For fruit flies, sleep deprivation leads to less aggression and less sex

The common fruit fly - a small but mighty model organism for studying behaviour. (Credit: NASA)
The common fruit fly – a small but mighty model organism for studying behaviour. (Credit: NASA CC BY 2.0)

Sleep—it’s something that we all need but can’t seem to get enough of. Not getting enough sleep can turn the sweetest, most patient person into a short-tempered and irritable crank. When you’re tanky (tired + cranky), you might say and do things that you don’t really mean, kind of like when you’re hangry (hungry + angry). While the effects of sleep deprivation on mood and mental functioning have been well documented, less is known about how sleep loss affects aggressive behaviour.

Dr. Amita Sehgal, a professor at the Perelman School of Medicine at the University of Pennsylvania, studies behaviour and its relationship with the body’s internal clock. For her research, she uses the common fruit fly, Drosophila melanogaster, as a model to study the interactions between sleep and behaviour. In a paper published last month in eLife, Sehgal and colleagues showed that sleep deprivation in fruit flies leads to less aggression. Continue reading

Science With Friends: on sexes and reproduction

What do scientists talk about when they get together? All sorts of random things. Welcome to the first installment of Science With Friends, a new series where friends write about science. I hope it is both entertaining and informative. Enjoy!

[Image: Praveer Sharma]
Female (left) and male (right) black-necked stilts showing moderate sexual dimorphism. (Image: Praveer Sharma)
Why do men and women exist? Why are there not just…people? Peace, dear reader—I’m not channelling Yoko Ono’s Twitter feed here, but addressing the biological question of why so many creatures (but not all!) are divided into male and female.

The simplest way to reproduce is to just make an identical copy of yourself. This is mainly how bacteria, the oldest and most numerous organisms on the planet, get it done. But plenty of more complex beings, such as plants and animals, can reproduce the same way, through cuttings, budding or other similar means. This asexual sort of reproduction has many advantages—there’s no need to wander around searching for a mate and all one’s tried-and-true genes get passed on, instead of taking a chance and ending up mixed and matched with some rando’s janky DNA.

Asexual reproduction does not result in absolutely unvarying organisms—there’s inherent randomness in the biochemical processes governing life and errant radiation or chemicals can also come by and scramble things. These generate genetic variation, on which the evolutionary processes of selection and drift can act. But this way is slow and conditions, whether they are climatic or pathogenic, can change fast. When a new critter comes along that wants to hitch a ride on you/feed on you/liquefy you from the inside out, it would helpful to have the tools to deal with it sooner rather than later. This is where grabbing some DNA from another individual of your species can come in handy—they just might have what you need to fend this threat off. This is sexual reproduction. Continue reading

Wounded by love: snails struck by love darts have lower survival and reproductive rates

"Shot through the heart and you're to blame, you give love a bad name" In this image of two mating snails, the snail on top shot a love dart through the head of its mating partner. (Credit: Chase and Blanchard, Proc. R. Soc. B (2006) 273, 1471–1475)
“Shot through the heart and you’re to blame, you give love a bad name” In this image of two mating snails, the snail on top shot a love dart through the head of its mating partner. (Credit: Chase and Blanchard, Proc. R. Soc. B 2006, 273:1471)

In classical mythology, Cupid carries two types of arrows: one with a sharp golden tip and one with a blunt tip made of lead. Those struck with the golden arrow are filled with uncontrollable desire while those wounded with the lead arrow are filled with revulsion. In these modern times, we humans are less likely to rely on a winged cherub carrying a quiver full of arrows to help us find love than on online dating sites and Tinder. That’s not to say that projectile weapon systems like the bow and arrow have become obsolete in affairs of the heart. Some species of land snails shoot love darts at their mating partners to increase their reproductive success.

As violent as it sounds, stabbing their mating partner with a love dart improves the likelihood that a snail will father offspring.  These sharp and pointy darts are made of a crystalline form of calcium carbonate called aragonite and coated with mucus. If the dart hits its target, chemicals in the mucus coating are released into the recipient snail’s blood stream. These chemicals serve as signals that trick the female reproductive organs to divert the shooter’s sperm away from the sperm digesting organs and into the sperm storage organs where they can fertilize eggs later. While love darts are known to carry clear benefits for the shooter, not a lot is known about how being hit by a love dart affects the recipient. For the first time, scientists have experimentally studied the costs of this violent and traumatic behaviour to the individual being stabbed. Continue reading