STATES CHRONICLE – Scientists found that a mystery bug called Spiroplasma which affects mostly male African Queen butterflies can prompt recently-hatched female offspring to cannibalize on their brothers that are too weak to hatch because of the virus.
Researchers also found that the microbe now forces two sub-species of the butterfly to morph into two completely new species as both sub-species lack males for reproduction. Scientists noticed that as the subspecies are unable to reproduce in a region they tend to overlap and result in full-fledged species.
Only African Queen adults are infected by the bug, but male offspring die before they hatch as they land on the dinner plate of their healthy and hungrier sisters. University of Exeter’s professor Richard ffrench-Constant, lead author of a study on the strange phenomenon, explained that males are able to turn into caterpillars but the bug weakens them so that they are unable to hatch the egg.
A team of international scientists have been studying the African Queen butterflies for 13 years to better understand the pathogen. The team learned that the subspecies tend to morph into separate species only in a region around Nairobi.
Researchers also found significant changes in the subspecies DNA as the microbe seems to alter their sex chromosomes. For instance, a new chromosome dubbed neo W emerged from two merging chromosomes: a sex chromosome and a non-sex one.
Researchers believe that when the transitioning to separate species is over, the two subspecies will no longer be able to interbreed. Co-author of the study David Smith noted that the new chromosome is a “genetic sink” for all male offspring among a mostly-female butterfly population in the African region.
That “genetic sink” is what prevents the two newly formed species to interbreed. Prof. ffrench-Constant explained that this is a rare stance when a bug drives two species apart. Usually, environmental changes are behind such phenomena.
Study authors believe that the chromosome is the “smoking gun” of how two sub species can part ways. The team acknowledged that it is very rare to find “molecular evidence” for such processes. And it is all the more rare for a male-killing bug to push two subspecies into two new species.
One researcher deemed the butterfly “fascinating” as a tiny microbe can have such a huge impact on its sex and death.
Image Source: Wikimedia