Why aren’t there more green butterflies?

May 29, 2017 • 10:00 am

Matthew found this question on the BBC’s Discover Wildlife site; click on the screenshot below to the “answer”, which I reproduce below. The picture is of the green hairstreak (Callophrys rubi), Britain’s only green butterfly.

First, though, this species is not completely green—the color is only on the bottom of the wings, which it folds as shown, perhaps for camouflage. The top of the wings look like this:

Now, onto the question and “answer,” which I find lacking. Here’s Jones’s answer (indented, plain text), with my responses in bold print and flush left:

Most ‘natural’ green insect pigments (in grasshoppers and plant bugs, for example) tend to fade, since they are chemically altered by light, and there is evidence that some are derived from chlorophyll eaten by the insects.

The green of the hairstreak, though, is not a pigment, but a metallic refraction effect caused by submicroscopic parallel grooves on the wing scales, which reflect only green light. Metallic green beetles use a similar mechanism.

In contrast, melanin (the default pigment across most animals) is highly stable, as are yellow and red pigments, which occur widely. There may be an evolutionary mechanism at work here.

Or maybe not! Jones’s answer is that green pigments tend to fade compared to others, so butterflies use them less. And that might be true, but, as Jones also notes, you can achieve a green color by altering the microstructure of the wings, which gives a stable green color. Further, it’s true, as Jones says, that orthopterans like grasshoppers and katydids are quite often green. Why orthopterans and not lepidopterans? Saying that “green pigments tend to fade” is not a good answer unless you show that that fading has particularly bad consequences for butterflies compared to other insects: 

Here, for instance, are the first four rows of images given by Google for “katydid”:

And for “grasshopper”:

If Jones is going to maintain that green pigments fade is part of the answer, he has to explain this difference between insect orders. I suppose he tries to do that in the last bit of his short answer:

Sedentary butterfly (and moth) larvae tend to eat green plants, and being all the same colour – as the caterpillars of many groups are – offers them camouflage.

Many butterflies tend to sit on green plants, too, and would undoubtedly benefit from camouflage. So that consideration doesn’t explain why there are so few green butterflies. 

But the day-flying adults need to combine bright colours (for mate recognition) with muted cryptic undersides (to hide or roost), so in this case green just may not be necessary.

I’m astounded at this bit. Green coloration is a a cryptic color, and so resting with green wings folded up seems a good way to achieve camouflage. As for needing bright colors for mate recognition, well, look at the green hairstreak above. It’s fricking BROWN on top! Further, we’re not sure if butterflies evolved to be brightly colored so they can recognize mates more easily. Some, for instance, are “aposematically” colored to warn predators of their toxicity, while others are mimics of the aposematically colored ones.  And if butterflies are brightly colored to recognize mates, why aren’t katydids or grasshoppers? 

The correct answer about why so few butterflies are green is this: “We don’t know.” Jones has simply offered a speculative answer, which has problems, and it’s an answer that a lay reader will take away as the truth. Jones may be correct in part, or there may be other factors at play: for example, it may be harder for butterflies to manufacture green pigments than for other insects. But finding a good answer requires either comparative studies (Do butterflies tend to sit more often on brown trees than on green plants?) or experimental studies (Do bright colors really help butterflies recognize mates? Do orthopterans have a pigment synthesis pathway not present in lepidopterans? If so, why are caterpillars—the juvenile stages of butterflies, able to make green?)

What we have here, in fact. is a just-so story. Not only does it not make a lot of sense to me, but appears to give a definitive answer when it doesn’t. It would be much better if Jones admitted up front that the answer isn’t known, and then speculated about some possible answers, suggesting how to test them. That would show people not only that scientists can admit their ignorance, and at the same time suggesting ways to remedy it, displaying the scientific mindset. 

Now what’s your (speculative) answer?

Jonathan Pie on the causes of and reactions to the Manchester bombing

May 29, 2017 • 8:45 am

The schtick of Jonathan Pie (real name Tom Walker) is to act as if he’s a news reporter doing a story, and then suddenly to lurch into a passionate and angry rant about one thing or another. As time passes, though, the rants seem to be getting a little less funny, but more than compensate for that with an increase in passion and “truthiness.” Here Pie discusses the Manchester bombing and terrorism, and I was pleased to see he agrees with me that the British reaction of “carrying on as normal”, as a way to show that the terrorists haven’t won, is a dumb response. He also argues that the response of “we win through love” (the PuffHo response) is equally fatuous.

And at 1:54 he says, “Isn’t it time to stop pretending that this has nothing to do with religion?” He’s right.

It’s not a funny piece, but it’s a truthful one.

h/t: pghwelshgirl

Readers’ wildlife photos and video

May 29, 2017 • 7:30 am

Reader Jim Blilie from Minnesota sent in some photos taken by his son Jamie, our youngest contributor. The notes are indented:

Here are some more photos from my son, Jamie, age 13.  Shot with his Canon Powershot SX530 HS camera. All are shot within feet of our house, most are shot from the back deck.
 
First, a video of Sandhill Cranes (Grus canadensis) calling and displaying in the wetland across the street from our house:

Northern Cardinals (Cardinalis cardinalis):

Red-winged Blackbird (Agelaius phoeniceus) male and female:

A tom turkey (Meleagris gallopavo) displaying (shot from a car!):

And an American robin (Turdus migratorius):

And a photo for our own Matthew from Stephen Barnard in Idaho:

Photo for Matthew Cobb. I think you said the Barn Swallow (Hirundo rustica) is his favorite bird.

Monday: Hili dialogue

May 29, 2017 • 6:30 am

Hooray, it’s Monday, May 29 (2017), and it’s not only a Memorial Day holiday in the U.S., but also National Biscuit Day! Now for you UK residents, be aware that the following photo shows what Americans call “biscuits”:

What Brits call biscuits are known in America as “cookies”. I love American biscuits, which, a staple of Southern cuisine, are one of America’s greatest contributions to world gastronomy. They are simple to make and best enjoyed with a breakfast of fried eggs, grits, and country ham with red-eye gravy (with homemade peach preserves on the side, as served in the Loveless Motel and Cafe near Nashville, Tennessee). Given that meal, it’s appropriate that today is also World Digestive Health Day.

On this day in 1660, the English Restoration began when Charles II became king of England, Scotland, and Ireland. On May 29, 1913, Stravinsky’s ballet for The Rite of Spring premiered in Paris, provoking a famous uproar in the theater. And exactly six years later, Arthur Eddington observed the bending of starlight during a total solar eclipse in the Atlantic, providing the first experimental evidence for Einstein’s general theory of relativity. It’s also a banner day for mountain aficionados like me, for it was on this day in 1953 that Tenzing Norgay and Edmund Hillary became the first people to verifiably reach the summit of Mount Everest (Tenzing was on top first). Finally, on May 29, 1999, the Space Shuttle Discovery first docked with the International Space Station.

It’s a big day for birthdays: notables born on this day include Patrick Henry (1736), G. K. Chesterton (1874), Bob Hope (1903), Tenzing Norgay (1914; he summited on his birthday!), John F. Kennedy (1917; today is the 100th anniversary of his birth), Peter Higgs (1929), Paul R. Ehrlich (1932), Al Unser (1939), mountaineer Doug Scott (1941), and Melissa Etheridge (1961).  Those who died on May 29 include W. S. Gilbert (1911), John Barrymore (1942), Fanny Brice (1951), Moe Berg (1972), Mary Pickford (1979), Barry Goldwater (1998), Archibald Cox (2004), Dennis Hopper (2010), and Doc Watson (2012). Let’s hear a few licks from Doc—one of his best-known songs and some traditional American blues:

Meanwhile in Dobrzyn, Hili asserts her hubris and hegemony:

Hili: We cats have a general principle.
A: What principle is that?
Hili: That we establish all principles.
In Polish:
Hili: My, koty, mamy generalną zasadę.
Ja: Jaką?
Hili: Że to my ustalamy zasady.

Some good news: Official Website Physicist™ Sean M. Carroll and his wife Jennifer Oullette appear to have adopted the two kittens that “showed up” at their home. The words “apparently adopted” are a bit strange, though! (h/t Jiten):

And in London, the black cat Theo, staffed by Laurie and Gethyn, is drinking his morning coffee. Yes, he likes it black—no sugar, no cream, and he prefers espresso.

Finally, a cat tw**t found by Grania. Are these Abyssinians??

https://twitter.com/landpsychology/status/869017761216942081

A heartwarming tail

May 28, 2017 • 2:30 pm

It’s a holiday weekend, so let’s end today’s posts on an upbeat note. Here’s a 6½-minute video of a wounded veteran who, on the verge of suicide, had his life saved by the appearance of a black and white kitten. The story is a bit sad, too, and if you don’t tear up at the end, you’re made of stone.

There are other videos at the Mutual Rescue site.

h/t: Karl

 

Child marriage in the U.S.: it’s far more common than you think

May 28, 2017 • 12:30 pm

Nick Kristof has a frightening column in today’s New York Times (click on screenshot to read it) detailing the extent of child marriages—nearly always involving young girls and older men—in the U.S. I had no idea, for instance, that 27 of our 50 states have no legal minimum age for marriage!

There are several hair-raising tales in his piece, including the title piece of an 11 year old forced to marry a 20 year old man who had raped her; it took place in Florida, one of those states with no minimum age. What struck me is the role of religion in all this. We know about Mormons, of course, but this also takes place in Christian and Jewish settings. The 11-year-old, for instance, married a member of her church. Few of these marriages work out, and in some places even constitute statutory rape, though that can be obviated. As Kristof notes:

Globally, a girl marries before the age of 15 every seven seconds, according to estimates by Save the Children. As in Africa and Asia, the reasons for such marriages in the U.S. are often cultural or religious; the American families follow conservative Christian, Muslim or Jewish traditions, and judges sometimes feel that they shouldn’t intrude on other cultures.

That cultural relativism is ridiculous; consequentialism alone dictates that no “respect” is due to such practices of any culture, much less in America.

Here are some facts:

  • Records show that over 167,000 people under 18 were married between 2000 and 2010, including girls as young as 12. That was from 38 states, but extrapolation from other states leads to an estimate of almost a quarter million child marriages during that decade.
  • Every state in the U.S. allows underage girls to get married, though some require consent of a judge or the parents.
  • New Hampshire has a law allowing girls to marry at 13; when a Girl Scout campaigned to raise the age to 18o, the Republican state legislature refused to change the law, with representative David Bates saying, ““We’re asking the Legislature to repeal a law that’s been on the books for over a century, that’s been working without difficulty, on the basis of a request from a minor doing a Girl Scout project.” How can he live with himself?
  • New Jersey has no minimum age for marriage. Last year the state legislature voted to raise the age to 18, but it was blocked by governor Chris Christie.

Here are the minimum ages for marriage by state:

Here’s the per capita landscape of child marriage:

And the number of child marriages from 2000-2010 from states with records; note that the highest numbers are in the South:

The reasons there should be an age threshold are clear: inability to give consent, the possibility of rape and underage (and dangerous) pregnancies, coercion by religion, and so on. And 18 seems about right to me. Perhaps there can be rare exceptions, but I can’t think of any, and surely the age should never be below 16. It’s appalling that any state should have no age limit, yet that’s the case for 54% of American states.

Setting limits is simply the right thing to do, and we need to make that happen.