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.