Parental Care Patterns of Fishes

The strength of natural selection for parental investment by either or both sexes depends on three factors, (a) the degree of confidence of paternity, (b) differences between the sexes in ability to provide PI after the eggs are laid, and (c) availability of mates. A theory based on those three factors leads to the following major conclusions. (1) Males should not contribute brood care in species with internal fertilization. (2) Males should tend the eggs if females spawn several times per breeding season. (3) Paternal care of free-swimming fry should occur only if males can tend more than one brood at a time. (4) Biparental brood care should occur only when parents tend free-swimming fry. (5) Multiparental brood care should occur if one sex provides brooding sites which protect the brooding parent from predators. Fish mating systems follow directly from these parental care patterns. This paper will serve its purpose if it stimulates the testing of these conclusions, especially in the field.