魚類における子の保護の進化と保護者の性 EVOLUTION OF PARENTAL CARE IN FISHES WITH REFERENCE TO DETERMINANTS OF THE CARE-TAKER'S SEX
Parental-care patterns of fishes are surveyed to examine their evolutionary courses and the factors influencing the care-taker's sex. The Agnatha are nonguarders, the Chondrichthyes are internal bearers (with internal fertilization), and in 99 (24%) out of 418 families of the Osteichthyes guarding, external bearing or internal bearing are exhibited in 69,21,and 24 families, respectively. Male care is the most common among guarders, but only females perform internal bearing. The care-taker's sex is believed to be determined primarily by the ancestral mating system and the method of care : 1. Because rates of gamete production are faster in males than in females, male mating territories will predominate among nonguarders. From ancestors of this mating system, guarding by males but bearing by females will evolve, because males can take care of multiple clutches by guarding but not by bearing. 2. A portion of external bearing is derived from guarding, and prolonged guarding after the end of internal bearing is rarely developed in fishes. The sexes of the secondary care-takers are usually the same as those of the ancestral ones, but are also influenced by the new methods of care and the ancestral mating systems. These and other predictions are examined in relation to current hypotheses.
日本生態学会誌 37(2), 133-148, 1987