Male Guppies Reproduce even 10 Months after Death: Study

A team of evolutionary biologists have revealed an interesting find: male guppies continue to reproduce for around 10 months after they die by living on the stored sperms in females, according to a news release.

To prove their finding, researchers at the University of California, Riverside, conducted experiments in a river in Trinidad. These were led by David Reznick, a professor of Biology at the University of California, Riverside.

According to Reznick, principal investigator of the study, populations that are less in number are at a risk of becoming extinct because close relatives breed with each other, and as a result of inbreeding, the offspring suffer. With stored sperms, the real population size is larger than the actual number of animals visible. Apart from this, stored sperms increase the genetic variation in other ways.

When compared to brightly colored male guppies, female guppies have a longer life span of two years, whereas male guppies live for just three-four months. Male guppies are variable in their coloration, and those with very rare color patterns are the ones that are chosen by females. According to the study researchers, a dead male that has a long-lost color pattern can later give birth to a son who will be chosen by females, as he has a different color pattern when compared to other males in the population. Due to the longer life span of the female guppies, those sons can be present in more than two generations even after the death of their father.

"Adult female guppies are the strongest swimmers and now we know they are the best able to colonize new habitats," Reznick said.  "Long term sperm storage means that a single female can colonize a new site and establish a new population that has a fair measure of genetic diversity since we have found that the older, larger females can carry the sperm of several males. Plants do the same sort of thing differently. They produce seeds that can lay dormant in the soil for decades so each year new offspring can appear that represent many prior generations of parents.  Water fleas also lay eggs that can lie dormant for long intervals of time.  But this is the first time we see such a phenomenon in a vertebrate."

The study was available online June 5 in Proceedings of the Royal Society B.