The relative importance of host-plant genetic diversity in structuring the associated herbivore community

Recent studies suggest that intraspecific genetic diversity in one species may leave a substantial imprint on the surrounding community and ecosystem. Here, we test the hypothesis that genetic diversity within host-plant patches translates into consistent and ecologically important changes in the associated herbivore community. More specifically, we use potted, grafted oak saplings to construct 41 patches of four saplings each, with one, two, or four tree genotypes represented among the host plants. These patches were divided among two common gardens. Focusing first at the level of individual trees, we assess how tree-specific genotypic identity, patch-level genetic diversity, garden-level environmental variation, and their interactions affect the structure of the herbivore community. At the level of host-plant patches, we analyze whether the joint responses of herbivore species to environmental variation and genetic diversity result in differences in species diversity among tree quartets. Strikingly, both species-specific abundances and species diversity varied substantially among host-tree genotypes, among common gardens, and among specific locations within individual gardens. In contrast, the genetic diversity of the patch left a detectable imprint on local abundances of only two herbivore taxa. In both cases, the effect of genetic diversity was inconsistent among gardens and among host-plant genotypes. While the insect community differed significantly among individual host-plant genotypes, there were no interactive effects of the number of different genotypes within the patch. Overall, additive effects of intraspecific genetic diversity of the host plant explained a similar or lower proportion (7-10%) of variation in herbivore species diversity than did variation among common gardens. Combined with the few previous studies published to date, our study suggests that the impact of host-plant genetic diversity on the herbivore community can range from none to nonadditive, is generally low, and reaches its most pronounced impact at small spatial scales. Overall, our findings strengthen the emerging view that the impacts of genetic diversity are system, scale, and context dependent. As the next step in community genetics, we should then start asking not only whether genetic diversity matters, but under what circumstances its imprint is accentuated.     

Active Biodegradable Film Based on Chitosan and Cenostigma Nordestinum' Extracts for Use in the Food Industry

Journal of Polymers and the Environment - Bioactive biodegradable films are emerging biomaterials in the food packaging field. This study aims to investigate the effect of different Cenostigma...     

Gene expression signatures in PCB-exposed Slovak children in relation to their environmental exposures and socio-physical characteristics

Environmental Science and Pollution Research - Our previous gene expression studies in a PCB-exposed cohort of young children in Slovakia revealed that early-life exposures to PCBs and other...     

Testing the Stochastic Dynamic Methodology (StDM) as a management tool in a shallow temperate estuary of south Europe (Mondego, Portugal)

A long-term monitoring program has been carried out since the early 1990s in the Mondego estuary, on Portugal's west coast, which is presently under heavy human pressure. In this shallow warm-temperate estuary, a significant macroalgal proliferation has been observed, which is a clear sign of nutrient enrichment. As a result of competition with algae, the extension of the seagrass meadows (mainly Zostera noltii) has been reduced. The present paper examined the applicability of a holistic Stochastic Dynamic Methodology (StDM) in predicting the tendencies of trophic key-components (macrophytes, macroalgae, benthic macroinvertebrate and wading birds) as a response to the changes in estuarine environmental conditions. The StDM is a sequential modelling process developed in order to predict the ecological status of changed ecosystems, from which management strategies can be designed. The data used in the dynamic model construction included true gradients of environmental changes and was sampled from January 1993 to September 1995 and from December 1998 to December 2005. The dynamic model developed was preceded by a conventional multivariate statistical procedure performed to discriminate the significant relationships between the selected ecological components. The model validation was based on independent data collected from January 1996 to January 1997 and from February 1999 to April 2000 for all the state variables considered. Overall, the simulation results are encouraging since they seem to demonstrate the StDM reliability in capturing the trophic dynamics of the studied estuary, by predicting the behavioural pattern for the most part of the components selected, with a focus on the Zostera noltii meadows recovery after the implementation of important management measures.     

Industrial production of recycled cement: energy consumption and carbon dioxide emission estimation

Environmental Science and Pollution Research - The urge to reduce greenhouse gas emissions, in particular carbon dioxide, is a global problem, not only in spatial terms but also in terms of the...     

Evaluating the ability of habitat suitability models to predict species presences

Models predicting species spatial distribution are increasingly applied to wildlife management issues, emphasising the need for reliable methods to evaluate the accuracy of their predictions. As many available datasets (e.g. museums, herbariums, atlas) do not provide reliable information about species absences, several presence-only based analyses have been developed. However, methods to evaluate the accuracy of their predictions are few and have never been validated. The aim of this paper is to compare existing and new presence-only evaluators to usual presence/absence measures.     

Keeping pace with forestry: Multi-scale conservation in a changing production forest matrix

The multi-scale approach to conserving forest biodiversity has been used in Sweden since the 1980s, a period defined by increased reserve area and conservation actions within production forests. However, two thousand forest-associated species remain on Sweden’s red-list, and Sweden’s 2020 goals for sustainable forests are not being met. We argue that ongoing changes in the production forest matrix require more consideration, and that multi-scale conservation must be adapted to, and integrated with, production forest development. To make this case, we summarize trends in habitat provision by Sweden’s protected and production forests, and the variety of ways silviculture can affect biodiversity. We discuss how different forestry trajectories affect the type and extent of conservation approaches needed to secure biodiversity, and suggest leverage points for aiding the adoption of diversified silviculture. Sweden’s long-term experience with multi-scale conservation and intensive forestry provides insights for other countries trying to conserve species within production landscapes.

     

Cephalopods and cetaceans as indicators of offshore bioavailability of cadmium off Central South Brazil Bight

Regarding Brazilian coast, industrial and urban developments are concentrated along Central South Brazil Bight. Samples from inshore and offshore species from the concerned area were analyzed, comprising 24 cetaceans (9 species) and 32 squids (2 species). Cadmium was determined by GFAAS and our results were in agreement with certified values (DOLT-2, NRCC). Mean cadmium concentration (in microg/g, wet weight) observed in the digestive gland of sexually mature Argentine short-finned squids (Illex argentinus) was 1002.9. To our knowledge this is the highest cadmium level ever reported for a cephalopod. Concerning cetaceans, our results include one of the highest renal cadmium concentrations described for striped dolphins (71.29 microg/g, wet weight). Anthropogenic action, upwelling and cannibalism of Argentine short-finned squid on the studied area are possible reasons for such remarkable cadmium concentrations.     

Evaluation of genotoxicity and toxicity of water and sediment samples from a Brazilian stream influenced by tannery industries

This paper reports results of genotoxicity and toxicity studies of water and sediment samples collected from the Estancia Velha stream of southern Brazil, a stream transporting both domestic sewage and effluents from regional factories working in the leather industry. Three sites were selected: in the stream headwaters (Site 1), located downstream of an urban area (Site 2), and near the basin outfall (Site 3). Results obtained with Allium cepa showed no evidence of chromosomal mutation, either in water or in sediment, during winter or summer seasons, but samples collected below Site 1 showed high toxicity. Physical and chemical analyses showed high concentrations of pollutants at these sites. Ecotoxicity tests with Daphnia magna and Ceriodaphnia dubia measured toxicity in water from Sites 2 and 3 in summer 2004. A toxic effect on Hyalella azteca was only found in sediment from Site 3 during winter 2003 and summer 2004. The results suggest that the synergy among different compounds in domestic and industrial sewage discharges can make it difficult to maintain system stability.