The Assassin (Flies) of Entomology

Editor's Note: This is the second in a series of videos we will release in 2016 about the use of scientific collections and DNA technology.

Torsten Dikow has traveled around the world to find the perfect fit. And he seems to have found it at the Smithsonian’s National Museum of Natural History (NMNH).

Originally from Germany, Dikow received his PhD at Cornell University and has worked at other premiere institutions, including the Field Museum in Chicago and the American Museum of Natural History in New York City. After joining NMNH’s Department of Entomology as a research scientist, Dikow discovered ancient species and continues to study the phylogenetic and taxonomic relationships of various fly groups.

Back 2009, after recent morphological studies conflicted with previous finding, Dikow decided to up the stakes. As part of his PhD dissertation, he looked into the evolutionary relationships of Asilidae flies - commonly known as assassin or robber flies - by looking at DNA sequences and morphological characteristics.

“There was very little research on their evolutionary history,” Dikow said. “So I set out my PhD dissertation to solve that problem.”

For his studies, Dikow used both museum collections and species collected in nature.

“For morphology, it’s easy to get species from this collection or other collections from around the world. So I was able to include species that are very rare in nature,” he said. “For the molecular (study), I had to rely on fieldwork that I conducted … or on specimens that other colleagues sent to me (for molecular study).”

The morphological matrix included approximately 158 species versus 82 species used in the combined molecular and morphological study matrix.

“I wasn’t able to catch all the same 158 out in the field,” Dikow said. “So it’s comparative, but it’s also a smaller sample of species that I was able to include.”

Dikow’s study showed that the morphology tree was different than the molecular tree; however, he thinks that the evolutionary relationships are best represented when molecular and morphological techniques are combined.

His ongoing research on insect taxonomy and evolution includes work with NMNH’s Global Genome Initiative, which seeks to preserve the planet’s genomic biodiversity.

“(Now) I always have a pinned fly and one in liquid nitrogen,” Dikow said of his recent collecting techniques. “And through our database that we use to keep track of all of the records, we do connect these two records.”

In order to view records that Dikow and others have contributed to genome project, visit the Global Genome Biodiversity Network.


References
(2014, April 21). Smithsonian Scientist Discovers Ancient Species of Assassin Fly. Newsdesk: Newsroom of the Smithsonian. http://newsdesk.si.edu/releases/smithsonian-scientist-discovers-ancient-species-assassin-fly

(2016) SI Entomology. Smithsonian National Museum of Natural History. http://entomology.si.edu/StaffPages/DikowT.html

Dikow, Torsten. (2009, February 9). A phylogenetic hypothesis for Asilidae based on total evidence analysis of morphological and DNA sequence data. Science Direct. doi:10.1016/j.ode.2009.02.004

Dikow, Torsten. (2009). Phylogeny of Asilidae inferred from morphological characters of imagines (Insecta, Diptera, Brachycera, Asiloidea). American Museum of Natural History Research Library Digital Repository. http://hdl.handle.net/2246/5949

(2016) Global Genome Initiative. Smithsonian National Museum of Natural History. https://ggi.si.edu/