Several species of bats in northern Europe undertake seasonal migrations between their summer roosts and wintering areas. Doing so, they are known to cross open sea in some cases. Taking account of the increase of wind farms in the Belgian part of the North Sea and the entire North Sea, the lack of information on the spatio-temporal distribution of bats in Belgian waters and the results of some studies (onshore) demonstrating wind turbines can cause high mortalities in bats, a taxon in global decline, it is important to quantify the risk of offshore wind farms in the North Sea to threaten bat populations. To investigate bat distribution, we installed an automated acoustic recorder on the Belgian research vessel ‘Belgica’ to record bats while the vessel is at sea at night. The acoustic detector on the Belgica was operational during 93 nights in autumn 2014 and spring 2015, hence covering two full bat migration periods. In autumn 2014, 117 call sequences were registered in the BPNS, belonging to four different species. In spring 2015, only four sequences were registered, all during one night. The few recordings were all registered during only three nights. These results are not sufficient to solidly determine spatio-temporal patterns of bats in the BPNS, but allow drawing some preliminary conclusions on their frequency of occurrence and distribution at sea. In 2015 and 2016, a network of nine Batcorders is collecting data in the Dutch and Belgian part of the North Sea and along the coastline. This detector network will increase our knowledge about the impact of offshore wind farms on bats as it will increase the number of detections of bats at sea and will allow direct comparison between data collected at the different locations, without seasonal or meteorological bias. This will allow addressing the question if bats are attracted to or avoid offshore wind farms. This may then lead to appropriate management or mitigation measures.
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RBINS Staff Publications 2016
Background: This study aims to reconstruct the evolutionary history of African shrews referred to the Crocidura olivieri complex. We tested the respective role of forest retraction/expansion during the Pleistocene, rivers (allopatric models), ecological gradients (parapatric model) and anthropogenic factors in explaining the distribution and diversification within this species complex. We sequenced three mitochondrial and four nuclear markers from 565 specimens encompassing the known distribution of the complex, i.e. from Morocco to Egypt and south to Mozambique. We used Bayesian phylogenetic inference, genetic structure analyses and divergence time estimates to assess the phylogenetic relationships and evolutionary history of these animals. Results: The C. olivieri complex (currently composed of C. olivieri, C. fulvastra, C. viaria and C. goliath) can be segregated into eight principal geographical clades, most exhibiting parapatric distributions. A decrease in genetic diversity was observed between central and western African clades and a marked signal of population expansion was detected for a broadly distributed clade occurring across central and eastern Africa and portions of Egypt (clade IV). The main cladogenesis events occurred within the complex between 1.37 and 0.48 Ma. Crocidura olivieri sensu stricto appears polyphyletic and C. viaria and C. fulvastra were not found to be monophyletic. Conclusions: Climatic oscillations over the Pleistocene probably played a major role in shaping the genetic diversity within this species complex. Different factors can explain their diversification, including Pleistocene forest refuges, riverine barriers and differentiation along environmental gradients. The earliest postulated members of the complex originated in central/eastern Africa and the first radiations took place in rain forests of the Congo Basin. A dramatic shift in the ecological requirements in early members of the complex, in association with changing environments, took place sometime after 1.13 Ma. Some lineages then colonized a substantial portion of the African continent, including a variety of savannah and forest habitats. The low genetic divergence of certain populations, some in isolated localities, can be explained by their synanthropic habits. This study underlines the need to revise the taxonomy of the C. olivieri complex.
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