Factors affecting female parental investment in the monogamous goby, Valenciennea longipinnis

摘要

Female Valenciennea longipinnis construct a conspicuous rubble mound on a burrow after spawning while the paired male tends eggs in the burrow until hatching occurs. The mound has a function of promoting water-exchange in the burrow through hydrodynamic effects, contributing to prevention of the male egg-desertion by reducing his parental costs. Although higher mounds are more effective in water exchange, they cost females much work after spawning. In this study, I investigated effects of six ecological and environmental factors on the mound height, i.e., female parental investment. Multiple regression analysis indicated that only female body size could explain the female parental investment: larger females tended to construct higher mounds. The size-assortative mound building suggests that the females strive to construct mounds as high as they can irrespective of the other ecological and environmental factors. Because current strength and oozing of underground water fluctuated even in a day, females may be obliged to construct high mounds on the basis of the worst condition.