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.

Monteiro enlisted Robertson to examine the different components of the eyespots on Bicyclus anynana, the African satyrid butterfly.

Robertson 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 selection.

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.

"(The 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.

e-mail: amiller@buffnews.com