Platypus genome decoded: even wierder than they thought

[Manedwolf]

Neither fish nor fowl: Platypus genome decoded

18 hours ago

PARIS (AFP)  Arguably the oddest beast in Nature's menagerie, the platypus looks as it if were assembled from spare parts left over after the animal kingdom was otherwise complete.

Now scientists know why. According to a study released Wednesday, the egg-laying critter is a genetic potpourri -- part bird, part reptile and part lactating mammal.

The task of laying bare the platypus genome of 2.2 billion base pairs spread across 18,500 genes has taken several years, but will do far more than satisfy the curiosity of just biologists, say the researchers.

"The platypus genome is extremely important, because it is the missing link in our understanding of how we and other mammals first evolved," explained Oxford University's Chris Ponting, one of the study's architects.

"This is our ticket back in time to when all mammals laid eggs while suckling their young on milk."

Native to eastern Australia and Tasmania, the semi-aquatic platypus is thought to have split off from a common ancestor shared with humans approximately 170 million years ago.

The creature is so strange that when the first stuffed specimens arrived in Europe at the end of the 18th century, biologists believed they were looking at a taxidermist's hoax, a composite stitched together from the body of a beaver and the snout of a giant duck.

But the peculiar mix of body features are clearly reflected in the animal's DNA, the study found.

The platypus is classified as a mammal because it produces milk and is covered in coat of thick fur, once prized by hunters.

Lacking teats, the female nurses pups through the skin covering its abdomen.

But there are reptile-like attributes too: females lay eggs, and males can stab aggressors with a snake-like venom that flows from a spur tucked under its hind feet.

The bird-like qualities implied by its Latin name, Ornithorhynchus anatinus, include webbed feet, a flat bill similar to a duck's, and the gene sequences that determine sex. Whereas humans have two sex chromosomes, platypuses have 10, the study showed.

"It is much more of a melange than anyone expected," commented Ewan Birney, who led the genome analysis at the European Bioinformatics Institute in Cambridge.

The animal also possesses a feature unique to monotremes -- an order including a handful of egg-laying mammals -- called electroreception.

With their eyes, ears and nostrils closed, platypuses rely on sensitive electrosensory receptors tucked inside their bills to track prey underwater, detecting electrical fields generated by muscular contraction.

"By comparing the platypus genome to other mammalian genomes, we'll be able to study genes that have been conserved throughout evolution," said senior author Richard Wilson, a researcher at Washington University.

In captivity, platypuses have lived up to 17 years of age.

In the wild, they feed on worms, insect larvae, shrimps and crayfish, eating up to 20 percent of their body weight every day.

Males grow to a length of 50 centimetres (20 inches) and weigh about two kilos (4.5 pounds), with females about 20 percent shorter and lighter.

The genome sequenced for the study belongs to a female specimen from New South Wales nicknamed Glennie and can be accessed at www.ncbi.nih.gov/Genbank.

http://afp.google.com/article/ALeqM5jpo2XUX22-9GvA0nItDWkpNMYCxA

[wmenorr67]

Of course it is fistful's fault.

[RocketMan]

Don't those scientists know the platypus is fistful's fault?  Sheesh, not very smart, are they?


wmenorr67 beat me to it.

[MrRezister]

I heard this story on NPR yesterday, and in it they were saying that they could use the Platypus to prove or disprove theories about evolution of creatures that devolped 150 million years ago, which made me wonder - why has the Platypus not evolved at all in 150 million years?  Is it perfect???

[mtnbkr]

If that's "perfect", I'll take imperfection any day.

Chris

[Manedwolf]

I heard this story on NPR yesterday, and in it they were saying that they could use the Platypus to prove or disprove theories about evolution of creatures that devolped 150 million years ago, which made me wonder - why has the Platypus not evolved at all in 150 million years?  Is it perfect???

It's perfectly suited for its environmental niche. Things only evolve if the environment changes or food becomes less available. If they're perfectly suited to their environment, the current form is that which is best suited to survive and reproduce.

The species I have on my avatar there is the same way. It's a wierd six-million-year-old canid offshoot that predates dire wolves, specifically evolved to have long legs to see over tall grass. The grasslands in South America it hunts in have not changed in that time, nor have the animals it preys on or the supplementary fruit it eats, so neither has it changed.

[K Frame]

A better way of looking at it might be that it's perfect for its environment.

[mtnbkr]

A better way of looking at it might be that it's perfect for its environment.

I know, I was just being snarky.

Chris

[Nitrogen]

I heard this story on NPR yesterday, and in it they were saying that they could use the Platypus to prove or disprove theories about evolution of creatures that devolped 150 million years ago, which made me wonder - why has the Platypus not evolved at all in 150 million years?  Is it perfect???

Whose to say it hasnt?

This is a common misconception regarding evolution; that predecessor species all evolve at the same time.  If this was the case, everything would be human, which isn't the case.

Mutations that can be caused by evolution don't happen to all species at the same time, so you still have the predecessors around.

Monotremes are an evolutionary beginning step between reptiles and other mammals, such as Metatheria (marsupials) and Eutheria (Placental mammals).

The egg that reptiles and monotremes lay needs to be attended, and is very vulnerable (as most reptiles found out when mammals ate them.) so animals that kept their developing young with them evolved.

Notice we still have reptiles laying eggs?  They aren;t perfect either, but the ones that stuck around were good enough to survive, even with their faults.

[K Frame]

A better way of looking at it might be that it's perfect for its environment.

I know, I was just being snarky.

Chris

Huh?

Oh, I didn't even see your message. I was responding to another one.

[AJ Dual]

Notice we still have reptiles laying eggs?  They aren;t perfect either, but the ones that stuck around were good enough to survive, even with their faults.

Yep.

Evolution strives for adequacy, not perfection.

[Manedwolf]

Notice we still have reptiles laying eggs?  They aren;t perfect either, but the ones that stuck around were good enough to survive, even with their faults.

Yep.

Evolution strives for adequacy, not perfection.

Hence the human lower back, which is certainly not an optimal design. Neither is the unprotected belly.

[mtnbkr]

Neither is the unprotected belly.

Some of us offset this deficiency by adding layers of fatty tissue to "protect" ourselves.

Chris

[K Frame]

Neither is the unprotected belly.

Some of us offset this deficiency by adding layers of fatty tissue to "protect" ourselves.

Chris

I add a .38 or a 9mm.

[Jamisjockey]

So...what caliber for plyatapus?

[Glock Glockler]

Hence the human lower back, which is certainly not an optimal design. Neither is the unprotected belly.

Aren't these basically tradeoffs for being bipedal?

[AZRedhawk44]

So...what caliber for plyatapus?

The duck part requires a 12 guage with steel shot.

The beaver part requires a .50 caliber hawkens rifle and a suitable mountain man outfit.

The reptile part mandates a Bond Arms derringer with .45LC snakeshot loads.

[mek42]

Don't forget to take the anti-venom with you on your platypus hunts in case one gets close and mistakes you for a mate!

That was my favorite part - the painful toxin that is thought to be involved in mating.  Talk about "Love Hurts"! 

[Manedwolf]

Hence the human lower back, which is certainly not an optimal design. Neither is the unprotected belly.

Aren't these basically tradeoffs for being bipedal?

Yes. In the transition from quadruped to biped, those parts weren't really optimized, since they're kind of good enough. The lower back is very easy to injure, though, and always has been.

Other bits are a tradeoff. We no longer have the thick forehead that could likely take a serious bash with no ill effect, but we have a larger brain.

[Glock Glockler]

An interesting tidbit is that the neanderthals, while having a much more pronounced brow also had a larger brain than we do, their braincases weren't as high but they were longer.  I wonder what effect that would have on cognative abilities, if any.

[Manedwolf]

Larger, but not as developed. Elephant brains are also larger, as are whales, but they're not as dense with neurons as ours are.

A good analogy is a large old computer vs. a tiny current one that's much more powerful.

[Regolith]

Don't forget to take the anti-venom with you on your platypus hunts in case one gets close and mistakes you for a mate!

That was my favorite part - the painful toxin that is thought to be involved in mating.  Talk about "Love Hurts"! 

As far as I know, there is no antivenin for their toxin.  And it's said to be one of the most painful experiences one could experience; most painkillers have absolutely no effect on it.  I remember watching something on Discovery that talked about it; they had to do a morphine block on a main nerve on someone who had been "bit" by a platypus, and even that just barely took the edge off.

[Glock Glockler]

maned,

What are you basing that on?

[wmenorr67]

Don't forget to take the anti-venom with you on your platypus hunts in case one gets close and mistakes you for a mate!

That was my favorite part - the painful toxin that is thought to be involved in mating.  Talk about "Love Hurts"! 

As far as I know, there is no antivenin for their toxin.  And it's said to be one of the most painful experiences one could experience; most painkillers have absolutely no effect on it.  I remember watching something on Discovery that talked about it; they had to do a morphine block on a main nerve on someone who had been "bit" by a platypus, and even that just barely took the edge off.

Ouch!

[Scout26]

If we just eradicated all of them, we could then tell Darwin (and G-d) to go pound sand.