Biohistory Jyournal, Winter, 2003
Research: Index > The reason the freshwater fish arowana live across the sea
The time of evolution
The reason the freshwater fish arowana
live across the sea
Yoshinori Kumazawa,
Graduate School of Science, Nagoya University, Division of Material Science
    The study of molecular evolution, which traces the history of living creatures using the molecular information written in their genome as clues, was a fresh breeze that blew through research into evolutionary history, formerly dominated by paleobiologist. A single method is insufficient to unravel the history of living creatures that have evolved in an unceasingly changing global environment. That requires a comprehensive view from several different aspects, including fossils, molecular information, and the environment. A new aspect in the history of the evolution of the arowana has emerged through the combination of molecular phylogeny and geology.

The arowana was carried to the Indian sub-continent.
    According to the analysis data for the DNA sequence, the Asian and Australian arowana diverged about 140 million years ago, much longer ago than the time assumed based on the similarities of form. At that time, the land masses of India and Madagascar, both part of the Gondwana supercontinent, broke off from the Antarctic land mass and began to drift north. Later, the Indian subcontinent continued to drift northward and collided with the Eurasian continent.
&   If the ancestors of the Asia arowana rode on the Indian subcontinent and were taken to Southeast Asia, it would explain without contradiction the period in which the arowana diverged, the geological history of the continental drift, and their requirement for fresh water. This is how the history of the arowana's origin and movement can be explained based on objective data.

Yoshinori Kumazawa
Received a Ph.D. from the School of Engineering at the University of Tokyo. He is a special research fellow of the Japan Society for the Promotion of Science. He did post-doctoral studies at the Department of Molecular and Cell Biology, University of California at Berkeley. After becoming an assistant in the Graduate School of Science at Nagoya University, he now serves as an associate professor in the Graduate School of Science at Nagoya University
The creation of form in multicellular organisms as seen through the volvox


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