Embryonic Onset of Sexually Dimorphic Heart Rates in the Viviparous Fish, <i>Gambusia holbrooki</i>

Abstract

In fish, little is known about sex-specific differences in physiology and performance of the heart and whether these differences manifest during development. Here for the first time, the sex-specific heart rates during embryogenesis of Gambusia holbrooki, from the onset of the heart rates (HRs) to just prior to parturition, was investigated using light cardiogram. The genetic sex of the embryos was post-verified using a sex-specific genetic marker. Results reveal that heart rates and resting time significantly increase (p p p p G. holbrooki could serve as a better model to study comparative vertebrate cardiovascular development as well as to investigate anthropogenic and climatic impacts on heart physiology of this species, that may be sex influenced.

Keywords

• sexual dimorphism
• somatic organ
• heart rate
• ventricle size
• embryo
• adult