Life history and the ecology of stress: how do glucocorticoid hormones influence life-history variation in animals?

Glucocorticoids hormones (GCs) are intuitively important for mediation of age-dependent vertebrate life-history transitions through their effects on ontogeny alongside underpinning variation in life-history traits and trade-offs in vertebrates. These concepts largely derive from the ability of GCs to alter energy allocation, physiology and behaviour that influences key life-history traits involving age-specific life-history transitions, reproduction and survival. Studies across vertebrates have shown that the neuroendocrine stress axis plays a role in the developmental processes that lead up to age-specific early life-history transitions. While environmental sensitivity of the stress axis allows for it to modulate the timing of these transitions within species, little is known as to how variation in stress axis function has been adapted to produce interspecific variation in the timing of life-history transitions. Our assessment of the literature confirms that of previous reviews that there is only equivocal evidence for correlative or direct functional relationships between GCs and variation in reproduction and survival. We conclude that the relationships between GCs and life-history traits are complex and general patterns cannot be easily discerned with current research approaches and experimental designs. We identify several future research directions including: (i) integration of proximate and ultimate measures, including longitudinal studies that measure effects of GCs on more than one life-history trait or in multiple environmental contexts, to test explicit hypotheses about how GCs and life-history variation are related and (ii) the measurement of additional factors that modulate the effects of GCs on life-history traits (e.g. GC receptors and binding protein levels) to better infer neurendocrine stress axis actions. Conceptual models of HPA/I axis actions, such as allostatic load and reactive scope, to some extent explicitly predict the role of GCs in a life-history context, but are descriptive in nature. We propose that GC effects on life-history transitions, survival probabilities and fecundity can be modelled in existing quantitative demographic frameworks to improve our understanding of how GC variation influences life-history evolution and GC-mediated effects on population dynamics Lay Summary Functional Ecology

Rethinking creativity: three case studies of the social processes of creativity

Creativity and innovation are often seen as being important in terms of organisations, not only dealing with large amounts of change, but also being able to flourish in uncertain times. Yet, despite large amounts of creativity research, it continues to be a contested subject and fragmented field which leaves researchers without clear direction. Thus the approach to studying creativity needs to be rethought in order to develop new insights into the phenomenon. This research contributes to the debate on creativity by developing concepts around how creativity unfolds within a specific social context. It does this by approaching the study of creativity from a critical perspective and conducting a series of case studies into creativity in organisations. This research finds that, while the production of an artefact is a prerequisite, creativity is not an enduring feature of a given artefact. Rather, creativity exists when an artefact is labelled creative within a particular social system. In addition, as part of the interpretive research process, aspects of identity work emerged. Exploration of creativity as part of the process of identity work provides novel insight into creativity and a conceptual map which may be utilized as part of ongoing research into creativity. This research makes a significant contribution to the understanding of creativity by unpacking the processes of creativity, in three diverse organisational settings, and showing how creativity may be conceptualised as a contextually bound, socially constructed label which is underpinned by identity related motives.

Feeding ecology of King George whiting Sillaginodes punctatus (Perciformes) recruits in seagrass and unvegetated habitats. Does diet reflect habitat utilization?

This study investigated the feeding ecology of King George whiting Sillaginodes punctatus recruits to determine how diet composition varies between habitat types (seagrass and unvegetated habitats), and between sites separated by distance. Broad-scale sampling of seagrass and unvegetated habitats at nine sites in Port Phillip Bay (Australia) indicated the diet composition varied more by distance into the bay than by habitat. Near the entrance to the bay the diet was dominated by harpacticoids and gammarid amphipods, in the middle reaches of the bay the diet was completely dominated by harpacticoids, while at sites furthest into the bay, mysids and crab zoea were also important. Abundances of prey in guts was significantly higher between 1000 and 2200 hours compared with other times, indicating diurnal feeding. Laboratory determined gut evacuation rate (based on an exponential model) was estimated to be -0·54. Daily rations were highly variable among sites and habitat types. Sillaginodes punctatus recruits consumed much higher quantities of prey on unvegetated habitat than seagrass habitat at some middle reach sites; with prey consumption of harpacticoid copepods on unvegetated habitat approaching 3000 individuals per day at one site. The results of this study provide insight into why habitat associations of S. punctatus recruits within mosaics of seagrass and unvegetated habitat show high spatial variation.

The microbiome: a biological mechanism underpinning the social gradient of musculoskeletal conditions?

We read with interest the article by Steves et al, published in J Bone Miner Res, 2016; 31(2):261-269 (1). The authors review available evidence and suggest that the modifiable nature of the gut microbiome (GM) provides a potential therapeutic target to intervene in musculoskeletal conditions of aging.