進化の捉え方 : エネルギー的観点の重要性(<特集>生物進化と人間の特性-生成文法の研究-)

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In starfish, Asterina pectinifera, parts of egg cytoplasm can be removed by microsugjcal techniques, and it is known that only 14 % of a whole egg (ca. 02 mm in diameter) is enough for the complete development including metamorphosis. Therefore 86 % of a whole egg is surplus. On metamorphosis adult buds are formed and larval mouth and anus are digested, and food supply ceases until adult mouth and anus are formed. Adult buds are never formed before larvae have reached a certain size, i.e. larvae have a critical size for metamorphosis (ca. 1mm). Larval bodies themselves can be regarded as a form of energy accumulation. These indicate that the function of the surplus energy in eggs is to shorten the larval duration and that of the larvae is to accumulate energy for the growth of adult buds. This is the case in extant starfishes: among hundreds starfishes, species with larger eggs (more than ca. 025 mm in diameter) do not have larval forms and develop into adults directly from eggs, whereas species with smaller eggs still keeps larval forms. Living organisms are always forced to keep the energy balance positive and to accumulate surplus energy as a whole for the continuation of the metabolism (avoidance of stop in metabolism, i.e. avoidance of starvation). Relationship between DNA changes and phenotypic evolution has been discussed. A new theory of evolution is proposed: the role of DNA in evolution is to stabilize the life styles that are adopted by species and not to control completely their life styles. Even if environments are kept unchanged, silent improvements (invisible metabolic improvements such as DNA reorganizations) progress because of premise of life.
生命の起原および進化学会の論文
2003-06-30

進化の捉え方 : エネルギー的観点の重要性(<特集>生物進化と人間の特性-生成文法の研究-)

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