杏吧原创

Stickleback fish may be able to pass on socially acquired information about a predator to their offspring.

In all organisms, life experience and environment 鈥� such as diet and exposure to pollution 鈥� can change the way genes are expressed. There is evidence that these epigenetic changes can be inherited by offspring.

at the University of Dayton in Ohio and her colleagues wanted to see if socially acquired information 鈥� learning that happens by way of observing someone else 鈥� could also be passed onto the next generation in a similar way.

For their experiment, the researchers chose three-spined sticklebacks (Gasterosteus aculeatus), a small fish common in the northern hemisphere. Previous studies have found that the fish can learn about predators by . When the fish encounter predators, they also to their offspring.

The researchers tested four groups of seven to 10 male sticklebacks, with each fish housed in its own tank. Fish in the 鈥渄irect鈥� group were chased by a fake predator 鈥� a model of a sculpin attached to a stick 鈥� every other day for two weeks. Fish in the 鈥渋ndirect鈥� group observed another fish after it had been chased with the stick sculpin. The researchers also transferred some of the tank water from the direct group to the indirect group to expose them to any chemical signals produced by the chased fish.

The final two groups were control groups, with one containing fish that hadn鈥檛 been exposed to the stick predator directly or indirectly, and the other containing fish that had been exposed in both ways.

The team then compared the behaviour of around 250 offspring from these groups, which had never seen either of their parents. When chased with the stick sculpin, the offspring of the direct and indirect groups froze for a similar amount of time, around 13 seconds on average. The offspring of males with no direct or indirect predator exposure froze for 43 seconds on average.

This 鈥渟tark difference in behaviour鈥� suggests information about a predator might have been acquired socially then passed to the next generation, says Hellmann.While it seems counterintuitive that the direct and indirect groups spent less time freezing than the control groups, Hellmann says this might be because spending more time in search of food could be a than trying to avoid predators in a high-risk environment.

The researchers found less of an effect in another measure of antipredator behaviour: fish in the indirect group spent roughly the same amount of time swimming together in groups as the non-exposed control, though the direct group spent 20 per cent less time swimming in groups compared to the control. Swimming in groups, or shoaling, can confuse predators.

鈥淭here are so many more environmental cues that can impact our traits than usually would have been thought,鈥� says at the University of North Carolina, Chapel Hill. 鈥淚t鈥檚 fascinating that information from your parent鈥檚 neighbour can impact your traits.鈥�

The researchers didn鈥檛 explain the mechanism behind this effect, but 鈥渋t had to be 鈥�, says , also at UNC Chapel Hill. Sperm or seminal fluid can have non-genetic effects on offspring, though researchers disagree about the importance of those effects.