Evolution of placentation and live birth

Overview

Extended embryo retention (EER) has long been recognised as pivotal in the transition from oviparity (egg-laying) to viviparity (live-bearing). Ascidians, invertebrate chordates closely related to vertebrates, provide a unique opportunity to study the evolution of viviparity. Comparative studies with ascidians reveal critical insights into viviparity, highlighting similarities with placental animals, such as reduced egg count, elongated gestation, and complex extraembryonic membranes. Hypsistozoa fasmeriana is a marine colonial ascidian, endemic to Aotearoa New Zealand, and demonstrates true viviparity, nurturing its offspring for approximately 5.5 months. Despite starting from a small, low-yolk egg, the resulting tadpole grows significantly during this period.

This project will identify those genes associated with nutrient transfer, hormone production, and embryonic development in ascidians critical for prolonged gestation and share functional similarities with genes involved in human placental development.

Useful information

• Graduate research at the University of Otago
• Scholarships at the University of Otago