Unraveling host regulation of gut microbiota through the epigenome-microbiome axis.

Recent studies of dynamic interactions between epigenetic modifications of a host organism and the composition or activity of its associated gut microbiota suggest an opportunity for the host to shape its microbiome through epigenetic alterations that lead to changes in gene expression and noncoding RNA activity. We use insights from microbiota-induced epigenetic changes to review the potential of the host to epigenetically regulate its gut microbiome, from which a bidirectional 'epigenome-microbiome axis' emerges. This axis embeds environmentally induced variation, which may influence the adaptive evolution of host-microbe interactions. We furthermore present our perspective on how the epigenome-microbiome axis can be understood and investigated within a holo-omic framework with potential applications in the applied health and food sciences.

Long-distance dispersal in the short-distance dispersing house sparrow (Passer domesticus).

The house sparrow (Passer domesticus) is a small passerine known to be highly sedentary. Throughout a 30-year capture-mark-recapture study, we have obtained occasional reports of recoveries far outside our main metapopulation study system, documenting unusually long dispersal distances. Our records constitute the highest occurrence of long-distance dispersal events recorded for this species in Scandinavia. Such long-distance dispersals radically change the predicted distribution of dispersal distances and connectedness for our study metapopulation. Moreover, it reveals a much greater potential for colonization than formerly recorded for the house sparrow, which is an invasive species across four continents. These rare and occasional long-distance dispersal events are challenging to document but may have important implications for the genetic composition of small and isolated populations and for our understanding of dispersal ecology and evolution.

Telomere length is not a useful tool for chronological age estimation in animals.

Telomeres are short repetitive DNA sequences capping the ends of chromosomes. Telomere shortening occurs during cell division and may be accelerated by oxidative damage or ameliorated by telomere maintenance mechanisms. Consequently, telomere length changes with age, which was recently confirmed in a large meta-analysis across vertebrates. However, based on the correlation between telomere length and age, it was concluded that telomere length can be used as a tool for chronological age estimation in animals. Correlation should not be confused with predictability, and the current data and studies suggest that telomeres cannot be used to reliably predict individual chronological age. There are biological reasons for why there is large individual variation in telomere dynamics, which is mainly due to high susceptibility to a wide range of environmental, but also genetic factors, rendering telomeres unfeasible as a tool for age estimation. The use of telomeres for chronological age estimation is largely a misguided effort, but its occasional reappearance in the literature raises concerns that it will mislead resources in wildlife conservation.