Developmental changes in the patterns of feeding in fourth- and fifth-instar Helicoverpa armigera caterpillars

Data are presented for developmental changes in feeding behaviour within and across the fourth and fifth stadium of Helicoverpa armigera (Lepidoptera, Noctuidae) caterpillars fed nutritionally homogeneous semi‐synthetic foods. We recorded the microstructure of feeding over continuous 12‐h periods on consecutive days throughout the two stadia, and in one experiment recorded continuously for 21 h. Larvae in the two stadia showed the same general pattern of macro‐events in feeding, including a similar duration of post‐ecdysis fast, which was usually broken by consumption of the exuviae, and then a sustained period in which discrete meals on the experimental food were taken regularly. There were, however, some distinct differences in the patterns of meal‐taking both between stadia and across different one‐third time segments within stadia. Considering between‐stadium differences, the proportion of time spent feeding differed significantly only in the last segment of the feeding period of the two stadia, with the value for the fourth‐instar larvae being substantially greater than for fifth‐instar larvae. As regards within stadium changes, the proportion of time feeding increased from the first to the second segment of both stadia. However, whereas the proportion of time feeding increased from the second to the final segment of the fourth stadium, it decreased across the same period in the fifth stadium. These patterns of changes in the proportion of time feeding within and between stadia, and their behavioural mechanisms (combination of meal durations and meal frequencies), can be explained only partially with reference to increasing food requirements with development. Three areas are identified where further study might help elucidate the reasons for the observed developmental changes in the microstructure of feeding: allometric constraint, the dynamic links between ingestion and post‐ingestive processing, and ecological factors such as predation.     

Analysis of the community structure of abyssal kinetoplastids revealed similar communities at larger spatial scales

Knowledge of the spatial scales of diversity is necessary to evaluate the mechanisms driving biodiversity and biogeography in the vast but poorly understood deep sea. The community structure of kinetoplastids, an important group of microbial eukaryotes belonging to the Euglenozoa, from all abyssal plains of the South Atlantic and two areas of the eastern Mediterranean was studied using partial small subunit ribosomal DNA gene clone libraries. A total of 1364 clones from 10 different regions were retrieved. The analysis revealed statistically not distinguishable communities from both the South-East Atlantic (Angola and Guinea Basin) and the South-West Atlantic (Angola and Brazil Basin) at spatial scales of 1000–3000 km, whereas all other communities were significantly differentiated from one another. It seems likely that multiple processes operate at the same time to shape communities of deep-sea kinetoplastids. Nevertheless, constant and homogenous environmental conditions over large spatial scales at abyssal depths, together with high dispersal capabilities of microbial eukaryotes, maintain best the results of statistically indistinguishable communities at larger spatial scales.     

Emergent and effective properties in ecology and evolution

Emergent properties are often discussed in arguments concerning relationships among different levels. However, the different definitions of emergent properties sometimes confuse the arguments about macro-level phenomena, since some authors regard emergent properties not only as observable global patterns but as properties that affect and cause change in ecological and evolutionary processes. Thus it is important to distinguish higher-level or larger-scale properties that can influence particular ecological and evolutionary processes from those that cannot. I call the former properties effective properties. I gave examples that show why the distinctions between effective and non-effective properties are important.

     

Comparison of growth,nutritional utilisation patterns,and niche overlap indices of toxigenic and atoxigenic Aspergillus flavus strains

The effects of temperatures (20–30 °C) and water activity (0.90–0.99 a_w) on the lag phase duration, mycelial growth, and nutritional utilisation patterns of two toxigenic (AFL1⁺ & AFL2⁺) and three atoxigenic (AFL1⁻, AFL2⁻, & AFL3⁻) Aspergillus flavus strains were evaluated in vitro. Both temperature and a_w and their interactions had a significant influence on the growth and nutritional utilisation patterns (p < 0.05). There were no significant differences between toxigenic and atoxigenic strains in terms of lag phase prior to growth and mycelial growth rates. Based on carbon source (CS) utilisation patterns, toxigenic and atoxigenic strains' niche size was greater at higher temperatures and in wetter conditions. Additionally, based on niche overlap indices (NOIs), regardless of temperature, when water was freely available, atoxigenic and toxigenic strains co-existed. However, under moisture stress, the nutritional competitiveness was variable. Temporal carbon utilisation sequences (TCUS) of toxigenic and atoxigenic strains were compared. At 0.99 a_w most CS sources were utilised by the strains and the time to detection (TTD) of each strain was shortest on monosaccharides at the same level of a_w. Conversely, under moisture stress the least number of CS was utilised. The current study has demonstrated that carbon utilisation patterns are equally important as are other determinants of competitiveness and that growth rate alone is not a key attribute which determines competitiveness.     

Cumulative bleaching undermines systemic resilience of the Great Barrier Reef

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Influences of temporal independence of data on modelling species distributions

Modelling species distributions has been widely used to understand present and future potential distributions of species, and can provide adaptation and mitigation information as references for conservation and management under climate change. However, various methods of data splitting to develop and validate functions of the models do not get enough attention, which may mislead the interpretation of predicted results. We used the Taiwanese endemic birds to test the influences of temporal independence of datasets on model performance and prediction. Training and testing data were considered to be independent if they were collected during different survey periods (1993–2004 and 2009–2010). The results indicated no significant differences of six model performance measures (AUC, kappa, TSS, accuracy, sensitivity, and specificity) among the combinations of training and testing datasets. Both species- and grid cell-based assessments differed significantly between predictions by the annual and pooled training data. We also found an average of 85.8% similarity for species presences and absences in different survey periods. The remaining dissimilarity was mostly caused by species observed in the late survey period but not in the early one. The method of data splitting, yielding training and testing data, is critical for resulting model species distributions. Even if similar model performance exists, different methods can lead to different species distributional maps. More attention needs to be given to this issue, especially when amplifying these models to project species distributions in a changing world.     

Freshwater marsh vegetation response to flooding patterns in the lower delta of the Parana river

Freshwater marshes are the only significant natural ecosystems remaining in the Buenos Aires province section of the Lower Delta of the Parana River (Argentina), occupying 80% of the total island area. The Lower Delta hydrology is dominated mainly by the Parana river and the De La Plata estuary; different temporal superpositions of floods and landscape configurations of the islands result in four distinct flooding patterns. We studied the response of freshwater marsh vegetation to the flooding patterns using principal component analysis and cluster analysis. The study area was gridded and 13 cells were selected representing the different flooding patterns. We found significant environmental heterogeneity in the region and a consequent response in the vegetation, expressed through successive species replacements, and variation in species richness and the number and type of dominant species. The environmental heterogeneity of the region is caused by hydrological variations, geomorphological changes in the islands from upstream to downstream areas of the delta, and patterns of human activity.