View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PubMed Central Biol. Lett. (2010) 6, 363–366 2003) occupy more basal positions in the published doi:10.1098/rsbl.2009.0989 phylogenies, Tsukamoto et al. (2002) hypothesized Published online 6 January 2010 two phases in the evolution of catadromous migrations Evolutionary biology of freshwater eels: (i) their migratory behaviour originated in tropical ocean areas and (ii) that tropical species subsequently expanded their ‘migration loops’ Deep-ocean origin of the (representative migratory pathway of a species), and began to use fresh waters at higher latitudes for their freshwater eels growth (figure 1a). This resulted in the diversification of freshwater eels to include temperate species that Jun G. Inoue1,*,†, Masaki Miya2,*, Michael make long migrations back to their tropical spawning J. Miller1, Tetsuya Sado2, Reinhold Hanel3, areas. This argument is consistent with the Gross Kiyotaka Hatooka4, Jun Aoyama1, Yuki Minegishi1, 1 1 et al. (1988) prediction that catadromy has evolved in Mutsumi Nishida and Katsumi Tsukamoto low-latitude tropical areas where productivity in fresh- 1Ocean Research Institute, The University of Tokyo, water exceeds that in the ocean. In contrast to eels, the Tokyo 164-8639, Japan 2Natural History Museum and Institute, Chiba, Chiba 266-8682, Japan freshwater origin of anadromous salmon has been 3Johann Heinrich von Thu¨nen-Institut 22767, Hamburg, Germany demonstrated (Ishiguro et al. 2003), which indicates 4Osaka Museum of Natural History, Osaka 546-0034, Japan that they expanded their life histories to include the *Authors for correspondence (
[email protected],
[email protected]) use of the ocean for growth while still returning to †Present address: University College London, London WC1E 6BT, UK.