Blind Scottish Centipede Genome Unlocks Evolutionary Secrets

November 26, 2014

Image Caption: This is Strigamia maritima, the centipede species genetically sequenced in the study. Credit: Dr. Carlo Brena

Eric Hopton for redOrbit.com Your Universe Online

An international group of scientists has completed the first ever genome sequence of a blind myriapod, Strigamia maritima. The species is one of a group of venomous centipedes that are unusual in the way in which they care for their eggs. The research also provides new insights into the biological evolution of Strigamia maritima and its unique absence of vision and circadian rhythm.

The work was partly carried out and the sequencing completed at Baylor College of Medicine in Houston, Texas, and the findings have been published online in the journal PLOS Biology.

This is the first myriapod and the last of the four classes of arthropods to have its genome sequenced, said Dr. Stephen Richards, assistant professor in the Human Genome Sequencing Center at Baylor. Arthropods are particularly interesting for scientific study because they diverged into more species than any other animal group as they adapted in many ways to conquer the planet. The genome of the myriapod in comparison with previously completed genomes of the other arthropod classes gives us an important view of the evolutionary changes of these exciting species.

Other scientists involved in the study were Dr. Ariel Chipman, of the Hebrew University of Jerusalem in Israel, Dr. David Ferrier, of The University of St. Andrews in the United Kingdom, and Dr. Michael Akam of the University of Cambridge in the UK.

Chipman, associate professor at the Hebrew University, said that The arthropods have been around for over 500 million years and the relationship between the different groups and early evolution of the species is not really well understood. We have good sampling of insects but this is the first time a centipede, one of the more simple arthropods simple in terms of body plan, no wings, simple repetitive segments, etc. has been sequenced. This is a more conservative genome, not necessarily ancient or primitive, but one that has retained ancient features more than other groups.

Fossil evidence shows that the myriapods, along with insects and spiders, were one of three independent arthropod invasions of the land from the sea. To adapt to life on land they had to learn to smell chemicals in the air, rather than taste them in the water. The research did indeed discover evidence of large gene expansions of the gustatory receptors which are believed to perform the same olfactory role that olfactory receptors play in insects, Richards said. This is a nice example of parallel evolution where different group of genes expanded, providing a different solution to the same problem, he added.

The findings indicate that this centipede group lost its eyes at least 200 million years ago. No vision-specific genes or genes related to the circadian (or internal) clock were found in the genome.

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Blind Scottish Centipede Genome Unlocks Evolutionary Secrets