previous studies, University at Buffalo researchers have determined
that the sparkle, not the size, of a butterfly's eyespot attracts
After two years of pairing butterflies and
studying mate choices, researchers from the biological sciences
department contradicted a study in the Netherlands that indicated
female butterflies may consider larger eyespots more desirable.
Instead, they found that the ultraviolet light shining off tiny white
pupils in the dorsal wing eyespots plays the largest role in a female
butterfly's sexual selection.
The paper, co-authored by
then-master's degree candidate Kendra Robertson and Antonia Monteiro,
an assistant professor of biological sciences at UB, was published
online last week.
"What makes our study different is that
these tiny pupils - such a small patch of ultraviolet light - were
really important in sexual selection," Robertson said.
Monteiro, a native of Portugal, came to UB in 2002 after studying the
evolution and development of butterflies since her undergraduate days.
Her research has made UB one of the leading butterfly research centers in the nation.
She attributed her interest in this topic to the lack of specific
research on the function of the pupils, which she believed could have
something to do with the mating process.
Robertson to examine the different components of the eyespots on
Bicyclus anynana, the African satyrid butterfly.
said that previous studies associating UV reflectivity with mate choice
prompted her to enter the experiment with the thought that the tiny
pupils, havens of UV reflection, had something to do with sexual
The theory proved correct.
After repeating portions of the Netherlands' experiment, Robertson added tests to alter wing patterns.
She carefully painted different sized eyespots or paired male
butterflies with eyespots of different size and color before testing
their attractiveness to females.
Painting the white pupils
with rutin, a plant extract that maintains the color and appearance of
the pupil but blocks the UV light, provided the most conclusive
evidence supporting Robertson and Monteiro's theory: The females were
not attracted to those males.
After numerous experiments,
Robertson found that the female butterflies always were attracted to
the males with the most intense UV reflectivity.
findings are) interesting because it is a very small pattern element
that is highly significant in mate choice scenarios," Monteiro said.
This is the first study that shows that a single element, a little spot, is really important in female choice.
Where research into the natural world usually attributes attraction to
bright colors and other dramatic features, these findings may inspire a
whole new look on sexual selection research, Monteiro said.
"It can lead other (researchers) to take more notice of smaller elements as being more important," she said.