AsianScientist (Aug. 25, 2016) – New research refuting the ‘single Hawaiian origin’ hypothesis shows that fruit flies have plural ancestors spanning various continents. The findings were published in the journal Entomological Science.
Hawaiian drosophilids (fruit flies) 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.
The other hypothesis of ‘multiple origins’ suggests that Hawaiian Scaptomyza and Idiomyia derived from different ancestors that independently colonized the Hawaiian Islands.
To test the two hypotheses, a research team led by Assistant Professor Toru Katoh of Hokkaido University determined the DNA sequence information of 11 non-Hawaiian Scaptomyza species and analyzed it along with existing sequence information for 79 species.
The researchers then constructed a phylogenetic tree and estimated ancestral distributions and divergence times. From their findings, the researchers thus inferred that the Hawaiian drosophilids had plural continental ancestors that independently migrated to Hawaii at different times.
Nonetheless, the exact route taken by the ancestors of the Hawaiian drosophilids remains unknown. The research team hopes to unravel this mystery through further related studies, including research into non-Hawaiian drosophilids endemic to the Pacific Islands.
The article can be found at: Katoh et al. (2016) Multiple Origins of Hawaiian Drosophilids: Phylogeography of Scaptomyza Hardy (Diptera: Drosophilidae).
Source: Hokkaido University.
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