Orchid mantis: does it really mimic an orchid?

March 9, 2015 • 9:45 am

I believe I’ve posted several times about the “orchid mantis,” a term for a variety of mantises that mimic—or appear to mimic—orchids. These mantids are believed to sit among flowers, and resemble the flower so strongly that pollinators like bees try to pollinate them. But instead of getting pollen, the bee gets snapped up by the mantid when they fly into its arms. Here are a few of the mantids showing their resemblance to flowers:

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Below is an Attenborough video showing the mantis deceiving a bush cricket, who loses its life. It also shows another cool fact: this species is not mimetic as a juvenile, but aposematic: it has “warning coloration” showing that it’s toxic. For some reason, perhaps connected with the mantis’s increasing size, it changes shape and color as it ages, changing from conspicuous to cryptic.

This is a classic example of “aggressive mimicry,” so called because the purported evolutionary pressure was to get food (through aggression) rather than simply to hide form predators. But, like many cases of mimicry, the “pollinator-deceiving” mimicry is inferred, and hasn’t been scientifically tested. To do that you’d have to experiment on these species (and they’re not easy to come by), showing that pollinators do indeed mistake the mantis for an orchid flower. And to test another hypothesis—that the mantis gains additional camouflage by hiding among the orchids it’s said to resemble—you’d have to show that the mantis gets more prey when it’s sitting among flowers than when sitting alone. That hadn’t been done either.

Further, there’s an alternative hypothesis: that the mantid isn’t camouflaged to deceive prey, but to deceive predators. After all, the aposematic coloration of the juvenile above probably evolved to warn away predators who have learned to avoid the toxicity associated with that coloration. And that implies that something tries to eat these creatures. Finally, the flower-resemblance of the adult could serve to simultaneously deceive both predators and prey.

To test these hypotheses, James O’Hanlon, Gregory Holwell, and Marie Herberstein, a group of researchers from Australia and New Zealand, did experimental tests on insects and flowers in Malaysia. The results appear in the two papers at bottom (with links). What they found is that the conventional wisdom is correct in some respects, but the story is more complicated.  I’ll just summarize the main findings. Tests were done on a single species of tropical flower mantid: Hymenopus coronatus.  Here’s a photo of a subadult female from the American Naturalist paper:

Screen Shot 2015-03-09 at 8.53.15 AMHere are the salient results:

  • Yes, the mantids do mimic flowers, but not necessarily a particular orchid. This conclusion comes from color-spectrum analysis of the insects and flowers filtered through what a pollinator (a bee) really sees. This shows that the mantid resembles the colors of a number of local flowers, but the authors weren’t able to find a specific orchid that the tested mantis resembled. (Note: they didn’t look all that hard.) But given their ability to find mantids sitting around on many flowers besides orchids, and even on vegetation, it’s likely that the mantis evolved to resemble a generalized flower rather than a given species of orchid. This makes more sense because a given species of orchid is not ubiquitous in the rain forests, and they flower irregularly.
  • Tests in which the researchers observed pollinators “inspecting” (deviating from a flight path to come closer to an object) a control object (a stick), a common species of flower in the area tied to a stick, and a mantid tethered to a stick showed that pollinators barely visited the stick, visited the flower moderately often, but visited the mantid most often (in fact, several instances of predation were observed).  This shows that the mantid by iteself is even more attractive than the flower, so it’s not simply hiding itself among flowers  to enhance its resemblance to a flower.
  • However, mantis sitting next to flowers got a higher rate of pollinator inspection than did solitary mantises, and the higher the density of flowers around a mantis, the more the mantis was “inspected”—and presumably the more noms it got. Therefore, although mantids can attract pollinators on their own, this ability is enhanced when they’re sitting amongst a bunch of flowers. Because solitary mantises seem more attractive to pollinators than are solitary flowers (implying that the mantids don’t have to hide to deceive the insect), this result probably reflects the fact that a patch of flowers simply draws more insects than do solitary flowers.
  • The authors tested, using a Y-tube, whether the mantids chose to go to flowers more often than to leaves, which would imply a form of habitat selection. They found no effect: mantids went down the “leaf” arm of the Y as often as down the “flower arm”.  So, though it may be adaptive for a mantid to be drawn to a group of flowers (because it gets more prey), that behavior hasn’t evolved. But a Y-tube test may not be the best way to test habitat selection, as it’s an extremely artificial situation.

So the conventional wisdom confirmed here is that the mantids do resemble flowers, fool predators that way, and can get noms by their resemblance. The conventional wisdom that was overturned is that these mantids resemble orchids, or a specific species of orchid. Also, the results don’t support the notion that the mimicry is imperfect, so that the mantids must hide among flowers to get any prey. They do get more prey when hiding among flowers, but that’s because more pollinators are attracted to large groups of flowers. Finally, the authors found no support for the idea that mantids seek out the flowers and hide among them. Because that behavior would seem adaptive, I’d like to see better tests, tests using, say, a large cage with flowers and leaves instead of a simple Y-tube choice experiment.

But, of course, lots of work remains. Did the authors miss an orchid that the mantis really resembles? Does the mimicry protect the insect from predation in addition to helping it find prey? Are there other cues that attract insects besides the color and shape of the mantis? It is possible, after all, that the insect has evolved pheromones, or a scent, that also attracts pollinators. Remember that the case of orchids that mimic insects to get pollinated (the reverse situation; deceived bees try to copulate with bee-mimicking orchids and, in the process, get pollen stuck to their bodies), those orchids have evolved a scent that mimics bee pheromones.

Finally, the photos above show that far more than color is involved in this mimicry. The mantids have developed elaborate petal-like extensions to their legs and bodies, as well as special markings, that also mimic flowers. The authors tested only color resemblance, but clearly the mantid also mimics the shape of flowers. It’s likely that a pollinator will be attracted to the general vicinity of the mantid by its color (bees don’t see that well!), and then make a final decision to approach more closely based on shape. That would impose strong selection on the mantids to look more like flowers.

h/t:Matthew Cobb

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References:

O’Hanlon, J. C.M.E. Herbersteinand G.I. Holwell. 2014. Habitat selection in a deceptive predator: maximizing resource availability and signal efficacy. Behavioral Ecology, online, doi: 10.1093/beheco/aru179.

O’Hanlon, J. C., Gregory I. Holwell, and Marie E. Herberstein. Pollinator Deception in the Orchid MantisThe American Naturalist, Vol. 183, No. 1 (January 2014), pp. 126-132

Readers’ wildlife photos

March 9, 2015 • 8:15 am

Reader Rick Mark sends us some photos of colorful nudibranches, which are shell-less gastropod mollusks. Rick notes that he loves nature photography, including birds and wildflowers (he produced a guide to wildflowers in an Indiana nature preserve as part of his master’s thesis).

I’m sending some photos of the bizarre life found in tide pools on the Oregon coast. I don’t think I’ve seen these represented in any of your wildlife photo contributions so far.
These are nudibranchs, which are sometimes called sea slug. I’m not really sure of the species identification, but I’ll take a shot.
A young friend of mine who is enthralled with marine biology told me that one reason he finds marine life so interesting is that species evolution in water is less restricted than it is on land. Since sea creatures just float, they can evolve a multitude of ways to locomote, so to speak.  I’d guess that each of these critters is about 1 to 2 inches long (3-6 cm)
Bi-colored nudibranch (Janolus fuscus)
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Sea lemon nudibranch or dorid (possibly Anisodoris nobilis) Wikipedia says: Sea lemon is a loosely-applied common name for a group of medium-sized to large shell-less colorful sea slugs or nudibranchs, specifically dorid nudibranchs in the taxonomic family Dorididae and other closely related families.
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 Nanaimo dorid (Acanthodoris nanaimoensis) seen from the side:
Nanaimo dorid side
Nanaimo dorid (Acanthodoris nanaimoensis) seen from above:
Nanaimo dorid top
Opalescent nudibranch (Hermissenda crassicornis) (may be up to 3″ in length)
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Ring-spotted dorid or leopard nudibranch (?) (possibly Diaulula sandiegensis) [JAC: It doesn’t resemble the species that goes by that name.]
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“Long River”

March 9, 2015 • 7:10 am

This poignant song, on Gordon Lightfoot’s best album, the 1965 “Lightfoot!,” resembles “Sixteen Miles” as a requiem for lost love in a cabin in the wilderness. But it’s not, as one reader has maintained, a clone of that song (that miscreant reader falsely claimed that all Lightfoot songs sound the same!). “Long River” was composed by Lightfoot.

Monday: Hili dialogue

March 9, 2015 • 4:57 am

I think I can announce with certainty that the worst of winter is over now. Temperatures will be above freezing much of the week, and although we may get some precipitation, it will likely be in the form of rain (which, I hope, will wash the grime and salt off my car):

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Meanwhile in Dobrzyn, Hili lays down the law to Cyrus (as if he didn’t know it already!):

Hili: Certain rules are obligatory in interspecies co-habitation.
Cyrus: What do you mean?
Hili: Rule No. 1: I’m always right.

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In Polish:
Hili: We współżyciu międzygatunkowym muszą obowiązywać reguły.
Cyrus: Co masz na myśli?
Hili: Pierwsza reguła, że ja mam zawsze rację.

Is ISIS full of “true believers”?

March 8, 2015 • 3:51 pm

You’ve probably seen or heard about the discussion between Sam Harris and Graeme Wood over at Sam’s website, a discussion called “The true believers.” Wood, of course, has become famous—and notorious—for his analysis of ISIS’s theological background in a piece that appeared in The Atlantic (see my post for the link). Wood’s thesis, which he supported by interviewing ISIS supporters outside the Middle East (the man is no fool and didn’t want to be beheaded), was that ISIS represents an apocalyptic strain of Islam, justified by the Qur’an, that aims to establish an ever-expanding Caliphate and longs for a final battle with the West, during which Jesus will appear and save Islam.

Wood was taken to task for the usual things: neglecting “other motivations” for ISIS’s behavior, failure to interview members of ISIS in the Middle East, and for his “un-nuanced” interpretations of theology. By and large, he took as truth what his subjects told him, and when that largely revealed religious motivations, the “Islamophobia-decriers” had to find reasons to discredit him.

In his long discussion with Sam, they go over these motivations again, and I recommend that you read the piece. I’ll highlight just three things:

1. Motivations: religious or otherwise? There is a slight disparity between Harris and Wood here, with Harris taking the religious motivations espoused by ISIS sympathizers at face value, while Wood says that some people might not be expressing other motivations, like resentment of Western colonialism. By and large, though, both men are on the same page; but Wood is a tad more cautious:

Wood: Yes. However, the countervailing current in social science is the tradition in ethnography and anthropology of taking seriously what people say. And this can lead to the exact opposite of the materialist, “root causes” approach. When Evans-Pritchard, for example, talks about witchcraft among the Azande, he’s describing exactly what they say and showing that it’s an internally consistent view of the world. This is something that anthropology has done quite well in the past, and it gives us a model for how we can listen to jihadis and understand them without immediately assuming that they are incapable of self-knowledge.

What I’m arguing for in the piece is not to discard either type of explanation but to remember the latter one and take the words of these ISIS people seriously. Even though at various points in the past we’ve ignored political or material causes, this doesn’t mean that ideology plays no role, or that we should ignore the plain meaning of words.

Of course, we don’t know what people actually think. Maybe they’re self-deluded; maybe they don’t really believe in the literal rewards of martyrdom. We can’t know; we’re not in their heads. But this lack of knowledge cuts both ways. Why do so many people instantly resort, with great confidence, to a material explanation—even or especially when the person himself rejects it?  It’s a very peculiar impulse to have, and I consider it a matter of dogma for many people who study jihadists.

Harris: Yes, especially in cases where a person meets none of the material conditions that are alleged to be the root causes of his behavior. We see jihadis coming from free societies all over the world. There are many examples of educated, affluent young men joining organizations like al-Qaeda and the Islamic State who lack any discernible material or political grievances. They simply feel a tribal connection to Muslims everywhere, merely because they share the same religious identity. We are seeing jihadis travel halfway around the world for the privilege of dying in battle who have nothing in common with the beleaguered people of Afghanistan, Syria, Iraq, or Somalia whose ranks they are joining, apart from a shared belief in the core doctrines of Islam.

. . . Again, the fact that most jihadis are generally rational, even psychologically normal, and merely in the grip of a dangerous belief system is, in my view, the most important point to get across. And it is amazing how resolutely people will ignore the evidence of this. Justin Bieber could convert to Islam tomorrow, spend a full hour on 60 Minutes confessing his hopes for martyrdom and his certainty of paradise, and then join the Islamic State—and Glenn Greenwald would still say his actions had nothing to do with the doctrine of Islam and everything to do with U.S. foreign policy.

I’m perfectly prepared to accept that some of these militants have motivations other than religion. Many may simply long for excitement, or to feel part of something larger than themselves. But what I’m not prepared to accept is that every one of them has nonreligious motivations. It’s curious to me—and this the one thing I think I’ve contributed to Sam’s thinking—that Western apologists like Greenwald and Karen Armstrong will question people’s motivations when they explicitly say their motivations are religious, but will not question them when they say their motivations are based on economics or resentment of Western imperialism. This is the double standard of Western liberals that so infuriates me.

2. So why the double standard? I think both men agree, and I agree too, that holding ISIS to standards different from those to which we hold, say, the Israelis, reflects a kind of paternalism: a tendency to give a break to people considered oppressed.

Harris: Do you have other ideas about why it’s so tempting for liberals to ignore the link between jihadism and religious belief?

Wood: There’s also a deep urge to deny agency to the Islamic State, and I think it’s fundamentally connected to a reluctance to see non-Western people as fully developed and capable of having intelligent beliefs and enough self-knowledge to express them. These people articulate well-thought-out reasons for what they do. And yet ignoring what they say somehow gets camouflaged in the minds of liberals as speaking up for them. It’s delusional.

I think this is on the mark, though liberals are notably reluctant to admit it, for it’s expressing a kind of reverse racism that they deplore. I consider myself a liberal, and am deeply distressed by the view that different groups should be held to different standards of behavior, with some groups excused or overlooked for performing barbaric acts.

3. The false notion of objective morality.  Wood’s interview with ISIS sympathizers convinces me even more that there are no universal moral truths.  Listen to what he says about some of his subjects:

Wood: Anjem Choudary is a fixture on Fox News. He talks to Sean Hannity, and many people would say that those two deserve each other. He’s known for screaming about the greatness and supremacy of shari’ah. But I had no interest in the screaming. Instead, I wanted details. We had a lucid, friendly exchange about what he believed a fully shari’ah-compliant caliphate would look like. I found him articulate, informed, and pleasant company in this regard. When I say “informed,” I mean he had answers to all my questions. They might not have been the right answers, but he was able to answer pretty much everything I could come up with about the Islamic State, about how it looks and why it’s so wonderful.

And he did this unflinchingly, even when he was endorsing what I would call rape or slavery—what even he would call slavery, in fact. This was not a tough call for him. If he has any compunction about these practices, it was completely undetectable. That was not true of some others I’ve interviewed who have literalist views of Islam. To be in the presence of someone who can say, in this modern day, that slavery is a good thing and that to deny its goodness is an act of apostasy was a very unsettling experience.

Most moral objectivists would say that slavery is objectively wrong. I say it’s “wrong” because a society that condones it is a dysfunctional society that promotes the subjugation and unnecessary suffering of individuals. But Choudary would say it’s fine, justifying it on Quranic grounds, or even on consequential grounds. How do you convince someone like him that he’s objectively wrong? Such people appeal to divine sanction, and although you can say that there is no god, and he should be appealing to something else, the fact is that many people hold religious dogma as the arbiter of morality.

I have seen attacks on the internet of my views that there are no objective moral truths, but I don’t find them convincing. Slavery is an example that most reasonable people would agree on, but there are other and harder issues, like abortion, that defy any objective “moral solution.” One must, at bottom, express some kind of preference, like for “overall well being,” that can be neither quantified not objectively justified.

 

An anti-Semitic good morning for Professor Ceiling Cat

March 8, 2015 • 1:58 pm

When Robin Ince asked me last night (offstage) what was the most common trope in the hate mail I get about religion or atheism, I had to think for a minute, and then decided it was stuff calling attention to and making fun of my Jewish background: phrases like “dirty Jew” and the like. Coincidentally, when I got to work this morning, I found this lovely email waiting for me—from one “Nathan Hull”:

Mr [not Professor]* Coyne
“Your” people have been stealing University spots from Asian-Americans and others for decades. That girl’s spot should have been taken by a Chan or Singh (or even a Khan). It’s time that US colleges stopped taking bribes from stockbrokers to allow their mediocre offspring onto campuses to waste billions of dollars that should be spent on more deserving people.
*you’ll get your title back when you stop whining (and posting videos of cats eating watermelons)

I presume that by “that girl” he means Rachel Beyda, the UCLA student who was initially rejected for a post on the UCLA student judiciary committee because she was Jewish.

Can there be any more stereotypical view of Jews than to call them “my people,” to imply that Jews are somehow buying their way into college campuses, and that there are inflated Jewish quotas on campuses. I’m sure at least one reader will be thinking that is is a joke, but really—who would try to make a joke like that?

Well, this person is a vile anti-Semite, though I don’t need reminders that these sentiments are alive and well. But they don’t much bother me, because I’m not upset by invective from loons like this. But what really stings is the comment on cats!

Readers’ wildlife photographs (and a video)

March 8, 2015 • 12:40 pm

For sheer colorful splendor, no animal beats the tropical hummingbirds. They’re like tiny animated gems, and are adorable. I had the pleasure, as a grad student, of mist-netting some of these in Costa Rica (you have to get them out of the nets quickly, or they die from starvation or dehydration), and of holding their tiny bodies in my loose fist, feeling their hearts drumming a mile a minute.

Reader Bruce Lyon sent a bunch of hummingbird photos, and I’ll put up only a few today:

On my annual family trip to Costa Rica I spent a couple of days at Monteverde, a cloud forest site well known to both biologists and tourists. Cloud forest and the wet montane habitat just downslope of cloud forest have a very high diversity of hummingbirds. The single hummingbird feeder at the place we stayed at attracted seven species, often at the same time. At times up to thirty individual birds were visiting the feeder or were perched very close by waiting for their turn. All of the photos here were taken with a Canon 6D body and a F4 500 Canon lens with a 1/4 X teleconverter.

My daughter Fiona took this photo of a swarm of hummingbirds at the feeder:

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The cloud forest viewed from our front porch:

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The most common hummingbird species around the feeder was the Green Violet-ear (Colibri thalassinus):

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Green Violet-ear coming in for a landing. Hummingbirds have favorite perches so one can prefocus on a favorite perch and get nice shots of landings:

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Green Violet-ears are pugnacious and constantly fight and chase each other. Much of the fighting seems to be who gets to use high quality perches closest to a feeder. Here two birds squabble over one of these favored perches. During fights, violet-ears often flare out their ‘violet-ears’—as the individual clinging to the perch is doing—which suggests to me that these plumage patches are likely to serve as social signals that convey information either about motivation to fight or fighting ability:

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Violet-ears also use squinting a threat display. Is this the avian version of ‘stink eye’?:

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More awesome hummers to come.

Moving southward, reader Pablo Flores sent a video and some photos he took during a recent trip to northern Chile. First the video, from Patagonia:

Here are a couple of Magellanic Woodpeckers [Campephilus magellanicus], first a male (head all red) looking for a grub, then a female (some red around the beak) getting fed. They are in the branches of a lenga beech (Nothofagus pumilio). The Nothofagus genus is interesting from the biogeographic point of view: you can find it in southern South America and in Australasia, and there are fossils of it in Antarctica: a sure sign that it originated when all the southern continents were joined.

Here are a couple of vicuñas (Vicugna vicugna). These are wild relatives of the llama. According to Wikipedia, “The Inca valued vicuñas highly for their wool, and it was against the law for anyone but royalty to wear vicuña garments”.
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The second picture shows a couple of Andean geese, locally known as “piuquén” (Chloephaga melanoptera).
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The third shows an Andean flamingo, locally “parina grande” (Phoenicopterus andinus), one of three species of flamingo that can be found in Chile. These pictures were all taken in a small high-altitude patch of wetland in the otherwise extremely arid Atacama Desert, at about 4000 meters above sea level, last January.
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