Sex and reproduction
edyong | March 18, 2010
One night of passion and you're filled with a lifetime full of sperm with no need to ever mate again. As sex lives go, it doesn't sound very appealing, but it's what many ants, bees, wasps and termites experience. The queens of these social insects mate in a single "nuptial flight" that lasts for a few hours or days. They store the sperm from their suitors and use it to slowly fertilise their eggs over the rest of their lives. Males have this one and only shot at joining the Mile High Club and they compete fiercely for their chance to inseminate the queen. But even for the victors, the war…
edyong | March 17, 2010For most men, the thought of taking on the burden of pregnancy from their partners would seem like a nightmare, but it's all part and parcel of seahorse life. After mating, female seahorses and pipefish lay their eggs into a special pouch in the male's belly and he carries the developing babies to term. They may seem like a shoe-in for a Dad-of-the-year award but this apparent display of paternal perfection has several macabre twists.
A recent study showed that pregnant pipefishes can also become vampiric cannibals, absorbing some of their brood for nutrition if their own food supplies are…
edyong | March 11, 2010Not Exactly Pocket Science is a set of shorter write-ups on new stories with links to more detailed takes by the world's best journalists and bloggers. It is meant to complement the usual fare of detailed pieces that are typical for this blog.
Geneticist sequences own genome, finds genetic cause of his disease
If you've got an inherited disease and you want to find the genetic faults responsible, it certainly helps if you're a prominent geneticist. James Lupski (right) from the Baylor College of Medicine suffers from an incurable condition called Charcot-Marie-Tooth (CMT) disease, which…
edyong | March 10, 2010The animal on the right is no ordinary chicken. Its right half looks like a hen but its left half (with a larger wattle, bigger breast, whiter colour and leg spur) is that of a cockerel. The bird is a 'gynandromorph', a rare sexual chimera. Thanks to three of these oddities, Debiao Zhao and Derek McBride from the University of Edinburgh have discovered a truly amazing secret about these most familiar of birds - every single cell in a chicken's body is either male or female. Each one has its own sexual identity. It seems that becoming male or female is a very different process for birds than…
edyong | March 7, 2010Sex might be fun but it's not without risks. As your partner exposes themselves to you, they also expose you to whatever bacteria, viruses or parasites they might be carrying. But some animals have a way around that. Ekaterina Litvinova has found that when male mice get a whiff of female odours, their immune systems prepare their airways for attack, increasing their resistance to flu viruses.
Litvinova worked with a group of mice that were exposed to bedding that had previously been soiled by females in the sexually receptive parts of their cycle. She compared them to a second more monastic…
edyong | February 21, 2010Whiptail lizards are a fairly ordinary-looking bunch, but some species are among the strangest animals around. You might not be able to work out why at first glance, but looking at their genes soon reveals their secret - they're all female, every single one. A third of whiptails have done away with males completely, a trick that only a small minority of animals have accomplished without going extinct.
Some readers might rejoice at the prospect of a world without males but in general, this isn't good news for a species. Sex has tremendous benefits. Every fling shuffles the genes of the two…
edyong | January 28, 2010
When our lives are in danger, some humans go on the run, seeking refuge in other countries far away from the threats of home. Animals too migrate to escape danger but one group - the pond-living bdelloid rotifers - have taken this game of hide-and-seek to an extreme.
If they are threatened by parasitic fungi, they completely remove any trace of water in their bodies, drying themselves out to a degree that their parasites can't stand. In this desiccated state, they ride the wind to safety, seeking fresh pastures where they can establish new populations free of any parasites.
This…
edyong | January 5, 2010
If you looked at the penis of a Drosophila fly under a microscope (for reasons best known only to yourself), you'd see an array of wince-inducing hooks and spines. These spines are present in all Drosophila and they're so varied that a trained biologist could use them to identify the species of the owner.
What's the purpose of these spines? Are they intended to actually wound the female during mating? Do they help the male fly to scrape out the sperm of his rivals? Do they actually pierce the walls of the female's genital tract, allowing the male to bypass any barriers to his sperm, as…
edyong | December 26, 2009In California's Jurupa Mountains, there is a very unusual group of tree - a Palmer's oak. Unlike the mighty trees that usually bear the oak name, this one looks like little more than a collection of small bushes. But appearances can be deceiving. This apparently disparate group of plants are all clones of a single individual, and a very old one at that.
By repeatedly cloning itself, the Palmer's oak has lived past the separation of Britain from continental Europe, the demise of the mammoths and saber-toothed cats, and the birth of human agriculture. It is among the oldest plants in…
edyong | December 22, 2009Patricia Brennan from Yale University is trying to encourage male Muscovy ducks to launch their ballistic penises into test tubes.
Normally, the duck keeps its penis inside-out within a sac in its body. When the time for mating arrives, the penis explodes outwards to a fully-erect 20cm, around a quarter of the animal's total body length. The whole process takes just a third of a second and Brennan captures it all on high-speed camera. This isn't just bizarre voyeurism. Duck penises are a wonderful example of the strange things that happen when sexual conflict shapes the evolution of animal…
edyong | December 16, 2009In science, we don't often get to talk about male repression, but a new discovery gives us just such a chance. It turns out that ovaries can only remain ovaries by constantly suppressing their ability to become male. Silence a single gene, and adult ovaries turn into testes. That adult tissues can be transformed in this way would be surprising enough, but doing so by changing a single gene is truly astonishing.
As embryos, our gonads aren't specific to either gender. Their default course is a female one, but they can be diverted through the action of a gene called SRY that sits on the Y…
edyong | November 24, 2009For the pipefish (and their relatives, seahorses and sea dragons), it's the males who get pregnant. After a male fertilises the female's eggs, he takes them up into a special brood pouch and shelters them until the babies hatch from his pot-bellied stomach several weeks later. He may seem like a shoe-in for the Dad-of-the-year award but this fatherly commitment has a sinister side to it. Not all of the babies he cares for make it out of his stomach alive.
Gry Sagebakken from the University of Gothenburg has proved that pregnant male pipefishes absorb some of the eggs and embryos within…
edyong | October 31, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science.
When it comes to sex, it makes sense to stick to your own species. Even putting aside our own innate revulsion, inter-species liaisons are a bad idea because they mostly fail to produce any young. In the few instances they do, the hybrid progeny aren't exactly racing ahead in the survival stakes and are often sterile (think mules).
But having poor unfit young is still better than having no young at all and if an animal's options are limited, siring a generation of hybrids may be a last resort. Karin…
edyong | October 27, 2009Many humans whinge about not getting oral sex often enough, but for most animals, it's completely non-existent. In fact, we know of only animal apart from humans to regularly engage in fellatio - the short-nosed fruit bat (Cynopterus sphinx).
The bat's sexual antics have only just been recorded by Min Tan of China's Guangdong Entomological Institute (who are either branching out, or are confused about entomology). Tan captured 60 wild bats from a nearby park, housed them in pairs of the opposite sex and voyeuristically filmed their liaisons using a night-time camera. Twenty of the bats got…
edyong | October 27, 2009In East Africa lives a species of spider that drinks mammalian blood. But fear not - Evarcha culicivora is an indirect vampire - it sates its thirst by preying on female mosquitoes that have previously fed on blood themselves.
Even though its habitat is full of non-biting midges called "lake flies", it can tell the difference between these insects and the blood-carrying mozzies it carries. Robert Jackson from the University of Canterbury discovered this behaviour a few years ago and one of his colleagues, Fiona Cross, has now found that the blood isn't just a meal for the spiders, it's an…
edyong | October 22, 2009By directing the evolution of a worm, scientists have confirmed answers to the age-old question: "What is the point of having sex with someone else?" For most people, that would hardly be a tricky query but it's no reflection on the lives of evolutionary scientists that sex has been one of biology's oldest puzzles.
The problem is this: many creatures can reproduce by fertilising themselves instead of getting someone else to do it, and at first glance they should do much better individuals that cross-fertilise. For a start, they'd ensure that all of their genes reach the next generation,…
edyong | October 3, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.
Every month, at the full moon, tourists and students gather on the beach at Koh Phangan, Thailand for a night of booze, dancing, and debauchery. But the moon-themed antics of these party-goers look positively tepid when compared to those of the Great Barrier Reef's corals. With the help of two genes and a spot of moonlight, the corals synchronise one of the greatest spectacles of the natural world - a mass annual…
edyong | September 30, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.
Sex is, on the whole, a good thing. I know it, you know it, and natural selection knows it. But try telling it to bdelloid rotifers. These small invertebrates have survived without sex for some 80 million years.
While many animals, from aphids to Komodo dragons, can reproduce asexually from time to time, it's incredibly rare to find a group that have abandoned sex altogether. The bdelloid rotifers (pronounced…
edyong | September 16, 2009
For humans and most other mammals, sex is a question is chromosomes. Two X chromsomes makes us female while an X and a Y makes us male. Birds use a similar but reversed system, where males are ZZ and females are ZW. But for reptiles, including crocodiles, turtles and many lizards, sex is determined not by genes, but by temperature.
In crocodiles, males hatch from eggs incubated at cooler temperatures while warmer conditions produce females. In turtles, it's the other way around, and lizards use a variety of criteria including some very complicated combinations of genes, temperature and…
edyong | June 29, 2009If the idea of a cold, motionless sexual partner isn't one of your turn-ons, then you're clearly not an echidna. The males of these spiny Australian animals will happily mate with females even if they're hibernating.
Gemma Morrow and Stewart Nicol from the University of Tasmania have spent the last decade studying the short-beaked echidnas of Tasmania. Over that time, they discovered many instances of males mating with torpid females in deep hibernation, or with females who roused themselves briefly only to re-enter their deep slumber. Over the last two years, the voyeuristic duo use a…