Plant Genome Size Influences Stress Tolerance of Invasive and Native Plants via Plasticity

Plant genome size influences the functional relationships between cellular and whole‐plant physiology, but we know little about its importance to plant tolerance of environmental stressors and how it contributes to range limits and invasion success. We used native and invasive lineages of a wetland plant to provide the first experimental test of the Large Genome Constraint Hypothesis (LGCH)—that plants with large genomes are less tolerant of environmental stress and less plastic under stress gradients than plants with small genomes. We predicted that populations with larger genomes would have a lower tolerance and less plasticity to a stress gradient than populations with smaller genomes. In replicated experiments in northern and southern climates in the United States, we subjected plants from 35 populations varying in genome size and lineage to two salinity treatments. We measured traits associated with growth, physiology, nutrition, defense, and plasticity. Using AICc model selection, we found all plant traits, except stomatal conductance, were influenced by environmental stressors and genome size. Increasing salinity was stressful to plants and affected most plant traits. Notably, biomass in the high‐salinity treatment was 3.0 and 4.9 times lower for the invasive and native lineages, respectively. Plants in the warmer southern greenhouse had higher biomass, stomate density, stomatal conductance, leaf toughness, and lower aboveground percentage of N and total phenolics than in the northern greenhouse. Moreover, responses to the salinity gradient were generally much stronger in the southern than northern greenhouse. Aboveground biomass increased significantly with genome size for the invasive lineage (43% across genome sizes) but not for the native. For 8 of 20 lineage trait comparisons, greenhouse location × genome size interaction was also significant. Interestingly, the slope of the relationship between genome size and trait means was in the opposite direction for some traits between the gardens providing mixed support for LGCH. Finally, for 30% of the comparisons, plasticity was significantly related to genome size—for some plant traits, the relationship was positive, and in others, it was negative. Overall, we found mixed support for LGCH and for the first time found that genome size is associated with plasticity, a trait widely regarded as important to invasion success

New Families of Third-Order Iterative Methods for Finding Multiple Roots

Two families of third-order iterative methods for finding multiple roots of nonlinear equations are developed in this paper. Mild conditions are given to assure the cubic convergence of two iteration schemes (I) and (II). The presented families include many third-order methods for finding multiple roots, such as the known Dong's methods and Neta's method. Some new concrete iterative methods are provided. Each member of the two families requires two evaluations of the function and one of its first derivative per iteration. All these methods require the knowledge of the multiplicity. The obtained methods are also compared in their performance with various other iteration methods via numerical examples, and it is observed that these have better performance than the modified Newton method, and demonstrate at least equal performance to iterative methods of the same order

Recent advances in understanding the roles of whole genome duplications in evolution

Ancient whole-genome duplications (WGDs)—paleopolyploidy events—are key to solving Darwin’s ‘abominable mystery’ of how flowering plants evolved and radiated into a rich variety of species. The vertebrates also emerged from their invertebrate ancestors via two WGDs, and genomes of diverse gymnosperm trees, unicellular eukaryotes, invertebrates, fishes, amphibians and even a rodent carry evidence of lineage-specific WGDs. Modern polyploidy is common in eukaryotes, and it can be induced, enabling mechanisms and short-term cost-benefit assessments of polyploidy to be studied experimentally. However, the ancient WGDs can be reconstructed only by comparative genomics: these studies are difficult because the DNA duplicates have been through tens or hundreds of millions of years of gene losses, mutations, and chromosomal rearrangements that culminate in resolution of the polyploid genomes back into diploid ones (rediploidisation). Intriguing asymmetries in patterns of post-WGD gene loss and retention between duplicated sets of chromosomes have been discovered recently, and elaborations of signal transduction systems are lasting legacies from several WGDs. The data imply that simpler signalling pathways in the pre-WGD ancestors were converted via WGDs into multi-stranded parallelised networks. Genetic and biochemical studies in plants, yeasts and vertebrates suggest a paradigm in which different combinations of sister paralogues in the post-WGD regulatory networks are co-regulated under different conditions. In principle, such networks can respond to a wide array of environmental, sensory and hormonal stimuli and integrate them to generate phenotypic variety in cell types and behaviours. Patterns are also being discerned in how the post-WGD signalling networks are reconfigured in human cancers and neurological conditions. It is fascinating to unpick how ancient genomic events impact on complexity, variety and disease in modern life

A Novel Iterative Scheme and Its Application to Differential Equations

The purpose of this paper is to employ an alternative approach to reconstruct the standard variational iteration algorithm II proposed by He, including Lagrange multiplier, and to give a simpler formulation of Adomian decomposition and modified Adomian decomposition method in terms of newly proposed variational iteration method-II (VIM). Through careful investigation of the earlier variational iteration algorithm and Adomian decomposition method, we find unnecessary calculations for Lagrange multiplier and also repeated calculations involved in each iteration, respectively. Several examples are given to verify the reliability and efficiency of the method