In this article, we compare the reaction norms to foliage shade (changes in light quality, spatially fine-grained environmental variation) and photoperiod (day length, spatially coarse-grained environmental variation) in several haplotypes of Arabidopsis thaliana from Scandinavia. We found that both across-environment means and phenotypic plasticities evolved continuously and very rapidly within this group. Both character means and trait plasticities were highly integrated, in part as predicted by the adaptive plasticity hypothesis for response to foliage shade (the so-called shade-avoidance syndrome). We found that a significant but small fraction of the variance in across-treatment trait means and plasticities in response to one environmental factor is explained by variation of the same traits in response to the other factor. Genetic relatedness based on chloroplast DNA sequence variation among haplotypes was not associated with variation in across-treatment character means or their plasticities, suggesting that evolution of these characters has occurred on a local geographic scale via reticulation (outcrossing) among maternal lines rather than by the differential survival of selfing lineages.
Fish assemblages in two reaches of the Hawkesbury–Nepean River were studied to determine the separate and combined effects of modifications to the riparian vegetation and nutrient enrichment on the composition of fish assemblages. Fish were sampled along vegetated and degraded banks where no vegetation was present, and upstream of and within zones of nutrient enrichment, associated with discharge of treated sewage effluent into the river and run‐off from nearby urban areas. Although the species composition differed between river reaches, both the number of fish species and total fish abundance were significantly greater in habitats adjacent to vegetated banks. Five species [Anguilla reinhardtii Steindachner, Macquaria novemaculeata (Steindachner), Cyprinus carpio L., Hypseleotris compressa (Krefft) and Myxus petardi (Castelnau)] were significantly (P < 0.05) affected by riparian degradation, with mean abundances ranging from 3.3 to 13.0 times larger than adjacent to vegetated banks. Species richness, total abundance and abundance of M. novemaculeata and H. compressa were also higher in zones with low levels of nutrient enrichment. Multivariate analyses showed that while eutrophication has a major effect on fish assemblages in the Hawkesbury–Nepean River, even greater effects may result from clearing of riparian vegetation leading to bank degradation.
The migratory butterfly Vanessa atalanta increased in abundance at monitored sites in Britain from 1976 to 1996. Three possible causes of the increase are improved winter survival within Britain, greater breeding success within Britain, and increased immigration.
Trends during most of the season were similar to those of immigrant or overwintered individuals in spring; thus the evidence does not support greater breeding success in Britain. As abundance in spring was not correlated with abundance in the previous autumn, when trend was taken into account, it seemed unlikely that overwintering in Britain was important. Thus the increase in abundance was probably due to increased immigration. Incidental to the main study, the mean index per site per year was closely correlated with the collated index, the usual measure of annual fluctuations. This agreement suggests that the mean index may be a useful check for trends in monitoring data for other wide‐ranging organisms.
Slnce the mid-1970s, several studies have investigated the feasibility of using acoustic emission (AE) to monitor the lntegrtty of aircraft structural components durtng flight. These studies are completely catalogued in an annotated bibliography of acoustic emission (1.2). AE has the advantage ofbeing capable ofmonitortng large components with a single sensor, is truly a passive technique, and can be conveniently used in hard-toreach locations. Successful development of this technique will offer tremendous savings by reducing the need for major disassembly in order to inspect crtticalload-bearing components.
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