The effects of season and devil facial tumour disease on the reproductive physiology of the male Tasmanian devil (Sarcophilus harrisii)

Abstract

Devil facial tumour disease (DFTD) is the cause of the rapid decline of wild Tasmanian devils. Female devils are seasonal breeders with births peaking during autumn (i.e. March) but the degree of reproductive seasonality in male devils is unknown. The objective of this study was to examine the potential effects of season and DFTD on reproductive function in male devils (n = 55). Testicular (1.90 ± 0.23 g) and epididymal (0.90 ± 0.06 g) weights were maximal during autumn and spring (P < 0.05), whereas prostate (3.71 ± 0.74 g) and Cowper’s gland (0.68 ± 0.22; 0.52 ± 0.21 g) weights peaked during autumn (P < 0.001). The motility of spermatozoa from the cauda epididymides extracted post-mortem was similar (P > 0.05) across season and disease state (31.5 ± 13.1% total motility). Testicular and epididymal weights were no different between animals displaying late or early-stage DTFD signs or disease-free animals (P > 0.1). The accessory sex glands were larger in late-stage DFTD animals than in animals with early-stage disease signs or which were disease-free (P < 0.01) but effects of season on this result can’t be excluded. Serum testosterone concentrations peaked during summer (0.25 ± 0.18 ng mL–1) but values were not different from the preceding and subsequent seasons (P > 0.05), nor influenced by disease stage (P > 0.1). Seasonal and DFTD-related changes in serum cortisol concentrations were not evident (P > 0.1). Male devil reproduction does not appear to be restricted by season nor inhibited by DFTD.