Chapter 12. Sex: Evolutionary, Hormonal, and Neural Bases
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By Christie Wilcox What does your voice say about you? Our voices communicate information far beyond what we say with our words. Like most animals, the sounds we produce have the potential to convey how healthy we are, what mood we’re in, even our general size. Some of these traits are important cues for potential mates, so much so that the sound of your voice can actually affect how good looking you appear to others. Which, really, brings up one darn good question: what makes a voice sound sexy? To find out, a team spearheaded by University College London researcher Xi Yu created synthetic male and female voices and altered their pitch, vocal quality and formant spacing (an acoustics term related to the frequencies of sound), the last of which is related to body size. They also adjusted the voices to be normal (relaxed), breathy, or pressed (tense). Through several listening experiments, they asked participants of the opposite gender to say which voice was the most attractive and which sounded the friendliest or happiest. The happiest-sounding voices were those with higher pitch, whether male or female, while the angriest were those with dense formants, indicating large body size. As for attractiveness, the men preferred a female voice that is high-pitched, breathy and had wide formant spacing, which indicates a small body size. The women, on the other hand, preferred a male voice with low pitch and dense formant spacing, indicative of larger size. But what really surprised the scientists is that women also preferred their male voices breathy. “The breathiness in the male voice attractiveness rating is intriguing,” explain the authors, “as it could be a way of neutralizing the aggressiveness associated with a large body size.”
Sunanda Creagh, The Conversation Testosterone may trigger a brain chemical process linked to schizophrenia but the same sex hormone can also improve cognitive thinking skills in men with the disorder, two new studies show. Scientists have long suspected testosterone plays an important role in schizophrenia, which affects more men than women. Men are also more likely to develop psychosis in adolescence, previous research has shown. A new study on lab rodents by researchers from Neuroscience Research Australia analysed the impact increased testosterone had on levels of dopamine, a brain chemical linked to psychotic symptoms of schizophrenia. The researchers found that testosterone boosted dopamine sensitivity in adolescent male rodents. “From these rodent studies, we hypothesise that adolescent increases in circulating testosterone may be a driver of increased dopamine activity in the brains of individuals susceptible to psychosis and schizophrenia,” said senior Neuroscience Research Australia researcher and author of the study, Dr Tertia Purves-Tyson, who is presenting her work at the International Congress on Schizophrenia Research in Florida. Dr Philip Mitchell, Scientia Professor and Head of the School of Psychiatry at the University of NSW, said the research was very interesting. © 2013 ScienceAlert Pty Ltd.
by Dennis Normile A human mother rocking a baby in her arms and a cat carrying her kitten by the scruff of its neck have the same physiological effect on both young animals and probably stem from the same maternal instinct to protect their young. That's the conclusion of a new study, which for the first time has compared the physiological impact of maternal carrying behaviors across species. The findings may lead to better parenting techniques for people and possibly to new ways to detect developmental disorders early in life. It's "really fascinating" work, says Oliver Bosch, a neurobiologist at the University of Regensburg in Germany, who was not involved in the research. "No one has looked at [this aspect] of maternal behavior in such detail." Japanese neuroscientist Kumi Kuroda began the study in her own home. She noticed that carrying her newborn baby boy while walking had a rapid calming effect on him. Back in her lab at the RIKEN Brain Science Institute, near Tokyo, she found that picking up mouse pups by the scruff of the neck makes them passive and easy to handle. Kuroda wondered if the same physiological processes were driving both behaviors. She and colleagues recorded pulse rates and observed the crying and squirming behavior of 12 infants, 1 to 6 months old, as each was left alone in a crib, held by its mother sitting in a chair, and carried as the mother walked around. In various durations and combinations of the three conditions, they found that the carried babies cried and squirmed the least and had the lowest pulse rates. Those left in the crib were the fussiest; holding the baby while sitting produced in-between results. What was particularly surprising, Kuroda says, was that when a mother started walking, the infant's pulse dropped, and the crying and squirming stopped within 2 to 3 seconds, not over several minutes. © 2010 American Association for the Advancement of Science.
By Bill Andrews In a paper sure to please lazy stand-up comics and beleaguered husbands everywhere, scientists say that men do indeed have a hard time understanding women. Recent results show that men have a significantly harder time recognizing women’s emotions than they do men’s, and that men seem to use different parts of their brain when ascribing intentions and feelings to women versus men. Previous experiments had suggested that men are naturally wired to be more intuitive toward other men’s mental states and emotions. Eager to figure out why and how this could be, the researchers studied the brains of 22 male participants as they received a version of a well-known empathy test called the “Reading the Mind in the Eyes Test.” (You can take a version of the test online here.) As the name suggests, the test consists of snapshots of pairs of eyes. Pairs of eyes were shown in succession to each participant, who had to determine either the gender or the emotional state of the person pictured. This all took place within an MRI machine, allowing the researchers to see which parts of the brain were active while participants made their determinations. Participants were about equally good at guessing the gender of male and female eyes, but the men did significantly worse at recognizing the emotions of the female eyes. They correctly interpreted about 87 percent of men’s eyes but only about 76 percent of women’s eyes. Participants also took longer to judge women’s emotions—about 40 milliseconds longer on average. Thus, in effect, men can “read” other men’s eyes faster and better, the researchers report in PLOS ONE.
Matt Kaplan By making noise that could potentially expose them to predators, young pied babblers get their parents to give them more attentions. Begging loudly has long been viewed as an offspring’s way of saying “I’m hungry”. But in predator-filled environments, these squawks can put young birds in harm's way, and may be a form of blackmail that forces parents to pay attention and feed the youngsters more than they might otherwise. The discovery comes from a three-year analysis of a well-studied community of pied babbler (Turdoides bicolor) in the Kalahari Desert of South Africa1. Alex Thompson of the University of Cape Town and colleagues from Britain and Australia, spent more than 200 hours observing the animals in the wild and recorded more than 3,000 incidents of parents feeding fledglings. Thompson and his team noted that fledglings were fed an average of 0.12 grams of food per minute when on the ground and away from cover, but just 0.03 grams per minute when begging from the safety of the trees. Furthermore, when the birds were played an audio recording of alarm calls indicating that a ground predator was in the vicinity, parents more than doubled the amount they gave to ground-based youngsters, but made no compensation for those in the trees. Fascinated, the team speculated that the young, which were slower than adults to respond to the alarm calls and cannot escape as quickly from danger, were intentionally putting themselves into a dangerous situation when hungry to force their parents to pay attention and feed them. © 2013 Nature Publishing Group,
by Dennis Normile Puberty has always been a time of stress and emotional turmoil for adolescents and for their parents. And scientists have long recognized that kids who start puberty ahead of their peers are particularly likely to have trouble getting along with other children and with adults. New research suggests that those difficulties can be traced back to even earlier ages, indicating that early puberty may not be the root cause. Australian researchers drew on data for 3491 children, roughly half boys and half girls, who were recruited at ages 4 or 5 and then followed until they reached ages 10 or 11. Every 2 years, a researcher visited each subject's home, evaluated the child, and interviewed the primary caregiver, which in most cases was a parent, who later completed and returned a questionnaire about their child's behavior. The primary caregiver was also asked to judge the child's pubertal status, based on indicators for an early phase of puberty such as breast growth in girls, adult-type body odor, and body hair; and growth spurts, deepening voices in boys, and menstruation in girls for a later stage. Girls typically enter puberty at age 10 or 11 and boys at 11 or 12. The researchers found that 16% of the girls and 6% of the boys in the study had entered puberty early, at age 8 or 9. Previously, researchers thought that any negative effects of early puberty showed up only after puberty's onset. But by tracking a cohort of children from age 4 to 5 to age 10 to 11, they found that problems thought restricted to postpuberty children actually appeared well before puberty. Retrospectively, they were able to show that children who later had early onset puberty had difficulty playing with other children and participating in normal school activities, even when they were 4 or 5 years old. Boys, though not girls, in this group had also showed behavior problems, such as being overactive, losing their tempers, and preferring to play alone from a young age. © 2010 American Association for the Advancement of Science.
By Felicity Muth With the historic supreme court hearings this week, there has been much discussion about homosexuality*. One of the ‘arguments’ that you often hear from the anti-gay rights side is that being gay isn’t natural. Evidence from the animal kingdom would refute this however, as same-sex behaviour is common and found in many different animals. There’s the famous example of ‘Roy’ and ‘Silo’, two male chinstrap penguins that formed a pair bond and raised a chick (‘Tango’) together, later turned into a distinctive children’s book (you can also read about their tragic breakup here – this part has yet to be made into a children’s book). Homosexuality is also common in many insects, and some flour beetle males actually mate 50% of the time with other males. But why does same-sex behaviour occur? How is it maintained by evolution? This is a complex question, and the answer is likely to differ from species to species. For example, flour beetle males that mate with other males can actually transfer to females this way. Other male insects like weevils or fruit flies may just not realise that the individual they’re mating with is also a male (it being better to mate with more animals, and get it ‘wrong’ sometimes, than be too discriminating and miss out on potentially fruitful mating attempts). However, in addition to specific cases, there may also be overarching patterns across species in how homosexuality is selected for and maintained by evolution. While many studies have concentrated on male-male sexual behaviour, females also engage in same-sex behaviour. Laysan albatrosses form female-female partnerships, performing the same mating rituals as in male-female pairs of this species, and these couples can last a lifetime. © 2013 Scientific American
Keyword: Sexual Behavior
Link ID: 17974 - Posted: 04.01.2013
Published by scicurious Today's post comes to you courtesy of Mary Roach (aka, the person I want to be when I grow up). I have a copy of her latest book, Gulp: adventures in the alimentary canal that I am reading for review, and a weird science connoisseur such as myself of course spends half her time in the bibliography section, wherein I located this paper. This paper may thus be taken as a pre-review of the book. Spoiler: so far, the book is FABULOUS, but should never be read while eating. Ah, goat milk. When I think of goat milk, I think of places like farmer's markets, Whole Foods, and little Heidi dancing through the alps. I'll admit to never having drunk raw goat milk (though I do LOVE goat cheese). But after having read this paper, I'm afraid that I do not WANT to try raw goat milk. Why? I'm afraid of the taste...the goaty taste...that is potentially hot, sexy goaty hormones. Hot sexy goat hormones sprayed around in hot, sexy goaty URINE. So, goat milk doesn't usually taste...well, goaty. Usually it tastes pretty much like cow milk (whole fat cow milk, that is). But sometimes, you'll get a bad batch. Nothing's WRONG with it, per se, it's still healthy and not bad, but it's...goaty. The flavor and smell are musky and weird, and not at all tasty. So obviously you want to find the source of that problem. For years, people who raise goats have pinpointed the MALE goat as the source of the issue. Male goats smell very goaty indeed, particularly during the goat mating season (the rutting season). Some of the odors they emit are so strong they can be smelled several hundred meters away. The odors are very volatile, so they will spread easily, and the idea has long been that if your male goat is around the ladies, his manly odors will get on them and in them, and thus in their milk, resulting in goaty milk (which, if the male goat is the cause, means that goaty milk is really just...MANLY). So goat farmers usually keep their male goats at a good distance from the females during the rutting season, to keep the males from getting their...manliness in the milk. Manliness is just not very tasty. Copyright © 2013
By Meghan Rosen With parasitic flies gorging on her guts and the end approaching, a variable field cricket may have only one thing to do: Find a mate. Usually, female Gryllus lineaticeps prefer males with fast chirps. But when being eaten alive by fly larvae, female crickets don’t wait around for a snappy tune. Instead, they settle for slow-chirping sexual partners, evolutionary biologists Oliver Beckers of Indiana University in Bloomington and William Wagner Jr. of the University of Nebraska-Lincoln report in the April Animal Behaviour. Parasitic flies seek out crickets as potential homes (and meal tickets) for their young. Before the fly larvae chew through crickets’ bellies, female crickets have about a week to find a mate and lay eggs before dying. To find out whether infestation lowered females’ mating standards, Beckers and Wagner placed fly larvae on female crickets and then played slow and fast chirp recordings from loudspeakers set in separate corners of a square chamber. Healthy females walked toward the fast chirping sound about 80 percent of the time, while infested females split their devotion about equally. “They don’t invest a lot of time and energy finding the super sexy guy,” says Becker. “They’ll go for the average Joe.” © Society for Science & the Public 2000 - 2013
by Beth Skwarecki If you thought the battle of the genders was complicated, try having seven sexes. When Tetrahymena, a single-celled creature covered in cilia, mates, the offspring isn't necessarily the same sex as either parent—it can be any of seven. Now, researchers have figured out the complex dance of DNA that determines the offspring's sex, and it's a random selection, they report today in PLOS Biology. Each Tetrahymena has a gene for its own sex—or mating type—in its regular nucleus, but it also carries a second nucleus used only for reproduction. This "germline nucleus" contains incomplete versions of all seven mating type genes, which are cut and pasted together until one complete gene remains and the other six have been deleted. The newly rearranged DNA becomes part of the offspring's regular nucleus, determining its mating type. Because the mating type gene helps Tetrahymena recognize others of a different sex, the researchers say that the finding could shed light on how other cells, including those in humans, recognize those that are different from themselves. © 2010 American Association for the Advancement of Science.
By Darryl Fears, Ten years have gone by since one of the weirdest discoveries in the Chesapeake Bay region, on the south branch of the Potomac River — male smallmouth bass with lady parts, eggs in places where they absolutely should not be. Over that decade, wildlife biologists have probed the bay’s tributaries, slicing open fish for more necropsies than anyone can count. And one thing is clear: They still aren’t sure why between 50 and 100 percent of bass in various locations are gender-bending, switching from male to something called intersex. Biologists say studies are falling short because of a lack of data on the type and quantity of pesticides that run into the bay from farms. This complaint, along with other factors, prompted Democrats in the Maryland House and Senate to sponsor two bills in the current legislative session that would for the first time require growers to record their use of insecticides and herbicides and submit it to the state. The pesticide-reporting rule would create a treasure trove of data that scientists could draw from for studies on human and animal health, supporters say. Scientists could use it to focus research on chemical “hot spots,” the exact moment high concentrations of pesticides hit waters where vulnerable young fish are growing, said Vicki Blazer, a biologist who studies bass for the U.S. Geological Survey. But opponents say the bills have major drawbacks. They would create a financial burden for farmers, who would be forced to purchase updated equipment such as Global Positioning System devices to log pesticide applications, said Valerie Connelly, director of government relations for the Maryland Farm Bureau. © 1996-2013 The Washington Post
Keyword: Sexual Behavior
Link ID: 17912 - Posted: 03.18.2013
By LAURIE EDWARDS TO the list of differences between men and women, we can add one more: the drug-dose gender gap. Doctors and researchers increasingly understand that there can be striking variations in the way men and women respond to drugs, many of which are tested almost exclusively on males. Early this year, for instance, the Food and Drug Administration announced that it was cutting in half the prescribed dose of Ambien for women, who remained drowsy for longer than men after taking the drug. Women have hormonal cycles, smaller organs, higher body fat composition — all of which are thought to play a role in how drugs affect our bodies. We also have basic differences in gene expression, which can make differences in the way we metabolize drugs. For example, men metabolize caffeine more quickly, while women metabolize certain antibiotics and anxiety medications more quickly. In some cases, drugs work less effectively depending on sex; women are less responsive to anesthesia and ibuprofen for instance. In other cases, women are at more risk for adverse — even lethal — side effects. These differences are particularly important for the millions of women living with chronic pain. An estimated 25 percent of Americans experience chronic pain, and a disproportionate number of them are women. A review published in the Journal of Pain in 2009 found that women faced a substantially greater risk of developing pain conditions. They are twice as likely to have multiple sclerosis, two to three times more likely to develop rheumatoid arthritis and four times more likely to have chronic fatigue syndrome than men. As a whole, autoimmune diseases, which often include debilitating pain, strike women three times more frequently than men. © 2013 The New York Times Company
Jennifer Raymond I have a bias against women in science. Please don't hold this against me. I am a woman scientist, mentor and advocate for women in science, and an associate dean in my school's Office of Diversity, with a budding field biologist as a daughter. Yet my performance on the Implicit Association Test (https://implicit.harvard.edu/implicit/demo), which measures unconscious associations between concepts, revealed that I have a tendency to associate men with science and career, and women with liberal arts and family. I didn't even need to wait for my score; I could feel that my responses were slower and that I made more mistakes when I had to group science words such as 'astronomy' with female words such as 'wife' rather than male words such as 'uncle'. The results from hundreds of thousands of people indicate that I am not an outlier — 70% of men and women across 34 countries view science as more male than female1. Gender bias is not just a problem in science. A host of studies shows that people tend to rate women as less competent than men across many domains, from musical abilities to leadership2, and that many individuals hold biases about competency on the basis of other irrelevant attributes, such as skin colour, body weight, religion, sexual orientation and parental status. Such biases have important consequences in the workplace. One study showed that mothers are 79% less likely to be hired and are offered US$11,000 less salary than women with no children3. By contrast, the same study shows that parenthood confers an advantage to men in the workplace. © 2013 Nature Publishing Group,
by Tim Wall Some feathered crooners may advertise their size to females by hitting the low notes. Ornithologists at the Max Planck Institute found that only bigger-bodied birds belt out the bass. The physical size of some birds may put a limit on the frequency of the birds’ songs, according to a study published in PLOS ONE. Since only a larger males hit lower notes, females may be able to use deeper voices as a reliable measure of a male’s size. Size matters to some songbird species, with females preferring larger males, so vocal limitations could affect some birds’ love lives. The songs of purple-crowned fairy-wrens, Malurus coronatus coronatus, hit a range of notes. However the study found that in some songs, larger body size related to lower-pitched singing ability. Further study will be needed to prove a relationship among body size, singing frequency and sexual success in fairy-wrens. The authors suggested that body size may be just one of many characteristics advertized by fairy-wrens songs. The authors also noted that low-frequency singing ability may have resulted from good health as the male fairy-wrens grew up. Better health may have allowed better development of singing structures in the birds’ anatomies. The same healthy conditions could have also resulted in larger size. So size and singing would be correlated, but not causally related. © 2013 Discovery Communications, LLC.
By Athena Andreadis Genes are subject to multiple layers of regulation. An early regulatory point is transcription. During this process, regulatory proteins bind to DNA regions (promoters and enhancers) that direct gene expression. These DNA/protein complexes attract the transcription apparatus, which docks next to the complex and proceeds linearly downstream, producing the heteronuclear (hn) RNA that is encoded by the gene linked to the promoter. The hnRNA is then spliced and either becomes structural/regulatory RNA or is translated into protein. Transcription factors are members of large clans that arose from ancestral genes that went through successive duplications and then diverged to fit specific niches. One such family of about fifty members is called FOX. Their DNA binding portion is shaped like a butterfly, which has given this particular motif the monikers of forkhead box or winged helix. The activities of the FOX proteins extend widely in time and region. One of the FOX family members is FOXP2, as notorious as Fox News – except for different reasons: FOXP2 has become entrenched in popular consciousness as “the language gene”. As is the case with all such folklore, there is some truth in this; but as is the case with everything in biology, reality is far more complex. FOXP2, the first gene found to “affect language” (more on this anon), was discovered in 2001 by several converging observations and techniques. The clincher was a large family (code name KE), some of whose members had severe articulation and grammatical deficits with no accompanying sensory or cognitive impairment. The inheritance is autosomal dominant: one copy of the mutated gene is sufficient to confer the trait. When the researchers definitively identified the FOXP2 gene, they found that the version of FOXP2 carried by the KE affected members has a single point mutation that alters an invariant residue in its forkhead domain, thereby influencing the protein’s binding to its DNA targets. © 2013 Scientific American
by Michael Balter Despite recent progress toward sexual equality, it's still a man's world in many ways. But numerous studies show that when it comes to language, girls start off with better skills than boys. Now, scientists studying a gene linked to the evolution of vocalizations and language have for the first time found clear sex differences in its activity in both rodents and humans, with the gene making more of its protein in girls. But some researchers caution against drawing too many conclusions about the gene's role in human and animal communication from this study. Back in 2001, the world of language research was rocked by the discovery that a gene called FOXP2 appeared to be essential for the production of speech. Researchers cautioned that FOXP2 is probably only one of many genes involved in human communication, but later discoveries seemed to underscore its importance. For example, the human version of the protein produced by the gene differs by two amino acids from that of chimpanzees, and seems to have undergone natural selection since the human and chimp lineages split between 5 million and 7 million years ago. (Neandertals were found to have the same version as Homo sapiens, fueling speculation that our evolutionary cousins also had language). In the years since, FOXP2 has been implicated in the vocalizations of other animals, including mice, singing birds, and even bats. During this same time period, a number of studies have confirmed past research suggesting that young girls learn language faster and earlier than boys, producing their first words and sentences sooner and accumulating larger vocabularies faster. But the reasons behind such findings are highly controversial because it is difficult to separate the effects of nature versus nurture, and the differences gradually disappear as children get older. © 2010 American Association for the Advancement of Science
By JANE E. BRODY The title of a recent report on smoking and health might well have paraphrased the popular ad campaign for Virginia Slims, introduced in 1968 by Philip Morris and aimed at young professional women: “You’ve come a long way, baby.” Today that slogan should include: “…toward a shorter life.” Ten years shorter, in fact. The new report is one of two rather shocking analyses of the hazards of smoking and the benefits of quitting published last month in The New England Journal of Medicine. The data show that “women who smoke like men die like men who smoke,” Dr. Steven A. Schroeder, a professor of health and health care at the University of California, San Francisco, wrote in an accompanying editorial. That was not always the case. Half a century ago, the risk of death from lung cancer among men who smoked was five times higher than that among women smokers. But by the first decade of this century, that risk had equalized: for both men and women who smoked, the risk of death from lung cancer was 25 times greater than for nonsmokers, Dr. Michael J. Thun of the American Cancer Society and his colleagues reported. Today, women who smoke are even more likely than men who smoke to die of lung cancer. According to a second study in the same journal, women smokers face a 17.8 times greater risk of dying of lung cancer than women who do not smoke; men who smoke are at 14.6 times greater risk to die of lung cancer than men who don’t. Women who smoke now face a risk of death from lung cancer that is 50 percent higher than the estimates reported in the 1980s, according to Dr. Prabhat Jha of the Center for Global Health Research in Toronto and his colleagues. After controlling for age, body weight, education level and alcohol use, the new analysis found something else: men and women who continue to smoke die on average 10 years sooner than those who never smoked. Copyright 2013 The New York Times Company
by Lizzie Wade When a male wasp decides it's time to settle down and start a family, he releases a chemical calling card in the form of pheromones, broadcasting his location, his availability, and, most importantly, his identity. Most other kinds of insects will either ignore his signal or be repelled by it, but female wasps of his own species will buzz over and get down to business. But how and why did different pheromone blends—and the species that prefer them—evolve in the first place? A new study offers a possible solution to this long-standing evolutionary mystery, suggesting that new sex pheromones may evolve through genetic mutation before potential mates develop the ability to detect them. Scientists have long been impressed by the perfect harmony of chemical communication among insects, especially when it comes to choosing mates by detecting and responding to the sex pheromones of only their own species. But scientists were puzzled by how such a delicate system evolved. If female wasps respond to only a specific blend of pheromones, males that produce even a subtly different blend shouldn't have much luck mating and passing on their mutant genes. It seemed that in order for males to evolve new pheromones, the female insects would need some preexisting adaptation that would cause them to prefer the new chemical blend. But how could they evolve a preference for something they had never encountered and should, logic suggests, find off-putting? In essence, the question is which came first, a new species or its sex pheromone? In order to answer this question, a team of researchers in Germany turned to the Nasonia vitripennis wasp, a species famous for its propensity to lay its parasitic eggs on doomed fly pupae. When the scientists analyzed the N. vitripennis male sex pheromone, they found it contained two important chemicals, which they call RS and RR. RS also turns up in the male sex pheromones of another species of wasp, N. giraulti, whereas RR appears to be unique. © 2010 American Association for the Advancement of Science.
By RAPHAEL SATTER, Associated Press LONDON (AP) — When it comes to mating, guppies treasure their ugly friends — because they look so good by comparison. An article published Wednesday by Britain's Royal Society says that male guppies prefer to associate with their drab-colored counterparts when females were around. "Males actively choose the social context that maximizes their relative attractiveness," the article said. Or, as lead author Clelia Gasparini put it, "If you are surrounded by ugly friends, you look better." Gasparini and her colleagues at Italy's University of Padua built their theory on a kind of guppy dating game. An aquarium was set up with one female in partition on either end. Guppy bachelorette No. 1 had two attractive, brightly-colored males placed on either side of her. Guppy bachelorette No. 2 was stuck with uglier, drab-colored fish. When a male guppy was put in the middle of the tank, and given the choice of which female to sidle up to, Bachelorette No. 2 was the more popular pick, with male guppies spending about 62 percent of their time hanging around her side of the aquarium. What's more, the researchers found that the time guppies spent with bachelorette No. 2 correlated with their unattractiveness. The uglier the guppy, the less likely it was that he would hang around the brightly colored fish placed next to bachelorette No. 1. © 2013 Hearst Communications Inc.
Keyword: Sexual Behavior
Link ID: 17798 - Posted: 02.13.2013
Matt Kaplan The astounding warning colours of the nudibranchs, a diverse group of sea slugs, are certainly enough to attract attention — but even they pale in comparison to the gripping news that one species of the soft-bodied molluscs has a habit of discarding its penis. Nudibranchs are hermaphrodites, meaning that they carry both male and female reproductive organs. Moreover, when they mate, they can perform the male role of donating sperm and the female role of receiving sperm at the same time. This process involves two penises and two vagina-like organs, and sperm transmission effectively happens simultaneously during the encounter. This is a relatively standard arrangement among nudibranchs, so the creatures' sexual organs might all be expected to look roughly the same. But the animals show incredible sex-organ diversity, and it was during an exploration of this diversity in the species Chromodoris reticulata that researchers made their jaw-dropping discovery. A Japanese team led by Ayami Sekizawa at Osaka City University and Yasuhiro Nakashima at Nihon University in Tokyo went scuba diving off the coast of Okinawa to collect the sea slugs. They then placed the creatures in aquaria in pairs. In some cases both members of a pair had been isolated from others for 24 hours; in other cases a recently-mated animal was placed with one that had been in isolation. © 2013 Nature Publishing Group,
Keyword: Sexual Behavior
Link ID: 17797 - Posted: 02.13.2013