Germination niche breadth varies inconsistently among three Asclepias congeners along a latitudinal gradient.

Species responses to climate change will be primarily driven by their environmental tolerance range, or niche breadth, with the expectation that broad niches will increase resilience. Niche breadth is expected to be larger in more heterogeneous environments and moderated by life history. Niche breadth also varies across life stages. Therefore, the life stage with the narrowest niche may serve as the best predictor of climatic vulnerability. To investigate the relationship between niche breadth, climate and life stage we identify germination niche breadth for dormant and non-dormant seeds in multiple populations of three milkweed (Asclepias) species. Complementary trials evaluated germination under conditions simulating historic and predicted future climate by varying cold-moist stratification temperature, length and incubation temperature. Germination niche breadth was derived from germination evenness across treatments (Levins Bn ), with stratified seeds considered less dormant than non-stratified seeds. Germination response varies significantly among species, populations and treatments. Cold-moist stratification ≥4 weeks (1-3 °C) followed by incubation at 25/15 °C+ achieves peak germination for most populations. Germination niche breadth significantly expands following stratification and interacts significantly with latitude of origin. Interestingly, two species display a positive relationship between niche breadth and latitude, while the third presents a concave quadratic relationship. Germination niche breadth significantly varies by species, latitude and population, suggesting an interaction between source climate, life history and site-specific factors. Results contribute to our understanding of inter- and intraspecific variation in germination, underscore the role of dormancy in germination niche breadth, and have implications for prioritising and conserving species under climate change.

Field trial of endotracheal intubation by basic EMTs.

STUDY OBJECTIVE: The 1994 basic-EMT (EMT-B) curriculum recommended teaching EMT-Bs the skill of endotracheal intubation. In this study we assessed the success and complication rates of endotracheal intubations in the field by EMT-Bs. METHODS: We conducted a prospective clinical trial over a period of 28 months in an urban out-of-hospital EMS system. Four first-responder EMT-B engine companies with paramedic backup received 10 hours; intubation training in three sessions spread over at least 2 weeks. The training module was similar to that of the 1994 EMT-B curriculum and included at least 10 intubations on manikins. The EMTs used manikins with closed chest cavities to learn assessment of endotracheal-tube placement. Patients were eligible for intubation by the EMTs if they were apneic and older than 15 years. We calculated 95% confidence interval (CIs) for intubation success rates. RESULTS: Sixty-six EMT-Bs passed the training examinations and were authorized to perform intubation in the field. Endotracheal intubation was attempted by EMTs in 103 patients; the attempt was successful in 53 (95% CI, 42% to 61%). All patients who were not intubated by EMT-Bs were intubated by paramedics, with the exception of six cases. One attempt at intubation was made in 52 patients, two attempts in 44, and three in 7. Three unrecognized esophageal intubations occurred. CONCLUSION: EMT-Bs trained in a short course successfully intubated about half the patients they encountered in this study. This low intubation success rate calls into question the validity of the endotracheal-intubation training module in the 1994 EMT-B national curriculum.