During the observations of a species of blue moon butterflies on the Samoan island of Upolu, 99% of the butterflies were female and only 1% were male. Only five years later the male:female sex ratio was 1:1. What caused this?
A) Wolbachia lost the ability to kill all male butterflies.
B) Genetic changes in the Upolu butterflies resulted in suppression of the male-killing effect of Wolbachia.
C) Upolu butterflies evolved to become resistant to Wolbachia infection.
D) Upolu was recolonized by butterflies from the nearby island Savali, where sex ratios were closer to 1:1.

Question

Quizplus · Accepted Answer

Wolbachia is a bacterium that can manipulate the reproductive systems of their hosts to increase the number of infected females. However, genetic changes in the Upolu blue moon butterflies could have resulted in suppression of the male-killing effect of Wolbachia, leading to an increase in male butterfly population and, hence, a balanced sex ratio. The other options are not supported by the information provided in the question.

During the Observations of a Species of Blue Moon Butterflies