相模川における, 一卵サイズ・一腹卵数を異にしたスジエビの2型群

概要

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Two types of reproduction of the freshwater prawn Palaemon paucidens DE HAAN were distinguished along the Sagami River, i. e., the spawning of many small eggs in the upper lake and the upper pool in the river, and the laying of fewer but larger eggs in the lower stream. The egg size was irrespective of the body size of the mother prawn within each group, and the body sizes of the major spawners did not differ between the two groups. Thus, the two types of reproduction are presumed to be undertaken by distinct populations whose habitats are roughly separated along the river. Between the two groups, the total amount of egg matter per spawning was quite close. The adaptive significance of the varied reproductive manners were discussed in connection with the difference in the environmental conditions at their habitat, especially in the nature of water flow.
1982-12-30