Author Archives: kathryn irwin

The current frontier in evolutionary genetics involves discovering how the evolution of new gene function is correlated with animal form diversification. A gene is a section of DNA in an organism that tells the organism what to produce to be able to look and act the way it does.

Understanding how species form throughout evolution can allow us to predict how our world will change in the future. A new technique has been developed that allows scientists to look specifically at genes, helping to broaden our knowledge.

Figure 1. A section of DNA which contains multiple forms of genes. The CRISPR/cas9 technology will make specific cuts in the DNA to remove individual genes. (Image Source)

The new CRISPR/cas9 method uses a nuclease, an enzyme that can cut DNA, and a synthetic guide RNA, a molecule that specifically binds to DNA. Precise cuts can be made in the genome that allow a particular gene to be deleted, effectively terminating that genes phenotypic expression (what can be observed).

This new technology was a scientific breakthrough that caught a lot of media attention when initially published. There is currently a moral dispute in the media due to the potential of modifying human babies with this technique. Being able to effectively communicate the new advances with this technology is necessary to get grant money to continue the research, and to show its importance to the public.

Recently, there have been several breakthroughs at Cornell University looking at the optix gene in butterflies, a master gene for wing pattern adaptation. The scientists discovered that the gene has different pigmentation and structural colouration functions, depending on the butterfly species.

Zhang et al. stated than until now the developmental function of the optix gene was unclear. By using the new CRISPR/cas9 method, they were able to observe species with this gene turned off. This gave the researchers a clear analysis on how the wings were directly affected by optix.

Figure 2. The Buckeye butterfly with the optix gene still intact. Without it , its wings will turn an iridescent blue. (Image Source)

Zhang et al. found that different species of butterflies had different reactions when the optix gene was turned off. The Junonia genus, including butterflies commonly known as Buckeyes, had their normal orange-brown wings turn iridescent blue when the optix gene was deleted.

Figure 3. The Gulf Fritillary butterfly with the optix gene intact. Without the optix gene, it will undergo melanization which turns its wings black and grey. (Image Source)

However, other species of butterflies, like the Gulf fritillary (A. vanillae), had melanin replace their normal pigments, which then produced black and grey colours.

Seeing how this master gene is conserved in butterflies allows scientists to make increasingly accurate predictions of past evolutionary change. They have stepped toward understanding how DNA specifies 3D structure by first looking at a manageable 2D gene form. In the future, Dr. Reed, one of the other scientists on the team, wishes to recreate butterfly wing pattern in different distinctive species.

This deep understanding of the optix gene will provide further knowledge into the evolution of butterfly wing colour adaptation. By understanding more about butterfly evolution, we can better understand evolution as a whole. Each step towards new knowledge provides a better basis for predicting future changes in genetics.

Author: Thryn Irwin