Hypolimnas bolina, is also known as the blue moon butterfly or the great eggfly. This butterfly has a wingspan of approximately 80 to 100mm and is a dark winged, black bodied butterfly within the Nymphalidae family. This species is found in wooded areas, scrub land and urban areas. It displays sexual dimorphism, in that the male and females look quite different to one another. This is due to the female butterfly’s ability to mimic other species. Mimicry is the ability to look like other species of butterfly in the region that is toxic; therefore, by copying their ‘warning markings’ the females have a reduction in predation.
This butterfly was affected by the parasite Wolbachia bacteria on the Samoan islands of Upolu and Savai'i. Interestingly, the parasite only affected males, and was passed on via the females but only killed males of this species before hatching. Male blue moon butterflies declined to only 1% of the population in 2001. Yet, after just 10 generations, males had developed resistance to the parasite via a genetic mutation that suppresses the bacteria. This evolutionary trajectory resulted in a massive increase of males, now representing approximately 40% of the population. This is an example of one of the most rapid instances of natural selection witnessed in a wild population.
Male (top) and female form one (middle), female form two (bottom) of Hypolimnas bolina. Bottom image attribution: © 2010 Jee & Rani Nature Photography
(License: CC BY-SA 4.0). Image rotated and cropped.