by Becky Crew
As part of the investigation, Wueringer compared the young sawfish’s abilities to that of giant shovelnose rays (Glaucostegus typus) and eastern shovelnose rays (Aptychotrema rostrata), a pair of Australian species of ray with broad, triangular snouts that give their bodies a strange arrowhead look. In stark contrast to the agile and precise movements of the sawfish, the shovelnose rays were a mess. Wueringer reported that “[they] repeatedly bumped into and spiraled around dipoles suspended in the water column, in an uncoordinated fashion.”
While sawfish have now been identified as the only jawed fish known to use their rostrum for both detecting and manipulating their prey, the appendage that gives them all their powers has also led to their devastating global decline. Their saws are just the right shape for getting accidentally caught in fishing gear, especially if they target the fish caught inside, but Wueringer hopes that research such as hers will lead to better conservation methods in the future.
A hushed silence descended on the room. Miss Scarlett checked her perfectly curled hair, twisting a strawberry blonde ringlet around a trembling finger tipped in carmine polish. Professor Plum tapped at his stalled pocket watch distractedly, muttering “Damn thing’s never worked properly” to no one in particular. Mrs. Peacock shot him a glare from across the dining room table.
The door to the study swung open suddenly and Colonel Mustard stormed out, yanking a pipe from the breast pocket of his custom-made yellow tweed suit. A disheveled detective followed him out, stripped down to his undershirt and suspenders, his brow glowing with sweat. “Okay, Mrs. White, your turn.”
Mrs. White was not coping well. The conditions in the mansion’s kitchen were wreaking havoc on her health and the stress of the situation wasn’t helping. She clutched her mother’s brooch in her apron pocket for comfort as she entered the study. The detective closed the door behind her and told her to sit down.
“Look, Mrs. White, I’m going to make this quick,” said the detective, standing over her with a knowing air. “I’ve ruled out every possible scenario, except one.”
“And what would that be, Detective?” Mrs White asked, removing her wilted bonnet.
“It was you, Mrs. White, with the revolver, in the conservatory.” The detective triumphantly snapped his notebook shut.
“What? Me? I never!”
“Save it, Mrs. White, it can’t possibly have been anyone else.”
“What are you talking about? The sawfish gardener was here the whole time! Why aren’t you interrogating him?”
“I have my reasons, Mrs. White. We’re going down to the station.”
The detective put her in handcuffs to the astonishment of the remaining guests. The sawfish gardener watered the indoor palms in silence.
“I knew it!” Reverend Green declared, knocking his chair to the floor as he rose.
“Reverend! Some decorum, please!” exclaimed Mrs. Peacock.
“Show’s over, everyone’s free to leave,” said the detective, dragging the raving cook out of the room.
“Fools! You’ve got it all wrong! It was the sawfish, look at him! Look at that saw! You’re all mad! Mad!”
“Please, Mrs. White. The sawfish? Impossible! Everyone knows he only uses it for detection.”
PART TWO
LOVERS AND FIGHTERS
All-Female Lizard Tribe
WHIPTAIL LIZARD
(Leiolepis ngovantrii)
“Look, for the last time, we’re not angry lesbians! We just considered all of the options and it makes more sense for us to reproduce on our own!”
“Ha! I told you she’d yell. You owe me fifty bucks.”
IN 2010, A FATHER-SON team of American researchers announced their discovery that a popular Vietnamese lizard dish featured a species completely unknown to science. And these handsome lizards, with thick, grey skin decorated with tessellated brown and bright yellow spots along their backs, turned out to be particularly special, because they reproduce via parthenogenesis—a form of asexual cloning.
Named Leiolepis ngovantrii, after lead researcher and herpetologist Ngo Van Tri from La Sierra University in Riverside, California, these lizards belong to the 1 percent of lizards and 0.1 percent of vertebrates that have done away with the need for sexual reproduction. Earlier in 2010, molecular biologist Peter Baumann from the Stowers Institute for Medical Research in Kansas City, Missouri, who was working with a different type of asexual lizard, figured out exactly how it’s done.
The whiptail lizard family from North America and Mexico contains some fifty species, one-third of which are all female. In the 1960s, professor of medical science William B. Neaves from the Stowers Institute ran a genetic analysis of lizards from the Leiolepis genus in the whiptail family. Looking at the results, he suggested that all-female whiptail species came about through a hybrid cross between a female of one sexually reproducing species and a male of another. Prior to this discovery, it was assumed that the males of these species were super-elusive—no one had imagined that they simply did not exist. “We now know that at least in vertebrates, interspecific hybridization has given rise to most, if not all, unisexual species,” says Baumann.
What wasn’t clear from these initial studies is how the hybrid she-lizards were able to maintain the diverse mix of genes from their parent species, which allowed them to survive and produce healthy offspring for several thousand generations over an extensive geographic area. Species with clonal offspring lacking any genetic material from a male parent often have very low genetic diversity, which can result in poor adaptability and vulnerability to disease because these genetic weaknesses have no chance of being overridden by new genetic material from a mate. Many hybrids, such as the mule, turn out to be sterile. But somehow whiptails have managed to overcome this fundamental problem in asexual reproduction to produce healthy offspring at a rate identical to that of sexually reproducing species. “In our experience, the reproductive success is very high and indistinguishable from sexually reproducing lizards,” says Baumann. “This is quite different from some arthropods where the hatch rate of parthenogenetically produced eggs is only 10 percent.”
Baumann and Neaves developed thirty microsatellite markers—specific pieces of repeating DNA that are used in genetic studies to identify parentage and kinship—and found that there was considerable variability in these pieces of DNA across species in the Aspidoscelis genus of the whiptail family. This variability appears to allow mutations to occur, which ensures the robustness of the asexual lizards. And how they achieve this variability through cloning is nothing short of genius.
In sexual reproduction, each parent contributes half of its chromosomes to their offspring. The random combination of the parents’ chromosomes results in the offspring having a complete and unique set of chromosomes. Reporting in a 2010 issue of Nature, Baumann and Neaves described how the process of meiosis (where the number of chromosomes are halved in order to create an animal’s egg or sperm cells) in asexual whiptail reproduction begins with cells containing 92 chromosomes—twice the number of their sexual peers—resulting in eggs containing 46 chromosomes. So while eggs from sexual species end up with just 23 chromosomes, whiptails have figured out a way to pass on an adequate amount of genetic material despite the fact that their eggs are never fertilized. “We are now trying to understand the molecular events that result in premeiotic doubling of chromosomes,” says Baumann. “One can speculate that there is something in the genetic makeup of these animals that predisposes them to activate parthenogenesis upon hybridization. We would like to know what that is.”
It is still unclear what triggers the reproductive process in the whiptails, but there has been some speculation that a behavior called pseudocopulation, which involves two females mounting each other to stimulate egg production, is required. But Baumann remains skeptical of this, pointing out, “When we keep a unisexual lizard by herself from the day she hatches out of the egg, she will produce just as many or more offspring than lizards housed in groups.”
At this stage, it is unclear whether the all-female whiptails will some day in the future become a sexually reproducing species once more through another round of hybridization, resulting this time in sexually reproducing offspring. But if they do remain parthenogenetic, they might have the success of other parthenogenetic species such as the bdelloid rotifers. These near-microscopic aquatic animals, or “evolutionary scandals,” as Baumann puts it, have survived as unisexuals for many millions of years and have even radiated into species groups without having sex.
And considering how costly sexual reproduction is in terms of resources, will other parthenogenetic species arise in the future? Males use up resources such as food, shelter, and water without contributing much to the next generation. A unisexual species comprised of only females will grow much faster assuming that equal numbers of offspring are produced, because each individual in that species has the capacity to produce offspring on her own. “Graham Bell called this ‘the queen of questions in evolutionary biology’,” says Baumann. “What is the advantage of sex that is large enough and acts on a short enough timescale to outweigh the two-fold cost of sex [more resource use for less offspring]? Clearly 99.9 percent of all species reproduce sexually, but we still don’t understand why that is so.”
The Loudest Penis on Earth
LESSER WATER BOATMAN
(Micronecta scholtzi)
AT JUST 0.08 INCHES long, the lesser water boatman is the loudest animal on Earth relative to body size. And perhaps even more impressive is the fact that this tiny insect makes its noises using not its mouth or legs or wings—it makes them using its penis.
In mid-2011, engineering expert James Windmill from the Centre for Ultrasonic Engineering at the University of Strathclyde in Scotland reported in PLoS ONE that the lesser water boatman (Micronecta scholtzi) can produce sounds at a level of 99.2 decibels, which is equivalent to sitting in the front row of a theatre and listening to a loud orchestra play. It achieves this through a process known as stridulation, which describes the rubbing together of two body parts to create a song that can travel over large distances. One of the most commonly heard products of stridulation is performed by grasshoppers, who scrape their hind legs against their adjacent forewing to produce their characteristic chirping sound. Crickets and katydids stridulate in the same way. The water boatman, on the other hand, rubs his penis against his abdomen in an effort to court females.
The lesser water boatman is a freshwater insect, found in ponds all over Europe—the more stagnant, the better. One of four species in the Micronecta genus, the lesser water boatman can be identified by its genitals and distinctive head pattern. From August 2009 to September 2010, Windmill and his colleagues collected a number of lesser water boatmen from a river in Paris and put them in plastic water tanks fitted with hydrophones—microphones specifically designed to record sounds underwater. Because water boatmen are only active in groups, the researchers put five in each tank, and then recorded the calls of thirteen males.
On average, the songs reached 78.9 decibels, which is equivalent to the sound of a freight train hurtling past 49 feet away. Fortunately for the people living around this river in Paris, or anywhere near a lesser water boatman, most of the sound doesn’t make it to human ears, says Windmill. According to his research, while 99 percent of sound is lost as it is transferred from water to air, the lesser water boatman’s song is so loud that if you’re walking along the bank, you can actually hear it singing from the riverbed.
Lesser water boatmen produce their songs to get females to notice them, and the loudness may be the product of what’s known as runaway or Fisherian sexual selection. A song produced at the loudest possible level might scramble the quieter songs emitted by competitors when the males call to the females in a chorus. Common sense dictates that natural selection would counterbalance runaway selection, as the loudest songs are the deadest giveaways for predators, but the researchers suggest that the lesser water boatmen don’t have predators that track them by sound, which is what has led to their boisterous songs.
The male produces the song by rubbing its pars stridens—an organ also used to grasp onto the female during copulation—against a particular abdominal ridge. What makes the volume of the song so impressive is that this ridge is only about 0.002 inches long, approximately equal to the width of a human hair. Plus, unlike all other species of stridulating organisms, the water boatman does not seem to possess any body parts that act to amplify the sound. So just how such a tiny insect can use its even tinier penis to produce such an impressive song remains a mystery.
Oh man, Lesser Water Boatman, how annoying would you be literally every time you talk to a female? I know being really loud is what you have to do for courting purposes, but just be aware that every time you take a girl on a date, it ruins everyone else’s night.
Say you’re in a restaurant on a first date with some girl you met on the Internet, and you’re all, “SO NICE TO FINALLY MEET YOU IN PERSON.”
The waitress will glower at you and half the patrons are going to leave while your date buries her face in her menu because she’s so mortified. She’ll say yes to a second date out of equal parts kindheartedness and cowardice, so you’ll take her to the movies. You’ll be like, “JEEZ THAT’S A SMALL COKE? WHAT’S THE LARGE SIZE, A CRUISE LINER? LOLOLOL.” And then the movie will start and you’ll be like “I THOUGHT HE WAS THE BAD GUY, BUT NOW I THINK MAYBE HE’S GOOD?” and “UH OH, ALL THAT COKE HAS REALLY MADE ME WANT TO PEE.”
Sorry, Lesser Water Boatman, but unless you can figure out how to lower your courting voice, you’re going to have to settle for a romantic career of picking up girls in a nightclub, where you’re literally the only male any of them can actually hear.
Battle of the Genitals
DUCKS
(Anatidae family)
“It’s hopeless! Every time we add some length or a new barb to our penises, the females respond with another dead end or another coil in their oviducts! We’re running out of ideas!”
“Why don’t we just stop forcing ourselves on them, then?”
“Hahahahaha. Good one.”
BEING MALE DOESN’T NECESSARILY mean you need to have a penis. Most birds, amphibians, reptiles, and monotremes don’t have one. Instead, they have a cloaca, which is a multipurpose opening on the rear for the intestinal, reproductive, and urinary tracts. If you’re a male with a cloaca, it acts as a vent for sperm, plus, rather unromantically, urine and excrement.
About 3 percent of birds have opted to keep the penis-vagina method of reproduction, but things are not any better for them either. Thirteen years ago, the existence of avian phalluses was brought to the attention of behavioral ecologist Patricia Brennan from the University of Massachusetts, when she saw birds called tinamous mating in Costa Rica. While biologists have known for decades that some birds have penises, it seemed that Brennan was the first to ask, and investigate, the question, “Why do ducks have penises?”
“My first interest was in studying why so few birds have maintained a penis while most birds have lost it,” says Brennan. “I began looking at ducks because they are the most common bird group where all species have a penis. There was virtually nothing known about bird genitalia when I first started doing my research, and the variation among species in the morphology (the form and structure) is so striking, that it seemed a great system to explore in detail.”
The male duck, or drake, penis, is very different from the male mammal penis. Each species equips a different variation, with lengths ranging from 0.5 inches to over 16 inches, some adorned with feathers, spines, or grooves. They can begin as tiny organs, a matter of hundredths of an inch, when the duck is growing, but can often end up long and twisted, like a slender tentacle extending from the cloaca wall. They are kept folded inside a phallic sac until provoked, when they will be forced out, quick as a flash, by an immune system fluid called lymph (rather than blood). The Argentine blue-bill duck (Oxyura vittata) from South America boasts
the longest penis relative to body size of any animal in the world, one famous specimen packing a 17-inch-long penis inside its 8-inch-long body. The drake’s penis grows at the beginning of the reproductive season and shrinks right down at the end, possibly because that’s the easiest way to keep such an enormous organ clean for a lifetime.
But what of the female ducks’ genitals, if they must somehow accommodate such a serpentine monstrosity? As Brennan told British science writer Carl Zimmer for a 2007 New York Times article, “You need a garage to park the car.” By 2005, Brennan had discovered something that, shockingly, no other biologist had ever thought to look for—female duck vaginas, or oviducts, are more incredible, complex, and labyrinthine than ever imagined. Publishing that year in PLoS ONE, Brennan described the oviducts of sixteen species of waterfowl to find that while each species had a different oviduct form, ranging from short, narrow, and muscular cavities to extremely long, complex, and counterclockwise-spinning tunnels, each one matched the complexity of the corresponding male. So in species such as the long-tailed duck (Clangula hyemalis), Brennan found that both the females and the males had equally elaborate genitalia.