Via PopSci, comes a study done with tiny shrimp to see the effects of having sex with members of your species from a different time. The study was done between mates that were 160 generations apart and resulted in an earlier death rate:
They found that females that mated with males from the past or future died off sooner than those that mated with their own generation. The longer the time-shift, the earlier they died: The 22-year time difference shortened female lifetimes by 12 percent; the effect was 3 percent for the 11-year time-shift.
Interestingly, this didn’t affect the females’ reproductive success. Those that lived shorter lives produced the same average number of offspring, they just did it at a faster pace. “Females’ life histories are complex and are constantly adjusted,” explains study co-author Thomas Lenormand. These adjustments reflect the trade-offs between survival and reproduction in nature.
Brine shrimp are part of an interesting class of animal whose eggs can survive decades of drought in a form of dormancy known as cryptobiosis. Once the eggs are reintroduced to water—either in nature or in the lab—they hatch. The species therefore makes an ideal subject for a time-traveling experiment like this one.
What makes time-shifting sex hazardous to health is something called antagonistic coevolution, a way that different species (parasites and hosts, for example) or members of the same species (males and females) adapt to each other to promote their own individual reproductive interests. In nature’s sex wars, males campaign for more offspring—the proverbial seed-spreading—while females play hard-to-get because they bear most of the burden of reproduction and parenthood.
