Reproductive Strategies Affect Telomere Dynamics across the Life Course.

AbstractBecause parental care has a heritable basis, the benefits of receiving increased parental provisioning early in life are genetically linked to the costs of providing increased parental provisioning at adulthood. Reproductive strategies thus result in distinct cost-benefit syndromes across the life course that may shape individual health and aging trajectories. Here we used an artificial selection approach in Japanese quail (Coturnix japonica) to test how reproductive strategies affect telomere length, a biomarker of somatic state, at different life stages. We show that males but not females from lines selected for low maternal investment (i.e., developing in a relatively small egg) had shorter telomeres at birth. These patterns were still weakly present at the end of the juvenile growth period. In contrast, significantly shorter telomeres were found in reproductively active adult birds from the high-investment lines, suggesting that telomere attrition was accelerated in these individuals once they had become reproductively active. Our study shows that reproductive strategies differentially affect telomere dynamics across the life course, highlighting the role of cross-generational constraints in shaping individual aging trajectories.

Naturally occurring Toll-like receptor 11 (TLR11) and Toll-like receptor 12 (TLR12) polymorphisms are not associated with Toxoplasma gondii infection in wild wood mice.

Toxoplasma gondii is a highly successful parasite with a worldwide prevalence. Small rodents are the main intermediate hosts, and there is growing evidence that T. gondii modifies their behaviour. Chronically infected rodents show impaired learning capacity, enhanced activity, and, most importantly, a reduction of the innate fear towards cat odour. This modification of host behaviour ensures a successful transmission of T. gondii from rodents to felids, the definitive hosts of the parasite. Given the negative fitness consequences of this behavioural manipulation, as well as an increased mortality during the acute phase of infection, we expect rodents to evolve potent resistance mechanisms that prevent or control infection. Indeed, studies in laboratory mice have identified candidate genes for T. gondii resistance. Of particular importance appear to be the innate immune receptors Toll-like receptor 11 (TLR11) and Toll-like receptor 12 (TLR12), which recognise T. gondii profilin and initiate immune responses against the parasite. Here we analyse the genetic diversity of TLR11 and TLR12 in a natural population of wood mice (Apodemus sylvaticus), and test for associations between TLR11 and TLR12 polymorphisms and T. gondii infection, as well as for epistatic interactions between TLR11 and TLR12 on infection status. We found that both TLR11 and TLR12 were polymorphic in wood mice, with four and nine amino acid haplotypes, respectively. However, we found no evidence that TLR11 or TLR12 genotypes or haplotypes were significantly associated with Toxoplasma infection. Despite the importance of TLR11 and TLR12 in T. gondii recognition and immune defence initiation, naturally occurring polymorphisms at TLR11 and TLR12 thus appear to play a minor role in mediating qualitative resistance to T. gondii in natural host populations of A. sylvaticus. This highlights the importance of assessing the role of candidate genes for parasite resistance identified in a laboratory setting in an ecologically meaningful context to quantify their role in mediating host-parasite interactions in the wild.