Polygyny,relatedness and nest founding in the polygynous myrmicine ant Leptothorax acervorum (Hymenoptera; Formicidae)

Summary There is high within-nest relatedness for functional queens (with corpora lutea), nonfunctional queens (without corpora lutea), and workers in polygynous nests of Leptothorax acervorum. The high functional queen relatedness suggests that young mated queens are adopted back to their mother nest. Functional queen relatedness does not change with the number of queens present in the nest, suggesting that the number of generations of queens, on average two to three, is rather stable. Worker relatedness decreases with increasing number of functional queens per nest (Tables 5, 6). The number of queens contributing offspring to the nest (mothers), estimated from worker and functional queen relatedness, is lower than the number of functional queens, particularly in highly polygynous nests. Estimates of number of mothers in monogynous nests indicate that these nests previously were polygynous (Table 7). There is no correlation between nest relatedness and distance between nests, and budding-off, if present, thus appears to be a rare mode of nest founding (Table 8). There are no indications of inbreeding in the two populations studied since the frequency of heterozygotes is as high as expected from random mating (Table 4). Most likely, polygyny is the rule in L. acervorum and serves to secure the presence of queens in the nest.     

Wind tunnel attraction of grapevine moth females, Lobesia Botrana, to natural and artificial grape odour

Summary. Host plant volatiles which attract insect herbivores for egg-laying are of principal interest with respect to insect ecology and evolution. Direct applications concern population monitoring and control through behavioural manipulation. Identification of behaviourally active plant secondary metabolites is essential also for plant breeding for insect resistance. Grapevine moth females Lobesia botrana are attracted by upwind flight to green grape berries Vitis vinifera. The headspace of grape berries was collected on air filters. A solvent extract of these filters, released from a sprayer, attracted females in the wind tunnel. The results demonstrate that volatile cues mediate attraction of grapevine moth females to grape berries, and that headspace collections capture the essence of this odour signal. The air filter extracts were examined by gas chromatography coupled with electroantennographic detection, and the compounds eliciting a consistent antennal response in L. botrana females were identified by mass spectrometry. The headspace collection apparatus was calibrated for collection efficiency of the active compounds. Their recovery rate ranged from 35 % for methyl salicylate to 83 % for (E,E)-α-farnesene. A synthetic ten-component blend was then formulated. The blend consisted of compounds eliciting an antennal response, formulated in a blend ratio corrected for differences in collection efficiency. Subsequent wind tunnel tests showed that female attraction to this synthetic ten-component blend was not significantly different from attraction to grape berries, or to headspace collections of the same berries. At a release rate of 35 ng/h of the most abundant compound (E)-β-caryophyllene, 20 % of the test females approached the source of sprayed headspace collections and the ten-component synthetic blend, respectively. In comparison, 100 g of green berries, releasing the main compound (E)-β-caryophyllene at a rate of ca. 4.7 ng/h, attracted 10 % of the females by upwind flight followed by source contact.     

Effect of ambient oxygen concentration on activities of enzymatic antioxidant defences and aerobic metabolism in the hydrothermal vent worm, Paralvinella grasslei

The alvinellid Paralvinella grasslei is a common endemic polychaete from the deep-sea hydrothermal vent communities located on the East Pacific Rise (EPR). These organisms colonise a large range of microhabitats around active sites where physico-chemical conditions are thought to generate reactive oxygen species (ROS). Furthermore, in this aerobic organism, ROS could also be generated by the activity of the mitochondrial respiratory chain. In this paper, we investigated the effect of ambient oxygen concentration on the activities of three essential antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPX) and their relationships with the activity of enzymes involved in aerobic metabolism (cytochrome c oxidase, COX; citrate synthase, CS). Results of incubation of P. grasslei in a high-pressure vessel with circulating seawater at different oxygen partial pressures indicate that this worm regulates COX and CS activities differently in gills and body wall. CAT and GPX activities increase in these tissues when animals are maintained in filtered surface seawater. Moreover, levels of malondialdehyde increase in gills, testifying that oxidative damage occurs under these conditions. CAT and GPX activities are positively related to COX and CS activities, but no correlation was detected between SOD and the metabolic enzyme activities. In comparison with littoral annelids, SOD activities are very high whereas CAT activities are very low or absent in P. grasslei. The possible reasons for the occurrence of such differences are discussed.     

Regional climate change projections for the Northeast USA

Climate projections at relevant temporal and spatial scales are essential to assess potential future climate change impacts on climatologically diverse regions such as the northeast United States. Here, we show how both statistical and dynamical downscaling methods applied to relatively coarse-scale atmosphere-ocean general circulation model output are able to improve simulation of spatial and temporal variability in temperature and precipitation across the region. We then develop high-resolution projections of future climate change across the northeast USA, using IPCC SRES emission scenarios combined with these downscaling methods. The projections show increases in temperature that are larger at higher latitudes and inland, as well as the potential for changing precipitation patterns, particularly along the coast. While the absolute magnitude of change expected over the coming century depends on the sensitivity of the climate system to human forcing, significantly higher increases in temperature and in winter precipitation are expected under a higher as compared to lower scenario of future emissions from human activities.     

Nested patterns in hyporheic meta-communities: the role of body morphology and penetrability of sediment

Nestedness has been regarded as a common pattern of species distribution especially in terrestrial systems and vertebrate faunas. However, a significantly lower degree of nestedness has been reported for aquatic invertebrates. We analyzed the vertical distribution patterns of taxa in the upper 70 cm of the hyporheic zone. This biotope is abundantly inhabited by epigean fauna, which is morphologically pre-adapted to life within the limited space of sediment interstices. We tested the hypotheses that in the vertical profile of the hyporheic zone sediment acts as a physical barrier (filter), allowing only the morphologically pre-adapted and adapted (i.e., smaller, narrower, more flexible) taxa to penetrate to deeper layers. We demonstrated that this mechanism can promote a strongly nested and colonization-driven pattern at higher taxa levels. The sediment filter (1) constricted the body width: 0.50 mm appeared to be the upper limit for successful sediment colonization at the study site, and (2) favored elongated taxa against small sized taxa. We tested also the assumption that distribution of fine sediment affects the accessibility of hyporheic zone for fauna (“filter density”) and thereby influences nestedness. However, we found that nestedness could be sufficiently explained by the depth itself. Our study offers a possible explanation of depth patterns in hyporeic meta-communities as a result of morphological characteristics promoting nestedness at higher taxa level.     

Improving marine water quality by mussel farming: a profitable solution for Swedish society

Eutrophication of coastal waters is a serious environmental problem with high costs for society globally. In eastern Skagerrak, reductions in eutrophication are planned through reduction of nitrogen inputs, but it is unclear how this can be achieved. One possible method is the cultivation of filter-feeding organisms, such as blue mussels, which remove nitrogen while generating seafood, fodder and agricultural fertilizer, thus recycling nutrients from sea to land. The expected effect of mussel farming on nitrogen cycling was modeled for the Gullmar Fjord on the Swedish west coast and it is shown that the net transport of nitrogen (sum of dissolved and particulate) at the fjord mouth was reduced by 20%. Existing commercial mussel farms already perform this service for free, but the benefits to society could be far greater. We suggest that rather than paying mussel farmers for their work that nutrient trading systems are introduced to improve coastal waters. In this context an alternative to nitrogen reduction in the sewage treatment plant in Lysekil community through mussel farming is presented. Accumulation of bio-toxins has been identified as the largest impediment to further expansion of commercial mussel farming in Sweden, but the problem seems to be manageable through new techniques and management strategies. On the basis of existing and potential regulations and payments, possible win-win solutions are suggested.     

Effects of whole spine alignment patterns on neck responses in rear end impact

Objective: The aim of this study was to investigate the whole spine alignment in automotive seated postures for both genders and the effects of the spinal alignment patterns on cervical vertebral motion in rear impact using a human finite element (FE) model.

Methods: Image data for 8 female and 7 male subjects in a seated posture acquired by an upright open magnetic resonance imaging (MRI) system were utilized. Spinal alignment was determined from the centers of the vertebrae and average spinal alignment patterns for both genders were estimated by multidimensional scaling (MDS). An occupant FE model of female average size (162 cm, 62 kg; the AF 50 size model) was developed by scaling THUMS AF 05. The average spinal alignment pattern for females was implemented in the model, and model validation was made with respect to female volunteer sled test data from rear end impacts. Thereafter, the average spinal alignment pattern for males and representative spinal alignments for all subjects were implemented in the validated female model, and additional FE simulations of the sled test were conducted to investigate effects of spinal alignment patterns on cervical vertebral motion.

Results: The estimated average spinal alignment pattern was slight kyphotic, or almost straight cervical and less-kyphotic thoracic spine for the females and lordotic cervical and more pronounced kyphotic thoracic spine for the males. The AF 50 size model with the female average spinal alignment exhibited spine straightening from upper thoracic vertebra level and showed larger intervertebral angular displacements in the cervical spine than the one with the male average spinal alignment.

Conclusions: The cervical spine alignment is continuous with the thoracic spine, and a trend of the relationship between cervical spine and thoracic spinal alignment was shown in this study. Simulation results suggested that variations in thoracic spinal alignment had a potential impact on cervical spine motion as well as cervical spinal alignment in rear end impact condition.     

Short and fast vs long and slow: age changes courtship in male orb-web spiders (<Emphasis Type="Italic">Argiope keyserlingi</Emphasis>)

Male reproductive performance can vary with condition, age and future reproductive opportunities. Web-building spiders are ideal models to examine the effects of senescence on fitness-related behaviours due to strong selection on male courtship to reduce pre-copulatory sexual cannibalism. Argiope keyserlingi spiders generate courtship vibrations, or ‘shudders’, that reduce female aggression. We found that male A. keyserlingi courtship slowed with chronological age. Older males took longer to travel across the courtship thread, and overall number of shudders increased. Males retained some ability to modulate courtship quality (shudder duration and number of rocks within each shudder) in response to female quality. A change in courtship performance over time, despite strong selection for repeatability, indicates that ageing in male A. keyserlingi may have direct impacts on reproductive performance.     

Mate choice,fecundity and sexual dimorphism in two pipefish species (Syngnathidae)

Summary In order to understand the causes of sexual dimorphism, mate choice and size-related fecundity were studied in two pipefish species, Syngnathus typhle and Nerophis ophidion. Sexual dimorphism is more pronounced in N. ophidion; females are larger, have sexual colourings, and are more active during courtship. In S. typhle the sexes are alike in all these respects. Males brood their offspring in both species. In N. ophidion fecundity was positively correlated with both body size and the amount of sexual colouring in females. In males no correlation between body size and fecundity, or between body size and embryo size existed. Predictably, in mate choice experiments with equal-sized females, males chose females with more extensive sexual colourings. We explain sexual dimorphism in this species as a consequence of both natural selection (fecundity increases with size in females but not in males) and sexual selection (males prefer larger females). We argue that sexual size dimorphism did not evolve by selection minimizing overlap in food niches between the sexes, because food production is high in the Zostera beds where the fishes live, and no size dimorphism was found in the sympatrically occurring S. typhle. Furthermore, in N. ophidion dimorphism is not greater in a particular mouth character than in overall body size. In S. typhle egg size and the average number of eggs transferred per spawning were positively correlated with female body size. Apparently more energy per offspring was provided by larger males than by smaller males, and larger males also carried more offspring. As predicted, large mates were preferred by both sexes in mate choice experiments. This is explicable in terms of both natural selection (fecundity increases with size in both sexes) and sexual selection (both sexes prefer large mates). As a consequence of selection acting in the same direction in both sexes, sexual dimorphism is absent in S. typhle.     

High Spatial and Temporal Variability of Dry Deposition in a Coastal Region

A real meteorological situation characterized by strong spatial and temporal variability of the meteorological fields in a coastal region of eastern Denmark is examined in view of the transport of a passive tracer and dry deposition. Model simulations using a full mesoscale NWP model (COAMPS^TM) at different horizontal resolutions are performed. A realistic simulation showed that the differences in the amount of dry deposited matter can reach one order of magnitude and larger, during the period of one afternoon, depending on the model horizontal resolution. In addition, the results of an idealized experiment with straight coastline indicate that the horizontal model resolution alone is responsible for most of the differences. This study confirms the importance of high spatial and temporal resolution modelling for environmental applications.