Research Press Release | August 19, 2016
A team from Hokkaido University and Ehime University has discovered that Hawaiian drosophilids (fruit flies) had plural ancestors that hailed from continents, refuting the “single Hawaiian origin” hypothesis.
|Scaptomyza pallida, one of the fruit fly species|
Like African cichlids and the Darwin finches found on the Galapagos Islands, Hawaiian drosophilids are a striking example of a single lineage diversifying by adapting to a wide variety of environments. The Hawaiian drosophilids are broadly divided into two main groups: the Hawaii-endemic genus Idiomyia and the Scaptomyza genus. About 60 percent of Scaptomyza species are unique to the Hawaiian Islands, with the other 40 percent distributed around the world.
Until now, the “single Hawaiian origin” hypothesis has held sway. This idea proposes that the different Hawaiian drosophilids diverged from a sole common ancestor that once colonized the Hawaiian Islands, then the Hawaiian Scaptomyza subsequently moved back to different continents.
However, by newly determining the DNA sequence information of 11 kinds of non-Hawaiian Scaptomyza species and analysing it along with existing sequence information, the researchers reconstructed the phylogeny, and estimated ancestral distributions and divergence times. The team thus inferred that the Hawaiian drosophilids had plural continental ancestors that independently migrated to Hawaii at different times.
|Hawaiian drosophilids had multiple ancestors that migrated from continents: Phylogenetic analysis of DNA sequences showed that ancestors of the Idiomyia genus migrated to Hawaii once, while ancestors of the Scaptomyza genus migrated twice.|
The exact route taken by the ancestors of the Hawaiian drosophilids remains unknown, but the research team, led by Assistant Professor Toru Katoh of Hokkaido University’s Faculty of Science, hopes to unravel the mystery through further related studies, including research into non-Hawaiian drosophilids endemic to the Pacific Islands.
- Katoh et al., Multiple origins of Hawaiian drosophilids: Phylogeography of Scaptomyza Hardy (Diptera: Drosophilidae), Entomological Science, July 13, 2016. DOI: 10.1111/ens.12222
Assistant Professor Toru Katoh
Faculty of Science
Naoki Namba (Media Officer)
Global Relations Office
Office of International Affairs