Seasonal changes in reproductive anatomy and gonadal hormone concentrations of African penguins (Spheniscus demersus)

Patrick Siyambulela Mafunda, Liana Maree, Andre Ganswindt, Antoinette Kotze, Gerhard van der Horst

Department of Medical Bioscience, University of the Western Cape, Bellville, 7535, South Africa; National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0001, South Africa; Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa; Genetics Department, University of the Free State, Bloemfontein, 9300, South Africa

Abstract: Several standard descriptions of the avian male and female reproductive tract have been reported, including effects of age, stage of reproductive maturity and gonadal hormone concentrations. Limited information on penguin reproductive biology and a lack of information on the African penguin (Spheniscus demersus) necessitated a detailed description of salient structural features of this species and provided an opportunity to evaluate seasonal changes in gonadal steroid hormone concentrations. Tissues from 36 males (adults and juveniles) and 29 females (adults and juveniles) were used for macro-anatomical descriptions and histology of the testes and ovaries. In addition, concentrations of gonadal steroid hormones for eight captive African penguins (four females and four males) were quantified during two breeding and one non-breeding season. The testes were asymmetrical, with the right testis having smaller dimensions compared to the left testis. Marked spermatogenic cellular associations and spermatid developmental stages were present in adult testes only during the breeding season. There was variation in the dimensions of the single ovary during follicular development related to the age and breeding status of the females. Testosterone, dihydrotestosterone, and estradiol concentrations fluctuated during the breeding and non-breeding periods, with males and females having similar steroid concentrations. The results from this study confirm that the breeding status in African penguins can be deduced based on testicular and ovarian histological structures. The results from the present study focused on African penguin reproductive biology should be considered in management strategies for the conservation of the species.

Animal Reproduction Science Volume 224, January 2021, 106664 – https://doi.org/10.1016/j.anireprosci.2020.106664
Received 6 July 2020, Revised 21 November 2020, Accepted 23 November 2020, Available online 26 November 2020.