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Variation in DNA methylation is associated with many ecological and life history traits, including niche breadth and lifespan. In vertebrates, DNA methylation occurs almost exclusively at “CpG” dinucleotides. Yet, how variation in the CpG content of the genome impacts organismal ecology has been largely overlooked. Here, we explore associations between promoter CpG content, lifespan and niche breadth among 60, amniote vertebrate species. The CpG content of 16 functionally relevant gene promoters was strongly, positively associated with lifespan in mammals and reptiles, but was not related to niche breadth. Possibly, by providing more substrate for CpG methylation to occur, high promoter CpG content extends the time taken for deleterious, age-related errors in CpG methylation patterns to accumulate, thereby extending lifespan. The association between CpG content and lifespan was driven by gene promoters with intermediate CpG enrichment—those known to be predisposed to regulation by methylation. Our findings provide novel support for the idea that high CpG content has been selected for in long-lived species to preserve the capacity for gene expression regulation by CpG methylation. Intriguingly, promoter CpG content was also dependent on gene function in our study; immune genes had on average 20% less CpG sites than metabolic- and stress-related genes.

 

Abstract Environmental change and biodiversity loss are but two of the complex challenges facing conservation practitioners and policy makers. Relevant and robust scientific knowledge is critical for providing decision-makers with the actionable evidence needed to inform conservation decisions. In the Anthropocene, science that leads to meaningful improvements in biodiversity conservation, restoration and management is desperately needed. Conservation Physiology has emerged as a discipline that is well-positioned to identify the mechanisms underpinning population declines, predict responses to environmental change and test different in situ and ex situ conservation interventions for diverse taxa and ecosystems. Here we present a consensus list of 10 priority research themes. Within each theme we identify specific research questions (100 in total), answers to which will address conservation problems and should improve the management of biological resources. The themes frame a set of research questions related to the following: (i) adaptation and phenotypic plasticity; (ii) human–induced environmental change; (iii) human–wildlife interactions; (iv) invasive species; (v) methods, biomarkers and monitoring; (vi) policy, engagement and communication; (vii) pollution; (viii) restoration actions; (ix) threatened species; and (x) urban systems. The themes and questions will hopefully guide and inspire researchers while also helping to demonstrate to practitioners and policy makers the many ways in which physiology can help to support their decisions. 

Abstract Flexibility in the regulation of the hypothalamic–pituitary–adrenal (HPA) axis is an important mediator of stress resilience as it helps organisms adjust to, avoid, or compensate for acute and chronic challenges across changing environmental contexts. Glucocorticoids remain the favorite metric from medicine to conservation biology to attempt to quantify stress resilience despite the skepticism around their consistency in relation to individual health, welfare, and fitness. We suggest that a cochaperone molecule related to heat shock proteins and involved in glucocorticoid receptor activity, FKBP5, may mediate HPA flexibility and therefore stress resilience because it affects how individuals can regulate glucocorticoids and therefore capacitates their abilities to adjust phenotypes appropriately to prevailing, adverse conditions. Although the molecule is well studied in the biomedical literature, FKBP5 research in wild vertebrates is limited. In the present article, we highlight the potential major role of FKBP5 as mediator of HPA axis flexibility in response to adversity in humans and lab rodents. 

From the northernmost tip of Scandinavia to the southernmost corner of Patagonia, and across six continents, house sparrows (Passer domesticus) inhabit most human-modified habitats of the globe. With over 7,000 articles published, the species has become a workhorse for not only the study of self-urbanized wildlife, but also for understanding life history and body size evolution, sexual selection and many other biological phenomena. Traditionally, house sparrows were studied for their adaptations to local biotic and climatic conditions, but more recently, the species has come to serve as a focus for studies seeking to reveal the genomic, epigenetic and physiological underpinnings of success among invasive vertebrate species. Here, we review the natural history of house sparrows, highlight what the study of these birds has meant to bioscience generally, and describe the many resources available for future work on this species. 

Synopsis Epigenetic potential, defined as the capacity for epigenetically-mediated phenotypic plasticity, may play an important role during range expansions. During range expansions, populations may encounter relatively novel challenges while experiencing lower genetic diversity. Phenotypic plasticity via epigenetic potential might be selectively advantageous at the time of initial introduction or during spread into new areas, enabling introduced organisms to cope rapidly with novel challenges. Here, we asked whether one form of epigenetic potential (i.e., the abundance of CpG sites) in three microbial surveillance genes: Toll-like receptors (TLRs) 1B (TLR1B), 2A (TLR2A), and 4 (TLR4) varied between native and introduced house sparrows (Passer domesticus). Using an opportunistic approach based on samples collected from sparrow populations around the world, we found that introduced birds had more CpG sites in TLR2A and TLR4, but not TLR1B, than native ones. Introduced birds also lost more CpG sites in TLR1B, gained more CpG sites in TLR2A, and lost fewer CpG sites in TLR4 compared to native birds. These results were not driven by differences in genetic diversity or population genetic structure, and many CpG sites fell within predicted transcription factor binding sites (TFBS), with losses and gains of CpG sites altering predicted TFBS. Although we lacked statistical power to conduct the most rigorous possible analyses, these results suggest that epigenetic potential may play a role in house sparrow range expansions, but additional work will be critical to elucidating how epigenetic potential affects gene expression and hence phenotypic plasticity at the individual, population, and species levels.