Manganese Exacerbates Seasonal Health Declines in a Suicidally-Breeding Mammal.

Reproductive costs must be balanced with survival to maximise lifetime reproductive rates; however, some organisms invest in a single, suicidal bout of breeding known as semelparity. The northern quoll (Dasyurus hallucatus) is an endangered marsupial in which males, but not females, are semelparous. Northern quolls living near mining sites on Groote Eylandt, Northern Territory, Australia, accumulate manganese (Mn) in their brains, testes, and hair, and elevated Mn impacts motor performance. Whether Mn is associated with other health declines is yet unknown. Here, we show that male and female northern quolls with higher Mn accumulation had a 20% reduction in immune function and a trend toward reduced cortisol concentrations in hair. The telomere lengths of male quolls did not change pre- to post-breeding, but those with higher Mn levels had longer telomeres; in contrast, the telomeres of females shortened during the breeding season but recovered between the first year and second year of breeding. In addition, the telomeres of quolls that were re-captured declined at significantly higher rates in quolls with higher Mn between pre-breeding, breeding, and/or post-breeding seasons. Future work should determine whether changes in cortisol, immune function, or telomere length affect reproductive output or survival-particularly for semelparous males.