Reproducing or dispersing? Using trait based habitat templet models to analyse Orthoptera response to flooding and land use

Habitat templet theory predicts that habitat provides the templet on which evolution shapes species’ multiple traits and thus their characteristic life-history strategies. By analysing entire trait communities (multiple species and traits) in this framework we can enhance our understanding of how species composition changes as environmental constraints vary across the landscape. Here, we study multiple traits of floodplain Orthoptera communities under the influence of two different sources of disturbance, land use and seasonal flooding.The application of two recently developed statistical techniques - qualitative RLQ analysis and subsequent fourth-corner permutation tests - revealed two different life history strategies in Orthoptera as a response to ecological disturbances, resulting from land use management and seasonal flooding. Orthoptera species seem to have developed two complementary strategies: (i) the high active dispersal-low reproduction strategy in intensive land use situations and (ii) the high passive dispersal-high reproduction strategy in areas with high flood disturbance. Disturbance gradients act as trait filters allowing only particular trait combinations i.e. species with particular preadaptations to survive, whereas others go regionally extinct. Reproduction and dispersal capacity seem to be inversely associated with the disturbance gradients. Ovariole number, taken as the measure for reproduction, showed significant phylogenetic signal, which could potentially confound this relationship. Nonetheless, RLQ analyses coupled with fourth-corner permutation tests proved a powerful tool to reveal and disentangle different evolutionary strategies.     

Fatty acid trophic markers elucidate resource partitioning within the demersal fish community of South Georgia and Shag Rocks (Southern Ocean)

Fatty acid analysis was used to study the trophic ecology of 10 demersal fish species in the South Georgia region. Principal component analysis grouped the species into three general clusters, revealing resource partitioning between species. Two groups were characterised by large proportions of either monounsaturated or polyunsaturated fatty acids, separating species according to their predominant feeding habitat. The third group showed fatty acid signatures overlapping with either or both of the previous two groups, suggesting a more opportunistic feeding behaviour for these species. Intraspecific comparisons furthermore revealed dietary variability with size, year and geographical location in several species. Mackerel icefish (Champsocephalus gunnari) in particular showed inter-annual differences in muscle lipid concentrations closely linked to prey availability with low lipid contents found in years of low krill (Euphausia superba) abundance. Despite the intraspecific differences the majority of species could be easily distinguished from each other, which indicates the utility of this method in the dietary analysis of higher predators.     

Using fatty acid analysis to elucidate the feeding habits of Southern Ocean mesopelagic fish

Fatty acid biomarkers were used to investigate the feeding ecology of 17 mesopelagic fish species occurring in the Southern Ocean. Fatty acid signatures of species where little or no dietary information exists were compared to fatty acid signatures of species of known diets in order to elucidate their trophic position. Principal component analysis grouped species of known diets into two clusters with amphipods and copepods comprising the main prey species, respectively. Although the majority of species of unknown diet were grouped with either of these feeding guilds, a third cluster comprising only Gymnoscopelus bolini was identified suggesting a significantly different diet for this species. Electrona antarctica also exhibited significant changes in fatty acid signatures with size. Furthermore, discriminant analysis of the four most abundant species classified species with a 90% success rate thus validating the usefulness of fatty acid signatures when trying to resolve the trophic position of species where no or little dietary information exists.     

The presence of females modulates the expression of a carotenoid-based sexual signal

Several environmental factors have been shown to shape the pattern of investment of carotenoids into the expression of sexual signals. Surprisingly, the impact of the social environment has been neglected. If a carotenoid-based sexual trait is used by females to choose a mate or by males to assess the quality of potential competitors for mates, males, in the presence of females, should upregulate expression of the trait. We tested this hypothesis in male zebra finches that were housed either with females or in a male-only social environment. Additionally, to investigate whether the social modulation of the expression of a sexual trait depends on the physiological need of carotenoids, we challenged half of the males with Escherichia coli lipopolysaccharide (LPS). We found that the social environment modulated the expression of bill color, with males kept in the presence of females harboring a redder bill at the end of the 3 weeks that the experiment lasted. Males injected with LPS showed duller bill color regardless of the presence of females, and social interactions with females result in upregulated bill color similarly for phosphate-buffered saline (PBS) and LPS males. Thus, social environment and immune activation had an additive effect on the expression of bill color. The effect of social environment on plasma carotenoids was less clear. Indeed, a first replicate of the entire experiment showed that both immune challenge and social context affected bill color, with a negative effect of immune challenge and a positive effect of the presence of females on circulating carotenoids. However, a second replicate of the experiment showed only a negative effect of the immune challenge. These results, therefore, suggest that the social environment can affect the expression of carotenoid-based sexual traits under both benign and carotenoid-demanding conditions. Whatever the signaling function of bill color (female mate choice or male–male competition for mates), the observed flexibility may be adaptive because the expression of the signal can be modulated depending on the expected rewards or costs associated with the presence or absence of females. Nevertheless, the mechanisms underlying such an effect are still unknown.     

Teil II: Analytik von Toxaphenrückst?nden (UWSF 2/1998)

Zusammenfassung  Die Rückstandsanalytik des Insektizides Toxaphen galt früher als problematisch wegen der gro?en Anzahl an Komponenten mit ?hnlicher Struktur und unterschiedlichem Chlorgehalt. Erschwerend kam hinzu, da? die Zusamensetzung von Toxaphenrückst?nden in Umweltproben sich von der des technischen Standards signifikant unterscheidet. Deshalb war die Quantifizierung einzelner Komponenten früher nicht m?glich. Seit jedoch eine ganze Reihe von Toxaphenkomponenten in ausreichenden Mengen isoliert wurden, von denen einige für Umweltproben repr?sentativ sind, besteht die M?glichkeit, Toxaphenrückst?nde in Umweltkompartimenten zuverl?ssig zu bestimmen. In der letzten Zeit konzentriert sich die Entwicklung vor allem auf die Trennung der chiralen Bestandteile des Gemisches, um anhand der Zusammensetzung der Rückst?nde Verteilungswege und Abbaumechanismen besser identifizieren zu k?nnen.

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Residue analysis of toxaphene has been difficult because of the complexicity of the technical mixture consisting of a high number of compounds with very similar structure and differing chloro content. Furthermore, the composition of toxaphene in environmental samples varies widely and is normally not like that of the technical mixture. Therefore, quantification of single components in environmental samples was impossible. After the isolation and identification of a great number of components during the last decade, enough standards are available for reliable quantification of toxaphene in all environmental compartments. Recently, most research has been done on the separation of chiral components of toxaphene with a view to identify degradation mechanisms and distribution pathways.

     

Long‐Term High‐Resolution Radar Rainfall Fields for Urban Hydrology

Accurate records of high‐resolution rainfall fields are essential in urban hydrology, and are lacking in many areas. We develop a high‐resolution (15 min, 1 km²) radar rainfall data set for Charlotte, North Carolina during the 2001‐2010 period using the Hydro‐NEXRAD system with radar reflectivity from the National Weather Service Weather Surveillance Radar 1988 Doppler weather radar located in Greer, South Carolina. A dense network of 71 rain gages is used for estimating and correcting radar rainfall biases. Radar rainfall estimates with daily mean field bias (MFB) correction accurately capture the spatial and temporal structure of extreme rainfall, but bias correction at finer timescales can improve cold‐season and tropical cyclone rainfall estimates. Approximately 25 rain gages are sufficient to estimate daily MFB over an area of at least 2,500 km², suggesting that robust bias correction is feasible in many urban areas. Conditional (rain‐rate dependent) bias can be removed, but at the expense of other performance criteria such as mean square error. Hydro‐NEXRAD radar rainfall estimates are also compared with the coarser resolution (hourly, 16 km²) Stage IV operational rainfall product. Stage IV is adequate for flood water balance studies but is insufficient for applications such as urban flood modeling, in which the temporal and spatial scales of relevant hydrologic processes are short. We recommend the increased use of high‐resolution radar rainfall fields in urban hydrology.     

Do the size and age of mating plugs alter their efficacy in protecting paternity?

An obvious means to secure paternity is the production of a mating plug that blocks the female genital opening after mating. Although the mechanical efficacy and persistence of plugs on/in the female genital openings are key traits that determine the degree of paternity protection, these factors have hardly been explored. We therefore investigated the influence of the size of the amorphous plug material (experimentally terminated mating duration as a proxy) and age of the mating plug (time interval between copulations with two successive males) on the efficacy of the plug by analysing the mating success of subsequent males in the dwarf spider Oedothorax retusus (Linyphiidae: Erigoninae). Overall, subsequent males attempted to mate in 82 % of trials but only 32.5 % of these resulted in copulation, demonstrating that the plugs are effective safeguards against remating. Remating probability was significantly higher after previous short copulations (~small plug size) compared to long copulations (~large plug size). In the small plug group, fresh plugs (short remating intervals) were significantly less effective compared to older plugs. In the large plug group, remating probability was similarly low over all remating intervals. The observed copulations, however, do not necessarily result in sperm transfer, since sperm masses were found on the plugged female genital area. Our study on O. retusus shows that mating plugs are a powerful mechanical safeguard whose efficacy varies with plug size and age. We discuss these findings in the light of theoretical considerations on the evolution of effective mating plugs.     

When the going gets tough: Employee reactions to large-scale organizational change and the role of employee Machiavellianism

Large-scale, long-term change initiatives take time to unfold, which can be a source of uncertainty and strain. Investigating the initial 19 months of a large-scale change, we argue that during these stages, employees' change-related beliefs become more negative over time, which negatively affects their work engagement and, ultimately, increases their turnover intentions. Furthermore, we investigate the impact of a trait, Machiavellianism, on change reactions and propose that employees high in Machiavellianism react more negatively during change processes as they are especially susceptible to uncertainty and stress. We test our (cross-level) moderated mediation model in a three-wave longitudinal study among employees undergoing a large-scale change (T1: n = 1,602; T2: n = 1,113; T3: n = 759). We find that employees' beliefs about the impact and value of the change are indeed negatively related to change duration and that decreases in these perceptions come with a decline in engagement and increases in turnover intentions. Moreover, employees high in Machiavellianism react more strongly to a deterioration in change-related beliefs, showing stronger reductions in engagement and stronger increases in turnover intentions than employees low in Machiavellianism. Our study offers explanations for the negative effects of large-scale changes including an explanatory factor for disparate employee reactions to change over time.     

Isolation and structure elucidation of azoricasterol,a new sterol of the deepwater sponge<Emphasis Type="Italic"> Macandrewia azorica</Emphasis>

Chemical investigation of the deepwater sponge Macandrewia azorica, collected from the flanks of the Gettysburg and Ormonde Sea Mount, North Atlantic, from a depth of 600 m, has led to the isolation of a new sterol with an unusual side chain (1), along with S-methylergothioneine (2). The structures of compounds 1 and 2 were established by employing spectroscopic techniques (NMR, MS, UV, IR and polarimetry). This is the first report of metabolites of a sponge belonging to the genus Macandrewia.     

Sperm allocation in relation to male traits, female size, and copulation behaviour in freshwater crayfish species

Sperm competition is a well-recognised agent in the evolution of sperm and ejaculate structure, as well as variation in female quality. Models of the evolution of ejaculate expenditure predict that male body condition, female fecundity and the risk and intensity of sperm competition may be the ultimate factors shaping optimal ejaculate size. We investigated sperm allocation in Austropotamobius italicus, a freshwater crayfish exhibiting a coercive mating system and external fertilisation, in relation to male and female traits and copulation behaviour under laboratory conditions. We found that mating males were sensitive to female size and produced larger ejaculates when mating with larger females, which were more fecund in terms of number of eggs produced. We found no evidence for female egg production being sperm-limited, as the number of eggs was not dependent on male sperm expenditure. Copulation duration and number of ejaculations reliably predicted the amount of sperm transferred, and both these behavioural measures positively covaried with female body size. These results indicate that male freshwater crayfish can modulate their sperm expenditure in accordance with cues that indicate female fecundity. In addition, a novel finding that emerged from this study is the decrease in sperm expenditure with male body size, which may either suggest that large, old male crayfish are better able than small males to economise sperm at a given mating to perform multiple matings during a reproductive season, or that they experience senescence of their reproductive performance.