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© 2017 The Authors Reproductive isolation caused by divergent natural selection arising from differences between ecological environments or ecological interactions represents a major mechanism contributing to speciation, but its relative importance is poorly known. In this study, controlled reciprocal crossings and seed germination experiments were combined with genetic and morphometric analyses to test the hypothesis that previously described differences in mycorrhizal communities between forest and dune ecotypes of Epipactis helleborine were sufficiently strong to create complete reproductive isolation between the two ecotypes. Molecular analyses using 770 SNP markers showed that the two ecotypes were genetically distinct and that populations of the dune ecotype were genetically impoverished compared to populations of the forest ecotype. Morphologically, the two ecotypes were also significantly different, with plants of the dune ecotype generally being smaller than plants of the forest ecotype. The results further showed that immigrant seeds had a significantly lower probability of protocorm formation than native seeds, indicating strong immigrant inviability. Although both ecotypes were able to cross easily and to produce a large number of viable seeds, hybrid seeds showed significantly lower protocorm formation than pure seeds, further contributing to reproductive isolation. Overall, these results indicate that interfertile populations of a widespread orchid adapting to contrasting environments diverge as a consequence of concurrent selection acting against immigrants and hybrids and suggest that mycorrhizal fungi can play a role in the early stages of plant speciation. ispartof: Oikos vol:127 issue:1 pages:73-84 status: published

An increasing number of regulatory tools aiming to impose preventive and control actions against invasive species are currently being developed in Europe. Both species prioritization and the choice of best preventive and potential control actions to reduce the risk require robust and transparent risk assessment. Two different generic tools, available from http://ias.biodiversity.be, have recently been developed in Belgium to help decision makers reaching these goals, i.e. a quick screening prioritization process (Harmonia+) and a detailed risk assessment scheme. Both tools may be applied to any non-native organism irrespective its taxonomic affiliation and encompass an evaluation of the probability of organism entry, establishment, spread, and of the potential and magnitude of environmental, economic and social consequences including plant, animal and human health. Harmonia+ is a quick screening tool that may be used for different purposes (D’hondt et al. 2014): (i) the elaboration of priority lists of invasive species that are established or could potentially establish in an area, (ii) the fulfillment of rapid assessment to help conservation managers to prioritize actions when a new non-native organism is found in the wild and (iii) the identification of non-native species with the highest priority for in-depth and time consuming risk analyses and (iv) the scoring of probability and magnitude of the different elements included in those risk analyses.The detailed scheme for invasive species risk analysis is based on the recommendations of the international standards for pest risk analysis for organisms of quarantine concern produced by the Secretariat of the International Plant Protection Convention. It follows a process defined by two main stages, i.e. the risk assessment stage itself and the risk management stage, which involves identifying options for reducing the identified risks. This detailed analysis is especially valuable to know whether trade restrictions could be considered as adequate and efficient to reduce the risk.The output of the risk assessments based on these new tools will be presented and discussed for five emerging non-native species in Belgium (water primrose, red swamp crayfish, American bullfrog, sacred ibis and raccoon dog). Different recommendations and priorities for decision making will be provided for the different species based on the outcome of these analyses. Potential uses for the selection of species of EU concern in the framework of the new EC proposal of Regulation on the prevention and management of the introduction and spread of IAS in Europe will also be discussed.

Rapid detection of potentially harmful invasive alien species (IAS) is essential to avoid future invasions and management costs. Until recently, the Flemish region (Flanders, Northern Belgium) - and by extension Belgium - had no dedicated portal for reporting observations of such species, despite the high political priority and ongoing current (inter) national initiatives. In 2011, the Agency for Nature and Forest and the Institute for Nature and Forest Research initiated a pilot. For some notorious IAS, an early warning system was launched through the widely used online recording platform www.waarnemingen.be. The system is primarily targeted towards naturalist observers. This was done in cooperation with all Belgian regions and the major non-governmental organisations in the field of nature conservation. The system allows for reporting sightings, consulting fact sheets and setting up user-driven automated e-mail alerts. The aim of the pilot phase (March-November 2012) was to examine how the system could work (which species are picked up, potential reporting bias, data quality). Apart from testing the reporting tool as an early warning system, the project had several spin-offs. In the longer run, we aimed at mobilizing volunteers for monitoring IAS. We also wanted to provide information and raise awareness amongst field workers and the public. Eventually, we hope to streamline the process from reporting to management intervention. The ultimate goal is to have an early warning system for IAS in Flanders (northern Belgium) that connects with federal initiatives and anticipates developments of a trans-European system. The current system is already being used for various rapid response projects in Flanders, including control of invasive aquatic plants such as floating pennywort Hydrocotyle ranunculoides, water primrose Ludwigia grandiflora, Parrot’s feather Myriophyllum aquaticum, ruddy duck Oxyura jamaicensis, Pallas’ squirrel Callosciurus erythreaus, quarantine insects, American bullfrog Lithobates catesbeianus, giant hogweed Heracleum mantegazzianum and Chinese muntjac Muntiacus reevesi.

Since the 1980s, the European eel Anguilla anguilla stock is in steep decline. Lipid reserves are essential to cover energetic requirements for silver eel migration and reproduction. Two large and independent data sets from Belgium and The Netherlands show an average one-third decrease in fat contents of yellow eels over the past 15 years. Also Le Cren’s relative condition factor decreased. On the basis of the somatic energy reserves, reproductive potential of eels from various latitudes over Europe was estimated, assuming fat levels in yellow eel are indicative of those in silver eels. Only large individuals, females as well as males, with high lipid content seem to be able to contribute to the spawning stock. The decrease in fat content in yellow eels may be a key element in the stock decline and raises serious concerns about the chances of the stock to recover.