Early-life telomere length predicts life-history strategy and reproductive senescence in a threatened wild songbird

Telomeres are well known for their associations with lifespan and ageing across diverse taxa. Early-life telomere length can be influenced by developmental conditions and has been shown positively affect lifetime reproductive success in a limited number of studies. Whether these effects are caused by a change in lifespan, reproductive rate or perhaps most importantly reproductive senescence is unclear. Using long-term data on female breeding success from a threatened songbird (the hihi, Notiomystis cincta), we show that the early-life telomere length of individuals predicts the presence and rate of future senescence of key reproductive traits: clutch size and hatching success. In contrast, senescence of fledging success is not associated with early-life telomere length, which may be due to the added influence of biparental care at this stage. Early-life telomere length does not predict lifespan or lifetime reproductive success in this species. Females may therefore change their reproductive allocation strategy depending on their early developmental conditions, which we hypothesise are reflected in their early-life telomere length. Our results offer new insights on the role that telomeres play in reproductive senescence and individual fitness and suggest telomere length can be used as a predictor for future life history in threatened species

Drivers of female reproductive failure in the hihi, Notiomystis cincta.

Reproductive failure is costly for individuals, representing a waste of energetic investment and fitness potential. This is particularly true for females, who typically invest more heavily in reproduction than males, producing larger and more energetically costly gametes than males. Despite this, reproductive failure is commonplace across taxa. This thesis addresses the proximate and ultimate drivers of female reproductive failure in a threatened bird, the hihi (Notiomystis cincta). The hihi is endemic to New Zealand and has undergone multiple genetic bottlenecks due to the impacts of invasive predators and habitat loss. On average, 28% of eggs fail to hatch in the focal study population. In this thesis I focus primarily on the early stages of reproduction, including fertilisation, clutch size, and embryo development, and investigate how these are influenced by genetics, demographics and ecology