Genome size variation in deep-sea amphipods

Funding: This work was supported by the HADEEP projects, funded by the Nippon Foundation, Japan (2009765188); the Natural Environment Research Council (NERC), UK (NE/E007171/1); Total Foundation, France; National Institute of Water and Atmospheric Research (NIWA), New Zealand (CO1_0906); Schmidt Ocean Institute, USA (FK141109) (A.J.J. and S.B.P); Marine Alliance for Science and Technology for Scotland (MASTS) (HR09011 and DSSG15) (H.R., A.J.J., S.B.P); and the Leverhulme Trust (S.B.P.). Acknowledgements: We thank the chief scientists, crew and company of the New Zealand RV Kaharoa (KAH1301 and KAH1310) and the United States RV Falkor (Cruise FK141109). From NIWA, we thank Malcolm Clark, Ashley Rowden, Kareen Schnabel, and Sadie Mills for logistical support at the NIWA Invertebrate Collection. We thank NOAA Marine National Monuments, Richard Hall and Eric Breuer for their support and collaboration. We also thank Attila Bebes and the Iain Fraser Cytometry Centre (IFCC) for technical assistance. Electronic supplementary material is available online at https://dx.doi.org/10.6084/m9.figshare.c.3868216.Peer reviewedPublisher PD

How much does education improve intelligence? A meta-analysis

Intelligence test scores and educational duration are positively correlated. This correlation could be interpreted in two ways: Students with greater propensity for intelligence go on to complete more education, or a longer education increases intelligence. We meta-analyzed three categories of quasiexperimental studies of educational effects on intelligence: those estimating education-intelligence associations after controlling for earlier intelligence, those using compulsory schooling policy changes as instrumental variables, and those using regression-discontinuity designs on school-entry age cutoffs. Across 142 effect sizes from 42 data sets involving over 600,000 participants, we found consistent evidence for beneficial effects of education on cognitive abilities of approximately 1 to 5 IQ points for an additional year of education. Moderator analyses indicated that the effects persisted across the life span and were present on all broad categories of cognitive ability studied. Education appears to be the most consistent, robust, and durable method yet to be identified for raising intelligence. </jats:p

Reading Disability, Visual Stress, and Coloured Filters: A Randomised Controlled Trial

Coloured filters, in the form of plastic overlays or tinted spectacle lenses, are in widespread use to alleviate visual stress (also known as Irlen Syndrome), a disorder posited to be a major cause of reading disability (Irlen, 1991; Wilkins, 2003). However, a recent systematic review (Albon et al., 2008) concluded that the evidence for the efficacy of coloured filters is insufficient to recommend the treatment. The existence of visual stress as a diagnostic entity has also been questioned (Royal College of Opthalmologists, 2009). This thesis first describes the various theoretical perspectives behind the use of coloured filters, and provides an in-depth review of the current evidence. A combined crossover study and randomised controlled trial of the coloured filters used by the Irlen Institute, the major proponent of the treatment, is then described. This experiment, which set out to avoid the methodological problems observed in previous trials - most importantly, double-blinding was employed - failed to find any evidence of visual stress, or for the statistically or clinically significant benefit of coloured overlays for reading rate or comprehension on two separate reading tests, in a sample of 61 Primary School-age children with reading problems. This was despite 77% of the sample having been diagnosed with visual stress by an Irlen diagnostician and prescribed coloured overlays. Visual stress theory and the current prevalence of the coloured filter treatment are discussed in the light of this new evidence

Interfertility of independently originated allopolyploid populations

The reduction in genetic diversity in polyploid lineages, formed from whole-genome duplication of a few individuals, can affect their long-term evolutionary potential. Because most polyploids originate multiple times, secondary contact and gene exchange among independently formed polyploids can create novel genetic combinations and reduce the severity of genetic bottlenecks. However, independently originated polyploids may be reproductively isolated from each other due to genetic and chromosomal differences predating the polyploidisation event, or evolving subsequently in the dynamic genomes of young polyploid populations. Here we conducted experimental crosses to investigate the phenotype and interfertility between two independently originated populations of the allopolyploid Mimulus peregrinus (Phrymaceae). We found that individuals from the two populations are phenotypically distinct, but that inter- and intrapopulation crosses are not statistically different. Interpopulation crosses produce viable and fertile offspring, although our results suggest the existence of partial reproductive barriers in the form of reduced pollen viability. We found no difference in pollen viability between F1 and F2 generations. In contrast, we detected a reduction in floral and vegetative size, and in the proportion of plants that flowered, between F1 and F2 generations for both intra- and interpopulation crosses. Together, our results indicate that populations of independent origin can partially exchange genes, producing variable offspring, and that the phenotype of M. peregrinus may be unstable in the early generations. Natural selection on genetically-based variation may be required for the evolution of more stable and fertile individuals of this nascent allopolyploid

Physical frailty and decline in general and specific cognitive abilities:The Lothian Birth Cohort 1936

Background: physical frailty is associated with many adverse outcomes including disability, chronic disease, hospitalisation, institutionalisation and death. It is unclear what impact it might have on the rate of normal cognitive ageing. We investigated whether physical frailty was related to initial level of, and change in, cognitive abilities from age 70 to 79 years.Method: participants were 950 members of the Lothian Birth Cohort 1936. Physical frailty was assessed at age 70 years using the Fried criteria. Cognitive function was assessed at ages 70, 73, 76 and 79 years. We used linear regression to examine cross-sectional and prospective associations between physical frailty status at age 70 years and factor score estimates for baseline level of and change in four cognitive domains (visuospatial ability, memory, processing speed and crystallised ability) and in general cognitive ability.Results: physical frailty, but not prefrailty, was associated with lower baseline levels of visuospatial ability, memory, processing speed and general cognitive ability after control for age, sex, education, depressive symptoms, smoking and number of chronic illnesses. Physical frailty was associated with greater decline in each cognitive domain: age-adjusted and sex-adjusted standardised regression coefficients (95% CIs) were: −0.45 (−0.70 to –0.20) for visuospatial ability, −0.32 (−0.56 to –0.07) for memory, −0.47 (−0.72 to −0.22) for processing speed, −0.43 (−0.68 to –0.18) for crystallised ability and −0.45 (−0.70 to –0.21) for general cognitive ability. These associations were only slightly attenuated after additional control for other covariates.Conclusion: physical frailty may be an important indicator of age-related decline across multiple cognitive domains

Processing speed differences between 70- and 83-year-olds matched on childhood IQ

AbstractProcessing speed is an important human cognitive capability that might underlie differences in other cognitive skills and their aging. We aimed to test aging-related processing speed differences using a novel cross-sectional design that adjusted for cognitive ability tested in youth. We examined aging differences on three different ways of assessing processing speed: psychometric, experimental, and psychophysical. We compared large narrow-age cohorts of 70- and 83-year-old people who were matched for cognitive ability in childhood. There were decrements of substantial effect size in all processing speed assessments in the older group that were not accounted for by prior cognitive ability, health, or fitness differences, though these factors also contributed to processing speed differences. These findings confirm age-related cognitive slowing using an unusual research design, and provide evidence against recent theories characterizing aging-related cognitive decline as a myth