In two new species of rare giant stick insects, males turn livid blue or multicolored at sexual maturity — but why?
Frontiers
Biodiversity hotspot Madagascar is one of the world’s biggest islands, and home to some of its biggest insects. Now German scientists have discovered two new species of giant stick insect, living only in the dry forests of Madagascar’s northernmost tip.
One giant female measures a whopping 24cm – but it is the smaller males that are most striking. At sexual maturity these daredevils abandon their stick-like camouflage for dazzling blue or many-colored shining armor.
Writing in Frontiers in Ecology and Evolution, the researchers describe their rare and exciting findings, and wonder at the reproductive success of the least stick-like stick insects on the planet.
When two become four
“Nearly all of the 3000+ known species of stick insects try to be inconspicuous and just look like twigs,” says senior author Dr. Sven Bradler of the University of Göttingen, Germany. “There are a very few, very large exceptions – and we have just discovered a couple more of them.”
The authors re-examined specimens they’d previously identified as odd-looking examples of two existing giant stick insect species, whose adult males remarkably are bright blue or multicolored.
“These were similar in size – 15 to 24cm – but generally less spiny and a bit differently colored than typical examples of their kind,” explains Bradler. “Now genetic tests confirm that the quirky individuals are in fact two new species, distinct from the original two but part of the same group.” explains Bradler.
Bradler’s reclassification places members of this group of species as close evolutionary relatives to other Madagascan stick insects, rather than cousins from overseas as previously thought. This is a potentially major finding, as it challenges the prevailing view that sticks insects colonized Madagascar multiple times.
He who dares, wins
The discovery also prompted the researchers to wonder: what reproductive advantage do these males gain from their bright colors, that is worth exposing themselves to predators?
The first author Dr. Frank Glaw of the Bavarian State Collection of Zoology in Munich, and colleagues bred the new giant stick insect species in captivity to observe their behavior.
“Males of one species started mating attempts only when they achieved their bright blue color.”
This might suggest that the males use their bright coloring to attract a mate. However, it is hard to believe the males could find a mate before being eaten – unless their bright coloring acts as a deterrent to predators.
“Males searching for a mate have to move about more, so pretending to be a stick becomes tricky. Better perhaps to plump for the opposite: a brightly colored warning.”
Bright colors – suggestive of toxicity – keep safe vivid members of other typically camouflaged species, like lividly colored Madagascan frogs.
“In support of this, all stick insects have neck glands that repellant substances, and these are typically well-developed in brightly colored species. Alternatively, like the Madagascan frogs some giant stick insects may have developed the ability to accumulate toxins from their food.”
But testing these hypotheses will be tough, admits Glaw.
Bradler adds “More than one factor may have played a role in the evolution of this remarkably conspicuous coloration. So even with more data on mate selection, habits, predators, natural food plants, toxins produced by defense glands and possible accumulation of toxins among giant stick insects, finding evidence for these ideas may prove difficult.”
Colorful stick insects have a bright future
Whatever its function, the splendid coloring of the male giant stick insects could make them a strong flagship species to promote the unique biodiversity of Madagascar, and the need for its protection.
“Already the once-uncertain future of these two new species seems secured, with their forest habitat in northern Madagascar a hotspot for conservation priorities,” says Glaw. “It is vital to maintain awareness and motivation to keep logging at bay. This precious area also harbors the highest density of critically endangered reptiles in Madagascar and is home of one of the most threatened primate species in the world, the lemur Lepilemur septentrionalis.”
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Original research may be found at this link: https://www.frontiersin.org/articles/10.3389/fevo.2019.00105/full
Frontiers is an award-winning Open Science platform and leading Open Access scholarly publisher. Our mission is to make research results openly available to the world, thereby accelerating scientific and technological innovation, societal progress and economic growth. We empower scientists with innovative Open Science solutions that radically improve how science is published, evaluated and disseminated to researchers, innovators and the public. Access to research results and data is open, free and customized through Internet Technology, thereby enabling rapid solutions to the critical challenges we face as humanity. For more information, visit http://www.frontiersin.org and follow @FrontiersIn on Twitter.
From EurekAlert!
Hardly a mystery.
Any species in other places that evolved such a colouring got eaten.
It seems in Madagascar that being bright blue is not getting you gobbled up before you can mate and produce more blue progeny.
And it is the female usually doing the eating, after “coitus”, esp in the insect/arachnid world.
Thank Gaia we’ve got an exciting new endangered insect species to keep logging at bay! Should keep multiple researchers in funding to study the all-important eating and mating habits of the stick insects. It’s going to be very difficult to test the new theories and so logging will need to be blocked for two or three decades at least!
EurekAlert! Ridiculae
theyre always so stingy with pictures;-(
In my male youth, maturity was advertised via Brylcreem. What is new? Geoff
I thought that stuff was banned in the 70’s, 1970’s!
A little dab will do ya
Madagascar doesn’t need protection, it needs industry, investment and cheap energy. The last thing the people of Madagascar need are Ecofascists interfering in their affairs, their economy and their society.
Here’s something related:
https://www.upi.com/Science_News/2019/04/02/Fairy-wrens-with-colorful-feathers-arent-more-vulnerable-than-duller-peers/8371554239964/?ts_=19
“These findings do not support the long-standing hypothesis that conspicuous plumage, in isolation, is costly due to increased attraction from predators,” researcher Kristal E. Cain said in a news release. “Our results indicate that conspicuousness interacts with other factors in driving the evolution of plumage coloration.”
end excerpt
How many of these insects’ predators can see in color? I had thought that a great many animals, including insects, are actually colorblind (though how we can tell, given the insects’ reluctance to undergo colorblindness testing, is a good question). Of course, not all predators are colorblind; but if enough of them are, that could give these bright blue creatures a break in the predation sweepstakes.
John – Most vertebrates, even fish, and any diurnal insects with well developed compound eyes are likely to have good to moderately good colour vision. Nocturnal animals tend to have poor colour vision (or so I’ve read), but B&W and grey scale are human technological artefacts (remember: Do you dream in black and white?). Diurnal birds have especially good colour vision and are likely the most important predators of large stick insects. Where I live a hawk (Crested Hawk) is a specialist on stick insects (and the males stick insects here are not colourful – except on their wings that they flash at a predator to try and scare them off) and even medium small birds like Grey Butcherbirds take stick insects not much smaller than themselves. Stick insects can be very large.
Tom Abbott: Another garbled press release: “Evolutionary biologists remain divided over the evolutionary origins of colorful plumage among female birds, but most assumed bright feathers increased the risk of being eaten.” IN birds in general and it Fairy Wrens in particular it is the males that are colourful and the females and immatures that are drab. I don’t think anyone really doubts why this is so.
Odd that Lemurs, and Stick insects seem to hit the headlines, when
https://reliefweb.int/report/madagascar/madagascar-humanitarian-snapshot-19-january-2018
161,000 affected people by the tropical cyclone Ava in Jan 2018
Cyclone Enawo in early 2017, 434,000 people were affected
15,000 displaced people (as of 17 January 2018)
810,000 people at risk of food insecurity
Pneumonic and Bubonic Plague :
2,603 cases (August 2017 to January 2018)
*225 deaths (August 2017 to January 2018) *
Article excerpts:
“DUH”, might suggest!!
Me thinks the author was simply trying to entice the “clueless” to read his/her writing.
If the males of a species turn a livid/bright color and start “strutting” their stuff at sexual maturity …. they sure aren’t prepping for hibernation or a vacation.
Being “inconspicuous” doesn’t ALWAYS mean they are trying to hide from their predators ….. because most predators try their bestest to be “inconspicuous” to their prey animal. Thus, the question is, what do the stick insects feed on?
Most predators are “creatures of habit” and maybe the bright colored stick insects are not on their “menu”.
When I was a young boy I found a small patch of “yellow” raspberries which were really great tasting. The birds would not eat them and I figured out why, …… the birds were waiting for them to ripen (turn dark bluish-black). .
That’s a problem the birds answered millions of years ago.
The males are brightly coloured because the females like them that way.
Like Boy George? What’s that song…?
In the human species, males displaying large amounts of money have been shown to increase their mating advantage.
Creepy crawlies might be fascinated, they appeared n millions years before the feeble anthropoids, and I assume they will be still going strong another n millions of years long after we have been exiled to another planet by the ‘catastrophic global warming’.
In order to facilitate our exo-planet exit NASA is rejuvenating their space flights technology.
Few days ago NASA announced: “Among the many topics discussed during our meeting at the U.S. Space and Rocket Center in Huntsville, Alabama, was to accelerate our return to the Moon:
NASA is charged to get American astronauts to the Moon in the next five years.
We are tasked with landing on the Moon’s South Pole by 2024.”
It should be of interest to NASA that the SC25 will peak somewhere around 2024/5 and our solar supreme dr. Svalgaard is predicting that SC25 will be considerably stronger than the current SC24, which might require stronger solar radiation protection for the ‘lunanauts’ (don’t the ‘astronauts’ travel to stars?)
Perhaps the NASA expects the SC25 max to be low?
vuk, this ‘nauts don’t need to go “astro” – thei’re already at the preferred solar system like all of us.
And don’t have to search for a discreet planet when starting from planet earth.
Just have to hop to Luna.
Wish them luck.
Read any pickup blog. For casual sex, males need to standout out from the crowd. Bright colors help human males attract girls. They call it “peacocking.”
All females like flamboyant males. This is cross cultural and cross-species.
Males can be flamboyant in many ways: Size, color, noise, dances, songs, and so on. The male needs to impress the female. Nerdy human males try to impress girls by being clever. Some even write love letters and poetry, but, let’s not dwell on such forms of self-debasement.
Only when males are going to invest in the female and her brood do dull males get to breed. The “family” guy who fixes stuff around the house. Just look at crows vs. peacocks.
This is cross species.
Human females will often deny this obvious fact.
There’s an old joke regarding this:
A man sits next to a good looking woman sitting alone at the bar.
To begin casual conversation he asks her, “So, what’s your sign?”
She replies without even glancing at him, “Dollar”
Call it a “sign” if you want to, …… but the females determine the “picking order”.
It is an obvious fact that local groups of females assign a per se “picking order” among the available males within their locale ….. and then all the females compete with each other for the male that has the best physical attributes and the “alpha” female gets the “alpha” male, …… and then the 2nd best “alpha” female gets the 2nd best “alpha” male, … and so, …. and so forth, ….. until everyone gets paired up that wants to get paired up.
But the female’s inherited instinct to procreate with the best male for fathering her offspring will cause many females from the 2nd best “alpha” female down to the least desirable female to want to breed with a “higher ranking” male than the “dull guy who fixes stuff around the house” that she ended up with as her husband.
Boy, now there’s a good resource to get accurate information. Pickup blogs. ROTFLMAO!
I admit, when I first happened onto such a blog, I thought the information/opinions were silly, if not offensive. Years later, I have decided these pickup artists are careful observers of humans and their reproductive behavior.
For example, there was a recent story, I think in China, of a woman giving birth to twins. Turns out, one of the twins was from her husband, the other from a “one night stand.” The pick up artists say this is not that uncommon. A woman cheats on her husband, and then makes sure she has sex with her husband, just in case she gets pregnant from the one night stand. Hiding her tracks, so to speak. BTW, popping two eggs, not one, may be the result of the increased excitement due to her illicit behavior.
So, like everything on line, read it with skepticism but rejecting it outright is probably unjustified.
It’s also a wealth of material if you’re into sociology.
…and China is a font of accurate information. 🤣🤣😂😅🤣
You prefer University of East Anglia, Pamela? 😛
When you think about it, provided your desired information is actually about human male/female sexual socialisation, pick up blogs are very logical places to investigate.
Remember they are free market fonts of knowledge. Excluding us ‘research only’ types the main traffic at these sites are going to be people seeking the wisdom of the writer so they can put their new knowledge into practical application.
If the advice works? They come back for more advice.
If the advice fails? They give up, move to the country and devote the rest of their lives to studying newts.
Hence the more popular ‘advice’ sites are likely, mocking aside, to be the ones that actually know their topic. Remember we are talking about ‘picking up’ here, which is the in built mammal instinct to get a bit of hot rumpy pumpy because let us be pragmatic here, we are MEANT to enjoy sex. Face it, if we didn’t enjoy sex the entire human race would have died out back at Generation One.
Now before everyone gets their Prude on, remember that the desire to enjoy a bit of rumpy is different from the parenting motivation that drives us to seek long term relationships and implement the pitter patter of tiny feet within your household, and people who are honestly looking out for the mother/father of their future children VERY RARELY go looking in bars. So we are talking here about the causal short term attraction process that revolves around not only making a good first (or only) impression on the other partner, but also being able to focus the attention of this other partner long enough for this first impression to take hold.
So are you here to show someone your deep and layered personality, to mention the happiness you receive from spending time cooking, expanding your shared understanding on the wit of Dickins compared to Wodehouse and being a good listener?
Grud No. You are picking up. Hey Gal, stop looking at these soy boys and cast your eyes on this glorious hunk of Man commonly referred to as ME! It’s attract the attention, dismiss the idea of competitions and complete the entire relationship before she discovers the other room in your pad is actually filled with your collection of Fallout bobbleheads.
Pick Up artists study the base level of human social interaction because that it their bread and butter. In context they are a completely valid source of information.
joel – April 3, 2019 at 7:35 am
The dull male who fixes stuff around the house get to engage in physical sex with their wife ….. but the question of whether or not they get to breed can only be determined by a DNA test.
Like they say, …
“Mommy’s baby, …. Daddy’s maybe, … and sometimes Mommy doesn’t know for sure”.
Hmmm. I’ve always relied on my rugged good-looks and roguish charm.
Stick insects may also, or more so, be camo-like so they can catch more unaware food. To prevent being eaten by a higher up animal may not be the main reason for their camo. Think Arctic fox and Arctic rabbit. One is white to sneak up on prey. One is white to prevent being eaten.
When I was in Thule for a month or so in the summer of 1961 I was told by some old timers ( those who had actually spent a winter there) that the Arctic hare was more aggressive than the fox and was more likely to eat the fox than the other way around. Only heard it that one time so it may be just a story for gullible newbies though.
Regarding blue, at night and early morning we seem to catch more salmon on blue glow lures. Why, I dunno, but I think blue can be seen at the furthest distance, at least undrwater. Maybe red represents danger, poison frogs and yuccky tasting stuff like ladybugs seems to be mostly red.
My genitals turned a livid blue when I reached sexual maturity, but I suspect for a different reason.
Brightly coloured adult males would usually be interpreted as sexual signalling. This would be more important than camouflage for short-lived males – if they don’t mate then their genes won’t be in the next generation. Bright colours can signal (sometimes deceitfully) bad taste, but usually aposematic colouration is strongly contrasting – e.g. black and yellow, red and black – and females would be similarly coloured. In my backyard birds are successful predators of cryptic stick insects, so brightly coloured morphs might be more easily seen, but neophobia may play a part. Like kids, most predators are more likely to eat something they already have eaten and liked before, then eat something new and possibly yucky.