Testis abnormalities in a population of the iconic Australian species, the eastern bearded dragon Pogona barbata

Testis volume is generally correlated with sperm production. Their size is, therefore, considered informative, and is widely used as a surrogate for reproductive ability in a range of species. Gonadal abnormalities that influence adult reproductive function as a result of endocrine disruption compounds (EDCs) have been reported. In response to the observation that the population of the bearded dragon Pogona barbata had crashed in peri-urban Western Sydney, we investigated the nature and extent of testis deformity. It was observed that individuals collected in Western Sydney since the introduction of unleaded petrol in 1985 have a high level of deformities that are consistent with disruption of the endocrine processes. While deformities, such as missing testes, extreme asymmetry between testes, and flattened testes were not associated with any single aspect of the reproductive cycle, and they were found across the range of the species, the problem was much greater in Western Sydney than elsewhere in the species' range. We suggest that the abnormalities in Western Sydney may, in part, be responsible for the crash in the local population of P. barbata.