Disclaimer: machine translated by DeepL which may contain errors.
~ Message from a graduate student~.
The History of Land Expansion of Animals Revealed by Small Scallop Shells
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| Karin Inoue |
| Department of Biological Sciences, 1st Year Doctoral Student |
| Birthplace Saitama Prefecture |
| High School Omiya Kaisei High School |
| Faculty Faculty of Science, Ochanomizu University |
When you step into a dense mangrove forest, a reed bed, a steep cliff, a forest of thorny coastal plants, or look under driftwood, rocks, or garbage, you will find small, pretty mollusks, which are the key to understanding the evolution of life.
Living organisms have adapted to various environments. Among them, the transition from sea to land is an event that drastically changes the habitat. Understanding this process leads to understanding the mechanisms that create biodiversity. I am currently a Benthic Biology Research Student at the Atmosphere and Ocean Research Institute, where I am studying the process by which animals adapt to diverse environments.
Landward expansion is accompanied by various changes in morphology, ecology, physiology, and other traits. Most of the previous studies on terrestrial invasion lacked detailed habitat assessments (e.g., elevation, distance from the coast, soil salinity) and comparisons with closely related species based on phylogenetic tree building, so the details of when and under what conditions each adaptive trait was acquired evolutionarily remain unclear. I am therefore conducting research on the marine mollusks of the family Graduate School (left) to elucidate the detailed process by which animals moved from the sea to land by means of high-precision molecular phylogenetic analysis, quantitative evaluation of habitat, and comparison of various traits.
(Left) Two species of cockles, one large and one small, found by moving rocks.
(Right) I was desperately searching for shells through the thorny vegetation.
The family of the cockle molluscs is a fascinating taxon, inhabiting the subtidal, intertidal, and supratidal zones, as well as forests further inland, and is thought to have made multiple independent forays onto land within the family. My M.S. research suggests that one Japanese species of this family has moved inland very recently (~5 million years ago), even by the standards of the animal kingdom as a whole. Because it is easy to identify traits associated with environmental changes during recent landward expansion events, this family of mollusks is a useful system for landward expansion studies. My research has focused on the initial ecology of the mollusks, and it has been suggested that the loss of the period of planktonic drift in the sea may have triggered their terrestrialization.
In my research, field surveys and captive observations are indispensable. Field surveys allow me to see and feel the habitat environment with my own eyes and provide me with many insights that are not available through specimen observation or literature research alone. Sometimes it is difficult to find the desired species or we have to collect in harsh environments (see the figure on the right), but the joy and sense of accomplishment we feel when we are able to do so is great. On the other hand, captive observation provides ecological information that cannot be obtained from short-term field surveys alone. In addition, the daily observation of their lovely appearance encourages us to study them. It is exciting to think that we may be able to elucidate the evolutionary process of animals that no one in the world knows about based on the specimens and ecological and environmental information obtained in this way.
Science is a discipline that values human intellectual curiosity and pursues the mysteries of nature. Solving simple questions about nature may lead to great discoveries that will save humanity in the future. I hope this article will convey the joy of natural history research to you. Would you like to enter the environment of "science"?