batemanater: a computer program to estimate and bootstrap mating system variables based on Bateman's principles

Bateman's principles continue to play a major role in the characterization of genetic mating systems in natural populations. The modern manifestations of Bateman's ideas include the opportunity for sexual selection (i.e. I_s – the variance in relative mating success), the opportunity for selection (i.e. I – the variance in relative reproductive success) and the Bateman gradient (i.e. β_ss – the slope of the least‐squares regression of reproductive success on mating success). These variables serve as the foundation for one convenient approach for the quantification of mating systems. However, their estimation presents at least two challenges, which I address here with a new Windows‐based computer software package called batemanater . The first challenge is that confidence intervals for these variables are not easy to calculate. batemanater solves this problem using a bootstrapping approach. The second, more serious, problem is that direct estimates of mating system variables from open populations will typically be biased if some potential progeny or adults are missing from the analysed sample. batemanater addresses this problem using a maximum‐likelihood approach to estimate mating system variables from incompletely sampled breeding populations. The current version of batemanater addresses the problem for systems in which progeny can be collected in groups of half‐ or full‐siblings, as would occur when eggs are laid in discrete masses or offspring occur in pregnant females. batemanater has a user‐friendly graphical interface and thus represents a new, convenient tool for the characterization and comparison of genetic mating systems.     

Deterministic convergence of chaos injection-based gradient method for training feedforward neural networks

It has been shown that, by adding a chaotic sequence to the weight update during the training of neural networks, the chaos injection-based gradient method (CIBGM) is superior to the standard backpropagation algorithm. This paper presents the theoretical convergence analysis of CIBGM for training feedforward neural networks. We consider both the case of batch learning as well as the case of online learning. Under mild conditions, we prove the weak convergence, i.e., the training error tends to a constant and the gradient of the error function tends to zero. Moreover, the strong convergence of CIBGM is also obtained with the help of an extra condition. The theoretical results are substantiated by a simulation example.     

Leaf‐litter breakdown in pasture and deciduous woodland streams: a comparison among three European regions

1. Human land‐use has altered catchments on a large scale in most parts of the world, with one of the most profound changes relevant for streams and rivers being the widespread clearance of woody riparian vegetation to make way for livestock grazing pasture. Increasingly, environmental legislation, such as the EU Water Framework Directive (EU WFD), calls for bioassessment tools that can detect such anthropogenic impacts on ecosystem functioning. 2. We conducted a large‐scale field experiment in 30 European streams to quantify leaf‐litter breakdown, a key ecosystem process, in streams whose riparian zones and catchments had been cleared for pasture compared with those in native deciduous woodland. The study encompassed a west–east gradient, from Ireland to Switzerland to Romania, with each of the three countries representing a distinct region. We used coarse‐mesh and fine‐mesh litter bags (10 and 0.5 mm, respectively) to assess total, microbial and, by difference, macroinvertebrate‐mediated breakdown. 3. Overall, total breakdown rates did not differ between land‐use categories, but in some regions macroinvertebrate‐mediated breakdown was higher in deciduous woodland streams, whereas microbial breakdown was higher in pasture streams. This result suggests that overall ecosystem functioning is maintained by compensatory increases in microbial activity in pasture streams. 4. We suggest that simple coefficients of breakdown rates on their own often might not be powerful enough as a bioassessment tool for detecting differences related to land‐use such as riparian vegetation removal. However, shifts in the relative contributions to breakdown by microbial decomposers versus invertebrate detritivores, as revealed by the ratios of their associated breakdown rate coefficients, showed clear responses to land‐use.     

Effect of opioid compounds on feeding and activity of the cockroach, Periplaneta americana

Opioid peptides have been implicated in regulation of feeding in invertebrates. Studies have suggested that receptors for opioids are present in cockroaches and that these receptors play roles in affecting both behaviour and feeding. We examined the effect of µ, δ, and κ opioid receptor agonists and antagonists on feeding, mass changes and activity in the cockroach, Periplaneta americana. The κ antagonist, nor-binaltorphimine, significantly increased food intake, while naltrexone (general antagonist) and naloxonazine (µ antagonist) both reduced feeding. A large mass loss was observed in cockroaches treated with nor-binaltorphimine, despite the increased food intake. Males did not lose as much mass during the 3 h as females, although drug treatment did have some effect on the loss. Time of activity (%) was not influenced by any drug. Water loss experiments suggested that nor-binaltorphimine increased water loss, accounting for the mass loss despite the increased feeding. We suggest that two populations of opioid receptors are present as previously reported, with one affecting feeding and the other involved with evaporative water loss.     

Multilevel phenotypic selection on morphological characters in a metapopulation of Silene tatarica

This study partitions selection in a natural metapopulation of a riparian plant species, Silene tatarica, into individual- and patch-level components by using contextual analysis, in which a patch refers to a spatially distinct stand of individual plants. We estimated selection gradients for two morphological characters (plant height and number of stems), their respective patch means, and plant density with respect to reproductive success in a two-year study. The approach was also extended to partition selection separately within habitats with varying degrees of exposure to river disturbances and herbivory. The selection differentials and gradients for plant height were positive at both individual and patch levels, with selection forces highest in the closed habitat with low exposure to disturbance. This pattern suggests that local groups with taller than average plants are more visible to pollinators than to groups that are shorter than average plants; and, within patches, individuals with short stature are visited less often than taller ones. Selection on the number of stems was in opposition at individual and patch levels. At the individual level the character was selected toward higher values, whereas selection at the patch-level favored smaller mean number of stems. The strength of the latter component was associated with the intensity of herbivory in different habitats, suggesting that the patch-level selection against a large number of stems might be due to high attractiveness of such patches to the main herbivore, reindeer. Consequently, direction and strength of selection in spatially structured populations may depend significantly on fitness effects arising at the group level.     

Fractionation of Hevea brasiliensis latex on ficoll density gradients

Fractionation of diluted Hevea brasiliensis latex on iso-osmotic Ficoll density gradients by sedimentation produces a sharp acid phosphatase-rich lutoid band at the density of ca1.04 g/cm³. Polyphenol oxidase (PPO) is not exclusively located in the Frey-Wyssling complexes as shown earlier by others; its distribution is variable. A complete separation of acid phosphatase and PPO activities can be obtained by flotation in a Ficoll density gradient. Ethephon stimulation of the tree reduces the acid phosphatase and PPO activities. A transient change in lutoid density soon after stimulation is observed. The occurrence of some new enzyme activities and their subcellular localization are reported.     

Variation and potential influence factors of foliar pH in land-water ecozones of three small plateau lakes

3个小型高原湖泊水陆交错带中植物叶片pH值变异及其潜在影响因素陆生植物叶片pH值是与植物生理功能和养分利用状况息息相关的重要植物属性,并随植物功能型和环境的变化而变化。然而,水生植物叶片pH值的变异特征及其与陆生植物间的差异性仍不清楚。在3个自然形成的小型高原湖泊的湖滨植物群落中,我们采集植物、土壤和湖水样品,检测了植物叶片pH值与碳、氮含量以及环境条件(水或土壤pH值、土壤水位状况)。从植物功能型和群落两个水平分析了湖滨植物叶pH值沿水分梯度的变化及其潜在影响因素。研究结果表明,不同类型的水生植物,以及水生、沼生和陆生环境中生长的植物的叶pH存在较大差异;浮叶植物叶片pH值(4.21 ± 0.05)显著低于挺水植物(5.71 ± 0.07)和沉水植物(5.82 ± 0.06);水生草本植物叶片pH值(5.43 ± 0.10)显著低于沼生草本植物(6.12 ± 0.07)和陆生草本植物(5.74 ± 0.05);陆生草本植物叶片pH值显著高于木本植物。植物功能群间叶片pH值的变异可能与叶片的结构、光利用特性和养分特性有关。群落水平的结果与植物功能型水平相一致：水生群落叶片pH值显著低于陆生群落。群落水平叶片pH值可能主要受物种组成、水分条件和环境pH值的影响。本研究首次探索了水生植物的pH值,并且在景观尺度上对比了不同功能型植物的叶片pH值,为深入探索植物pH值变异机制以及其在水生和湿地生态系统中的生态意义提供参考。