- University of Utah
Summary
Why is parental care performed by the female in some species and the male in others?Several answers have been proposed by theoretical studies (Trivers,1972;Williams,1975;Dawkins and Carlisle, 1976;Maynard Smith,1977, 1978;Perrone and Zaret,1979), but there have been few efforts to test alternative hypotheses against observed patterns of vertebrate parental behavior. The present paper attempts to (1) derive specific predictions from three alternative hypotheses which deal with mode of fertilization (internal versus external) and parental care evolution, and (2) test these predictions using a compilation of published data on occurrence and correlates of parental care in amphibians and teleost fishes.
Methodology
Our compilation of the distribution of parental care among the amphibians and the teleosts (which comprise about 95% of all living fishes and more than 99% of the bony ones) is based mainly on recent reviews which we supplemented with current literature. Although not exhaustive,the data should correctly identify any major patterns: references are given in the Appendix. Our taxonomy follows Green-wood etal. (1966) for teleosts, and Goinet al. (1978) for amphibians. We have characterized each family according to the mode of fertilization and the presence of male, female, or no parental care. Parental care was defined as investment into offspring after fertilization, such investment presumably increasing off spring survival. Hence, our definition includes all cases where the offspring and parent remain together after fertilization of the oocytes. For example,our definition includes both viviparity and egg-guarding, but excludes activities (e.g.,construction of elaborate nests) prior to ovulation. The function of these latter activities is often unknown.