Guppies father fry after they die

By John Upton

You have to be quite the stud to sire a clutch of ankle-biters long after you’ve croaked it.

Yet that’s just what male members of many species of animals can do. And with apologies to any ghostly egos of dead dads of the animal world, the reality is that these feats are not to their credit.

Females of some species of crabs, salamanders, turtles, lizards, bats and fish can store sperm inside their bodies, which they use to fertilize their eggs many months or even a year or more after they have mated. That means that males can father offspring long after they are dead.

Illustrated by Perry Shirley.
Illustrated by Perry Shirley.

One such species is the Trinidadian guppy. Female guppies live much longer lives than do male guppies, but the longevity of the sperm when stored inside special ovarian receptacles can make up for the difference.

Researchers introduced a population of lab-reared guppies into a pond beneath a waterfall in Trinidad’s Lower LaLaja. They fastidiously monitored each of the fish as the population grew, studying the Poecilia soap opera dramas of who was mating with who.

The scientists discovered that many guppy fry were fathered by fish that had died generations prior to their births. Within eight months of research, around one quarter of the guppies being born (described as “new recruits” in the following graph) were being fathered by dead males.

Lo ́pez-Sepulcre A, Gordon SP, Paterson IG, Bentzen P, Reznick DN. 2013 Beyond lifetime reproductive success: the posthumous reproductive dynamics of male Trinidadian guppies. Proc R Soc B 280: 20131116.
Lo ́pez-Sepulcre A, Gordon SP, Paterson IG, Bentzen P, Reznick DN. 2013 Beyond lifetime reproductive success: the posthumous reproductive dynamics
of male Trinidadian guppies. Proc R Soc B 280: 20131116.

“Clearly, posthumous reproduction has important fitness consequences for males, as it allows them to expand their reproductive lifespan to equal that of females,” the scientists wrote in a paper, published this month in the journal Proceedings of the Royal Society B. “[L]ong-term sperm storage by females can also buffer the loss of genetic variation in organisms where females outlive males, enabling males represented in stored sperm to reproduce, even after death.”