Evolution in the Dark

by Fuse, Naoyuki; Kitamura, Tasuku; Haramura, Takashi; Arikawa, Kentaro; Imafuku, Michio

• ISBN13: 9784431541462
• ISBN10: 4431541462
• Format: Paperback
• Copyright: 2013-09-24
• Publisher: Springer Verlag

Summary

(tentative) Organisms are remarkably adapted to diverse environments by specialized metabolisms, morphologies or behaviors. How organisms come to possess adaptive traits is a fundamental question for evolutionary biology. Although it is mostly impossible to demonstrate evolution in the laboratory, we try to address this issue using an unusual organism, the Dark-fly. In 1954, the late Dr. Shuichi Mori started to maintain Drosophila melanogaster in complete darkness. Even after his death, members of the laboratory inherited his project, and the Dark-fly has evolved in the dark for 56 years (1,400 generations). Is the Dark-fly adapted to a dark environment? What is the molecular nature of their adaptation? In the early phase of the project, Dr. Mori and others revealed that the Dark-fly did not have poor eyesight, but rather exhibited higher phototaxis ability compared with the wild-type fly and that the Dark-fly displayed lengthened bristles on the head, which function as touch sensors. More recently, it was found that circadian rhythms induced by light and dark cycles are still retained by the Dark-fly. Recent progress in genome science enabled us to perform whole genome sequencing for the Dark-fly. We identified a large number of mutations. These include genes encoding a light receptor, olfactory receptors, and enzymes involved in eye pigmentation and xenobiotics. We found that a light receptor acts in audition and that the Dark-fly has a nonsense mutation in it and exhibits higher sensitivity to sound. Their heightened audition might be advantageous for life in a dark environment. Since Drosophila is a model organism amenable to genetic and genome analyses, we utilize the Dark-fly to investigate the molecular nature of adaptive evolution. We aim to identify genes and traits involved in the environmental adaptation.