Category Archives: You choose

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!

Racing pigeons juice city populations

Stray homing pigeons appear to be boosting feral populations / Flickr: mugley

By John Upton

Visit any of the world’s cites and you will almost certainly encounter hordes of the world’s most ubiquitous and well-adapted avian urban dwellers.

The humble rock dove, or pigeon, is derided as a flying rat, spreader of disease and graceless depositor of mounds of guano. But it is also a prized domestic species that has been bred for nearly 5,000 years as a food source, message deliverer, racer, and show bird boasting a startling array of plumages and physiques.

It is this very popularity that has seen the species transported around the world, where captive and racing birds have escaped into the wild to establish vast feral populations amid the same irritated humans who were responsible for its spread.

Cities suit rock doves superbly. Before they were domesticated, the birds nested along cliffs in Europe, North Africa and parts of Asia. Today, buildings in cities provide plentiful cliff-like environments for their nests; humanity’s wont to waste grants them plenty of grain and other food; and the hostile nature of cities for most large animals protects them from predation, although raptors are increasingly moving into cities to feast on their meat.

Feral rock dove populations are virtually immune to human-led efforts to snuff them out. And new research suggests that pigeon racers could be constantly fueling the wild populations with physical prowess-imbuing genes, helping to spawn today’s urban super-pigeons.

University of Utah researchers studied the genes of hundreds of domestic and free-living pigeons in the United States in an effort to map their family tree. What they discovered, and reported in February in the journal Current Biology, was a free flow of genes from specially bred racing pigeons into the wild.

Anywhere from five to 20 percent of racing pigeons fail to complete any given race. Some fall prey to predators. But others may simply get lost, or choose to not return home, and then blend into wild populations, where they coo and carry on and breed with feral lovers.

“[Racing homers] are bred for speed, endurance and navigation ability,” researcher Mike Shapiro told me. “They’re great flyers, unlike many of the ornamented or other exhibition breeds, so it’s not too surprising that they do well in the wild.”

All free-living rock pigeons in North America are feral, having first arrived some 400 years ago, with modern racing pigeons appearing a couple of centuries ago, Shapiro said, meaning that all of the continent’s populations must have been established by domestic breeds at some point.

“We hypothesized that they probably had major genetic contributions from racing homers because the breed is so popular and they, perhaps more than any other breed, have ample opportunities to fly free and escape,” Shapiro said. “This hypothesis is supported by our genetic data.”

Next time you see a broken-legged pigeon plunging its filthy face into trash strewn by the side of a busy street, spare a moment to give thanks to pigeon racers for potentially growing the species’ vigor. After all, these dumpster divers help push our wasted French fries and other food scraps up a nascent food chain and into the stomachs of the awe-inspiring hawks and Peregrine falcons that also inhabit our cities. That seems better than leaving the food to rot – and belch out its hydrocarbons as climate-changing methane.

Some of the pigeon breed studied by University of Utah researchers / Courtesy: Current Biology

[This pigeon story was requested by reader John Fleck. Request your own here or on my Facebook page!]

Your favorite wildlife goes here

By John Upton

What’s your favorite plant, animal, pathogen or natural phenomenon? Let me know in the comments section or on my Facebook page. I’ll pick at least one suggestion, dig up the latest scientific research about it and write a blog that’s guaranteed to fascinate. If I don’t get any ideas I swear I’ll just write about my favorite kingdom of life, fungus, from now on!

My brother with a finger’s worth of swarming bees.