An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules,metabolism, fate,and transport

Environmental Science and Pollution Research - With the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been...     

Biotechnological intervention for societal development (BioSangam 2020)

Environmental Science and Pollution Research -     

Intraspecific competition affects population size and resource allocation in an ant dispersing by colony fission

Intraspecific competition is a pervasive phenomenon with important ecological and evolutionary consequences, yet its effect in natural populations remains controversial. Although numerous studies suggest that in many cases populations across all organisms are limited by density-dependent processes, this conclusion often relies on correlative data. Here, using an experimental approach, we examined the effect of intraspecific competition on population regulation of the ant Aphaenogaster senilis. In this species females are philopatric while males disperse by flying over relatively long distances. All colonies were removed from 15 experimental plots, except for one focal colony in each plot, while 15 other plots remained unmanipulated. After the first reproductive season, nest density in the experimental plots returned to a level nonsignificantly different from that in the control plots, which was not expected if the populations were indeed regulated by density-independent phenomena. In both the control plots and the experimental plots colonies remained overdispersed throughout the experiment, suggesting colony mutual exclusion. Nests outside the plots rapidly extended their foraging span, but we did not detect any significant inward migration into the experimental plots. Experimental reduction in density did not significantly affect the focal colonies' biomass, measured just before the first reproductive season. However, the ratio of males to workers-pupae biomasses was smaller in experimental plots, suggesting that colonies there had redirected part of the resources normally allocated to male production to the production instead of new workers. Microsatellite analysis indicated that, after the reproductive season, many colonies in the experimental plots were headed by a young queen that was the mother of the brood but not of the old workers, indicating that reduction in colony density stimulated fission of the remaining colonies. Finally, at the end of the experiment, 14 months after experimental reduction in density, colonies that derived from fission were smaller in the experimental than in the control plots, suggesting that the former had undergone fission at a smaller size than in control plots, which presumably allowed them to colonize the emptied areas. We conclude that colonies adjust resource allocation and colony fission to the degree of intraspecific competition.     

The trait contribution to wood decomposition rates of 15 Neotropical tree species

The decomposition of dead wood is a critical uncertainty in models of the global carbon cycle. Despite this, relatively few studies have focused on dead wood decomposition, with a strong bias to higher latitudes. Especially the effect of interspecific variation in species traits on differences in wood decomposition rates remains unknown. In order to fill these gaps, we applied a novel method to study long-term wood decomposition of 15 tree species in a Bolivian semi-evergreen tropical moist forest. We hypothesized that interspecific differences in species traits are important drivers of variation in wood decomposition rates. Wood decomposition rates (fractional mass loss) varied between 0.01 and 0.31 yr(-1). We measured 10 different chemical, anatomical, and morphological traits for all species. The species' average traits were useful predictors of wood decomposition rates, particularly the average diameter (dbh) of the tree species (R2 = 0.41). Lignin concentration further increased the proportion of explained inter-specific variation in wood decomposition (both negative relations, cumulative R2 = 0.55), although it did not significantly explain variation in wood decomposition rates if considered alone. When dbh values of the actual dead trees sampled for decomposition rate determination were used as a predictor variable, the final model (including dead tree dbh and lignin concentration) explained even more variation in wood decomposition rates (R2 = 0.71), underlining the importance of dbh in wood decomposition. Other traits, including wood density, wood anatomical traits, macronutrient concentrations, and the amount of phenolic extractives could not significantly explain the variation in wood decomposition rates. The surprising results of this multi-species study, in which for the first time a large set of traits is explicitly linked to wood decomposition rates, merits further testing in other forest ecosystems.     

Nest desertion is not predicted by cuckoldry in the Eurasian penduline tit

Engagement in extra-pair copulations is an example of the abundant conflicting interests between males and females over reproduction. Potential benefits for females and the risk of cuckoldry for males are expected to have important implications on the evolution of parental care. However, whether parents adjust parental care in response to parentage remains unclear. In Eurasian penduline tits Remiz pendulinus, which are small polygamous songbirds, parental care is carried out either by the male or by the female. In addition, one third of clutches is deserted by both male and female. Desertion takes place during the egg-laying phase. Using genotypes of nine microsatellite loci of 443 offspring and 211 adults, we test whether extra-pair paternity predicts parental care. We expect males to be more likely to desert cuckolded broods, whereas we expect females, if they obtain benefits from having multiple sires, to be more likely to care for broods with multiple paternity. Our results suggest that parental care is not adjusted to parentage on an ecological timescale. Furthermore, we found that male attractiveness does not predict cuckoldry, and we found no evidence for indirect benefits for females (i.e., increased growth rates or heterozygosity of extra-pair offspring). We argue that male Eurasian penduline tits may not be able to assess the risk of cuckoldry; thus, a direct association with parental care is unlikely to evolve. However, timing of desertion (i.e., when to desert during the egg-laying phase) may be influenced by the risk of cuckoldry. Future work applying extensive gene sequencing and quantitative genetics is likely to further our understanding of how selection may influence the association between parentage and parental care.     

Comparison and ranking of different modelling techniques for prediction of site index in Mediterranean mountain forests

Forestry science has a long tradition of studying the relationship between stand productivity and abiotic and biotic site characteristics, such as climate, topography, soil and vegetation. Many of the early site quality modelling studies related site index to environmental variables using basic statistical methods such as linear regression. Because most ecological variables show a typical non-linear course and a non-constant variance distribution, a large fraction of the variation remained unexplained by these linear models. More recently, the development of more advanced non-parametric and machine learning methods provided opportunities to overcome these limitations. Nevertheless, these methods also have drawbacks. Due to their increasing complexity they are not only more difficult to implement and interpret, but also more vulnerable to overfitting. Especially in a context of regionalisation, this may prove to be problematic. Although many non-parametric and machine learning methods are increasingly used in applications related to forest site quality assessment, their predictive performance has only been assessed for a limited number of methods and ecosystems.In this study, five different modelling techniques are compared and evaluated, i.e. multiple linear regression (MLR), classification and regression trees (CART), boosted regression trees (BRT), generalized additive models (GAM), and artificial neural networks (ANN). Each method is used to model site index of homogeneous stands of three important tree species of the Taurus Mountains (Turkey): Pinus brutia, Pinus nigra and Cedrus libani. Site index is related to soil, vegetation and topographical variables, which are available for 167 sample plots covering all important environmental gradients in the research area. The five techniques are compared in a multi-criteria decision analysis in which different model performance measures, ecological interpretability and user-friendliness are considered as criteria.When combining these criteria, in most cases GAM is found to outperform all other techniques for modelling site index for the three species. BRT is a good alternative in case the ecological interpretability of the technique is of higher importance. When user-friendliness is more important MLR and CART are the preferred alternatives. Despite its good predictive performance, ANN is penalized for its complex, non-transparent models and big training effort.     

Spatio-temporal ranging behaviour and its relevance to foraging strategies in wide-ranging wolverines

Conservation of carnivores in an increasingly changing environment is greatly helped by understanding the decision-making processes underlying habitat patch choice. Foraging theory may give us insight into spatio-temporal search patterns and consequent foraging decisions that carnivores make in heterogeneous and fluctuating environments. Constraints placed on central-place foragers in particular are likely to influence both foraging decisions and related spatio-temporal movement patterns. We used discrete choice models to investigate the spatio-temporal ranging behaviour of GPS collared female wolverines (Gulo gulo) with dependent cubs in south-central Norway. Activity patterns, home range use and selection for elevation were analyzed in relation to spatial and temporal covariates (daily and seasonal) and related to different foraging behaviours. In spring, wolverines showed restricted movement patterns around rendezvous sites at high elevations by day, whereas during the night animals were active at lower elevations. Over the summer, this daily pattern in intensity of use diminished and their overall selectiveness for elevation decreased as cubs grow more mobile and independent. At the onset of autumn, wolverines showed intensive use of the profitable forest-alpine tundra ecotone. We argue that reproducing wolverines deployed a foraging strategy attuned to altering their movement patterns throughout the summer to address a continuous, but diminishing, trade-off between providing both food and shelter for their offspring. Incorporating spatially and temporally explicit activity patterns and home range use in discrete choice resource selection models thus enhances the understanding of the motives behind wolverine resource utilization in space and time. Such knowledge may provide guidance to managers designing regional-scale zoning, in order to facilitate carnivore recovery and to minimize conflicts with human activities.     

Nonlinear effects of food aggregation on interference competition in mallards

Previous studies of interference competition have shown an asymmetric effect on intake rate of foragers on clumped resources, with only subordinate individuals suffering. However, the food distributions in these studies were uniform or highly clumped, whereas in many field situations, food aggregation is intermediate. Here we investigated whether food distribution (i.e., uniform, slightly clumped, and highly clumped) affects the behavioral response of mallards foraging alone or competing with another. Although the amount of food was the same in all distributions, the mallards reached higher intake rates, visited fewer patches, and showed longer average feeding times in the highly clumped distribution. Competing mallards had lower intake rates on the slightly clumped than on the uniform or highly clumped food distributions. Subordinates generally visited more patches and had shorter feeding times per patch, but their intake rates were not significantly lower than those of dominants. Therefore, we propose that subordinates do not necessarily suffer from interference competition in terms of intake rate, but do suffer higher search costs. In addition, although dominants had significantly higher average feeding times on the best quality patches of the highly clumped food distribution, such an effect was not found in the slightly clumped distribution. These findings indicate that in environments where food is aggregated to a lesser extent, monopolization is not the best strategy for dominants. Our results suggest that interference experiments should use food distributions that resemble the natural situation animals are faced with in the field.     

Complementarity,impatience, and the resilience of natural-resource-dependent economies

We study how society's preferences affect the resilience of economies that depend on more than one type of natural resource. In particular, we analyze whether the degree of complementarity of natural resources in consumer preferences may give rise to multiple steady states and path dependence even when resources are managed optimally. We find that, for a given social discount rate, society tends to be less willing to buffer exogenous shocks if resource good are complements in consumption than if they are substitutes. The stronger the complementarity between the various types of natural resources, the less resilient the economy is, and even more so the higher is the social discount rate.     

Predator guild does not influence orangutan alarm call rates and combinations

Monkey alarm calls have shown that in the primate clade, combinatorial rules in acoustic communication are not exclusive to humans. A recent hypothesis suggests that the number of different call combinations in monkeys increases with increased number of predator species. However, the existence of combinatorial rules in great ape alarm calls remains largely unstudied, despite its obvious relevance to ideas about the evolution of human speech. In this paper, we examine the potential use of combinatorial rules in the alarm calls of the only Asian great ape: the orangutan. Alarm calls in orangutans are composed of syllables (with either one or two distinct elements), which in turn are organized into sequences. Tigers and clouded leopards are predators for Sumatran orangutans, but in Borneo, tigers are extinct. Thus, orangutans make a suitable great ape model to assess alarm call composition in relation to the size of the predator guild. We exposed orangutans on both islands to a tiger and control model. Response compositionality was analyzed at two levels (i.e., syllable and syllable sequences) between models and populations. Results were corroborated using information theory algorithms. We made specific, directed predictions for the variation expected if orangutans used combinatorial rules. None of these predictions were met, indicating that monkey alarm call combinatorial rules do not have direct homologues in orangutans. If these results are replicated in other great apes, this indicates that predation did not drive selection towards ever more combinatorial rules in the human lineage.