Category Archives: Charismatic fauna

How are emus related to ostriches?

By John Upton

Which came first — the chicken or the egg?

It’s inside an egg that genes combine to code for an individual, so we’re going to go with ‘the egg.’ Next question, please.

Which came first — the ostrich or the emu?

Looking at pictures of these flightless birds, you’d be forgiven for mistaking them for kissing cousins. They’re both swift-footed birds with buns of feathers hitched high — alluring outfits that show off their slender legs and necks.

emu and ostrich
Illustrated by Perry Shirley.

But they’re not as closely related as they might at first seem.

Ostriches and emus are both ratites — members of a group of large flightless birds endemic to the Southern Hemisphere. Ratites were all thought to have descended from a common ancestor; examples of what scientists dub vicariance biogeography, or convergent evolution, in which members of once-conjoined populations become geographically separated, such as through the geological manifestation of a new river, gulf, or mountain, and then pursue their own evolutionary trajectories. In the case of ratites, they were thought to have gone their separate ways following the bust-up of Gondwana, from where their presumed ancestor was thought to have hailed.

Just a decade ago, in his book The Ancestor’s Tale: A Pilgrimage to the Dawn of Evolution, famed biologist and writer Richard Dawkins described ratites as a “truly natural” group. “Ostriches, emus, cassowaries, rheas, kiwis, moas and elephant birds really are more closely related to each other than they are to any other birds,” he wrote. “And their shared ancestor was flightless too.”

Dawkins’ statement reflected leading science from the time. But advances in molecular phylogenetics have since revealed the folly of longheld assumptions about ratite evolution. The apparent similarities between different species of ratites are now thought to have been the consequence of convergent evolution — the independent evolution of similar features by different species in far-flung places that inhabit similar ecological niches.

It seems that flightlessness just makes sense in the right environments. Research in recent years has revealed that selection pressures independently pushed the forebears of today’s ratites to shrink their wings, bloat their bodies, flatten their sternums, and evacuate the skies.

Several years ago, University of Florida researchers used BUCKy software to analyze the genomes of various birds, and found that the ratite family tree includes a surprising cousin — tinamous, an order of grouse-resembling birds from Central and South America. These birds spend much of their lives on the ground, but many of the species are perfectly capable of flying. The tanimous were found to be more closely related to emus then they were to ostriches, providing further evidence of the independent evolution of flightlessness in different ratites. The findings were published in the journal Systematic Biology:

(Credit: Systematic Biology)
(Credit: Systematic Biology)

“The independent evidence we obtained provided strong corroboration of the hypothesis that nonostrich paleognaths form a clade,” wrote the three scientists involved with the research in their paper. “This sharply alters our understanding of the evolutionary history of the flightless ratites by providing support for multiple losses of flight. It remains possible there was a single loss of flight early in paleognath history followed by a regain of flight in tinamous, but this is unlikely because the loss of flight appears to be a relatively easy transition for birds whereas the loss followed by the regain of flight has never been documented. The hypothesis that flight has been lost multiple times in the ratites suggests that some of the most distinctive morphological characters in ratites arose through convergent evolution.”

We asked one of the authors of the paper, Edward Braun, an associate professor in the university’s biology department, how this information and similar analyses could help answer our question. Which species is older — the emu or the ostrich?

Braun said that’s a tough question to answer; but he suggested a couple of alternatives, which he then answered.

“One valid question is, ‘When did ostriches start looking like ostriches, and when did emus start looking like emus?'” Braun said. “I suspect that, if the question is asked that way, the answer is, ‘About the same length of time.'”

“On the other hand, another way of asking the question is, ‘When did ostriches separate from other extant birds, relative to emus?’ The answer to that is clear. Ostriches have no close relatives. Ostriches separated from other birds a long time ago; probably in the Paleocene [66 to 56 million years ago], since there are middle Eocene fossils that are probably now extinct parts of the ostrich lineage. Emus are more closely related to rheas, kiwis, and quite close to cassowaries.”

Enjoy this fun video of emus and an ostrich playing with a motorized ball, which helps to reveal differences in the appearances of the species:

Easter Bilby protects Australia’s outback

By John Upton

Some Australian kids don’t believe in the Easter Bunny.

The clutches of chocolate and colored eggs hidden in the yards and living rooms of environmentally-aware households Down Under are deposited, through orifice unknown, by the Easter Bilby.

Browse the easter sweets selection in just about any Australian store right now and you’ll find foil-wrapped chocolate icons of the adorable outback-dwelling marsupials.

Rabbits are ravenous, fast-breeding, and destructive pests in Australia, where they were introduced by hunters and graziers during the 19th Century. The bare rabbit-resembling bilby, on the other hand, is a native Australian species that’s vulnerable to extinction. Celebrating the Easter Bilby helps Australian kids learn about the ecological importance of native mammals — while avoiding the awkward passions for invasive counterparts that the Easter Bunny can imbue.

bilby
Illustrated by Perry Shirley.

The beauty of the bilby lies in its relationship with Australia’s fragile, old, and nutrient-poor land. It digs through arid and semi-arid soils, bioturbing them, improving water drainage and reducing flooding and erosion. The digging helps spread seeds. It creates microhabitats for bugs and fungi. It turns over soils and helps with nutrient cycling.

From the Mammal Review paper by P. A. Fleming et al.
Mammal Review

The effect of native Australian diggers, such as bilbies, echidnas, and wombats, is “increased plant vigour and resilience, increased biodiversity and consequently improved ecosystem functioning,” scientists wrote in a Mammal Review paper published last year.

But Australian ecosystems have been ravaged during the past two centuries by introduced species, including rabbits, pigs, and camels, and by land clearing. The native diggers are hunted by introduced cats and foxes. Those pressures have helped push half of the nation’s digging mammals toward extinction, the researchers concluded following an exhaustive review of scientific literature. “[T]he loss of digging mammals has contributed to the deterioration of ecosystems,” they wrote.

Rabbits dig as well — but they apparently do not dig deep enough to produce the same benefits as bilbies. Previous research has shown that digging bilbies foster 80 percent more seedlings than do digging rabbits.

“When bilbies, bandicoots, and bettongs dig for food, their diggings are deep, roughly-conical pits which penetrate deep into the soil layers,” Murdoch University wildlife biologist Trish Fleming, one of the coauthors of the Mammal Review paper, told Wonk on the Wildlife.

“Rabbits dig shallower pits, which disturb a large area of the top soil layers. This would expose the soil to drying out, which means it’s less suitable for soil microorganisms or for new seeds.”

Then there’s the wee issue of rabbit plagues. Looking out across an affected Australian farm, the land can appear as if it is moving.

“Rabbits feed on soft shoots of plants, and then will dig up any vegetation within reach, including the roots and bark off trees.  In plague numbers, they wipe out any living plant material.  There are expanses of productive lands which have never recovered from plagues of rabbits,” Fleming said.

So go and get stuffed with caramel, Easter Rabbit. Aussies don’t need your type sniffing about in their gardens.

Here comes the peacockstepper

By John Upton

What’s hotter than a cutie in decadent clothes?

A cutie in decadent clothes — who can dance like no one is watching.

Sexual selection is a term coined by Charles Darwin to explain why some species have developed elaborately ornamental feathers and antlers — appendages that help woo mates. In humans, it has been argued that sexual selection pressures gave rise to facial hair and ample bosoms.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

The elaborate trains of peacocks are among the most classical examples of sexual selection. During breeding time, peahens will visit areas where peacocks vie for their attention with spectacular dances. The peacocks raise their trains in a semicircle and whip them around, sometimes leaning them over the judging peahen. They shake their tail feathers and perform a jig with their feet.

A peahen readied for an eye-tracking experiment. Photo by Jessica Yorzinski.
A peahen readied for an eye-tracking experiment. Photo by Jessica Yorzinski.

A team of researchers set out to try to figure out just what actually interests the peahens during these spectacular courtship displays. They trained captive peahens to wear a patch over one eye and an infrared eye-tracker on the other. Then they watched while peacocks wooed their ridiculously-attired subjects inside black-plastic enclosures that minimized distractions.

After analyzing the footage and data, the scientists realized something surprising. The peahens weren’t looking at the tops of the brightly colored feathers. They were watching the peacocks’ lower regions.

“Based on the scanpath of where the females are looking, you can see that their gaze is focused on the lower train — that is, the lower feathers as well as the legs,” Jessica Yorzinski, an evolutionary biologist who studies animal communication, told Wonk on the Wildlife.

what-peahens-watch

“The peahens may be assessing the width or symmetry of the peacock’s lower train and this could indirectly tell the peahens about the quality of that potential mate,” Yorzinski said. “For example, it’s possible that peacocks with more symmetrical trains produce peachicks that are healthier.”

So what’s the point of having such long and elaborate feathers if peahens are so interested in peacocks’ lower bodies? Yorzinski and fellow researchers explain their theory in a recent paper published in The Journal of Experimental Biology:

Even though we found that the peahens were primarily assessing the lower train, the upper train of the peacock may play an important role in courtship as a long-distance attraction signal in dense vegetation.

In The Descent of Man and Selection in Relation to Sex, published in 1871 (which the researchers awesomely cite in their paper), Darwin noted that peahens can appear coy and uninterested in males, despite the elaborate mating displays. Yorzinski and her colleagues helped explain this phenomenon by discovering that peahens spend more than two-thirds of their time scanning the environment for predators and the like, even as a beautiful peacock dances in front of them.

It’s nice to watch a beautiful dancer, but, from a peahen’s perspective, there’s not much point in finding an idyllically cute male if they’re going to be eaten before they get the chance to mate with them.

Western Australia to use “archaic” method to cull sharks

By John Upton

Great white sharks are among Earth’s most formidable predators. They are apex predators. They prey on fish, mammals and birds — but nothing preys on them.

Except humans.

And in Western Australia, the state government, tired of losing surfers and other beach-goers to the toothy jaws of these ferocious elasmobranchs, has become a predator.

“The preservation of human life is our number one priority,” said Troy Buswell, the state’s fisheries minister, in announcing new policies that will see white sharks killed if they venture within a kilometer of popular beaches. The state’s decision to cull sharks has sparked a global controversy, and polling suggests that even West Australians are overwhelmingly opposed.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

“The decision by Western Australia officials to cull sharks off the coast is alarming,” said Ashley Blacow, a policy and communications official with nonprofit Oceana. “Sharks play a critical role in keeping ocean ecosystems healthy. The presence of sharks ultimately increases species stability and diversity of the overall ecosystem. White sharks in particular are a vulnerable species and they should be protected, not killed.”

One of Western Australia’s most controversial approaches to culling sharks will see floating drums placed around beaches, attached to baited hooks. The trapping equipment are known as “drum lines” — and conservationists regard them as appallingly cruel. Drum lines are illegal in many parts of the world, including in the U.S. One shark expert described the killing method as “archaic” in an interview with Nature.

“Drum lines are 55-gallon steel drums with heavy tackle-like chains or large lines connected to bait,” David McGuire, director of Shark Stewards, told us. “They’re usually anchored to the bottom or they can be linked in chains. I’ve seen them used illegally in Mexico to catch sharks. Essentially, the shark bites the bait, is hooked, and drowns.”

Perhaps most troublingly, there is a lack of scientific evidence that such culling actually protects humans from shark attacks. It might feel satisfying to kill a member of a species that has been killing humans, but that sense of satisfaction might be more of the revenge variety than anything else. Hawaii culled nearly 5,000 sharks between 1959 to 1976, yet there was no change in the rate at which sharks attacked humans in those same waters.

Unfortunately, it may take years of shark culling and shark attacks before the West Australian government can determine whether its new policies are having the effect that it desires.

“True effectiveness cannot be assessed by simply counting the number of sharks captured and killed,” writes University of Hawaii researcher Carl Mayer in an article published by The Conversation. “Demonstrable effectiveness means a measurable decrease in shark bite incidents in response to culling activities.”

Rare bluefin sells for $1.8 million

sushi
Illustrated by Perry Shirley.

By John Upton

Couple quick facts about Pacific bluefin tuna, a fish that’s sold as sushi, mostly in Japan:

1. A 490-pound specimen caught off northeastern Japan sold during a fish market auction for ¥155 million. That’s nearly $US1.8 million. For a single fish. The winning bidder, Kiyoshi Kimura, president a sushi restaurant chain, broke the record for the highest price paid for a single bluefin tuna. Kimura set the previous record of ¥65 million one year earlier. Read all about it.

2. The Pacific bluefin population has plummeted 96.4 percent because of decades of overfishing, scientists reported in a recent stock assessment. Pew Environment Group’s Amanda Nickson warned that the species “is in danger of all but disappearing.”

So get your bluefin sushi on while you can. Or don’t.

Fate of world’s ‘ugliest’ fish unknown, presumed miserable

By John Upton

The blobfish routinely ranks high in publishers’ “ugliest animals” lists. But its maligned existence is as mysterious as the creature is aesthetically challenged.

The fish live along the floor of the ocean off Southeastern Australia,  leading generally lethargic lives and grabbing at passing sea urchins and mollusks. These deep-sea creatures share similar habitats with lobsters and crabs. They are often plucked from the ocean as by-catch by fishermen targeting the nearby crustaceans with their trawlers.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

A flurry of news articles appeared a few years ago warning that the destructive trawling practices had left the blobfish in danger of extinction. Problem is, the fish is so rarely encountered by humans and it has been studied so little by scientists that nobody really knows how it’s faring.

“The assertion that the blobfish is threatened is the overlap of its small geographic range and habitat with the areas hit hard by deep sea bottom trawling,” said University of York Professor Callum Roberts, a marine conservation biologist whose research focuses on human impacts on marine ecosystems, “and the fact that it seems to be rare.”

Fungus helped create us, could destroy us

By John Upton

In a story about plagues of fungus diseases that I wrote for Slate’s pandemics series, I touched on fungi’s role in the rise of the mammals.

The last great extinctions occurred 65 million years ago, when land-dwelling dinosaurs disappeared and mammals began an ascent that eventually led to our own evolution. The dinosaurs were doomed when the Earth clouded over with smoke. The darkened world grew cold, reptiles were unable to bask effectively and plants struggled to photosynthesize. While other kingdoms of life flailed, fossil records indicate that fungi flourished.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

Fungi are the world’s great decomposers, and during periods of environmental upheaval they can become savagely pathogenic, feasting on the living flesh of the weak. But fungus does not grow well in hot conditions. In 2005, Arturo Casadevall suggested that the rise of fungus during the Cretaceous–Paleogene extinction event selectively killed off cold-blooded dinosaurs and gave warm-blooded mammals the opportunity to prosper. In August, the Albert Einstein College of Medicine professor published a followup paper in PLOS Pathogens that expanded and built upon his theory.

“Mammals are highly resistant to systemic fungal diseases,” Casadevall wrote in the paper.

Not a real dinosaur / Kamala Kelkar
Not a real dinosaur / Kamala Kelkar

“Primitive mammals like the platypus, with core temperatures near 32°C, are susceptible to Mucor amphibiorum, a fungus with a maximal thermal tolerance of 36°C that would make it avirulent for higher mammals. The resistance of mammals to fungal diseases is in sharp contrast to the vulnerability of other vertebrates, such as amphibians, a group that is currently under severe pressure from a chrytrid. Like mammals, amphibians have adaptive immunity, but unlike mammals, they are ectotherms and lack a thermal environment that is exclusionary to fungi.”

Casadevall tells me he’s more confident now in his theory than he was when he first described it seven years ago. That’s partly because of a study that he co-authored in 2010 that indicated that the human body temperature is almost ideally optimized for warding off fungal diseases while maintaining metabolic needs. He said the spread of white nose syndrome, a soil fungus that in North America has killed millions of hibernating bats, whose temperatures plummet during winter, provides additional support for his theory.

“People have been intrigued with the fungal-mammalian hypothesis,” Casadevall told me. “There has been no significant pushback.”

In his new essay, Casadevall says global warming could help fungi adapt to warmer temperatures, potentially reaching a point where pathogenic species could develop newfound abilities to infect warm-blooded mammals. Such a development could be disastrous for humanity, as I explain in Slate.

[To join a LinkedIn group devoted to the discussion of fungus diseases, click here.]

Tasmanian devil — radical experiment to rescue a radical animal

Not a real Tasmanian devil / Looney Tunes

By John Upton

The Australian island state of Tasmania is home to two famous species of marsupial, both of them carnivorous dog-like creatures. The striped Tasmanian tiger went extinct in the 1930s. And now the Tasmanian devil, a stockier creature with mostly solid black fur, is staring down a similar fate.

The species is dying from a face cancer that kills swiftly and spreads from one devil to another when the creatures bite during fights. More than 90 percent of the wild population has been killed since scientists first noticed the contagious tumors in the mid-’90s.

In a desperate bid to save the species, Australian officials are embarking upon a radical experiment: Some of the few remaining healthy specimens, bred in captivity, will be introduced into an environment where they will become an invasive species.

The 14 healthy devils will be released Thursday on Maria Island, a tiny island off Tasmania’s eastern coast that is wholly comprised of national parkland. More than 100 of the animals could eventually be released there.

A real Tasmanian devil / Flickr: rogersmithpix

“The Maria Island translocation is designed to establish a self-sustaining population of healthy wild devils in a safe haven where they are protected from interaction with the deadly facial tumour disease,” Tasmania’s environment minister, Brian Wightman, told the AFP.

Although the devils can swim, they have never before reached the 22,000 acre island. When they get there, they will feast on penguins, geese and other native animals that are unaccustomed to their vicious presence. They will compete with wedge-tailed eagles for prey; they could help an invasive population of rats flourish by killing off the invasive population of feral cats; and they might damage World Heritage–listed buildings by burrowing under them.

That said, most of the Australian conservation movement and political establishment appears to support of the project, with the widespread caveat that it is done carefully and with extensive monitoring.

The risk of the devils going the way of the dodo is too much for most Australians to bear.

“Translocation is one of the methods of last resort,” Australia’s environment minister, Tony Burke, a supporter of the project, told Fairfax Media. “It has to be done carefully, with good scientific oversight.”

Platypus — doing awesome

A platypus at Tamar Island Wetlands near Launceston, Tasmania, in 2010 / Flickr: Arthur Chapman

By John Upton

It’s a mammal that lays eggs. It’s one of the few mammals in the world equipped with venomous barbs, which are found on the males’ rear legs. The feet of those legs are shaped like otters’, yet the bills are duck-shaped and the tails resemble beavers. It has no visible ears and its sex chromosomes more closely resemble those of a bird than those of virtually any other type of mammal.

And today we’re going to shower you with some wonderful news: In the rivers of eastern Australia, where the species is native, the ecological freak show known as the platypus is doing awesome.

These little guys are elusive; they can be impossibly tough to spot as they get about their semi-aquatic lives. But get about their semi-aquatic lives they do, even as great cities pop up around them, diving frequently for worms, yabbies and other prey, and laying thumbnail-sized eggs in nests on vegetated riverbanks.

Sure, there are probably substantially fewer platypuses today than there were hundreds of years ago, before Britain started using the sparsely populated continent as a jail, paving the way for widespread urbanization. The critters have pretty much disappeared from the mighty Murray River, for example. But in a country where wildlife populations have been wrecked by invasive species, water diversions and salinity woes, this primitive beast is a freakin’ soldier.

The greatest unnatural threats to the platypus comes from freshwater diversions, declining water quality, the loss of vegetation along waterways and the popular past-time of yabbying. Baited traps are thrown into rivers and hauled back out full of yabbies, which are a ubiquitous freshwater crayfish in Australia. Unless a trap is specially modified, any platypus that darts into it to grab a yabby runs the risk of drowning.

Despite those threats, and with a little help from conservationists, the platypus faces no looming threat of extinction. It’s not considered endangered or threatened. It continues to do awesome.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

It should perhaps be unsurprising that the species is thriving: It has been doing so for hundreds of millions of years.

To help understand the genetic history of our own sexuality, researchers studied platypus genes. Humans and most modern mammals have two sex chromosomes, with the arrangement of X and Y chromosomes determining gender. But the researchers discovered that the complex sex chromosome arrangements of platypus are more similar to birds than they are to us.

“Platypus sex chromosomes have strong homology with bird, but not to therian (marsupial and placental mammal) sex chromosomes,” the researchers wrote in a 2008 paper in Genome Research. That led the scientists to conclude that our modern sex chromosomes evolved after egg-laying mammals, known as monotremes, split away from the other mammalian varieties as evolution took its course some 170 million years ago.

So not only are these monotreme mammals outwardly unusual, they are extremely genetically unique. Along with egg-laying echidnas, the platypus is a mammal that is far more primitive than even the pouch-bearing marsupials that dominate the Australian lanscape. And when it comes to sex, they resemble egg-laying birds, not gestating humans.

Which we think is pretty awesome.

Peer inside a platypus nest:

This platypus blog was requested by reader Ross Pearson. Request your own on my Facebook page or here!

Cow residue lingering in modern buffalo

A bull American plains bison grazing in Theodore Roosevelt National Park, North Dakota. / Flickr: Furryscaley

By John Upton

Look an American plains bison in the eye. Stare deep into those dark, gaping peepers and you may catch a glimpse of something foreign, something slightly un-bison-like: A dash of contemporary cow.

The ancestors of domestic cows and American plains bison split apart 1 to 2 million years ago. But their genes washed together again 100 to 150 years ago, at a time when North America’s bison population had been hunted down from tens of millions of specimens to fewer than 100. During that time, ranchers bred surviving buffalo with their cows in a bid to toughen up the domesticated creatures and improve meat yields and flavor.

But genes flowed in both directions and cow DNA ended up in the tiny buffalo herds from which all of today’s buffaloes were descended. New research shows that those cow genes are still swirling around in the buffalo DNA, reducing individuals’ height and weight – and perhaps even their ability to survive.

Researchers studied the DNA of two very different buffalo populations. One of the populations was introduced by a filmmaker in the 1920s to an island off California, where the animals have prospered, wild but hungry, well outside the species’ normal range. The other population sampled was a well-fed private herd in Montana.

According to the results of the analysis, published this month in the journal Conservation Biology, cow genes were present in about half of the Catalina Island population and in five percent of the Montana population. In both populations, buffaloes with cow genes were smaller than the pure buffalo.

I asked lead researcher James Derr, a professor at Texas A&M University’s veterinary medicine college, whether the presence of cow genes reduces a buffalo’s fitness and makes it less likely to survive.

“Fitness is a tricky issue and not easy to prove,” Derr emailed back. “What we do know is that bison with domestic cattle mtDNA are, on average, smaller than bison with bison mtDNA. Runts are seldom at an advantage, I would guess.”

If it’s true that cow genes make a bison less likely to survive in the wild, evolution would be expected to run its course and continue to weed those genes back out of the native American ungulates. It may take a while, but the lingering cow bits will probably fade out of the almighty buffaloes eventually.