattered throughout Mexico, which their sighted ancestors colonised in the middle of the Pleistocene era. In this environment of perpetual darkness, the eyes of these forerunners were of little use and as generations passed, they disappeared entirely. Today, the fish are born with eyes that degenerate as they get older. Eventually, their useless husks are covered by skin.

They went through other changes too. For example, their skin lost its pigment so they are all pinkish-white in colour. And now, Erik Duboué from New York University had found that they also sleep less than their relatives on the surface.


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Two fish families evolved electric powers by tweaking the same gene


The rivers of Africa and South America are full of shocking conversations. Both continents are home to fish that can talk to each other using electric fields: the elephantfishes of Africa, and the knifefishes of South America (including the famous electric eel). Both groups live in dark, murky water where it’s hard to see where you’re swimming. Both have adapted by using electricity to guide their way. Their bodies have become living batteries and their muscles can produce electric currents that help them communicate, hunt, navigate and court.

But both elephantfishes and knifefishes evolved their electric powers independently. Their common ancestors had no such abilities. They are a great example of how two groups of animals, faced with a similar problem, can arrive at the same solution. And this similarity is all the more striking because it is based on the same gene. For a fish, it seems there are only so many ways to be electric.