96 research outputs found
Landscape genetics: applications to the agricultural habitat
No full textThis thesis describes the work I have done during my Ph.D. studies at the Department of Bioscience, Aarhus University, under the supervision of Volker Loeschcke and Liselotte Wesley Andersen. This project is part of a larger project (REFUGIA project) aiming at understanding the effect of pesticide use and agricultural intensity in Denmark on a variety of species using genetic, ecological and simulation tools. The main aim of my part of this project was the investigation of the effects of pesticide use and agricultural intensity on wild animal species in the agricultural landscape, with particular focus on testing the hypothesis that organic fields act as genetic reservoirs for the re-colonization of organic fields
Harbour porpoises (<i>Phocoena phocoena</i>) in the North Atlantic: Distribution and genetic population structure
No full textThe known geographical distribution (based on ship surveys, aerial surveys, incidental sightings, stranding and bycatch data) and the population genetic structure obtained from mitochondria DNA and nuclear DNA (isozymes and microsatellites) data analyses of the harbour porpoise in the North Atlantic have recently been reviewed and revised by the International Whaling Commission. The present review builds on these documents by integrating more recent genetic and distributional studies. Studies of the genetic structure of harbour porpoise populations tend to be concentrated in areas where samples are available which coincide with areas where incidental or directed catches or stranding take place. Nevertheless, recently, several genetic studies on the population structure have been able to reveal a more comprehensive picture of the harbour porpoise population structure in the Northwest and Northeast Atlantic, although not all areas have been subjected to analyses
Effects of Land Management Strategies on the Dispersal Pattern of a Beneficial Arthropod
No full textSeveral arthropods are known to be highly beneficial to agricultural production. Consequently it is of great relevance to study the importance of land management and land composition for the conservation of beneficial aphid-predator arthropod species in agricultural areas. Therefore our study focusing on the beneficial arthropod Bembidion lampros had two main purposes: I) identifying the physical barriers to the species’ dispersal in the agricultural landscape, and II) assessing the effect of different land management strategies (i.e. use of pesticides and intensiveness) on the dispersal patterns. The study was conducted using genetic analysis (microsatellite markers) applied to samples from two agricultural areas (in Denmark) with different agricultural intensity. Land management effects on dispersal patterns were investigated with particular focus on: physical barriers, use of pesticide and intensity of cultivation. The results showed that Bembidion lampros disperse preferably through hedges rather than fields, which act as physical barriers to gene flow. Moreover the results support the hypothesis that organic fields act as reservoirs for the re-colonization of conventional fields, but only when cultivation intensity is low. These results show the importance of non-cultivated areas and of low intensity organic managed areas within the agricultural landscape as corridors for dispersal (also for a species typically found within fields). Hence, the hypothesis that pesticide use cannot be used as the sole predictor of agriculture’s effect on wild species is supported as land structure and agricultural intensity can be just as important
Genetic indications of translocated and stocked grey partridges (Perdix perdix): Does the indigenous Danish grey partridge (Perdix perdix) still exist?
No full textNon-local population stocking can have adverse genetic effects through loss of genetic diversity and introgressive hybridisation in wild populations exploited by man. The grey partridge (Perdix perdix) has been an important European game species for centuries, widely subject to translocation and stocking. After ca 80 years releasing reared grey partridges into Danish wild partridge areas, this study investigated whether an indigenous Danish grey partridge still existed. We predicted that (i) an indigenous Danish partridge would belong to the western European clade (W1) and (ii) would be more closely related to the historical, indigenous grey partridges than to farm bred partridges. These predictions were tested analysing the variation in the mitochondrial control region (CR1) and
microsatellite markers in museum samples representing the ancestral indigenous Danish grey partridge, contemporary (recent) wild grey partridges and farmed grey partridges from the five largest farms in Denmark. Phylogeography- and population structure analyses showed traces of the
indigenous Danish grey partridges amongst recent wild partridges in certain areas and significant genetic differences between reared, farmed partridges and historical- and recent partridges. The results also showed that the indigenous Danish grey partridges belonged to the western European clade (W1 haplotype). A foreign stocking effect was detected on the remote island of Bornholm, where the current population originated from introduced Danish and Bohemian grey partridges. The loss of haplotype diversity over time in certain geographical areas probably results from serious declines in wild Danish grey partridge numbers in recent decades. This combined with the 2
observation that hybridisation between released stocked and wild partridges can occur may complicate recovery of partridge populations
Genetic evidence for migration of males between schools of the long finned pilot whale, Globicephala melas.
No full text
Gene flow values.
No full text<p>The log<sub>10</sub> of the gene flow values are shown on a heatmap for both areas. The populations of origin are shown on the vertical axis.</p
Landscape population genetics and the role of organic farming
No full textThis project aims at understanding the effect of different farming systems on the genetic diversity of common agricultural species. It is well known that organic farming generally improves the biodiversity and abundance of species in the agricultural landscape (Hole et al., 2005). A reduction in species number and abundance has been shown as a result of the intensification of farming suggesting a relationship between farming intensity and species abundance (e.g. Stoate et al., 2001). Anyway, none of the studies that investigated the effects of pesticides presence and farming intensity has investigated the effect
on the genetic diversity and isolation of the populations.
It has been shown that, despite the theoretical expectations, also very abundant species like Abax parallelepipedus can be divided in isolated and genetically distinct populations within very few years in response to human activity (e.g. construction of streets: Keller et al., 2004). Therefore, we chose two common agricultural species (field vole, Microtus agrestis, and a non-pest ground beetle, Bembidion lampros) belonging to different taxa and with different dispersal abilities, to
investigate the effect of pesticide use and intensiveness of farming on their genetic structuring and diversity
Following the plough: genetic evidence of population expansions of Perdix perdix during early transition and late intensification of agriculture in Denmark and Western Europe
No full textThe analysis of the haplotype diversity represented by the sequences of the control region in the mitochondria in Danish partridges identified signals of population expansion as was the case in other European grey partridges. Based on this genetic analysis of the Danish recent and historical grey partridges together with previously analysed grey partridges from Germany, Poland, Hungary, France and Italy, it is hypothesized that the timing of the Grey partridge population expansions up through western Europe and the following dispersal of the grey partridge from the last LGM refugium in the French Pyrenees might be explained by the origin and spread of agriculture through Europe i.e. “following the plough”
Results of gene flow analyses (Bjerringbro).
No full text<p>For each of the 9 runs performed with BIMr the most significant factor(s), their posterior probability and the alpha value for that factor(s) are reported. The results from the best run (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066208#s2" target="_blank">Materials and methods</a> for details) are shown in italics.</p
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