Thursday, April 17, 2014

Here's a challenge for both creationists and evolutionists: a really odd insect from a cave in Brazil

Brazilian cave insects (female in inset, and above the male in larger photo) Yoshizawa et al., Current Biology (2014)

For creationists, the problem here is to explain WHY God would specifically decide to create one insect species in which the females have a penis and the males have a vagina.

For evolutionists, the problem is to explain HOW this insect evolved. The second article below sets up the general requirements for the explanation, which will be every bit as fascinating as hearing a creationist explain why God made this animal. But I think I it's clear why God might have decided to hide the animal in caves in Brazil: he didn't want his loyal followers to break their brains thinking about it.

Scientists discover the first known case of sex-reversed genitals
The female insect has a penis and the male insect has a vagina. And that's not even the strangest part
Lindsay Abrams
Apr 17, 2014

Scientists discover the first known case of sex-reversed genitalsAn N. aurora female releases its penis-like organ, in preparation for mating.

It’s a big day for science. At NASA, they’ve announced the discovery of a new, Earth-like planet that could potentially harbor extraterrestrial life. And over in Brazil, they’ve discovered the first known case of “female penis.”

That’s right: as detailed in the journal Current Biology, four species of Brazilian insects sport sex-reversed genitalia. It’s not impossible, as the Verge explains: Rather than sex organs or chromosomes, biologists use gametes (sperm in males and oocytes in females) to determine sex. In this case, the females, which have the biggest gametes, also happen to have a penis. Here, courtesy of the journal, is what it looks like:

Smithsonian Mag has as weird an account of the bugs’ mating ritual that you can ever hope to read:

During mating, the female’s spiny penis gets tightly anchored to the male vagina’s sperm duct, allowing the female to receive the semen. In other words, this penis functions more like a straw than a spout. If the male tried to break away, his abdomen would rip open, and he would dramatically lose his genitals. These female insects also mate with multiple males and can store two batches of sperm in the body.

So that’s how that happens. The “why,” on the other hand, is a much bigger question. Here’s the Verge, again:

Michael Siva-Jothy, an entomologist at the University of Sheffield, UK, who didn’t participate in this study, said in an email to The Verge that the findings are “really, really exciting.” Examples like this, he noted, allow researchers to examine various factors that drive how these traits evolve. When asked how the female penis might have evolved, however, Siva-Jothy was stumped. “This is so bizarre,” he said. “I don’t know where to begin.”

Yoshizawa was equally surprised upon seeing these insects for the first time. “Usually, a new structure evolves as a modification of a previously existing structure,” he said. But this female penis has no precedent. Evolving a structure like this, Yoshizawa said, is “exceptionally difficult” because the development of this form of mating would have necessitated the harmonious evolutions of both male and female genitalia, and their exact match.

“Obviously more research is needed,” evolutionary biologist Marlene Zuk, who was not associated with the study, told Smithsonian, “but the whole thing is completely wild.”

ScienceShot: Females Sport Penises in Genital-Swapped Insects
Yoshizawa et al.
Current Biology
17 April 2014

Ecologists spelunking in a Brazilian cave have found a new variety of insect with an unusual sex life. Females of the newly discovered genus Neotrogla, 3-mm-long flylike insects, boast large, penislike structures called gynosomes (inset). Although other animals such as seahorses take on reversed gender roles, species in the new genus are the first to be found with swapped genital structures. During copulation—which lasts 40 to 70 hours—the female mounts the male from behind (as seen in the above photo), thrusting her gynosome into the male’s vaginalike opening. Once inside, the female uses spines on the gynosome to latch on to the potentially reluctant male. The lady’s grasp is so strong that when the researchers tried to separate a fornicating pair, the male’s abdomen was ripped from its body without breaking the genital link. During breeding, the male transfers a large amount of nutritious ejaculate via the gynosome to the female, the researchers report online today in Current Biology. The team suggests that in the resource-scarce cave system, this nutritious seminal gift causes females to compete for sustained breeding. Over time, the scientists believe this female-initiated intercourse could have led the insects to evolve reversed genitals. Still unclear is whether the females worry about the size of their gynosome.

Here's another article on the subject from Current Biology:

Female Penis, Male Vagina, and Their Correlated Evolution in a Cave Insect
Kazunori Yoshizawaemail, Rodrigo L. Ferreira, Yoshitaka Kamimura, Charles Lienhard


•Females of the cave insect genus Neotrogla have an elaborate penis-like organ
•The female penis acts as an intromittent organ and anchors the female to the male
•Correlated evolution is detected between the female penis and male genitalia


Sex-specific elaborations are common in animals and have attracted the attention of many biologists, including Darwin [ 1 ]. It is accepted that sexual selection promotes the evolution of sex-specific elaborations. Due to the faster replenishment rate of gametes, males generally have higher potential reproductive and optimal mating rates than females. Therefore, sexual selection acts strongly on males [ 2 ], leading to the rapid evolution and diversification of male genitalia [ 3 ]. Male genitalia are sometimes used as devices for coercive holding of females as a result of sexual conflict over mating [ 4, 5 ]. In contrast, female genitalia are usually simple. Here we report the reversal of intromittent organs in the insect genus Neotrogla (Psocodea: Prionoglarididae) from Brazilian caves. Females have a highly elaborate, penis-like structure, the gynosome, while males lack an intromittent organ. The gynosome has species-specific elaborations, such as numerous spines that fit species-specific pouches in the simple male genital chamber. During prolonged copulation (∼40–70 hr), a large and potentially nutritious ejaculate is transferred from the male via the gynosome. The correlated genital evolution in Neotrogla is probably driven by reversed sexual selection with females competing for seminal gifts. Nothing similar is known among sex-role reversed animals.

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