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Butterfly genome reveals promiscuous exchange of mimicry adaptations among species

Smithsonian Libraries
The evolutionary importance of hybridization and introgression has long been debated(1). Hybrids are usually rare and unfit, but even infrequent hybridization can aid adaptation by transferring beneficial traits between species. Here we use genomic tools to investigate introgression in Heliconius, a rapidly radiating genus of neotropical butterflies widely used in studies of ecology, behaviour, mimicry and speciation(2-5). We sequenced the genome of Heliconius melpomene and compared it with other taxa to investigate chromosomal evolution in Lepidoptera and gene flow among multiple Heliconius species and races. Among 12,669 predicted genes, biologically important expansions of families of chemosensory and Hox genes are particularly noteworthy. Chromosomal organization has remained broadly conserved since the Cretaceous period, when butterflies split from the Bombyx (silkmoth) lineage. Using genomic resequencing, we show hybrid exchange of genes between three co-mimics, Heliconius melpomene, Heliconius timareta and Heliconius elevatus, especially at two genomic regions that control mimicry pattern. We infer that closely related Heliconius species exchange protective colour-pattern genes promiscuously, implying that hybridization has an important role in adaptive radiation.

Inka Engineering Symposium 6: Road Construction Technologies

National Museum of the American Indian
In Part 6 of Engineering the Inka Empire: A Symposium on Sustainability and Ancient Technologies, Christine Fiori and Cliff Schexnayder present Road Construction Technology in the High Cordillera. The engineers of the Inka Empire had a unique consciousness of nature, with construction skills founded in lessons learned from careful observation of the power of nature. The Inka Road demonstrates the superior Inka understanding of nature. Built without the use of iron, the wheel, or stock animals, it represents important milestones in the development of civil engineering knowledge. The road's creators understood the fundamental laws of nature and employed impressive engineering strategies in response to the challenges presented by the aggressive physical geography of western South America. The Inka Road, or Qhapaq √Ďan, in scale alone is one of man's monumental engineering achievements. This engineering masterpiece rests on careful attention to the power of water, the energy expended by the users of the road (man and llama), and the energy required to construct the road. Keeping these concepts in mind, with the support of the University of Piura, Peru, and the assistance of Professor Luis Gerardo Chang Recavarren, the researchers investigated the construction techniques employed by the Inkas in the building of the road. Ground penetrating radar technology was employed to assess the subsurface structure of the road, slopes were measured, and grade and width were verified to understand the construction methods utilized. The investigation of the various methods to control water and erosion helped in developing an understanding of why the road has endured for centuries. Christine Fiori is the Associate Director of the Myers-Lawson School of Construction at Virginia Tech. She received her PhD in Civil Engineering with a concentration in Geotechnical Engineering from Drexel University in 1997. Her interest in ancient construction led to a National Science Foundation grant to explore the construction techniques of the Inka, specifically the Inka road throughout Peru. Fiori leads the Construction Engineering and Management program and also facilitates the service learning programs for the Myers-Lawson School of Construction. She has led diverse groups of student teams to Vietnam, Kenya, Belize, Haiti, and Guatemala to complete construction projects and community engagement programs. Currently her work is focused in Haiti and Belize. Cliff Schexnayder (Choctaw) is the Emeritus Eminent Scholar, Del E. Webb School of Construction, Arizona State University. He holds Civil Engineering BS and MS degrees from Georgia Institute of Technology and a PhD from Purdue University. Before entering academia he worked with major heavy/highway construction contractors as field engineer, estimator, and corporate Chief Engineer. In South America he has taught construction engineering at the Universidad de Piura and Ricardo Palma Universidad in Peru. Schexnayder is a member of the National Academy of Construction, the Academia Panamericana de Ingenier√≠a, and is a Distinguished Member of the American Society of Civil Engineers (ASCE). He served as chairman of the ASCE's Construction Division and the Transportation Research Board's Construction Section. This symposium was webcast on November 14, 2013 from the Rasmuson Theater at the National Museum of the American Indian in Washington, D.C.