RELATIONSHIPS BETWEEN POPULATION-DENSITY AND REPRODUCTIVE SUCCESS IN THE FEMALE GUPPY, POECILIA-RETICULATA (PETERS)

Individual fecundity was found to be significantly higher in females exposed to a low population density compared with females living at a higher population level. This results was observed in ordinary freshwater and also when conditioned water existed. The frequencies of adult females with intrafollicular embryos existing alone in the gonad and those with only ova were pronouncedly higher at a comparatively low population level. Ovarian proportions and gonad weight of females showed significantly higher values in low densities than in high population densities.