Timing matters: traffic noise accelerates telomere loss rate differently across developmental stages

Background Noise pollution is one of the leading environmental health risks for humans, linked to a myriad of stress-related health problems. Yet little is known about the long-term effects of noise on the health and fitness of wildlife. We experimentally investigated the direct and cross-generational effects of traffic noise on telomeres; a measure of cellular ageing that is predictive of disease and longevity in humans and other organisms. We exposed zebra finches (Taenopygia guttata) to three different treatment groups: 1) parents were exposed to traffic noise before and during breeding, together with their nestling young, 2) fledged juveniles but not their parents were exposed to traffic noise, and 3) control group birds were never exposed to traffic noise. Results Although there was no significant effect of traffic noise exposure at early (pre-fledging) stages of offspring telomere length or loss rate, traffic noise exposure accelerated telomere loss in older (post-fledging) juveniles. Conclusions The age-dependent differences found in this study in telomere loss could occur if parents buffer younger offspring against the detrimental effects of noise exposure and/or if younger offspring are less sensitive to noise exposure. Telomere length during early life has been shown to be positively related to lifespan and the observed noise-induced increase of telomere attrition rate could reduce the fitness of the affected birds and potentially alter the population dynamics of birds in noise polluted areas. Our data highlight the need to consider the developmental stage of an organism to better understand the ecological consequences of anthropogenic change

Tracking the effect of climate change on ecosystem functioning using protected areas: Africa as a case study

Protected areas represent important core 'units' for in situ conservation. However, the current static system is at risk from the effects of global environmental change. This is especially true in Africa, a biodiversity-rich continent expected to be hit hard by climate change. Focusing on African protected areas that experience limited human impact (International Union for Conservation of Nature (IUCN) categories I and II), we tested three hypotheses regarding the impact of climate change on the dynamics of net primary productivity (NPP). We expected a lower annual NPP and higher seasonality in NPP in Eastern and Southern Africa; changes in NPP dynamics to coincide with changes in precipitation; no correlation between changes in NPP dynamics and human development. To test these expectations, we used the Normalised Difference Vegetation Index (NDVI) as an index of NPP. Results show that, between 1982 and 2008, an increased vegetation greenness was observed in 27% of the protected areas monitored (mostly in Western Africa), and an increased seasonality in 9% of them (mostly in Eastern and Southern Africa). Our results lend support to current expectations regarding the impacts of climate change, and demonstrate how protected areas of IUCN categories I and II could be used to track the effect of climate change on ecosystem functioning in Africa, and possibly elsewhere. The study highlights the need for a dynamic approach to conservation, where the relevance and efficiency of management actions need to be regularly evaluated. It also demonstrates that satellite-based approaches offer a cheap, verifiable way to quickly identify protected areas of concern at a global scale, supporting managers in their effort to design and apply adaptive management strategies

Influence of early-life nutritional stress on songbird memory formation

In birds, vocal learning enables the production of sexually selected complex songs, dialects and song copy matching. But stressful conditions during development have been shown to affect song production and complexity, mediated by changes in neural development. However, to date, no studies have tested whether early-life stress affects the neural processes underlying vocal learning, in contrast to song production. Here, we hypothesized that developmental stress alters auditory memory formation and neural processing of song stimuli. We experimentally stressed male nestling zebra finches and, in two separate experiments, tested their neural responses to song playbacks as adults, using either immediate early gene (IEG) expression or electrophysiological response. Once adult, nutritionally stressed males exhibited a reduced response to tutor song playback, as demonstrated by reduced expressions of two IEGs (Arc and ZENK) and reduced neuronal response, in both the caudomedial nidopallium (NCM) and mesopallium (CMM). Furthermore, nutritionally stressed males also showed impaired neuronal memory for novel songs heard in adulthood. These findings demonstrate, for the first time, that developmental conditions affect auditory memories that subserve vocal learning. Although the fitness consequences of such memory impairments remain to be determined, this study highlights the lasting impact early-life experiences can have on cognitive abilities

Parent-embryo acoustic communication: a specialised heat vocalisation allowing embryonic eavesdropping

Sound is arguably the external cue most accessible to embryos of many species, and as such may constitute an unrivalled source of early information. Recent evidence shows that prenatal sounds, similarly to maternal effects, may shape developmental trajectories. Establishing whether parental vocalisations are signals directed at embryos, or parental cues on which embryos eavesdrop, can elucidate whether parents or embryos control developmental outcomes. Prenatal exposure to a characteristic heat-related parental call was recently shown to alter zebra finch growth and fitness. Here, we test the ecological context of this behaviour in the wild, and assess the information value and specificity of this vocalisation for an embryonic audience. We show that wild zebra finches also produce this characteristic call, only at high temperatures. In addition, in the lab, we demonstrate experimentally that calling is specifically triggered by high air temperatures, can occur without an embryonic audience, and importantly, is predicted by individuals\u27 body mass. Overall, our findings reveal a specialised heat vocalisation that enables embryonic eavesdropping, by indicating high ambient temperatures, and parents\u27 capacity to cope with such conditions. This challenges the traditional view of embryos as passive agents of their development, and opens exciting research avenues on avian adaptation to extreme heat

Low-noise CMOS analog-to-digital interface for MEMS resistive microphone

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