An investigation into factors affecting breeding success in the Tasmanian devil (Sarcophilus harrisii)

Abstract

Wild populations of Tasmanian devils (Sarcophilus harrisii) were thought to be under the threat of extinction from devil facial tumour disease (DFTD). To ensure this species’ survival, an insurance population was developed in 2005 with the aim of saving the devils from extinction and to maintain 95% of the wild genetic diversity for 50 years. To achieve this aim breeding success needs to be optimal. Within this PhD I explore factors influencing the breeding success within the Tasmania devil insurance population. The major findings are: i) in order to improve breeding success females should be bred at the onset of sexual maturity at age two. Pairing is recommended in the first oestrous period, and females should be paired with older males (Chapter 2), ii) multiple paternity has been documented for the first time and appears to be a common female reproductive strategy. This could have positive implications for the captive breeding program by increasing genetic diversity within litters, iii) additionally, and for the first time, precocial male breeding has been documented in populations where older cohorts have succumbed to DFTD (Chapter 3), iv) I have demonstrated that disruptive selection on MHC Class-I loci significantly enhances devil reproductive success (Chapter 4) and v) through hormone analyses, I have confirmed, that the timing of pairing of devils by zoo keepers is in line with female receptivity, and that glucocorticoid levels do not appear to affect captive devil reproductive success (Chapter 5). My thesis has explored the behavioural, animal husbandry and genetic factors influencing breeding success in captive populations. I highlight new life history traits and breeding strategies that could greatly enhance the success of the captive breeding program and which may well prove successful in other endangered species where breeding success is suboptimal.