Landscape genetic connectivity in a riparian foundation tree is jointly driven by climatic gradients and river networks

Fremont cottonwood (Populus fremonti) is a foundation riparian tree species that drives community structure and ecosystem processes in southwestern U.S. ecosystems. Despite its ecological importance, little is known about the ecological and environmental processes that shape its genetic diversity, structure, and landscape connectivity. Here, we combined molecular analyses of 82 populations including 1312 individual trees dispersed over the species’ geographical distribution. We reduced the data set to 40 populations and 743 individuals to eliminate admixture with a sibling species, and used multivariate restricted optimization and reciprocal causal modeling to evaluate the effects of river network connectivity and climatic gradients on gene flow. Our results confirmed the following: First, gene flow of Fremont cottonwood is jointly controlled by the connectivity of the river network and gradients of seasonal precipitation. Second, gene flow is facilitated by mid-sized to large rivers, and is resisted by small streams and terrestrial uplands, with resistance to gene flow decreasing with river size. Third, genetic differentiation increases with cumulative differences in winter and spring precipitation. Our results suggest that ongoing fragmentation of riparian habitats will lead to a loss of landscape-level genetic connectivity, leading to increased inbreeding and the concomitant loss of genetic diversity in a foundation species. These genetic effects will cascade to a much larger community of organisms, some of which are threatened and endangered

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Unique arthropod communities on different host-plant genotypes results in greater arthropod diversity

Studies on the effect of plant-species diversity on various ecological processes has led to the study of the effects of plant-genetic diversity in the context of community genetics. Arthropod diversity can increase with plant-species or plant-genetic diversity (Wimp et al. in Ecol Lett 7:776-780, 2004). Plant diversity effects can be difficult to separate from other ecological processes, for example, complementarity. We asked three basic questions: (1) Are arthropod communities unique on different host-plant genotypes? (2) Is arthropod diversity greater when associated with greater plant-genetic diversity? (3) Are arthropod communities more closely associated with host-plant genetics than the plant neighborhood? We studied canopy arthropods on Populus fremontii trees randomly planted in a common garden. All trees were planted in a homogeneous matrix, which helped to reduce P. fremontii neighborhood effects. One sample was comprised of few P. fremontii genotypes with many clones. A second sample was comprised of many P. fremontii genotypes with few clones. A second data set was used to examine the relationships between the arthropod community with P. fremontii genetic composition and the neighborhood composition of the focal host plant. Unique arthropod communities were associated with different P. fremontii genotypes, and arthropod community diversity was greater in the sample with greater P. fremontii genotypic diversity. Arthropod community similarity was negatively correlated with P. fremontii genetic distance, but arthropod community similarity was not related to the neighborhood of the P. fremontii host plant. © 2012 Springer Science+Business Media B.V

Conservative leaf economic traits correlate with fast growth of genotypes of a foundation riparian species near the thermal maximum extent of its geographic range

Plant functional traits involved in carbon and water acquisition are likely to be adaptive across the range of a species if the availability of these resources varies across this range and are limiting to growth or fitness. At the interspecific level, leaf economic traits associated with rapid resource capture are correlated with fast growth rates. However, relationships between leaf traits and growth are poorly understood at the intraspecific level. We examined two hypotheses: (i) leaf traits vary genotypically among Populus fremontii populations from different thermal environments; and (ii) leaf traits are related to growth rate of these P. fremontii populations. We used a common garden at the warm edge of P. fremontii distribution that included individuals transplanted from 11 provenances. Provenances varied in mean annual maximum temperature by 5·9 °C, reflecting a range of expected increases in temperature over the next 80 years. Conservative leaf traits (e.g. low specific leaf area, N content, stomatal conductance, net photosynthetic rate and high leaf water-use efficiency) were positively related to growth rates of genotypes and populations, a pattern opposite of that widely reported among species in other studies. Provenance temperature explained 75% of the variation in multivariate leaf traits with the warmest provenances having the most conservative traits and highest growth rates. Clinal genetic variation suggests that P. fremontii may be adapted to thermal environments. Leaf area-to-sapwood area ratio was positively associated with growth rate, while leaf area-based net photosynthetic rate was negatively associated with growth rate; these results suggest that hydraulic architecture was more important than leaf-level photosynthetic rate in determining growth rate. Synthesis. Our results suggest that conservative leaf traits promote rapid growth of P. fremontii genotypes in extremely hot environments. Thus, relationships between leaf economic traits among species do not necessarily apply to the range of variation among genotypes within species. The generality of this pattern should be examined for other species that will be exposed to climate warming. Moreover, our research shows that common garden provenance trials are useful for identifying genotypes best suited to a predicted warmer climate and for improving understanding of the physiological basis for adaptation to warm environments

The proportion of three foundation plant species and their genotypes influence an arthropod community: Restoration implications for the endangered southwestern willow flycatcher

As part of a restoration project, multiple genotypes of two tree species, Fremont cottonwood (Populus fremontii) and Goodding\u27s willow (Salix gooddingii), and one shrub species, Coyote willow (S. exigua), were experimentally planted in different proportions at the Palo Verde Ecological Reserve near Blythe, California, U.S.A. These common woody plant species are important to the endangered southwestern willow flycatcher, providing perch, nesting, and foraging habitat. We conducted this study to evaluate plant species proportion and plant genotype effects on the arthropod community, the prey base for the endangered southwestern willow flycatcher. Three patterns emerged. First, plant species proportions were important; the arthropod community had the greatest richness and diversity (H′) when Goodding\u27s willow proportion was high and Fremont cottonwood proportion was lower; that is, fewer Fremont cottonwoods are required to positively affect overall arthropod diversity. Second, we found significant genotypic effects, for all three plant species, on arthropod species accumulation. Third, while both planting proportion and genotype effects were significant, we found that the effect of planting proportion on arthropod richness was about twice as large as the effect of plant genotype. This shows that both plant species proportions and genotype should be utilized in restoration projects to maximize habitat heterogeneity and arthropod richness. Similar studies can determine which planting proportion and specific genotypes may result in a more favorable arthropod prey base for the southwestern willow flycatcher and other species of concern. Greater attention to planting design and genotype can result in significant gains in diversity at little or no additional project cost. © 2012 Society for Ecological Restoration

Appendix B. Figures showing the results of the intermediate steps of the reciprocal causal modeling analysis to optimize relative resistance to gene flow presented by rivers and climate gradients.

Figures showing the results of the intermediate steps of the reciprocal causal modeling analysis to optimize relative resistance to gene flow presented by rivers and climate gradients

The impact of selecting different contrasts in phonological therapy

Previous research indicates that the extent of progress made by children with phonological disorders depends upon the nature of the word pairs contrasted in therapy. For example, phonemes that differ maximally in terms of place, manner, voicing and sound class (e.g., fan - man) in comparison to therapy where the word pairs presented differ minimally (e.g., fan - van). To investigate the implications of target selection within a typical clinical context (as opposed to a rigorous research setting) eight speech-language pathologists implemented intervention with appropriate children from their caseloads. Nineteen children each received 6 hours of therapy over one school term. They were randomly allocated to two groups. One group (of nine children) received intervention based on a traditional minimal pair approach, targeting homonymy as well as distinctive feature contrast. The other group (ten children) received intervention targeting contrasts differing across a range of distinctive features. Children made considerable progress in therapy in terms of speech accuracy and number of error patterns suppressed. However, there was no difference between the progress of the two groups. Follow-up assessment of 14 of the 19 children indicated maintenance of progress by both groups. Reasons for the lack of difference between the groups in the current study are considered and clinical implications are drawn