Growth rates of interface-feeding spionid polychaetes in simulated tidal currents

Most spionid polychaetes switch from surface deposit feeding to suspension feeding as current speed and the flux of suspended food increase. Previous experiments testing the effects of flow on the growth of facultative, interface feeders have been limited to very simplified flow regimes such as constant, unidirectional currents. To measure the growth of interface-feeding spionids in more realistic currents, we programmed two identical counter-rotating annular flumes to simulate two different semidiurnal tidal currents. Each regime included four speeds that varied in hourly steps. At 5 mm above bottom, speeds in the slower flow regime were 0, 2.5, 5, and 7.5 cm s−1. Speeds in the faster regime were 0, 4, 8, and 12 cm s−11. Every 6 h, after each hour at 0 cm s−11, the flume rotation was reversed to simulate the directional shift between ebb and flood currents. The 12-h periods were repeated over 96 h. The experiment included eight 4-d runs of paired slow- and fast-flow flumes. Field-collected sediment and a nonliving algal slurry were added to control deposited and suspended food. Individuals of four species were measured for body volumes before and after each 4-d run: Polydora cornuta, Streblospio benedicti, Pygospio elegans, and Spio setosa. Each species except S. setosa was divided a priori into two size classes. Both small and large P. cornuta grew significantly faster in the fast-flow regime. Large P. elegans grew significantly faster in the fast-flow regime, but the growth rates of small P. elegans did not differ between regimes. Neither size class of S. benedicti grew at significantly different rates between flow regimes, and the broad size class of S. setosa did not show significant flow-dependent growth. The significant growth responses of two of the four species to moderate differences in tidal flow over a short time period underscore the impact flow can have on the population dynamics of some interface-feeding spionids. The differences among species suggest that variability in tidal currents can influence the structure and dynamics of communities in which spionids are often important and abundant

Seedling Defoliation and Drought Stress: Variation in Intensity and Frequency Affect Performance and Survival

Our ability to restore rangelands is limited, and it is unknown if seedling herbivory on its own, or in interaction with other stressors, is a major contributor to restoration failure. To address this, we conducted two experiments: a No Defoliation (ND) experiment (n = 48), in which seedlings from three perennial grasses (crested wheatgrass [Agropyron cristatum {(L.} Gaertn.], bluebunch wheatgrass [Psuedoroegnaria spicata {Pursh} Á. Love], Sandberg bluegrass [Poa secunda J Presl]) were subjected to wet and dry water regimes for 4 mo, and a concurrent Defoliation (D) experiment (n = 95), in which seedlings were factorially assigned to two defoliation treatments—frequency (LOW, HIGH) and intensity (30% vegetation removal, 70% vegetation removal). Indicators of seedling performance were aboveground and belowground biomass (AGB and BGB), root:shoot ratio, tillering, and mortality. The effect size statistic, Hedge's g, allowed for comparisons between performance measures. Water stress induced reductions in most performance measures: BGB (g = ND: –1.3; D: –1.6), root:shoot ratio (g = ND: n.s.; D: –0.2), and tillering (g = ND: –1.7; D: –1.2), though not significantly for all species. For ABG, water stress interacted with defoliation, reducing performance less at an intensity of 70% (g = –2.0) as opposed to 30% (g = –3.0), but not always significantly in the former. Water stress also caused less reduction in AGB when no defoliation occurred (ND: –0.8; g = D: –2.5). Intensity and frequency of defoliation interacted; seedlings were generally resistant to reductions in performance except at high frequency, 70% defoliation. Agropyron cristatum and P. spicata displayed similar sensitivity to treatments, mostly in terms of changes in AGB and BGB, while P. secunda also experienced increased mortality and reduced tillering. If these differences in sensitivity result in differential survival, herbivory could impact species postrestoration population demographics.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Effectiveness of Pfizer-BioNTech and Moderna Vaccines Against COVID-19 Among Hospitalized Adults Aged ≥65 Years — United States, January–March 2021

Adults aged ≥65 years are at increased risk for severe outcomes from COVID-19 and were identified as a priority group to receive the first COVID-19 vaccines approved for use under an Emergency Use Authorization (EUA) in the United States (1-3). In an evaluation at 24 hospitals in 14 states,* the effectiveness of partial or full vaccination† with Pfizer-BioNTech or Moderna vaccines against COVID-19-associated hospitalization was assessed among adults aged ≥65 years. Among 417 hospitalized adults aged ≥65 years (including 187 case-patients and 230 controls), the median age was 73 years, 48% were female, 73% were non-Hispanic White, 17% were non-Hispanic Black, 6% were Hispanic, and 4% lived in a long-term care facility. Adjusted vaccine effectiveness (VE) against COVID-19-associated hospitalization among adults aged ≥65 years was estimated to be 94% (95% confidence interval [CI] = 49%-99%) for full vaccination and 64% (95% CI = 28%-82%) for partial vaccination. These findings are consistent with efficacy determined from clinical trials in the subgroup of adults aged ≥65 years (4,5). This multisite U.S. evaluation under real-world conditions suggests that vaccination provided protection against COVID-19-associated hospitalization among adults aged ≥65 years. Vaccination is a critical tool for reducing severe COVID-19 in groups at high risk

DNA methylation networks underlying mammalian traits

Using DNA methylation profiles ( = 15,456) from 348 mammalian species, we constructed phyloepigenetic trees that bear marked similarities to traditional phylogenetic ones. Using unsupervised clustering across all samples, we identified 55 distinct cytosine modules, of which 30 are related to traits such as maximum life span, adult weight, age, sex, and human mortality risk. Maximum life span is associated with methylation levels in subclass homeobox genes and developmental processes and is potentially regulated by pluripotency transcription factors. The methylation state of some modules responds to perturbations such as caloric restriction, ablation of growth hormone receptors, consumption of high-fat diets, and expression of Yamanaka factors. This study reveals an intertwined evolution of the genome and epigenome that mediates the biological characteristics and traits of different mammalian species