POSTZYGOTIC MATERNAL INFLUENCES AND THE MATERNAL-EMBRYONIC RELATIONSHIP OF VIVIPAROUS FISHES

Viviparous reproduction in fishes provides opportunities for maternal phenotypic modifications to influence offspring phenotype following fe rtilization. Various physiological adaptations associated with the mai ntenance and control of prenatal embryonic development may provide the means by which postnatal phenotype is impacted by maternal phenotype. It is widely recognized that postzygotic maternal influences may be m ediated through the maternal-embryonic trophic relationship in matrotr ophic species. I propose that 1) postzygotic maternal influences in vi viparous fishes may also be mediated through immunological, respirator y, osmoregulatory/excretory, endocrinological, and thermoregulatory as pects of the maternal-embryonic relationship, and 2) any modification of embryonic and/or postnatal physiology through influence of the mate rnal physiological state should be regarded as a maternal effect that has potential ecological and evolutionary significance. This approach should help to identify trends and provide a framework, for comparing the evolution of adaptations for viviparity and their ecological impac t across the vertebrate classes as well as to facilitate identificatio n of selective factors contributing to evolution of various forms of v iviparous reproduction.