Serum prolactin and testosterone levels in captive and wild brown kiwi (Apteryx mantelli) during the prebreeding, breeding, and incubation periods

Recent advances in reproductive research in Australia and New Zealand: highlights from the Annual Meeting of the Society for Reproductive Biology, 2022

In 2022, the Society for Reproductive Biology came together in Christchurch New Zealand (NZ), for its first face-to-face meeting since the global COVID-19 pandemic. The meeting showcased recent advancements in reproductive research across a diverse range of themes relevant to human health and fertility, exotic species conservation, and agricultural breeding practices. Here, we highlight the key advances presented across the main themes of the meeting, including advances in addressing opportunities and challenges in reproductive health related to First Nations people in Australia and NZ; increasing conservation success of exotic species, including ethical management of invasive species; improvements in our understanding of developmental biology, specifically seminal fluid signalling, ovarian development and effects of environmental impacts such as endocrine-disrupting chemicals; and leveraging scientific breakthroughs in reproductive engineering to drive solutions for fertility, including in assisted reproductive technologies in humans and agricultural industries, and for regenerative medicine.

An updated look at the mating system, parental care and androgen seasonal variations in ratites

Androgens modulate multiple key aspects of male reproduction, from morphology to mating behavior. Across animals the seasonal patterns of androgens are tightly linked to many of the species' life-history traits and their evolution. One popular framework to address this issue has been the Challenge Hypothesis, which proposed a testosterone-mediated trade-off between mating and parental care in males. Given the lack of empirical support, especially in birds, this hypothesis has been recently revisited (Challenge Hypothesis 2.0), integrating aspects such as male-female interactions and the diversity of reproductive systems in birds. Ratites constitute the most basal avian group (Palaeognathae: ratites together with Tinamiformes) and have certain characteristics that make them unique. They are flightless and generally have promiscuous mating systems with communal nests and male-only parental care (nest building, incubation and chick rearing). Furthermore, male testosterone concentrations remain high during the entire parental care period. Here we review the reproductive biology of ratites, integrating information on seasonal variations in parental care, social interactions and androgen levels across the group, in light of the Challenge Hypotheses and the Challenge Hypothesis 2.0 (there are no seasonal hormonal data for Tinamiformes, therefore they are not included in this review). We also discuss the constraints that could explain the lack of experimental approaches in behavioral endocrinology across ratites. I hope this review will motivate further research on this basal group of birds and further our understanding of the evolution of the mechanisms in the endocrine system that underly reproductive behavior across birds.