The functional diversity and redundancy of corals

Corals are major contributors to a range of key ecosystem functions on tropical reefs, including calcification, photosynthesis, nutrient cycling and the provision of habitat structure. The abundance of corals is declining at local and regional scales, and the species composition of assemblages is responding to escalating human pressures, including anthropogenic global warming. An urgent challenge is to understand the functional consequences of these shifts in abundance and composition in different biogeographical contexts. To address this problem, I develop and analyse a series of coral traits to quantify the trait-based dissimilarity (functional diversity) and similarity (functional redundancy) of corals using multidimensional trait space. This thesis is focused on (i) biogeographical patterns in the functional diversity and redundancy of corals, (ii) how these patterns are changing in response to anthropogenic pressures, and (iii) the implications of these changes for the biodiversity and functioning of coral assemblages. Biogeographical patterns of coral species richness are well known. However, the biogeography of coral functions in provinces and domains with high and low redundancy is poorly understood. My first objective was therefore to quantify the functional traits of all currently-recognized zooxanthellate coral species (n = 821) in both the Indo-Pacific and Atlantic domains, to examine the relationships between species richness and the diversity and redundancy of functional trait space. I found that trait diversity was conserved (> 75% of the global total) along latitudinal and longitudinal gradients in species richness, falling away only in species-poor provinces (richness < 200), such as the Persian Gulf (52% of the global total), Hawaii (37%), the Caribbean (26%) and the East-Pacific (20%), where redundancy is also diminished. In the more species-poor provinces, large and ecologically important areas of trait space are empty, or occupied by just a few, highly distinctive species. These striking biogeographical differences in redundancy could affect the resilience of critical reef functions, and highlight the vulnerability of relatively depauperate, peripheral locations which are often a low priority for targeted conservation efforts. I next analyse temporal trends in the regional-scale trait diversity of corals before and after a severe episode of mass coral bleaching within the Great Barrier Reef (GBR). I show that in the aftermath of the record-breaking marine heatwave on the GBR in 2016, an exposure of 6°C-weeks or more drove an unprecedented, regional-scale shift in the trait composition of coral assemblages, reflecting markedly divergent responses to heat stress by different taxa. Fast-growing staghorn and tabular corals suffered a catastrophic die-off, transforming the three-dimensionality and ecological functioning of 29% of the 3,863 reefs comprising the world's largest coral reef system. The increasing prevalence of post-bleaching mass mortality of corals represents a radical shift in the disturbance regimes of tropical reefs, and poses a severe threat to the functional diversity of all regions. Nonetheless, long-term analysis is required to understand how trait composition is likely to be permanently affected by these recurrent disturbances. A key challenge is to understand whether assemblages exposed to recurrent disturbances will lack important functional attributes, or whether a range of species with diverse ecological roles can respond differently to environmental change, and replace those in decline (response diversity). To explore these patterns, I next analysed case studies of long-term trends in coral composition from three biogeographical provinces (the Great Barrier Reef, French Polynesia, and Jamaica) to quantify shifts in multidimensional trait space throughout cycles of disturbance and recovery. The analysis shows that decades after disturbances, assemblages with diverse functional attributes have failed to recover at sites in all regions. Abundance-weighted trait diversity in recovering assemblages was diminished by 29% on the Great Barrier Reef, 18% in Polynesia, and 48% in Jamaica. Disturbance and recovery has favoured a subset of species with limited functional attributes, including smaller, shorter and morphologically simpler taxa with submassive, tabular or bushy morphologies. The degree to which depleted areas of trait space ('losers') were restored by taxa which have increased in abundance ('winners') reveals limited response diversity across locations. To understand the ecological implications of these shifts in functional diversity through time, we must test the relationship between diversity and ecosystem function. To analyse this relationship at a local scale, experimental coral communities were assembled to quantify the performance of coral colonies with and without neighbours, and in the presence of conspecifics versus heterospecifics. I found a positive effect of coral species richness on primary productivity (gross and net photosynthesis), indicated by a 53% increase in productivity in multispecies assemblages (2 or 4 species) relative to monocultures. Productivity in monocultures was predicted by traits associated with different species morphologies. In contrast, multispecies assemblages maintained high levels of productivity even in the absence of the most productive species, reflecting non-additive effects of species richness on community functioning. Assemblage performances were regulated by positive and negative interactions between colonies, with many colonies performing better among functionally diverse heterospecific neighbours than in isolation (facilitation). Facilitation occurred primarily among flow-sensitive taxa with simple morphological traits, and did not occur under low flow, suggesting that modifications to flow microclimates by corals generated beneficial, interspecific interactions. Overall, the results of this thesis suggest that future trajectories in the functioning of reefs will depend on how different biogeographical pools of distinctive and redundant species will reassemble in the wake of global warming. The thesis demonstrates that the diversity and identity of corals within colony aggregations can influence coral community productivity, and highlights the importance of traits or trait diversity in regulating ecosystem function. Nevertheless, the functional trait diversity of corals is changing rapidly at local and regional scales, driven by recurrent disturbances, including mass bleaching. The thesis also reveals a considerable amount of similarity, or redundancy, among corals, and the role of this redundancy in maintaining functional diversity through time. Nevertheless, redundancy varies in the major coral reef provinces of the world, revealing locations that are potentially more vulnerable to the collapse of ecological functions

Net effects of life-history traits explain persistent differences in abundance among similar species

JSM and MM were supported by the National Science Foundation (NSF)1948946. MD is supported by the Warman Foundation, the Leverhulme Centre for Anthropocene Biodiversity (RC-2018-021) and NSF-NERC grant NE/V009338/1. MM is supported by a Leverhulme Trust Early Career Fellowship (ECF-2021-512).Life-history traits are promising tools to predict species commonness and rarity because they influence a population's fitness in a given environment. Yet, species with similar traits can have vastly different abundances, challenging the prospect of robust trait-based predictions. Using long-term demographic monitoring, we show that coral populations with similar morphological and life-history traits show persistent (decade-long) differences in abundance. Morphological groups predicted species positions along two, well-known life-history axes (the fast-slow continuum and size-specific fecundity). However, integral projection models revealed that density-independent population growth (λ) was more variable within morphological groups, and was consistently higher in dominant species relative to rare species. Within-group λ differences projected large abundance differences among similar species in short timeframes, and were generated by small but compounding variation in growth, survival, and reproduction. Our study shows that easily-measured morphological traits predict demographic strategies, yet small life-history differences can accumulate into large differences in λ and abundance among similar species. Quantifying the net effects of multiple traits on population dynamics is therefore essential to anticipate species commonness and rarity.Publisher PDFPeer reviewe

Studying functions on coral reefs : past perspectives, current conundrums, and future potential

This work was funded by the Australian Research Council (DRB; grant number FL190100062).Function-based studies have opened a new chapter in our understanding of coral reefs. Unfortunately, we are opening this chapter as the world’s reefs rapidly transform. In this context, one of the most important roles of function-based studies is to inform coral reef conservation. At this critical juncture, we have a chance to reflect on where we have come from, and where we are going, in coral reef functional ecology, with specific consideration of what this means for our approaches to conserving reefs. As focal examples, we examine the role of corals on reefs, and the practice of culling crown-of-thorns starfish, from a functional perspective. We also consider how the papers in this special issue build on our current understanding. Ultimately, we highlight how robust scientific investigation, based on an understanding of ecosystem functions, will be key in helping us navigate reefs through the current coral reef crisis.Peer reviewe

Detailed Chemical Abundances of Four Stars in the Unusual Globular Cluster, Palomar 1

Detailed chemical abundances for twenty one elements are presented for four red giants in the anomalous outer halo globular cluster Palomar 1 ($R_{\rm{GC}} = 17.2$ kpc, $Z=3.6$ kpc) using high-resolution (R=36000) spectra from the High Dispersion Spectrograph (HDS) on the Subaru Telescope. Pal 1 has long been considered unusual because of its low surface brightness, sparse red giant branch, young age, and its possible association with two extragalactic streams of stars---this paper shows that its chemistry further confirms its unusual nature. The mean metallicity of the four stars, $[\rm{Fe/H}] = -0.60 \pm 0.01$, is high for a globular cluster so far from the Galactic center, but is low for a typical open cluster. The [$\alpha$/Fe] ratios, though in agreement with the Galactic stars within the $1\sigma$ errors, agree best with the lower values in dwarf galaxies. No signs of the Na/O anticorrelation are detected in Pal 1, though Na appears to be marginally high in all four stars. Pal 1's neutron capture elements are also unusual: its high [Ba/Y] ratio agrees best with dwarf galaxies, implying an excess of second-peak over first-peak s-process elements, while its [Eu/$\alpha$] and [Ba/Eu] ratios show that Pal 1's contributions from the r-process must have differed in some way from normal Galactic stars. Therefore, Pal 1 is chemically unusual, as well in its other properties. Pal 1 shares some of its unusual abundance characteristics with the young clusters associated with the Sagittarius dwarf galaxy remnant and the intermediate-age LMC clusters, and could be chemically associated with the Canis Majoris overdensity; however it does not seem to be similar to the Monoceros/Galactic Anticenter Stellar Stream.Comment: 24 pages, 25 figures; to appear in the Astrophysical Journa

Peer support for discharge from inpatient mental health care versus care as usual in England (ENRICH): a parallel, two-group, individually randomised controlled trial.

BACKGROUND: High numbers of patients discharged from psychiatric hospital care are readmitted within a year. Peer support for discharge has been suggested as an approach to reducing readmission post-discharge. Implementation has been called for in policy, however, evidence of effectiveness from large rigorous trials is missing. We aimed to establish whether peer support for discharge reduces readmissions in the year post-discharge. METHODS: We report a parallel, two-group, individually randomised, controlled superiority trial, with trial personnel masked to allocation. Patients were adult psychiatric inpatients (age ≥18 years) with at least one previous admission in the preceding 2 years, excluding those who had a diagnosis of any organic mental disorder, or a primary diagnosis of learning disability, an eating disorder, or drug or alcohol dependency, recruited from seven state-funded mental health services in England. Patients were randomly assigned (1:1) to the intervention (peer support plus care as usual) or control (care as usual) groups by an in-house, online randomisation service, stratified by site and diagnostic group (psychotic disorders, personality disorders, and other eligible non-psychotic disorders) with randomly permuted blocks of randomly varying length to conceal the allocation sequence and achieve the allocation ratio. The peer support group received manual-based, one-to-one peer support, focused on building individual strengths and engaging with activities in the community, beginning during the index admission and continuing for 4 months after discharge, plus care as usual. Care as usual consisted of follow-up by community mental health services within 7 days of discharge. The primary outcome was psychiatric readmission 12 months after discharge (number of patients readmitted at least once), analysed on an intention-to-treat basis. All patients were included in a safety analysis, excluding those who withdrew consent for use of their data. The trial is registered with the ISRCTN registry, ISRCTN10043328. The trial was complete at the time of reporting. FINDINGS: Between Dec 1, 2016, and Feb 8, 2019, 590 patients were recruited and randomly assigned, with 294 allocated to peer support (287 included in the analysis after withdrawals and loss to follow-up), and 296 to care as usual (291 in the analysis). Mean age was 39·7 years (SD 13·7; range 18-75). 306 patients were women, 267 were men, three were transgender, and two preferred not to say. 353 patients were White, 94 were Black, African, Caribbean, or Black British, 68 were Asian or Asian British, 48 were of mixed or multiple ethnic groups, and 13 were of other ethnic groups. In the peer support group, 136 (47%) of 287 patients were readmitted at least once within 12 months of discharge. 146 (50%) of 291 were readmitted in the care as usual group. The adjusted risk ratio of readmission was 0·97 (95% CI 0·82-1·14; p=0·68), and the adjusted odds ratio for readmission was 0·93 (95% CI 0·66-1·30; p=0·68). The unadjusted risk difference was 0·03 (95% CI -0·11 to 0·05; p=0·51) in favour of the peer support group. Serious adverse events were infrequent (67 events) and similar between groups (34 in the peer support group, 33 in the care as usual group). Threat to life (self-harm) was the most common serious adverse event (35 [52%] of 67 serious adverse events). 391 other adverse events were reported, with self-harm (not life threatening) the most common (189 [48%] of 391). INTERPRETATION: One-to-one peer support for discharge from inpatient psychiatric care, plus care as usual, was not superior to care as usual alone in the 12 months after discharge. This definitive, high-quality trial addresses uncertainty in the evidence base and suggests that peer support should not be implemented to reduce readmission post-discharge for patients at risk of readmission. Further research needs to be done to improve engagement with peer support in high-need groups, and to explore differential effects of peer support for people from different ethnic communities. FUNDING: UK National Institute for Health Research

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

Genome-wide survey of SNP variation uncovers the genetic structure of cattle breeds

status: publishe

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

mikemcwilliam/intraspecific_diversity

No description provided

Neighbor diversity regulates the productivity of coral assemblages

Sustaining ecological functions as biodiversity changes will be a major challenge in the 21st century [1]. However, our understanding of the relationship between biodiversity and ecosystem function is still emerging on tropical coral reefs [2], where reef-building corals form highly productive assemblages [3, 4] and species respond in different ways to their neighbors [5] and their environment (e.g., water flow) [6]. Experimental coral communities were assembled to quantify the performance of coral colonies with and without neighbors and in the presence of conspecifics versus heterospecifics. Under higher flow, we identified a positive effect of coral species richness on primary productivity (gross and net photosynthesis) indicated by a 53% increase in productivity in multispecies assemblages (2-4 species) relative to monocultures. Productivity in monocultures was predicted by surface areas associated with different species morphologies. In contrast, multispecies assemblages maintained high levels of productivity even in the absence of the most productive species, reflecting non-additive effects of species richness on community functioning. Assemblage performances were regulated by positive and negative interactions between colonies, with many colonies performing better among heterospecific neighbors than in isolation (facilitation). Facilitation occurred primarily among flow-sensitive taxa with simple morphologies and did not occur under lower flow, suggesting that modifications to flow microclimates by corals generated beneficial, interspecific interactions. Our results show that competition and facilitation among neighbors may be important mechanisms regulating coral assemblage productivity in variable environments. Furthermore, shifts in the diversity and identity of neighbors can impair these interactions, with potentially widespread consequences for coral community functioning