Does the beauty of butterfly wings hold the key to understanding evolution?

Understanding how the genetic information of an organism (its genotype) relates to its physical characteristics (its phenotype) and how these characteristics evolved, is an ongoing challenge in biological science. According to Antónia Monteiro and Diane Ramos of the University at Buffalo in the US, Lepidoptera - the order of insects that includes butterflies and moths - are very useful for these sorts of studies as their diversity and two-dimensional nature make them very amenable to experimentation and mathematical modelling.

Recently, several new tools have allowed the US researchers and their peers to manipulate gene expression in Lepidoptera during the larval or pupal stages. These include a way to control gene expression using heat shock: introducing gene promoters and using lasers to activate them. The methods have enabled evolutionary biologists to test gene functions in wing pattern creation.

Wing pattern development in butterflies and moths can provide crucial insights, said Monteiro. 'The patterns are ultimately produced by activating different biochemical pigmentation pathways in different parts of the wing,' she explained. 'The challenge has been to identify the genes and developmental mechanisms that recruit these pigment pathways to their particular location. Several diffusible proteins and regulatory genes have been identified as possible candidates in playing that recruitment role but, until now, we lacked the tools to actually test their function.'

Further challenges lie ahead - in particular in the logistics of breeding the butterflies, said Monteiro. But she hopes the rich variety of Lepidopteran wing patterns will help reveal whether novel characteristics are created through adaptation of existing genetic interactions or built from scratch.

Edward Morgan