Lots of animal species have males with weapons to fight each other—invariably over females or territory, which is a proxy for mating success, But I wasn’t aware until now of a species whose males grew their weapons only during the breeding season, and then shed them. (I may be wrong here, and I’m sure a savvy reader will correct me if I am. Deer, of course shed their antlers and regrow them each year before the breeding season, so this may be a similar phenomenon.)
But the spiny facial protrusions of the Emei moustache toad, Leptobrachium boringii, studied and described in a new paper in PLoS ONE by Cameron Hudson and Jinzhong Fu, clearly represent a case of evolution promoting the development of weapons only when they’re needed, and then discarding them when they’re no longer needed. This is a great case of developmental plasticity over the mating season. (The paper is free online; reference and link below.)
Meet this bizarre amphibian:
Two males from a Facebook photo:
Those spikes on the snout are produced only in males, and last only 2-3 weeks during the breeding season. According to the paper, the males use them when fighting, head-butting each other in battles over nest sites and females. In a “news and views” on the article at New Scientist, first author Cameron Hudson notes that, “During the breeding season, each male grows 10 to 16 spines. “They are as sharp as a pencil lead,” says Hudson, adding that the frogs “do try to stab you a bit when you pick them up”.
The New Scientist piece also has a short video clip (I can’t embed it) showing how the males fight; do watch it. The fights often result in injuries when the males stab each other in the head and flanks, though the authors never saw or found a toad killed this way.
The toad lives in Szechuan, China, and males have a mean size of about 75 mm (3 inches), while females are about 12% shorter and 46% lighter. The males build nests in fast-flowing streams, and thereby attract females. Females are apparently fertilized while visiting the nests, and then hie off back to the forest while males remain in the nests, guarding the clutches of eggs until they hatch.
The results of the paper aren’t earth-shaking; I’m putting up this post mainly because the beast is so weird. The authors found that males can take over other males’ nests, though nest possession isn’t correlated with body size (that may reflect only small sample size).
The most interesting result is from DNA analysis, showing that the eggs guarded by a single male can actually be fathered by several different males. That almost certainly reflects males taking over the nests of other males after head-butting contests. There were also cases of single clutches of females having eggs from more than one father, implying multiple insemination of individual females.
Why do the males guard the eggs of other males? That would seem to be maladaptive, because you’re protecting the genes of rivals. Well, there’s no cost to doing that, so you’re not expending more energy. Still, you’re protecting genes that will compete with your own. Clearly the optimum adaptive strategy for a male would be to immediately destroy the eggs of another male when taking over his nest. (This is analogous to male lions who, when taking over a new pride of females, kill all the cubs and then inseminate the females to produce their own progeny.) But perhaps these toads don’t have the ability to do that, or perhaps there’s no way for them to distinguish between their own clutches and those of other males. This study was a short one, but is ongoing, and maybe we’ll have some answers later.
In the meantime, here are two pictures from the PLoS ONE paper, showing the spines in their full glory as well as when a male has shed most of his spines after the breeding season:
_________
Hudson, C. M., and J. Fu. 2013. Male-biased sexual size dimorphism, resource defense polygyny, and multiple paternity in the Emei Moustache Toad Leptobrachium boringii. PLoS ONE 8:e67502 EP.
Reblogged this on Mark Solock Blog.
What a crime that such an interesting toad has the word “boring” embedded in its name, Leptobrachium boringii 😉
“Deer, of course shed their antlers and regrow them each year before the breeding season, so this may be a similar phenomenon.”
Why WOULDN’T it be a similar phenomenon?
Antlers grow at the beginning of rut, and are shed after rut is over. If it were not a similar phenomenon, why does it coincide with breeding season? L
Almost all species of birds moult at least annually, usually after the breeding season. This resulting covering of feathers, which will last either until the next breeding season or until the next annual moult, is known as the basic plumage. Many species undertake another moult prior to the breeding season known as the pre-alternate moult, the resulting breeding plumage being known as the alternate plumage or nuptual plumage. One example is the Ruff. (https://en.wikipedia.org/wiki/Ruff)
Many species of bird, particularly ducks. have bright, colourful plumage to attract females. Some, however, moult into a dull ‘eclipse’ plumage after breeding in mid-summer. When they shed feathers to go into eclipse, the ducks become flightless for a short period of time. Some duck species remain in eclipse for one to three months in the late summer and early autumn. The eclipse plumage is often retained until the next spring when they undergo another moult to return to their breeding plumage. Two examples of eclipse plumage can be found in the Mandarin Duck (https://en.wikipedia.org/wiki/Mandarin_Duck) and Red Junglefowl (https://en.wikipedia.org/wiki/Red_Junglefowl).
While compiling my comment about breeding plumage, I was reminded that several species of bird also develop breeding beaks or bills. Three that spring to mind are Puffins (http://en.wikipedia.org/wiki/Puffin), Pelicans (http://en.wikipedia.org/wiki/Pelican) and Hornbills (http://en.wikipedia.org/wiki/Hornbill).
In Hornbills, the female, with the assistance of the male, will seal herself inside the nest hole with mud, leaving just a small opening. Once the eggs are laid, the female undergoes a complete moult.
sub
How about salmon and trout jaws?
That’s pretty cool!
Reminds me a bit of the Letherii turtles in the Malazan series.
If anyone is interested: http://tinyurl.com/mwkr9nb Turtles with opposable (WHY is Chrome insisting that is misspelled???) thumbs, males only, who guard the floating nests on their long journey to the ocean. The most amazing fantasy series I’ve had the pleasure of reading.
Yet another critter that looks like it belongs in a Jim Henson production….
b&
As a young girl, I was so fascinated with the Skeksis of ‘The Dark Crystal’. There was something beautiful about them…
As far as I’m concerned, Henson was every bit as brilliant a sculptor as Rodin or any other master. And Henson’s sculptures move and talk!
b&
I think I saw those on the insomnia cable channel. Only they were going for world domination or something.
What is going on with our species, I belong to an older generation, but by observing newer generations it seems as if it is the females fighting for the male, a good example the astronaut girl who drove with a diaper on not to have to stop, on her way to get rid of her rival.
At the risk of sounding like a broken record, here is yet another phenomenon that makes perfect sense in the light of evolution, and which is entirely inexplicable in creationist terms.
Wait, I just thought of a creationist explanation: the
godcreatorintelligent designerangry wizard in the magic garden (thanks, Ben!), noticing that the two naked people had eaten a poisoned apple given to them by a talking snake, got all huffy (he is a bit full of himself, isn’t he?) and cursed the whole universe. Part of this was to give the Emei moustache toad males horns that would only appear at mating time, so that he could watch while they fought over females, with the winner getting to make “the toad with two backs” (or however toads do it), thus showing himself to be a vicarious sexual gladiator.It’s a Ray Comfort video, just waiting to be made! Alert Ken Ham–evidence for creationism!
This is actually quite common. For example, in a great many cyprinid fishes (the family of carps and minnows)the males’ heads are covered in spiny-looking “breeding tubercles” which are then cast off after the breeding season. Ageniosid catfishes develop a bony, elongated structure on their dorsal fin spine that apparently aids in holding the female during spawning, and perhaps may also play a role in sexual display (not sure about the display part, but it is certainly conspicuous enough to people). Then there are the sexually dimorphic teeth of many elasmobranchs (sharks and rays) in which the males have pointy teeth the better to grab and manhandle their mates during intercourse, but these may be present all the time, not just during peak breeding season.
Despite the notable and numerous examples of seasonal sexual acoutrements, this frog rocks them all.
Now if anyone wishes to assert as a fact that this creature was “created” by some “intelligent being”, I would only ask that he replaces intelligent with ” bloody weird”!
Amazing creature….but at the risk of being pedantic, isn’t it quite inappropriate to label this as a “freak of nature”? I can see how this term would be justified for developmental abnormalities such as Siamese twins, two-headed calves and so on, but that’s not what we have here. The spiky upper lip of the male toads is a normal feature for the species, presumably shaped by natural/sexual selection, and therefore in no way “freakish”. If these toads could answer back, they might label our large brains or bipedal posture as “freakish”, and they’d be just as wrong for doing so.
I think that this phenomenon is driven almost exclusively by the female . She selects males with dangerous impediments who spar for her attention. She gets the fittest gametes by the gladiatorial arrangement and if some males are injured or die in the process so much the better for her offspring if the weaker males don’t survive. The female is not likely to select males that kill her embryos. If this process is slightly detrimental for her male offspring, it is offset by the fact that enough of her female offspring will thrive and perhaps a few male offspring will father a multitude of offspring. In other words, since the female seems to be holding the cards, ask what ‘s in it for her to establish this arrangement and not be so concerned with the male perspective because the selective pressures are determined by the female. So long as the male conforms to the whims of female selective pressure, he may have very little to “say” about how he evolves. Food for thought.
Great post. Males guarding several clutches with different fathers is actually reasonably common in fish, IIRC. Several explanations have been offered, including 1) the male can eat some of the eggs if he gets hungry, so the more he has the less likely he is to eat all his own; 2) females are attracted to males who already have eggs in their nest/territory, so actually stealing eggs can be adaptive; and 3) the unrelated eggs were fertilized by “sneaker” males that dive-bombed the pair when they were spawning. I guess not all apply here, but it’s not that unusual.