Helpful Parasites?

Charles Q. Choi, writing for LiveScience, describes the “surprisingly rapid” evolution many parasites exhibit that causes them “to become helpful instead of harmful.” In particular, Choi reviews research evolutionary biologist Andrew Wells and colleagues at the University of Melbourne have conducted into Wolbachia, a microbial parasite that—the team discovered—actually aids its host by boosting its host’s fertility.

Wells’s theory is that, while parasites are traditionally thought as disabling their hosts’ survivability (as Wolbachia can do), parasites can also benefit from boosting their hosts’ rates of reproduction and, thus, improving their own chances of spreading to new hosts:

[I]ntuition suggests that in order to prosper, these microbes should try and evolve ways to crank up the number of offspring that their hosts birth in order to infect more victims.

“We had a very thorough theoretical analysis which suggested that this could and should evolve, but we had no idea of the timeframe that this might take,” Weeks said.

In other words, Wells et al. expected Wolbachia may eventually evolve from a detrimental parasite to a beneficial symbiont, but, per evolutionary preconceptions, thought this transformation would occur over a long timetable (thousands or millions of years). Imagine the team’s surprise after discovering that, during the 20 years that Wolbachia’s effects have been studied, its effects have dramatically shifted from a 20% reduction in host fertility to a 10% boost.

“We just didn't expect it to happen so quickly,” Weeks told LiveScience. . . . Such a dramatic evolutionary change is traditionally thought to take place over thousands to millions of years, and not in just two decades, “although it is becoming clearer that evolution does work on such short time scales,” Weeks said.

Chalk this up as yet another example of rapid “evolution”—the sort that not only goes against traditional evolutionary thought, but also supports the idea of rapid post-Fall and post-Flood speciation that explains the diversity of animal species existing today that have descended from the original created kinds.

Also, although Wells and his team are “uncertain how exactly Wolbachia triggers such fertility,” we are confident Wolbachia’s ability (and, hence, its “evolution”) is not the result of information-gaining mutations, but instead the result of natural selection sustaining the existing, successful Wolbachia genomes that already contain the genetic information to boost host fertility.