Male parental care in the polyandrous emu, Dromaius novaehollandiae

Abstract

The ratites, including the Australian emu Dromaius novaehollandiae, are one of the few groups that engage in polyandrous and promiscuous mating, but the male alone cares for clutches with mixed maternity and paternity. Male only parental care is uncommon (2% of avian species) and the coupling of male only parental care with polyandry, presents an interesting phenomenon in the study of mating systems. Despite this, limited research has been conducted on male only parental care with polyandry, and behavioural and reproductive success has been relatively unstudied in the emu. This project aims to investigate male parental care and reproductive success in the emu. I look predominately at male investment in incubation and its correlations between clutch traits, egg traits and parentage, using a free-ranging captive population to perform observational and manipulative studies. I also investigate changes in climate suitability of emus across Australia, indicating how this may be driven by winter breeding. This work aims to address the following questions: 1) A review of the evolutionary divergence of mating systems in the ratites; 2) Are egg and clutch traits under selection that is mediated by hatching success for increase parental and offspring fitness? 3) What is the optimal clutch size in the emu and is hatching success limited by the male incubation capacity? 4) Does paternity drive male investment in incubation? 5) What determines emu distribution across Australia and is distribution likely to change under past and future climate scenarios? The findings of this thesis provide insights into the uncommon coupling of polyandry with male parental care, indicating the potential benefits of polyandrous and promiscuous mating not only for the female but also for the male emu. My findings may not only help to inform future studies on the evolution and maintenance of parental care and mating systems, but also future management strategies of this species.

Date of Award	2020
Original language	English