Category: mimicry and crypsis

A beautiful planthopper that mimics an ant (with a twist)

July 17, 2020 • 10:00 am

Planthoppers are in the order Hemiptera—the “true bugs”—along with cicadas and aphids, and are in the suborder Auchenorrhyncha. I’ve written about them before: they have all kinds of bizarre appearances that sometimes defy explanation (e.g., these ones).  In 2012 I wrote a report about a strange planthopper (Formiscurra indicus) that mimicked an ant, but the kicker was that the mimicry was described as being limited to one sex: the males. The females looked pretty much like “normal” planthoppers.

Sex-limited mimicry is known in some species, like butterflies, and I discuss it in my 2012 post, but there are reasonable (though untested) explanations for it. Some butterflies, for instance, have mimicry limited to females, with females of a single species varying in appearance across their range to mimic the local distasteful species (“Batesian mimicry“), but males look the same everywhere. That’s usually explained by sexual selection: females have a hardwired search image for males of their species, and while the females may change appearance based on local selection pressures to resemble distasteful “model” species, the males are prevented from doing so because they’d lose more in sexual attractiveness than they’d gain in protection from predation.

That 2012 article appeared in the Guardian (the report has disappeared) but there were no scientific papers describing it. Now, after seven years, one has finally showed up, in the Czech journal Acta Entomologica Musei Nationalis Pragae. Click on the screenshot below to see it and get a free pdf; the reference is at the bottom.

There are actually two species mentioned in this paper: Formiscurra atlas, found in Ethiopia, which was wrongly named in the Guardian report as Formiscurra indicus.  (The latter species, from India, had already been named in 2011.)  In the present paper, published in January of this year, the author (who co-wrote the 2011 paper) formally describes and names Formiscurra atlas, goes into great detail about its unusual morphology, and mention, though not in detail, the fact that in this species only the males are mimics—mimics of ants, or “myrmecomorphs”.

We can ignore the morphological details save that the species, in one sex only, is a mimic.  Here are pictures of a male and female. Fig 1 and 2 show the male, side and dorsal (top) view, respectively, while 3 and 4 show the female. The male has a round protuberance on its head (see the eyes behind it) that makes it look more antlike. The curious thing to me is that, according to the authors, they say that this ball-shaped protuberance evolved to resemble an ant’s abdomen, while to me, and in the pictures of its relative below, it looks like an ant’s head, while the male planthopper’s abdomen has evolved to resemble an ant’s abdomen. I’m not sure whether this is a mistake, but it’s at least clear that one sex but not the other has evolved to resemble an ant.

In Figs. 3 and 4 you see the female of the species, pretty “normal” for a planthopper. She does have a small cylindrical protuberance on her head that may be a vestigial remnant of the larger protuberance in males.

The authors, however, don’t say how they know that these are two sexes of the same species. DNA would tell, but no molecular analyses are described.

 

The authors also provide a photograph of a live specimen of the relative F. indicus, which is remarkably antlike, though I still say that in the first picture below (from the paper), as well as the second (from Wikipedia), the head protuberance is “supposed” to resemble the head rather than the abdomen of the ant:

From Wikipedia’s article on F. indicus. “Male climbing a twig.”

There remains only one thing to consider: why are only the males ant mimics? We know the benefits of ant mimicry, which I described in my earlier post:

Why mimic ants?  Ant mimicry is common in many diverse groups; in fact, Wikipedia has an article on it.  There could be several explanations for why the planthopper is such a mimic.  The mimicry could be aposematic, that is, the ants that are being mimicked are poisonous and distasteful, and predators have learned to avoid them.  By mistaking the leafhopper for an ant, the hoppers gain respite from being eaten, an obvious selective advantage.  Alternatively, the leafhopper could live in an ant colony and gain advantages that way, including protection by being in a group or getting access to the ants’ food. I find this less plausible since ants are good at sniffing out intruders.  And there are undoubtedly other possible reasons for mimicry.

I still think that the advantage of mimicry here is “Batesian”: that is, many ants are distasteful to predators like birds and lizards, as ants are full of poisons and other distasteful or toxic compounds, and very few species have them as a steady diet. If you’ve learned to avoid an ant, then a reproductive advantage accrues to any planthopper (planthoppers are tasty because they feed on sap and vegetation) that looks more like an avoided ant species. And there’s no evidence that these planthoppers are associated with ant colonies.

But on to the burning question: why is mimicry limited to one sex? If the mimics were females and the males were non-mimetic, we might explain it as we do in butterflies: males are constrained not to evolve because females retain the ancestral preference for how a mate “should” look. But in this case the mimics are the males and the females presumably didn’t evolve that much.  I don’t even want to speculate here (nor does author Gnezdilov), except to say that I’d like better evidence that these are indeed two sexes of the same species. Maybe I’ve missed earlier data on that.

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Gnezdilov, V. M. 2019. A new species of the myrmecomorphic planthopper genus Formiscurra (Fulgoroidea: Caliscelidae) from Ethiopia. Acta Entomologica Museu Nationalis Pragae. 59(1): DOI: https://doi.org/10.2478/aemnp-2019-0002  Published online:  24 Jan 2020

A stunning case of mimicry

January 21, 2020 • 9:00 am

I don’t remember encountering this case of mimicry, but it’s so amazing that, when I became aware of it from a tweet (yes, Twitter has its uses), I decided to give it a post of its own.

First the tweet, sent to me by Matthew. He added, “This is the Iranian viper, as featured in Seven Worlds, One Planet, made by the BBC. Amazing.”

You don’t need to translate the Spanish, though, as the video below tells all. I swear that when I first watched it, I thought there was a real spider crawling on the snake’s back.

The snake is the spider-tailed horned viper, Pseudocerastes urarachnoides, which has a small range in Western Iran (map from Wikipedia):

It wasn’t described as a new species until 2006 in the paper below (free access); before that it was thought to be the already-describe Persian horned viper. (I guess they overlooked the tail ornament.)

Here’s a photo of the tail “spider” from the paper; the one below that is from Wikipedia. The resemblance may not be precise, but (as you see above), when the ornament is moved about, it looks remarkably like a spider—certainly good enough to fool birds.

In that paper, the authors didn’t know how the tail ornament was used, but were impressed at its spider-like appearance. And they guessed accurately:

This raises the question of the elaborate and sophisticated appearance of the caudal appendage in our new species, as the waving or wriggling motion of a distinctively colored tail tip seems perfectly adequate to attract lizard and anuran prey. We can only speculate that in the case of the present species, the caudal lure serves to deceive a more specific kind of prey, such as shrews or birds. Indeed, ZMGU 1300 [the specimen number] contains an undigested, unidentified passerine bird in the stomach (the feet protruding through the body wall).

Only later, using live captive specimens, did researchers see that the ornament did indeed attract birds that the snake caught and consumed, as in the video above.

Any biologist who sees this is immediately impressed by the ability of natural selection to mold not only morphology, but the behavior of the snake: the twitching of its tail so that the spider ornament appears to “walk.”  But any adaptation like this ornament must have incipient stages, and each subsequent modification must improve the adaptation—that is, it much give the snake possessing the “improved” improvement a reproductive advantage. (That advantage would derive from the better nutrition of a snake who caught more birds, and thus might have more offspring, increasing the proportion of genes for more spider-like ornaments.)

My own guess was that the ornament started with the simple twitching of the tail of an immobile snake, a twitching that might attract predators and, moreover, is already known in several snakes. After that, any mutation that modified the tail, making it look more like a spider, would give the snake a further reproductive advantage. And so we get the spider ornament, which might of course still be evolving. Concurrent with the evolution of the ornament itself would be the evolution of the snake’s tail-twitching behavior, which makes the caudal appendage resemble a spider nearly perfectly.

It turns out, of course, that I’m not the first person to think of this scenario. Discover Magazine wrote about this snake last spring, and speculated about its evolution:

“The evolution of luring is more complex than contrasting color or simple shaking — the movement is precisely adapted to duplicate prey movement frequencies, amplitudes and directions, at least in specialized cases.”It’s not uncommon for many snakes to do something similar with their tails to deceive prey. The common death adder of Australia buries itself in leaves, then writhes its tail like a worm to catch lizards and frogs. The Saharan sand viper conceals itself in sand with only its eyes and nostrils visible. When a lizard comes along, it sticks its tail out from the dirt, making it squirm like an insect larvae.  The behavior — and the elaborate body modifications that can accompany it — likely arose from a behavior common to many reptiles, Schwenk explains. When they are about to strike prey, any lizards and snakes enter a hyper-alert pose. The reptiles will focus their vision by cocking their heads to the side, arching their backs, and certain species will commonly vibrate their tail tip against the ground. This can distract the prey, which will shift its attention to the vibrating tail, ignoring the reptile mouth opening to grab them.“This simple pattern leads to selection causing refining of the tail form and motion to be more attractive to such prey by more accurately mimicking actual prey movements,” Schwenk theorizes. “The other ancestral condition that could have led to caudal luring, or possibly an intermediate step in the process, is the use of tail vibration for prey distraction rather than for luring.” Indeed, those most famous tail shakers, the rattlesnakes, sometimes also use caudal luring. For example, juvenile dusky pygmy rattlesnakes, whose rattle is so small it barely makes noise, wiggle their tails to attract prey. The behavior, in fact, may be key to how rattlesnakes evolved their distinctive rears, although this theory is somewhat controversial. “Like many other apparently simple things in biology, there is a lot of complexity to caudal luring that has barely been explored,” Schwenk says. “Much of this has been considered in a piecemeal fashion, but a thorough review and synthesis … has not been attempted.”

Now we’re not sure if this is the correct evolutionary pathway, but constructing a plausible step-by-step scenario like this, and showing that the intermediate “stages” occur as adaptations among existing species, is sufficient to refute the creationist claim that structures like the spider ornament could not have evolved and thus much have been created by God (or a “designer”, which means the same thing). The same kind of argument was used by Darwin in The Origin to refute Paley’s argument that the camera eye must have been created by God. Dawkins discusses it in the video below (and, as I recall, in his book The Blind Watchmaker).

 

Readers’ wildlife photos

January 10, 2020 • 7:45 am

Down in burning Australia, Tony Eales has managed to photograph some of the insects that haven’t yet been incinerated. Note that there is some mimicry as well as crypsis (camouflage) in the photos below. Tony’s notes are indented:

Today is a mish-mash of recent things that may be of interest.

Last year I photographed a female Clear-wing Persimmon Borer (Ichneumenoptera chrysophanes), a beautiful wasp-mimicking moth whose larvae bore into the stems of certain fruit trees. My first photograph of the new decade was of the male of this species. I was having friends over for a BBQ on the first of January and I was standing around talking when, out of the corner of my eye, I noticed something odd looking on a leaf. I announced loudly “I have to get my camera” and ran off to the office, came back and got the shot.

Next a couple of possible wasp-mimicking Stiletto flies. I say possible because the first one, Agapophytus aterrimus, certainly has some of the wasp-mimicking characteristics but also is reminiscent of some Jewel Beetles in the genus Castiarina:

Castiarina sp:

The second wasp-mimic is more straightforward. The fly Agapophytus pallidicornis is a striking mimic of the common spider-wasps in the genus Fabriogenia. In fact, when I photographed it, the only clue I had that I might be dealing with something other than a spider-wasp was that it was sitting still, whereas spider-wasp’s restless searching for prey never seems to pause for even a  second.

Fabriogenia sp.:

I finally got to photograph the Giant Bulldog Ant (Myrmecia brevinoda). It was a hulking 35mm long and not at all impressed with me. They’re a terrifying ant to play around with, they’re fast defensive and have excellent eyesight and reportedly an unbelievably painful sting. Even so I messed with this one a lot to make sure I got the shot. The only bigger ant in Australia is the queen of this species which can be over 40mm long.

I found the larvae of a species of Tortoise Leaf Beetle which I think is probably Aspidimorpha deusta. The larvae in this family are unusual for carrying around a “faecal shield” made up of excretions, poisonous chemicals from the plants they eat and shed exoskeletons. A. deusta tend to hold the shield over them like an umbrella.

From mimicry to defence to camouflage. I’ve been finding these transparent and green cockroaches on the underside of leaves in the local rainforest. They are in the genus Mediastinia and they have exoskeletons so transparent that from certain angles it simply doesn’t show up in photographs.

Also in the rainforest I found a tiny Pygmy Grasshopper in the family Tetrigidae. They’re only a couple of millimetres in length as adults and well camouflaged as  a piece of moss that they’re very easy to miss.

But of course no stings, or camouflage or mimicry can defend an insect from fungal parasites like this Ophiocordyceps that I found after having consuded what looks like some sort of Hoverfly.

On the climate apocalypse front, the fires are still raging with no real end in sight as we come to the hottest end of the traditional fire season (note these fires have been burning since September), the latest estimates are that 10 million hectares have burned leading to the loss of an estimated one billion “animals” (and you know they’re only talking about the vertebrates). While these fires and the loss of lives, homes and forests is rightly the big news, as bad as they are, the devastation from unusually warm ocean temperatures on tropical reef systems is even worse.

That story is only just coming out now but we’ll be counting the cost for decades to come. On my way to my favourite little rainforest patch I was horrified at the state of the surrounding forest. This moist eucalyptus forest looked like it had already been burned but you could see that it wasn’t. It was that every young tree was dead from drought and all the older trees had dead limbs and drooping dry foliage. This kind of forest has rare and low intensity understory burns and it protects the rainforest that it surrounds; however in these conditions one can easily imagine a fire getting into the dry crowns and wiping out everything.

All we can do is cross our fingers and wait for rains and hoping nothing sets it off beforehand.

Monday: Hili dialogue and farmyard rush hour

November 4, 2019 • 5:49 am

by Matthew Cobb

Hili has some odd culinary choices, but she is a cat after all:

Paulina: Do you like sausages with salmon?
Hili: And the ones with chicken as well, and the ones with turkey.


Paulina: Smakują ci te kiełbaski z łososiem?
Hili: Te z kurczakiem też i te z indykiem.
.
In Devises, the animals of Marsh Farm are all ready to come rushing out of the barn, into a glorious sunrise:

A Canada goose found its way onto a football pitch in Macclesfield, south of Manchester:

Academics – always complaining about the same thing:

Some absolutely gorgeous geology. It’s unsigned, but appears to have come from the workshop of Slartibartfast, I believe:

 

There are some parts of Earth where life can’t find a way. Doesn’t look good for the hypersaline water sludge that may be just beneath the surface of Mars:

Speaking of Mars:

The new BBC Natural History Unit series Seven Worlds: One Planet, narrated by David Attenborough, has got off to a flying start, although I found bits of a bit too brutal to watch (I went to do the washing up while trapped walruses tumbled and bounced off the top of a cliff). These next two tweets were the highlight of last night’s episode for me – a viper that lives in the Iranian desert which has adapted the end of its tail as a lure – it looks remarkably like a spider scuttling about, but the incredibly camouflaged snake soon puts paid to the illusion…

Readers’ wildlife photos

October 8, 2019 • 8:00 am

Tony Eales from Brisbane sent us some lovely photos of arthopods, including some great examples of mimicry and camouflage (“crypsis”). Tony’s captions are indented.

Some mimicry and a few other random arthropods.

Three shots of a wraparound spider, Dolophones sp. These are small, only about 8mm across and fairly common, but rarely seen for obvious reasons. I find them mostly in the late afternoon as they start to build their web for the night. When building the web they just look like any other small orb-weaving spider, but when they see you approaching they scurry up a silk-line to the nearest twig and virtually disappear. As you can see in the third picture, when not all folded up in camouflage pose they display quite a bit of colour.

The ones I normally see have flattened dome-shaped abdomen but I knew there were ones out there with these weird turrets on their backs and had been wanting to photograph one for ages. Evolution is weird.

Next is a Hangingfly Harpobittacus sp. Hangingflies are in a separate order of insects Mercoptera along with Scorpionflies. We don’t have a lot of species diversity in this family in Australia but do have a lot of diversity at higher levels, with two families being endemic. Hangingflies are famous for their elaborate mating rituals in which the male captures prey to present to the females. I hope to observe this one day.

This female Clear-wing Persimmon Borer moth (Ichneumenoptera chrysophanes) is so far the find of the season for me. I have never seen such a striking wasp-mimicking moth.

The model is probably something like this Ichneumenon wasp Xanthopimpla sp.

And lastly just a little cutie. A very tiny Sandalodes sp. jumping spider with a tiny katydid nymph as prey. [JAC: Doesn’t it look excited?}

Spot the insect, from Piotr Naskrecki

August 10, 2019 • 12:00 pm

Here are two lovely photos of a mimic taken by photographer/biologist/naturalist Piotr Naskrecki in Gorongosa Park in Mozambique. These appeared on his Facebook page, and I asked for permission to reproduce them. I give his captions below. I’ve also turned this into a “spot the. . .” quiz for those who want a not-too-hard puzzle. The reveal is below the fold.

Piotr’s captions are indented.

Every now and then somebody posts a similar photo so, now is my turn. It is not a difficult one and you will get an extra point for naming the family of the subject. I ran across it today on the Cheringoma Plateau in Gorongosa.

Click below to see the critter:

Continue reading “Spot the insect, from Piotr Naskrecki” →

A remarkable case of mimicry: Jumping spider imitates caterpillar

May 7, 2019 • 9:15 am

Tony Eales, who provided this morning’s mushroom photos, called my attention to this paper in the Israel Journal of Entomology, describing a remarkable case of mimicry seen in a newly described species of salticid (jumping spider). Click on the screenshot below to see the paper, or you can download the pdf here. It’s remarkable because, at least as far as I know, it’s the first known case of a spider mimicking a caterpillar—and the mimicry seems quite good. There are cases of caterpillars apparently mimicking spiders, like the monkey slug caterpillar, but this is the reverse situation.

The authors, one of whom (Logunov) is at the Manchester Museum at the University of Manchester and the other a citizen scientist in Hong Kong who may have spotted the beast and recognized it as new, describe a jumping spider found in, of all places, Hong Kong. It was first spotted on a metal railing in Shek O Country Park (see photo 9 below showing it it on the railing), with the single known male kept alive for a few days for observation before being preserved and sent to Manchester. They speculate that another specimen in a different museum might be an immature female spider of the species, but don’t know for sure. The authors believe, though, that other individuals of the species might occur in tree canopies, as do other species in the genus Uroballus.

The species was named Uroballus carlei, and the story of its name is cute:

Etymology: The species is dedicated to Eric Carle (b. 1929), the American illustrator and author of more than 70 books for children and adults. His most renowned books include ‘The Very Hungry Caterpillar’, which chronicles the growth and metamorphosis of a caterpillar, and ‘The Very Busy Spider’. Indeed, these and other books by Eric Carle provide the first conscious contact of young readers with the natural world, being innovative tools for early-age environmental and biodiversity education.

It’s a fuzzy spider with a thin abdomen and covered with hairs: here are dorsal, ventral, and lateral views from the paper:

(from the paper): Figs 1–7: Somatic characters and copulatory organs of Uroballus carlei sp. n. (holotype ♂): (1) body, dorsal view; (2) ditto, lateral view; (3) ditto, ventral view. Scale bars for Figs 1–3 = 1 mm

The one putative conspecific female in a museum differs by having a “wide brown serrate longitudinal stripe on the dorsum” and shorter spinnerets, so the species is not markedly sexually dimorphic.

The nice part is that the authors noted “a striking resemblance of live specimens of U. carlei to a small-sized hairy caterpillar (below). This similarity was noted in 2016 in this species by another researcher, who didn’t name the spider as a new species but put it in the genus Uroballus. (One other putative caterpillar mimic seems to be the salticid U. koponeni from Malaysia, but pictures aren’t given.)

The notion that U. carlei is indeed a caterpillar mimic comes from three considerations. First, it looks like a moth caterpillar (Brunia antica; shown in photos 16 and 17 below) that is found in Southeast Asia, along with similar-looking “lichen moth caterpillars”, which eat lichens and are found in Hong Kong. In particular, the skinny appearance of the spider and its dense and protruding hairs making it look caterpillar-like (the hairs in the caterpillars are “urticating” or irritating to predators).

So the possible sympatry of the model (caterpillar) and mimic (spider) is point number two. For this kind of mimicry to take place (see below), both spider and caterpillar have to live in the same place—at least during the evolution of mimicry. Finally, observations of the spider kept alive in the lab showed that “the male moved rather slowly and often stopped”, erecting its anal tubercle while moving.  This is not how most salticids move (they are quick and jerky), but it seems to resemble caterpillar movement.

Here is the putative model, U. carlei (8-15), and a member of the group of lichen moth caterpillars that it’s supposed to resemble (photos 16 and 17). It does look distinctly un-spider like, and, especially in photos 9, 12, and 13, caterpillar-like:

(from paper): Figs 8–17: General appearance of live male of Uroballus carlei n. sp. (holotype ♂; 8–15) and the caterpillars of Brunia antica (Walker, 1854) (16, 17). Scale bars = 1 mm.

So what kind of mimicry is this? It could involve three forms, all of which could have evolved roughly simultaneously.

Batesian mimicry.  Because the model caterpillars sequester lichen toxins in their body and are supposed to be distasteful, and also have irritating hairs, the spider could have evolved a resemblance to a caterpillar that is already avoided by predators who have learned that it’s toxic and distasteful.

Aggressive mimicry. There could be two forms of this:

a.) In the first, the spider would, by resembling a caterpillar, get close to prey who haven’t evolved an evolutionary fear of these caterpillars. (After all, the caterpillars eat lichens, not insects.) Salticids, though, are carnivores, and could jump on unwitting insects like flies and beetles who approach them thinking they’re just caterpillars.

b.) The authors observe that caterpillars are “prone to attack by specialized parasitoids” who lay their eggs in the caterpillars and then the hatched parasitoids, like tiny wasps, can eat the caterpillar from the inside. It’s possible that these salticids could also attract these parasitoids because the spiders resemble caterpillars, and then, when the parasitoids come to lay eggs on them, the spiders grab them and eat them.

As the authors note, the mimicry hypothesis requires a lot more work—both in the field and the lab. Do predators who learn to avoid the caterpillars also avoid the salticids? Do parasitoids attack the salticids in the lab and then get eaten? And do insects that have experience with caterpillars, and learn not to fear them, then approach the spiders and get eaten? All this, of course, depends on finding more of these spiders, as well as some of the caterpillars they’re supposed to resemble.

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Logunov, D. V. and S. M. Obenauer. 2019. A new species of Uroballus Simon, 1902 (Araneae: Salticidae) from Hong Kong, a jumping spider that appears  to mimic lichen moth caterpillar. Israel  Journal of Entomology 49:1-9.

 

Readers’ wildlife photos

March 9, 2018 • 7:30 am

Reader/biologist Jacques Hausser from Switzerland sends us another batch of lovely orthopterans (see here and here for parts I and II). Jacques’s notes are indented:

The third group of Orthopterans, the grasshoppers sensu stricto (suborder Caelifera) can be easily told apart from the Ensifera (bushcrickets/katydids and crickets) by their rather short and sturdy antennae and by the lack of a long ovipositor, replaced by four short chisels or burins allowing the female to bore a hole in the substrate to lay her eggs (Caelifera means “chisel bearer”). Their stridulatory and auditory equipment is also different: they stridulate by rubbing their hind legs against the elytrae, and their ears are located in the first abdominal segment. Grasshoppers are morphologically very homogenous (with exceptions!), and the coloration of most species is highly variable. The biblical locusts belong to this group.
Stenobothrus lineatus, the stripe-winged grasshopper, female. One can discern the dark eardrum just under the wing, to the right of the last green plate.
Mecostethus parapleurus, the leek grasshopper, male. This species likes reeds and other tall grasses in marshes and wet meadows. I don’t know what kind of relationship it has with leeks…
Chorthippus brunneus female, the common field grasshopper. It’s not obvious from this picture, but, like other mostly brown species, it prefers dry meadows with sparse vegetation.
Sphingonotus caerulans, the slender blue-winged grasshopper, and a well camouflaged one. The rear wings, hidden at rest, are pale blue (other related species have red hindwings), which makes it very visible in flight – but it instantly disappears when landing, fooling a would-be predator. Each time it moults, this spendid species can adapt its color to the environment – but it cannot change it between moults. It belongs to the subfamily of Locustinae together with the famous migratory locust.
Gomphocerippus rufus male, the rufous grasshopper, is easily recognizable by its black and white spatulate antennae. I call it the grasshoppers’ Pluto.
Same species, pairing. In grasshoppers the female is usually larger than the male.
Chrysochraon dispar, the large gold grasshopper. Like this one, females of several species are almost wingless, but the males keep fully developped wings, even if they are too short to fly—they need them to sing!
Another solution: they give up stridulating. Here is Miramella alpina, the green mountain grasshopper, a mountain species that replaces stridulation with grinding of the mandibles.
Acrida ungarica, the cone-headed grasshopper, a Mediterranean and East-European species. This is what happens to your head when the natural selection has decided that you should look like a bunch of twigs.

Monday: Hili dialogue

January 15, 2018 • 6:30 am

Good morning on a snowy Monday (January 15, 2018); I’ll have some snow pictures shortly. It’s holiday in the U.S. since it’s Martin Luther King Day (always the third Monday in January, and, as you’ll see below, it’s also King’s actual birthday). Here’s today’s Google Doodle about King.

Here are the final minutes of King’s famous “I have a dream” speech (full speech here), delivered at the March on Washington on August 28, 1963, a march shown in the Doodle. I’ve never heard a more stirring piece of rhetoric in my life, although some of Churchill’s wartime speeches come close. This was televised live to the nation, and I watched it.

This was King’s moment, and he took it big time. The Civil Rights Act of 1964 was passed the next year. I ask you to spare five minutes to listen to this, and remember that when it was given, there was still rampant and legal segregation in America:

It’s also National Pastrami Sandwich Day, which is weird because we just had National Pastrami Day. I sense the machinations of Big Pastrami.  And in Indonesia it’s Ocean Duty Day.

On this day in 1759, the British Museum opened. On January 15, 1870, Thomas Nast published in Harper’s Weekly a cartoon that first symbolized the Democratic party with a donkey. Here it is:

On this day in 1889, the Coca-Cola Company (then called the Pemberton Medicine Company) was incorporated in Atlanta, Georgia. Exactly three years later, James Naismith published the rules of “basketball.” On this day in 1919, two events happened: Rosa Luxemberg and Karl Liebknecht German socialists, were murdered by the Freikorps (German mercenaries); and the Great Molasses Flood occurred in Boston, an explosion that loosed a huge tsunami of the sweet stuff, killing 21 people and injured 150. On January 15, 1943, during WWII, the Pentagon was dedicated in Arlington, Virginia. On this day in 1967, the first Super Bowl was played in Los Angeles, with the Green Bay Packers beating the Kansas City Chiefs 35-10. And on this day in 2001, only 17 years ago, Wikipedia went online.

Notables born on this day include Molière (1622), Josef Breuer (1842), Osip Mandelstam (1891), Aristotle Onassis (1906), Edward Teller (1908), Gene Krupa (1909), Gamal Abdel Nasser (1918), mountaineer Maurice Herzog (1919), and Martin Luther King, Jr. (1929, assassinated 1968).

Those who expired on this day include Mathew Brady (1896), Karl Liebknecht and Rosa Luxemburg (1919; see above), Jack Teagarden (1964), Ray Bolger (1987), and Harry Nilsson (1994).

Teagarden is one of only two jazz trombonists I can name (the other is Juan Tizol of Ellington’s Band). He could also sing, and here he is with Louis Armstrong peforming the classic “Basin Street Blues” (Barney Bigard on clarinet):

Meanwhile in Dobrzyn, Hili is about to finish the last of the Japanese “cat’s snacks” sent her by Hiroko:

Hili: If I eat the last Japanese treat now, will I be sad later?
A: Probably.
Hili: Oh well, I will suffer later.
In Poliah:
Hili: Czy jak teraz zjem ten ostatni japoński przysmak, to potem będzie mi przykro?
Ja: Prawdopodobnie. 
Hili: Trudno, będę cierpieć.

A tweet from Matthew. Spot the longhorn beetle. (Translations of the Japanese welcome.)

And three more from Dr. Cobb:

https://twitter.com/historylvrsclub/status/952279620044369920

Be sure to watch the video. I’ve seen something like this in Scotland:

https://twitter.com/AMAZlNGNATURE/status/952554438421442560

A hedgehog comes alive when it smells food (h/t: Barry):

And a last-minute contribution by Grania:

A Müllerian mimicry ring

January 8, 2018 • 2:45 pm

Professor Ceiling Cat continues to be distressed at the lack of interest (reflected in comments, at least) on the science posts: those posts that are the hardest to write. Nevertheless, he persists.

Here is a likely example of aposematic (warningly colored) mimics in different orders of insects having evolved to resemble each other (tweet courtesy of Matthew Cobb).  This phenomenon is well known in biology, and is known as Müllerian mimicry after the German zoologist Fritz Müller.

If distasteful, noxious, or dangerous species share a common predator, they may evolve a convergent pattern or color that the predator recognizes and avoids. The presumed advantage is that if these species have a common pattern, the predator has to undergo less “learning” to recognize and avoid the shared pattern. What that means to one of these insects like those below is that if an individual of species 2 gets a mutation that somehow resembles a pattern that predators have already learned to avoid in species 1, it has a reproductive advantage over individuals of species 2 with some other aposematic mutation. Do you see why that is? It’s because the first few individuals of species 2 with a different aposematic pattern stick out in the environment, and the predator hasn’t yet learned to avoid them. Learning means that it has to sample the insect (likely killing it) before it learns to avoid the new pattern. You have a survival advantage if you fit in to an already-evolved/learned system rather that starting another one with a mutation that hasn’t been “learned.”

This, biologists presume, is the reason why members of different species evolve to resemble each other when they’re all noxious to predators.

Here we have species from three different insect orders—Coleoptera, Diptera, and Lepidoptera—which have evolve a common orange and black striped pattern.

While we can’t observe the evolution of this convergent pattern, we can make predictions from our evolutionary scenario.

First, these insects have to share a common predator: that is, there should be one or more species of predator that lives in the area that all these species inhabit, and has learned to recognize and avoid the pattern. That, of course, can be tested. (There are some twists here, but not important enough to mention.)

Second, that common predator has learned or can be taught to learn to avoid the pattern.

Third, if you have trained a predator (say, a naive, hand-reared bird) to avoid the pattern, introducing the predator to a different species with the same pattern should show that it’s avoided more often than a brightly colored species with a different pattern.

I know that the second prediction has been tested and confirmed for some aposematic insects, but I’ve no idea whether the first and third have been for members of Müllerian mimicry rings. (Hypothesis three has been tested and confirmed for members of singe aposematic species.)

The important thing is that the evolutionary hypothesis is testable. Creationists, of course, could just say “God made a group of insects this way so they’d survive”, but that assertion can lead to different predictions. I won’t go into those, but perhaps you can think of some.