Comparative phylogeography of two related plant species with overlapping ranges in Europe, and the potential effects of climate change on their intraspecific genetic diversity

BACKGROUND: The aim of the present study was to use a combined phylogeographic and species distribution modelling approach to compare the glacial histories of two plant species with overlapping distributions, Orthilia secunda (one-sided wintergreen) and Monotropa hypopitys (yellow bird's nest). Phylogeographic analysis was carried out to determine the distribution of genetic variation across the range of each species and to test whether both correspond to the "classic" model of high diversity in the south, with decreasing diversity at higher latitudes, or whether the cold-adapted O. secunda might retain more genetic variation in northern populations. In addition, projected species distributions based on a future climate scenario were modelled to assess how changes in the species ranges might impact on total intraspecific diversity in both cases. RESULTS: Palaeodistribution modelling and phylogeographic analysis using multiple genetic markers (chloroplast trnS-trnG region, nuclear ITS and microsatellites for O. secunda; chloroplast rps2, nuclear ITS and microsatellites for M. hypopitys) indicated that both species persisted throughout the Last Glacial Maximum in southern refugia. For both species, the majority of the genetic diversity was concentrated in these southerly populations, whereas those in recolonized areas generally exhibited lower levels of diversity, particularly in M. hypopitys. Species distribution modelling based on projected future climate indicated substantial changes in the ranges of both species, with a loss of southern and central populations, and a potential northward expansion for the temperate M. hypopitys. CONCLUSIONS: Both Orthilia secunda and Monotropa hypopitys appear to have persisted through the LGM in Europe in southern refugia. The boreal O. secunda, however, has retained a larger proportion of its genetic diversity in more northerly populations outside these refugial areas than the temperate M. hypopitys. Given that future species distribution modelling suggests northern range shifts and loss of suitable habitat in the southern parts of the species' current distributions, extinction of genetically diverse rear edge populations could have a significant effect in the rangewide intraspecific diversity of both species, but particularly in M. hypopitys

Cryptic introgression into the kidney saxifrage (Saxifraga hirsuta) from its more abundant sympatric congener Saxifraga spathularis, and the potential risk of genetic assimilation

Background and Aims Although hybridization can play a positive role in plant evolution, it has been shown that excessive unidirectional hybridization can result in replacement of a species’ gene pool, and even the extinction of rare species via genetic assimilation. This study examines levels of introgression between the common Saxifraga spathularis and its rarer congener S. hirsuta, which have been observed to hybridize in the wild where they occur sympatrically. Methods Seven species-specific single nucleotide polymorphisms (SNPs) were analysed in 1025 plants representing both species and their hybrid, S. × polita, from 29 sites across their ranges in Ireland. In addition, species distribution modelling was carried out to determine whether the relative abundance of the two parental species is likely to change under future climate scenarios. Key Results Saxifraga spathularis individuals tended to be genetically pure, exhibiting little or no introgression from S. hirsuta, but significant levels of introgression of S. spathularis alleles into S. hirsuta were observed, indicating that populations exhibiting S. hirsuta morphology are more like a hybrid swarm, consisting of backcrosses and F(2)s. Populations of the hybrid, S. × polita, were generally comprised of F(1)s or F(2)s, with some evidence of backcrossing. Species distribution modelling under projected future climate scenarios indicated an increase in suitable habitats for both parental species. Conclusions Levels of introgression observed in this study in both S. spathularis and S. hirsuta would appear to be correlated with the relative abundance of the species. Significant introgression of S. spathularis alleles was detected in the majority of the S. hirsuta populations analysed and, consequently, ongoing introgression would appear to represent a threat to the genetic integrity of S. hirsuta, particularly in areas where the species exists sympatrically with its congener and where it is greatly outnumbered

Pure species within a continuum of genetic and morphological variation:Sympatric oaks at the edge of their range

Background and Aims Studies on oaks (Quercus spp.) have often been hampered by taxonomic confusion, a situation further compounded by the occurrence of extensive interspecific hybridization. In the present study, a combination of genetic and morphological analyses was used to examine sympatric populations of Q. petraea and Q. robur at the north-western edge of their ranges in Northern Ireland, since it had previously been suggested that hybridization could facilitate the apparent rapid, long-distance dispersal of oaks following the glaciations. Methods Samples were collected from 24 sites across Northern Ireland that had been previously designated as ancient or semi-natural woodland. Genotypes were obtained from a total of 950 trees using 12 nuclear microsatellite loci, and admixture coefficients were calculated based on a Bayesian clustering approach. Individuals were also classified as Q. petraea, Q. robur or hybrids based on two objective morphometric characters shown previously to delineate pure individuals effectively. Genetically ‘pure’ individuals of both species, as defined by the Bayesian clustering, were also genotyped for five chloroplast microsatellites. Key Results Genetic and morphological analyses both indicated the presence of pure individuals of both species, as well as a continuum of intermediates. There was a good agreement between the molecular and morphological classification, with a generally clear separation between pure individuals. Conclusions Despite millennia of hybridization and introgression, genetically and morphologically pure individuals of both Q. petraea and Q. robur can be found at the edge of their range, where both species occur sympatrically. The high proportion of individuals exhibiting introgression compared with previous studies may reflect the historical role of hybridization in facilitating dispersal following the glaciations. This is further supported by the significantly higher chloroplast diversity in Q. robur compared with Q. petraea

Prognostic Indicators and Outcome Measures for Surgical Removal of Symptomatic Nonadvanced Cataract

This article is made available in accordance with the publisher's public repositories policy.Objectives To report changes in perceived visual functioning after surgery for symptomatic cataract with preoperative corrected distance visual acuity [CDVA] of 0.4 logMAR or better (Snellen equivalent, 20/50) and to investigate the relationship between any observed changes and preoperative physical characteristics and psychophysical consequences of the lens opacity and any changes in psychophysical findings after the procedure. Methods Eighty-five patients with cataract completed a validated questionnaire concerning functional vision satisfaction and a series of visual performance assessments before and 2 months after cataract surgery. The lens optical density and Lens Opacities Classification System III score of the cataract were recorded. Correlations between changes in the Rasch-analyzed questionnaire score and changes in visual performance after cataract surgery, as well as preoperative psychophysical measures, lens optical density, and Lens Opacities Classification System III score, were determined. Results The mean (SD) questionnaire score improved from 2.15 (0.36) to 1.54 (0.41) (P > .05 for both). Conclusion Psychophysical tests alternative to CDVA better represent improvements in self-reported visual functioning following removal of symptomatic nonadvanced cataract

Self-Sorting in Dynamic Combinatorial Libraries Leads to the Co-Existence of Foldamers and Self-Replicators

Nature segregates fundamental tasks such as information storage/transmission and catalysis between two different compound classes (e.g. polynucleotides for replication and folded polyamides for catalysis). This division of labor is likely a product of evolution, raising the question of how simpler systems in which replicators and folded macromolecules co-exist may emerge in the transition from chemistry to biology. In synthetic systems, achieving co-existence of replicators and foldamers in a single molecular network remains an unsolved problem. Previous work on dynamic molecular networks has given rise to either self-replicating fibers or well-defined foldamer structures (or completely un-sorted complex systems). We report a system in which two cross-reactive dithiol (nucleobase- and peptide-based) building blocks self-sort into a replicator fiber and foldamer that both emerge spontaneously and co-exist. The self-sorting behavior remains prevalent across different building block ratios as two phases of emergence occur: replicator growth followed by foldamer formation. This is attributed to the autocatalytic formation of the replicator fiber, followed by enrichment of the system in the remaining building block, which is subsequently incorporated into a foldamer

Introduction of a Toric Intraocular Lens to a Non-Refractive Cataract Practice: Challenges and Outcomes

AIM: To identify challenges inherent in introducing a toric intraocular lens (IOL) to a non-refractive cataract practice, and evaluate residual astigmatism achieved and its impact on patient satisfaction. METHODS: Following introduction of a toric IOL to a cataract practice with all procedures undertaken by a single, non-refractive, surgeon (SB), pre-operative, intra-operative and post-operative data was analysed. Attenuation of anticipated post-operative astigmatism was examined, and subjectively perceived visual functioning was assessed using validated questionnaires. RESULTS: Median difference vector (DV, the induced astigmatic change [by magnitude and axis] that would enable the initial surgery to achieve intended target) was 0.93D; median anticipated DV with a non-toric IOL was 2.38D. One eye exhibited 0.75D residual astigmatism, compared to 3.8D anticipated residual astigmatism with a non-toric IOL. 100% of respondents reported satisfaction of ≥ 6/10, with 37.84% of respondents entirely satisfied (10/10). 17 patients (38.63%) reported no symptoms of dysphotopsia (dysphoptosia score 0/10), only 3 respondents (6.8%) reported a clinically meaningful level of dysphotopsia (≥ 4/10). Mean post-operative NEI VF-11 score was 0.54 (+/-0.83; scale 0 – 4). CONCLUSION: Use of a toric IOL to manage astigmatism during cataract surgery results in less post-operative astigmatism than a non-toric IOL, resulting in avoidance of unacceptable post-operative astigmatism

The Impact of Macular Pigment Augmentation on Visual Performance in Normal Subjects: COMPASS

This study was conducted to investigate whether augmentation of macular pigment (MP) enhances visual performance (VP). 121 normal subjects were recruited. The active (A) group consumed 12 mg of lutein (L) and 1 mg of zeaxanthin (Z) daily. MP optical density (MPOD) was assessed by customized heterochromatic flicker photometry. VP was assessed as best corrected visual acuity (BCVA), mesopic and photopic contrast sensitivity (CS), glare disability, photostress, and subjective visual function. Subjects were assessed at baseline; 3; 6; 12 months (V1, V2, V3 and V4, respectively). Central MPOD increased significantly in the A group (p \u3c 0.05) but not in the placebo group (p \u3e 0.05). This statistically significant increase in MPOD in the A group was not, in general, associated with a corresponding improvement in VP (p \u3e 0.05, for all variables), with the exception of a statistically significant time/treatment effect in “daily tasks comparative analysis” (p = 0.03). At V4, we report statistically significant differences in mesopic CS at 20.7 cpd, mesopic CS at 1.5 cpd under high glare conditions, and light/dark adaptation comparative analysis between the lower and the upper MP tertile groups (p \u3c 0.05) Further study into the relationship between MP and VP is warranted, with particular attention directed towards individuals with low MP and suboptimal VP. Research highlights ► Identifying that macular pigment significantly increased in the active group. ► Less glare disability for subjects with high macular pigment. ► Improved mesopic contrast sensitivity for subjects with high macular pigment. ► Identifying the need for further research in subjects with low macular pigment

Prognostic Indicators and Outcome Measures for Surgical Removal of Symptomatic Nonadvanced Cataract

Objectives: To report changes in perceived visual functioning after surgery for symptomatic cataract with pre-operative corrected distance visual acuity [CDVA] of 0.4 logMar or better (Snellen equivalent, 20/50) and to investigate the relationship between any observed changes and preoperative physical characteristics and psycho-physical consquences of the lens opacity and any changes in psychophysical findings after the procedure

The influence of cultural-linguistic background on family and SLP perceptions of pragmatic communication skills following right-hemisphere stroke

Pragmatic communication abilities are frequently impaired in persons who have had a right-hemisphere stroke. Speech-language pathologists (SLPs) often supplement their own pragmatic communication assessment ratings with ratings from the patients’ family members. These ratings, by both SLPs and family members, are likely to be biased by their respective cultural-linguistic backgrounds. The pragmatic communication ratings of Caucasian SLPs were compared with Caucasian and African-American families’ ratings for patients following right-hemisphere stroke. SLPs’ ratings agreed more closely with Caucasian families, but not to a degree that reached statistical significance. The nature of this agreement regarding specific pragmatic communication behaviors, as well as clinical implications, are discussed