Manipulating glucocorticoids in wild animals: Basic and applied perspectives

One of the most comprehensively studied responses to stressors in vertebrates is the endogenous production and regulation of glucocorticoids (GCs). Extensive laboratory research using experimental elevation of GCs in model species is instrumental in learning about stressor-induced physiological and behavioural mechanisms; however, such studies fail to inform our understanding of ecological and evolutionary processes in the wild. We reviewed emerging research that has used GC manipulations in wild vertebrates to assess GC-mediated effects on survival, physiology, behaviour, reproduction and offspring quality. Within and across taxa, exogenous manipulation of GCs increased, decreased or had no effect on traits examined in the reviewed studies. The notable diversity in r

Poetry as a Creative Practice to Enhance Engagement and Learning in Conservation Science

Creativity is crucial to the capacity to do science well, to communicate it in compelling ways, and to enhance learning. Creativity can be both practiced and enhanced to strengthen conservation science professionals’ efforts to address global environmental challenges. We explore how poetry is one creative approach that can further conservation scientists’ engagement and learning. We draw on evidence from peer-reviewed literature to illustrate benefits of integrating science and poetry, and to ground our argument for the growth of a science-poetry community to help conservation scientists develop skills in creative practices as a component of professional development. We present examples from literature as well as two short poetry exercises for scientists to draw on when considering writing poetry, or deciding on forms of poetry to include, in their practice. Opportunity exists to grow science–poetry projects to further our understanding of what such initiatives can offer

Egg glucocorticoids and maternal stressor exposure as modulators of offspring quality in Pacific salmon

Maternal experiences can have profound effects on offspring phenotype. In oviparous animals, prolonged maternal exposure to stressors can elevate circulating cortisol and is thought to also elevate egg cortisol. Experimental increases in egg cortisol are known to affect offspring performance. In fishes, past research has focused on how chronic maternal exposure to stressors affects egg size and embryonic survival, but changes to egg hormones and progeny phenotype beyond early development are not well understood. The aim of this thesis was to test the hypothesis that maternal exposure to a stressor alters behavioural and physiological attributes of offspring, and that those alterations are mediated by increases in egg cortisol. The research focused on Pacific salmon; animals that, as adults, encounter diverse stressors during their once-in-a-lifetime migration to spawning areas. I found that experimentally elevating egg cortisol, mimicking the presumed outcome of maternal stress, modified offspring morphology, swimming performance, and behavioural responses to conspecific intruders and simulated predator attacks. However, when I chronically exposed females to a daily chase stressor during sexual maturation, egg cortisol at spawning was not affected. Despite the absence of differences in egg hormone content, maternal stressor exposure did have latent effects on offspring swimming performance and physiological stress responses. Collectively, the evidence presented in this thesis suggests that, in Pacific salmon, experimentally manipulating egg cortisol elicits changes in offspring, but maturing females may have the capacity to buffer eggs from increases in cortisol. Gametic properties other than the concentration of cortisol are likely affected by maternal stress and responsible for the observed changes to offspring performance. The multidirectional effects of maternal stress and egg cortisol treatment on offspring traits I report in this thesis support an emerging notion that the intergenerational effects of stress are highly-context dependent, as are interpretations of the adaptive versus maladaptive nature of changes to offspring. I conclude that the complexities of maternal stress and egg hormone deposition are not always captured when examining a single offspring trait at one life stage, without consideration of all components of the intergenerational process.Forestry, Faculty ofGraduat

Prenatal Stress Exposure Generates Higher Early Survival and Smaller Size without Impacting Developmental Rate in a Pacific Salmon

Prenatal exposure to elevated glucocorticoids can act as a signal of environmental stress, resulting in modifications to offspring phenotype. While “negative” phenotypic effects (i.e., smaller size, slower growth) are often reported, recent research coupling phenotype with other fitness-related traits has suggested positive impacts of prenatal stress. Using captive Chinook salmon (Oncorhynchus tshawytscha), we treated eggs with biologically relevant cortisol levels—low (300 ng mL−1), high (1,000 ng mL−1), or control (0 ng mL−1)—to examine the early-life impacts of maternally transferred stress hormones on offspring. Specifically, we measured early survival, rate of development, and multiple measures of morphology. Low and high cortisol dosing of eggs resulted in significantly higher survival compared to controls (37% and 24% higher, respectively). Fish reared from high dose eggs were structurally smaller compared to control fish, but despite this variation in structural size, exposure to elevated cortisol did not impact developmental rate. These results demonstrate that elevations in egg cortisol can positively influence offspring fitness through an increase in early survival while also altering phenotype at a critical life-history stage. Overall, these results suggest that exposure to prenatal stress may not always produce apparently negative impacts on offspring fitness and further proposes that complex phenotypic responses should be examined in relevant environmental conditions

Envisioning the scientific paper of the future

Consider for a moment the rate of advancement in the scientific understanding of DNA. It is formidable; from Fredrich Miescher’s nuclein extraction in the 1860s to Rosalind Franklin’s double helix X-ray in the 1950s to revolutionary next-generation sequencing in the late 2000s. Now consider the scientific paper, the medium used to describe and publish these advances. How is the scientific paper advancing to meet the needs of those who generate and use scientific information? We review four essential qualities for the scientific paper of the future: (i) a robust source of trustworthy information that remains peer reviewed and is (ii) communicated to diverse users in diverse ways, (iii) open access, and (iv) has a measurable impact beyond Impact Factor. Since its inception, scientific literature has proliferated. We discuss the continuation and expansion of practices already in place including: freely accessible data and analytical code, living research and reviews, changes to peer review to improve representation of under-represented groups, plain language summaries, preprint servers, evidence-informed decision-making, and altmetrics

Considerations for effective science communication

It is increasingly common for scientists to engage in sharing science-related knowledge with diverse knowledge users—an activity called science communication. Given that many scientists now seek information on how to communicate effectively, we have generated a list of 16 important considerations for those interested in science communication: (1) Define what science communication means to you and your research; (2) Know—and listen to—your target audience; (3) Consider a diverse but coordinated communication portfolio; (4) Draft skilled players and build a network; (5) Create and seize opportunities; (6) Be creative when you communicate; (7) Focus on the science in science communication; (8) Be an honest broker; (9) Understand the science of science communication; (10) Think like an entrepreneur; (11) Don’t let your colleagues stop you; (12) Integrate science communication into your research program; (13) Recognize how science communication enhances your science; (14) Request science communication funds from grants; (15) Strive for bidirectional communication; and (16) Evaluate, reflect, and be prepared to adapt. It is our ambition that the ideas shared here will encourage readers to engage in science communication and increase the effectiveness of those already active in science communication, stimulating them to share their experiences with others

Examining the relationships between egg cortisol and oxidative stress in developing wild sockeye salmon (Oncorhynchus nerka)

Maternally-derived hormones in oocytes, such as glucocorticoids (GCs), play a crucial role in embryo development in oviparous taxa. In fishes, maternal stressor exposure increases circulating and egg cortisol levels, the primary GC in fishes, as well as induces oxidative stress. Elevated egg cortisol levels modify offspring traits but whether maternal oxidative stress correlates with circulating and egg cortisol levels, and whether maternal/egg cortisol levels correlate with offspring oxidative stress have yet to be determined. The objective of this study was to examine the relationships among maternal and egg cortisol, and maternal and offspring oxidative stress to provide insight into the potential intergenerational effects of stressor exposure in sockeye salmon (Oncorhynchus nerka). Antioxidant concentration and oxidative stress were measured in maternal tissues (plasma, brain, heart and liver) as well as offspring developmental stages (pre-fertilization, 24. h post-fertilization, eyed, and hatch), and were compared to both naturally-occurring and experimentally-elevated (via cortisol egg bath) levels of cortisol in eggs. Oxygen radical absorptive capacity of tissues from maternal sockeye salmon was measured spectrophotometrically and was not correlated with maternal or egg cortisol concentrations. Also, naturally-occurring and experimentally-elevated cortisol levels in eggs (to mimic maternal stress) did not affect oxidative stress or antioxidant capacity of the offspring. We conclude that the metrics of maternal stress examined in sockeye salmon (i.e., maternal/egg cortisol, maternal oxidative stress) are independent of each other, and that egg cortisol content does not influence offspring oxidative stress