Professor KOKITA Tomoyuki and his research team have, for the first time, elucidated hidden population-specific adaptations in a marine biological resource found around the coastal waters of Japan.

Local Adaptations of Northern and Southern Ice Goby Populations to Latitudinal Environments in the Sea of Japan

POINT

• In open marine environments, population-specific adaptive evolution (local adaptation), well-documented in terrestrial and freshwater organisms, is thought to be less common. As a result, clear examples of local adaptation in marine species are scarce worldwide.
• By focusing on the ice goby (family Gobiidae), a species widely distributed in the coastal waters of the Japanese archipelago and renowned for its role in the culinary tradition of "odorigui" (eating live fish), we have, for the first time, demonstrated the existence of local adaptation in Japanese marine and economically important fishery species. This was achieved through phenotypic analysis using common garden experiments ^*1 with local populations from different latitudes, as well as population genomics analysis ^*2 utilizing extensive DNA data.
• Elucidating the reality of local adaptation in wild fishery resource organisms through an integrated approach, as demonstrated in this study, and conducting geographical mapping of physiological and ecological adaptations are crucial for developing resource management, propagation, and conservation plans for local populations. Moreover, this provides an essential foundation for the advancement of genomic breeding, aimed at creating aquaculture strains with economically advantageous traits.

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SUMMARY

In open marine environments, gene flow ^*3 between populations is actively facilitated primarily by the dispersal of early life stages through ocean and tidal currents. As a result, population-specific adaptive evolution of phenotypic traits (local adaptation), which is well-documented in terrestrial and freshwater environments, is generally considered less likely to occur in marine environments. While the theoretical potential for local adaptation to evolve under conditions of gene flow has been demonstrated, definitive evidence of such adaptation in open marine environments remains extremely limited worldwide. The Japanese archipelago spans a significant latitudinal range, creating pronounced environmental gradients in the surrounding marine environment. This suggests a high potential for local adaptation among marine organisms inhabiting these waters. However, until now, no reports had conclusively confirmed the existence of such local adaptation in open marine environments.
Known as "haru-tsuge-uo" (spring herald fish) and renowned for its early spring flavor and the culinary tradition of "odorigui" (eating live fish), the ice goby (family Gobiidae) is a diadromous species widely distributed along the coastal waters of the Japanese archipelago. Local populations inhabit diverse climatic environments, suggesting a high potential for local adaptation, as noted above. A research team led by Professor Tomoyuki Kokita from the Faculty of Agriculture at Kyushu University and Assistant Professor Shotaro Hirase (currently Associate Professor) from the Graduate School of Agricultural and Life Sciences at the University of Tokyo utilized the Sea of Japan, characterized by the north-south flow of the Tsushima Current, as their model system. Through common garden experiments and population genomics analyses using extensive DNA data, the team provided compelling evidence of local adaptation among latitudinally distinct populations of this species. This marks the first documented case of local adaptation in Japanese marine and fishery species.
This discovery was made possible through an integrated research approach that, for the first time, combined phenotypic analysis via common garden experiments with population genomics analysis. Applying a similar approach to uncover local adaptation in various marine biological resources and to geographically map physiological and ecological adaptations is crucial for developing effective resource management, propagation, and conservation plans for local populations within species. Furthermore, this approach offers significant potential for genomic breeding applications, which use DNA sequence information to identify individuals with economically advantageous traits in wild fishery populations and create valuable aquaculture strains. The findings of this study were published online in the international journal Molecular Ecology on December 17, 2024, at 10:01 AM JST.

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Comment from the Researcher

We assume that similar phenomena occur in various coastal biological resources. Elucidating hidden patterns of local adaptation through an integrated approach, as demonstrated in this study, is highly significant not only for advancing fundamental marine biology and evolutionary ecology but also for promoting sustainable fisheries and conserving biological resources. Furthermore, the ice goby is a particularly valuable fishery resource in Fukuoka City, home to Kyushu University, making it especially rewarding to achieve these results using this species as a model system.

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GLOSSARY

*1 Common garden experiment
An experimental method where offspring from different populations or lineages are reared from early developmental stages in a common environment. This approach eliminates the influence of environmental factors on phenotypic expression, allowing researchers to investigate genetic differences in phenotypes.
*2 Population genomics analysis
A research field that uses genome analysis to elucidate patterns of genetic diversity within and between populations of a species, the history of speciation, population demography, and adaptive evolution.
*3 Gene flow
The transfer of genes between different biological populations via the movement of individuals or the dispersal of gametes.

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Paper Information

Journal: Molecular Ecology
Title: Phenotypic and genomic signatures of latitudinal local adaptation along with prevailing ocean current in a coastal goby
Authors: Shotaro Hirase*, Atsushi J. Nagano, Kenji Nohara, Kiyoshi Kikuchi, Tomoyuki Kokita* *Co-corresponding Author
DOI：10.1111/mec.17599

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For Research-related inquiries

KOKITA Tomoyuki, Professor