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So as the cautious man (or my mother) says, “Safety first.” However, for the male cricket–as gallant as he is–he’ll risk his life for a lady friend. In danger, a male cricket will wait until his female partner dives into their hiding burrow to ensure that if she’s pregnant, his genes will survive.
At the entrance, it’s ladies first: the male cricket waits while his partner dives in first. It’s a delay that could cost him his life. This may all seem very chivalrous, but the male’s seemingly selfless actions also make selfish sense. He may die, but he ensures that his genes pass on to the next generation.
Male insects often stay close to female ones after they mate, and people have generally assumed that they’re standing guard. If the female mates again, the first male’s sperm will be flushed out by the second male’s contributions. If he wants to ensure that he fathers he offspring, he’d do well to keep other suitors at bay.
But Rolando Rodriguez-Munoz from the University of Exeter found that this narrative of conflict doesn’t quite work for field crickets. He set up a network of infrared cameras to study a wild population of the crickets that had all been individually marked and genetically analysed. The cameras recorded thousands of hours of video, and Rodriguez-Munoz watched them all.
The article goes on to describe the advantages both partners have when the male is accommodating to the female. Men, take notes.
-Link | Image Credit Roberto Zanon
An artificial uterus sounds like a scene from Brave New World. In reality, scientists at the Port Stephens Fisheries Institute in New South Wales, Australia, have so far only nursed six embryos of a wobbegong shark through their last 18 days before birth successfully in a souped-up aquarium with delicately balanced chemicals, filters, and monitors that copy a shark’s womb. The ultimate goal is to incubate embryos of the endangered grey nurse shark throughout their gestation. What’s really strange is the reason they need to do it. The grey nurse shark is endangered in part because of its weird way of reproducing:
After mating, a female produces as many as 40 fertilized embryos, separated between two separate wombs. The embryos take nearly a year to fully develop, but they begin hunting long before that. After about two months, their own yolk sacs go dry. Hungry, they start eating their brothers and sisters. After the rampant in utero cannibalization, only one shark — the biggest and strongest — is left in each womb.
At birth they’re three feet long and experienced hunters, with a good chance of survival. But the tiny brood size, nearly year-long gestation period, and relatively restricted maternal capacity — after giving birth, mothers must wait a year to reproduce again — limit the number of young sharks.
Read more about this research in artificial shark gestation at Wired Science. Link
(Image credit: Port Stephens Fisheries Institute)
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An insect called the cottony cushion scale has developed a way to produce offspring without a mate. Some females develop with their father’s sperm growing into an bundle of male tissue inside the female’s body. This tissue can later produce sperm needed for the female to produce baby scales.
This parasitic tissue, genetically identical to the female’s father, lives inside the female and fertilizes her eggs internally—rendering the female a hermaphrodite and making her father both the grandfather and father of her offspring, genetically speaking.
Though this new form of reproduction hasn’t replaced cottony cushion scale sex, “this parasitic male has taken off like an epidemic in population,” said study leader Andy Gardner, an evolutionary theorist at the University of Oxford.
“Once [this trend] gets started, it’s going to sweep through the population so all the females carry it. So there’s no point for regular males to exist,” Gardner added.
If the females begin passing on the parasitic male to their offspring, there may eventually be no more need for “baby boy” cushion scales that grow up and produce sperm and fertilize females, Gardner said.
Self-fertilizing species do not flourish as well as those that reproduce by sex because the genetic variability tends to die out. Gardner clarified that the female insects are not truly hermaphroditic, as much as they are two different individual insects within one body. Link
(Image credit: Peter Hollinger)
What if you could put your baby on hold for twenty years? Would you do it? Scientists have now been able to achieve just that.
Imagine being born at the age of 20. Doctors at the Jones Institute for Reproductive Medicine in Virginia have made history by implanting a 20 year old frozen embryo and having it successfully brought to term.
They must have done something to reproduce, considering they roamed the earth for millions of years. Yet they died out for one reason or another. And some dinosaurs, like the stegosaurus, were covered in armor and spikes, which doesn’t lead one to think of intimacy.
Figuring out how Stegosaurus even could have mated is a prickly subject. Females were just as well-armored as males, and it is unlikely that males mounted the females from the back. A different technique was necessary. Perhaps they angled so that they faced belly to belly, some have guessed, or maybe, as suggested by Timothy Isles in a recent paper, males faced away from standing females and backed up (a rather tricky maneuver!). The simplest technique yet proposed is that the female lay down on her side and the male approached standing up, thereby avoiding all those plates and spikes. However the Stegosaurus pair accomplished the feat, though, it was most likely brief—only as long as was needed for the exchange of genetic material. All that energy and effort, from growing ornaments to impressing a prospective mate, just for a few fleeting moments to continue the life of the species.
Smithsonian has the details on what we know, and how we came to know it, on the subject of dinosaur sex. Link -via Boing Boing
(Illustration by Luis Rey)
A 400 million-year-old fossil fish with a reproductive organ resembling a penis has been identified by Australian scientists. This is the earliest known structure used for sexual reproduction as we know it. The bone attached to the pelvis is called a clasper, and was used to penetrate a female during mating. The fish was a member of the extinct class of armored fish called placoderms.
Study author and palaeontologist Dr Kate Trinajstic, of Curtin University in Perth, says the clasper was discovered in a fish specimen uncovered in the Gogo region of Western Australia in 2001.
She says the team originally discounted the bone as the reproductive organ because they thought it was part of the pelvic gurdle.
On closer inspection, Trinajstic says they realised it was a sexual organ.
“We were surprised because it’s so big,” she says. “We were expecting something smaller.”
(image credit: John Long)
