THE RELATIONSHIP BETWEEN INTRASPECIFIC AND INTERSPECIFIC BROOD AMALGAMATION IN WATERFOWL

Interspecific brood amalgamation in waterfowl has been hypothesized to be an extension of intraspecific brood amalgamation behavior that inc reases the likelihood of successful amalgamation by increasing the ran ge of potential recipients. I tested this hypothesis using recent phyl ogenetic information. The analysis revealed that the likelihood that a lineage carries the interspecific brood amalgamation state increases significantly when the lineage also carries the intraspecific amalgama tion state, thus supporting the hypothesis. The likelihood of a transi tion to interspecific brood amalgamation was similar across categories of several ecological and life-history factors, including nesting dis persion, nesting substrate, type of brood care, and level of reproduct ive effort. Nevertheless, several lineages carrying the intraspecific brood amalgamation state failed to show the interspecific counterpart suggesting that the expression of interspecific brood amalgamation ten dencies can be constrained by other factors.