Gene expression and alternative splicing contribute to adaptive divergence of ecotypes.

Regulation of gene expression is a critical link between genotype and phenotype explaining substantial heritable variation within species. However, we are only beginning to understand the ways that specific gene regulatory mechanisms contribute to adaptive divergence of populations. In plants, the post-transcriptional regulatory mechanism of alternative splicing (AS) plays an important role in both development and abiotic stress response, making it a compelling potential target of natural selection. AS allows organisms to generate multiple different transcripts/proteins from a single gene and thus may provide a source of evolutionary novelty. Here, we examine whether variation in alternative splicing and gene expression levels might contribute to adaptation and incipient speciation of dune-adapted prairie sunflowers in Great Sand Dunes National Park, Colorado, USA. We conducted a common garden experiment to assess transcriptomic variation among ecotypes and analyzed differential expression, differential splicing, and gene coexpression. We show that individual genes are strongly differentiated for both transcript level and alternative isoform proportions, even when grown in a common environment, and that gene coexpression networks are disrupted between ecotypes. Furthermore, we examined how genome-wide patterns of sequence divergence correspond to divergence in transcript levels and isoform proportions and find evidence for both cis and trans-regulation. Together, our results emphasize that alternative splicing has been an underappreciated mechanism providing source material for natural selection at short evolutionary time scales.

Beliefs About Traumatic Memories, Thought Control Strategies, and the Impact on PTSD Symptoms After a Natural Disaster.

ABSTRACT: This study aimed to investigate the relationships among self-reported meta-memory beliefs, thought control strategies ( i.e. , distraction, reappraisal, worry, social control, and punishment), and posttraumatic stress disorder (PTSD) symptomology, among a sample of earthquake survivors ( N = 412). Correlational analysis and structural equation modeling were used on the responses and showed that stronger positive and negative meta-memory beliefs, and greater worry and punishment, were associated with greater PTSD symptom severity. The results also indicated that meta-memory beliefs had a prominent indirect influence toward PTSD symptomology via their effects toward thought control strategies. Follow-up analysis of variance indicated that those with a history of mental health difficulties reported higher levels of PTSD symptom severity, were more likely to score in the range of clinically relevant PTSD, and had a stronger tendency to negatively appraise unwanted thinking styles. The results of this research provide overall support for the validity of the metacognitive model for PTSD.

Beliefs about Memory Questionnaire: psychometric properties in a natural disaster sample.

Several theories exist regarding the role of memory in the development of PTSD. The metacognitive model of PTSD contends beliefs about trauma memory are pivotal in the development and maintenance of PTSD. The Beliefs About Memory Questionnaire (BAMQ) was developed to measure metacognitive beliefs about trauma memory. This study aimed to test the psychometric properties of the BAMQ and its relationship to PTSD in a community sample of 674 adults exposed to the 2010-2011 Canterbury earthquakes and Queensland floods. Participants completed a series of online, self-report questionnaires between October and December 2012, exploring thinking and memory processes related to their experience of a natural disaster. Factor analysis validated the two-factor, positive and negative structure of the BAMQ. Convergent, concurrent, and discriminant validity was established through positive relationships with relevant metacognitive beliefs, thought control variables, and risk factors related to PTSD. Logistic regression revealed scores on the BAMQ predicted clinically significant symptoms of PTSD. The psychometric properties of the BAMQ suggest the instrument is a valuable addition to the assessment of metacognitive beliefs about trauma memory, and the utility of the BAMQ in the prediction of clinically significant symptoms of PTSD.

Leaf trait variation is similar among genotypes of Eucalyptus camaldulensis from differing climates and arises in plastic responses to the seasons rather than water availability.

We used a widely distributed tree Eucalyptus camaldulensis subsp. camaldulensis to partition intraspecific variation in leaf functional traits to genotypic variation and phenotypic plasticity. We examined if genotypic variation is related to the climate of genotype provenance and whether phenotypic plasticity maintains performance in a changing environment. Ten genotypes from different climates were grown in a common garden under watering treatments reproducing the wettest and driest edges of the subspecies' distribution. We measured functional traits reflecting leaf metabolism and associated with growth (respiration rate, nitrogen and phosphorus concentrations, and leaf mass per area) and performance proxies (aboveground biomass and growth rate) each season over a year. Genotypic variation contributed substantially to the variation in aboveground biomass but much less in growth rate and leaf traits. Phenotypic plasticity was a large source of the variation in leaf traits and performance proxies and was greater among sampling dates than between watering treatments. The variation in leaf traits was weakly correlated to performance proxies, and both were unrelated to the climate of genotype provenance. Intraspecific variation in leaf traits arises similarly among genotypes in response to seasonal environmental variation, instead of long-term water availability or climate of genotype provenance.

Assessment of biogeographic variation in traits of Lewis flax (Linum lewisii) for use in restoration and agriculture.

Lewis flax (Linum lewisii) is widely distributed across western North America and is currently used in native ecosystem restoration. There is also growing interest in de novo domestication of Lewis flax as a perennial oilseed crop. To better understand this species and facilitate both restoration and domestication, we used common gardens to assess biogeographical variation in a variety of seed and growth traits from 37 flax accessions, consisting of 35 wild populations from the Intermountain West region, the pre-variety germplasm Maple Grove (L. lewisii) and the cultivar 'Appar' (L. perenne) and related this variation to collection site geography and climate. Results from linear mixed models suggest there is extensive phenotypic variation among populations of Lewis flax within the Intermountain West. Using a multivariate approach, we identify a key suite of traits that are related to latitude and climate and may facilitate adaptation, including flowering indeterminacy, seed mass and stem number. These traits should be taken into account when considering the release of new germplasm for restoration efforts. We also find that Lewis flax seed contains desirably high amounts of alpha-linolenic acid and is otherwise mostly indistinguishable in fatty acid composition from oil-type varieties of domesticated flax (L. usitatissimum), making it a strong candidate for domestication. This study provides fundamental knowledge for future research into the ecology and evolution of Lewis flax, which will inform its use in both restoration and agriculture.

Complete mitochondrial genomes provide current refined phylogenomic hypotheses for relationships among ten Hirundo species.

Hirundo is the most species-rich genus of the passerine swallow family (Hirundinidae) and has a cosmopolitan distribution. Here we report the complete, annotated mitochondrial genomes for 25 individuals from 10 of the 14 extant Hirundo species; these include representatives from four subspecies of the barn swallow, H. rustica. Mitogenomes were conserved in size, ranging from 18,500 to 18,700 base pairs. They all contained 13 protein-coding regions, 22 tRNAs, a control region, and large and small ribosomal subunits. Phylogenetic analysis resolved most of the relationships between the studied species and subspecies which were largely consistent with previously published trees. Several new relationships were observed within the phylogeny that could have only been discovered with the increased amount of genetic material. This study represents the largest Hirundo mitochondrial phylogeny to date, and could serve as a vital tool for other studies focusing on the evolution of the Hirundo genus.

Learning in oral biology: a comparison between deep and surface approaches.

It has been suggested that students approach their learning in at least two qualitatively different ways. In the surface approach, students see tasks as being imposed, for which they develop coping strategies focused on reproduction of essentials and memorising information for assessment rather than for understanding. In the deep approach, students seek to understand ideas to allow them to relate and integrate knowledge from other parts of their study and thereby develop conceptual frameworks from which they can derive solutions to novel problems. To these two approaches, a third, achieving approach, is often added, in which students aim to obtain the highest grades, whether or not they grasp the learning material. In this study we used a subject-specified version of Biggs' Study Process Questionnaire to obtain data about the way dental and dental technology students perceived and approached their learning in oral biology. Questionnaires were distributed to 62 second-year dental students and 23 second-year dental technology students. Within each group the dependent variables examined were deep, surface or achieving approaches to learning. Analysis of these data showed that significant differences between dental and dental technology students centred on their approaches to learning. However, there were no significant differences attributable to gender, country of origin or ethnicity. While dental students, who had a relatively well developed understanding of the nature of their studies in oral biology at the start of their course, adopted deep learning strategies, dental technology students, who had had no prior experience of university education per se, were significantly more surface-orientated.