Genetic divergence and one-way gene flow influence contemporary evolution and ecology of a partially migratory fish.

Recent work has revealed the importance of contemporary evolution in shaping ecological outcomes. In particular, rapid evolutionary divergence between populations has been shown to impact the ecology of populations, communities, and ecosystems. While studies have focused largely on the role of adaptive divergence in generating ecologically important variation among populations, much less is known about the role of gene flow in shaping ecological outcomes. After divergence, populations may continue to interact through gene flow, which may influence evolutionary and ecological processes. Here, we investigate the role of gene flow in shaping the contemporary evolution and ecology of recently diverged populations of anadromous steelhead and resident rainbow trout (Oncorhynchus mykiss). Results show that resident rainbow trout introduced above waterfalls have diverged evolutionarily from downstream anadromous steelhead, which were the source of introductions. However, the movement of fish from above to below the waterfalls has facilitated gene flow, which has reshaped genetic and phenotypic variation in the anadromous source population. In particular, gene flow has led to an increased frequency of residency, which in turn has altered population density, size structure, and sex ratio. This result establishes gene flow as a contemporary evolutionary process that can have important ecological outcomes. From a management perspective, anadromous steelhead are generally regarded as a higher conservation priority than resident rainbow trout, even when found within the same watershed. Our results show that anadromous and resident O. mykiss populations may be connected via gene flow, with important ecological consequences. Such eco-evolutionary processes should be considered when managing recently diverged populations connected by gene flow.

Increasing stability of a native freshwater fish assemblage following flow rehabilitation.

Stream restorations are increasingly critical for managing and recovering freshwater biodiversity in human-dominated landscapes. However, few studies have quantified how rehabilitative actions promulgate through aquatic communities over decades. Here, a long-term dataset is analyzed for fish assemblage change, incorporating data pre- and post-restoration periods, and testing the extent to which native assemblage stability has increased over time. In the late 1950s, a large capacity dam was installed on Putah Creek (Solano County, CA, USA), which altered the natural flow regime, channel structure, geomorphic processes, and overall ecological function. Notably, downstream flows were reduced (especially during summer months) resulting in an aquatic assemblage dominated by warm-water nonnative species, while endemic native species subsisted at low levels as subordinates. A court-mediated Accord was ratified in 2000, providing a more natural flow regime, specifically for native and anadromous fishes in the stream. The richness of nonnative species decreased at every site following the Accord, while the richness of native species increased or stayed constant. At the three most upstream sites, native species richness increased over time and ultimately exceeded nonnative richness. Native assemblage recovery was strongest upriver, closer to flow releases and habitat restoration activities, and decreased longitudinally downstream. Rank-abundance curves through time revealed that, while species evenness was low throughout the study, dominance shifted from nonnative to native species in the upstream sites coincident with rehabilitation efforts. Mean rank shifts decreased following flow rehabilitation; thus the assemblage became increasingly stable over time following flow rehabilitation. Putah Creek's rehabilitation may represent a model for others interested in improving endemic freshwater communities in degraded ecosystems.

A Novel Method for Estimating Right Atrial Pressure With Point-of-Care Ultrasound.

BACKGROUND: Current noninvasive estimation of right atrial pressure (RAP) by either bedside jugular venous pressure exam or inferior vena cava measurement during a comprehensive echocardiogram offers imprecise estimates of actual RAP. METHODS: We enrolled 41 patients in a prospective, blinded study to validate a novel point-of-care ultrasound method using direct right atrial depth (RAD) measurement and jugular venous ultrasound to estimate RAP. Two subjects were excluded, and 39 were included in the final analysis. A parasternal long-axis view was obtained, and the depth of the noncoronary cusp attachment to the posterior left ventricular outflow tract was recorded as the RAD. This was added to an estimate of the jugular venous pressure obtained during a jugular vein ultrasound to calculate an estimated RAP (RAPUS). The RAPUS was compared to the RAP measurement during right heart catheterization (RAPcath) both as measured and as corrected for where the catheter was zeroed. RESULTS: The correlation coefficient between RAPcath and RAPUS was +0.75; regression R2, 0.56; and bias, -0.49 mm Hg (95% CI, -1.42 to +0.43 mm Hg), with the limits of agreement -5.56 to +7.24 mm Hg and accuracy of 3 mm Hg or less in 29 (74%) of the subjects. For the RAPUS corrected for the catheter zero point, the correlation coefficient between RAPcath and RAPUS was +0.72; regression R2, 0.52; and bias, -0.60 mm Hg (95% CI, -1.60 to +0.39 mm Hg), with the limits of agreement -5.56 to +7.24 mm Hg and accuracy of 3 mm Hg or less in 26 (67%) of the subjects. CONCLUSION: This simple ultrasound evaluation of RAD and the right jugular vein correlates well with actual RAP and can accurately estimate RAP within 3 mm Hg in most patients. This has the potential to improve our bedside volume status exam, as well as improve the accuracy of RAP estimation during comprehensive echocardiogram.

Ventricular Diastolic Pressure Ratio as a Marker of Treatment Response in Pulmonary Hypertension.

BACKGROUND: Pulmonary hypertension (PH) is diagnosed and classified through right-sided heart catheterization, with a number of hemodynamic markers used to help guide treatment decisions. These markers may not reflect the complex remodeling of the right ventricle or the interplay between ventricles and struggle to predict treatment response. This study investigates the use of a novel marker: the ratio of left ventricular end-diastolic pressure to right ventricular end-diastolic pressure (LVEDP/RVEDP) in predicting treatment outcomes in a cohort of patients with PH. METHODS: We performed a retrospective analysis of patients with PH at INOVA Fairfax Hospital's advanced lung disease program with simultaneous left-sided and right-sided heart catheterization. The primary end point was the time to clinical improvement, defined by an improvement in distance walked on the 6-min walk test (6MWT) of > 35 m in a year without interceding hospitalization for worsening PH or the need for additional PH therapy. RESULTS: A total of 51 patients were included in the final analysis, 21 of whom (41.2%) had a salutary treatment effect with a mean improvement in the 6MWT of 75 m. Treatment responders were more likely to have a lower LVEDP/RVEDP ratio (1.08 vs 1.62; P = .051). This association persisted in the final multivariate regression model after adjustment for age and sex and controlling for severity of PH (OR, 0.17; 95% CI, 0.03-0.65; P = .024). CONCLUSIONS: The LVEDP/RVEDP ratio is a novel marker for therapeutic response in patients with PH treated with pulmonary vasodilator medications and may offer robust predictive value independent of existing markers of disease severity.

Climate change vulnerability of native and alien freshwater fishes of California: a systematic assessment approach.

Freshwater fishes are highly vulnerable to human-caused climate change. Because quantitative data on status and trends are unavailable for most fish species, a systematic assessment approach that incorporates expert knowledge was developed to determine status and future vulnerability to climate change of freshwater fishes in California, USA. The method uses expert knowledge, supported by literature reviews of status and biology of the fishes, to score ten metrics for both (1) current status of each species (baseline vulnerability to extinction) and (2) likely future impacts of climate change (vulnerability to extinction). Baseline and climate change vulnerability scores were derived for 121 native and 43 alien fish species. The two scores were highly correlated and were concordant among different scorers. Native species had both greater baseline and greater climate change vulnerability than did alien species. Fifty percent of California's native fish fauna was assessed as having critical or high baseline vulnerability to extinction whereas all alien species were classified as being less or least vulnerable. For vulnerability to climate change, 82% of native species were classified as highly vulnerable, compared with only 19% for aliens. Predicted climate change effects on freshwater environments will dramatically change the fish fauna of California. Most native fishes will suffer population declines and become more restricted in their distributions; some will likely be driven to extinction. Fishes requiring cold water (<22°C) are particularly likely to go extinct. In contrast, most alien fishes will thrive, with some species increasing in abundance and range. However, a few alien species will likewise be negatively affected through loss of aquatic habitats during severe droughts and physiologically stressful conditions present in most waterways during summer. Our method has high utility for predicting vulnerability to climate change of diverse fish species. It should be useful for setting conservation priorities in many different regions.

Restoring native fish assemblages to a regulated California stream using the natural flow regime concept.

We examined the response of fishes to establishment of a new flow regime in lower Putah Creek, a regulated stream in California, U.S.A. The new flow regime was designed to mimic the seasonal timing of natural increases and decreases in stream flow. We monitored fish assemblages annually at six sample sites distributed over approximately 30 km of stream for eight years before and nine years after the new flow regime was implemented. Our purpose was to determine whether more natural stream flow patterns would reestablish native fishes and reduce the abundances of alien (nonnative) fishes. At the onset of our study, native fishes were constrained to habitat immediately (<1 km) below the diversion dam, and alien species were numerically dominant at all downstream sample sites. Following implementation of the new flow regime, native fishes regained dominance across more than 20 km of lower Putah Creek. We propose that the expansion of native fishes was facilitated by creation of favorable spawning and rearing conditions (e.g., elevated springtime flows), cooler water temperatures, maintenance of lotic (flowing) conditions over the length of the creek, and displacement of alien species by naturally occurring high-discharge events. Importantly, restoration of native fishes was achieved by manipulating stream flows at biologically important times of the year and only required a small increase in the total volume of water delivered downstream (i.e., water that was not diverted for other uses) during most water years. Our results validate that natural flow regimes can be used to effectively manipulate and manage fish assemblages in regulated rivers.

Flows, droughts, and aliens: factors affecting the fish assemblage in a Sierra Nevada, California, stream.

The fishes of Martis Creek, in the Sierra Nevada of California (USA), were sampled at four sites annually over 30 years, 1979-2008. This long-term data set was used to examine (1) the persistence and stability of the Martis Creek fish assemblage in the face of environmental stochasticity; (2) whether native and alien fishes responded differently to a natural hydrologic regime (e.g., timing and magnitude of high and low flows); and (3) the importance of various hydrologic and physical habitat variables in explaining the abundances of native and alien fish species through time. Our results showed that fish assemblages were persistent at all sample sites, but individual species exhibited marked interannual variability in density, biomass, and relative abundance. The density and biomass of native fishes generally declined over the period of study, whereas most alien species showed no significant long-term trends. Only alien rainbow trout increased in both density and biomass at all sites over time. Redundancy analysis identified three hydrologic variables (annual 7-day minimum discharge, maximum winter discharge, and number of distinct winter floods) and two habitat variables (percentage of pool habitat and percentage of gravel substrate) that each explained a significant portion of the annual variation in fish assemblage structure. For alien taxa, their proportional contribution to the total fish assemblage was inversely related to mean annual streamflow, one-day maximum discharge in both winter and spring, and the frequency of springtime floods. Results of this study highlight the need for continuous annual monitoring of streams with highly variable flow regimes to evaluate shifts in fish community structure. Apparent successes or failures in stream management may appear differently depending on the time series of available data.

Thirty-Year follow-up of an African American family with macular dystrophy of the retina, locus 1 (North Carolina macular dystrophy).

PURPOSE: To describe clinical characteristics, including visual acuity (VA), genetic analysis, and management of complications, over a 30-year period in an African American family with macular dystrophy of the retina, locus 1 (MCDR1), commonly referred to as "North Carolina macular dystrophy." DESIGN: Observational, cohort study. PARTICIPANTS: Twelve family members from a 4-generation pedigree. METHODS: A total of 12 African American patients in an affected family were examined. Clinical examination was documented during 2 different follow-up periods from 1979 to 1982 in 10 patients and from 2005 to 2009 in 11 patients. Genetic analysis was performed in 4 affected members during this time. Foveal microperimetry, fundus autofluorescence, and spectral domain optical coherence tomography (OCT) data were also obtained. MAIN OUTCOME MEASURES: Change in VA of 8 members followed over 3 decades and clinical data and management of complications for all patients. RESULTS: Nine of 11 living family members had classic findings ranging from disease grade 2 (confluent foveal drusen, 8 eyes) to grade 3 (central coloboma-like lesion, 10 eyes). Two members developed choroidal neovascularization (CNV) requiring laser ablation, and 1 member developed non-clearing vitreous hemorrhage and underwent 25-gauge pars plana vitrectomy. Another family member developed exotropia and amblyopia in 1 eye by age 7 years. Those without CNV had no significant change in VA over 30 years. Linkage studies of 4 affected family members showed the same short tandem repeats on markers spanning D6S249 and D6S283 within the MCDR1 region of chromosome 6q16. Microperimetry analysis of an affected member with grade 3 MCDR1 revealed absent function in the region of the central coloboma-like lesions, corresponding to photoreceptor absence on OCT, although there were preserved foveal function and intact photoreceptors adjacent to the lesion. CONCLUSIONS: This African American family shares similar clinical findings as other MCDR1 pedigrees and the same haplotype as the originally described family from North Carolina. Clinical characteristics, including retinal features and stable VA in the absence of amblyopia and CNV, are similar to those in other reports. Eccentric viewing around impaired photoreceptors may explain good VA in patients with clinically severe-appearing macular lesions. Sequencing of the MCDR1 interval may help identify a protein responsible for early macular development. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

The value of computed tomography scanning for the detection of coronary artery disease in patients with idiopathic pulmonary fibrosis.

BACKGROUND AND OBJECTIVE: Patients with idiopathic pulmonary fibrosis (IPF) have a higher prevalence of coronary artery disease and this could have an impact on their outcomes. We investigated the predictive ability of coronary artery calcification, assessed by routine CT, which may predict the presence of coronary artery disease. METHODS: The study cohort consisted of patients with IPF and with left heart catheterization data plus CT scans from July 2003 to July 2008. Grades of coronary calcification on CT were compared with left heart catheterization determination of coronary artery disease. RESULTS: There were 57 patients in whom left heart catheterization review demonstrated significant coronary artery disease in 28.1% (16/57), mild disease in 40.3% (23/57) and none in 31.6% (18/57). The median time interval between the catheterization and the reviewed CT scan was 39 days. The sensitivity of moderate to severe calcification for significant coronary artery disease was 81%, while the specificity was 85%, with an associated odds ratio of 25.2 (4.64-166, P < 0.005). There was excellent agreement among three radiologists in the grading of coronary calcification. CONCLUSIONS: Coronary calcification, as assessed by routine CT of the chest, has very good performance characteristics in predicting underlying significant coronary artery disease in patients with IPF. The routine availability of this study enables the ready screening for coronary artery disease in IPF patients.

Prevalence and impact of coronary artery disease in idiopathic pulmonary fibrosis.

INTRODUCTION: Idiopathic Pulmonary Fibrosis (IPF) is a progressive disease with a poor prognosis for which there is no effective medical therapy. An awareness of comorbidities that are treatable and might impact outcomes in these patients is therefore very important. We sought to determine the prevalence of coronary artery disease (CAD) in IPF patients in comparison to a control group of patients with chronic obstructive pulmonary disease (COPD). We also sought to assess the impact of CAD on IPF patient outcomes. PATIENTS AND METHODS: IPF and COPD transplant candidates whose work-up included left heart catheterization were categorized as having significant CAD, non-significant CAD or no disease. The risk factor profile and prevalence of CAD in both groups was compared. RESULTS: There were 73 IPF and 56 COPD patients. The prevalence of CAD was 65.8% in the IPF group compared to 46.1% in the COPD patients (p<0.028). Significant disease was present in 28.8% of IPF patients vs.16.1% of the COPD patients (p<0.081). Unsuspected significant CAD was found in 18% of IPF patients versus 10.9% of COPD patients (p<0.004). Outcomes of IPF patients with significant CAD was worse than those with no or non-significant disease (p<0.003) with a median survival of 572 days from the time of left heart catheterization. CONCLUSION: There is a higher prevalence of CAD in IPF patients compared to a similarly matched COPD group. This increased association appeared to be independent of common coronary artery risk factors. IPF patients with significant CAD appear to have worse outcomes.