Hierarchical top-down control of biodiversity in agricultural landscapes across organisational levels and spatial scales

Biodiversity is one of the fundamental manifestations of life. Nevertheless, is has been increasingly threatened by anthropogenic activities. Land-use change is predicted to have the largest global impact on biodiversity by the year 2100. In European countries, land use is dominated by agriculture which shapes more than half of the land area. In the 20th century, industrialisation supported major changes in agricultural land use, which led to significant declines in biodiversity. These changes were driven by both the intensification of agricultural land management and a loss of area, connectivity and diversity of semi-natural habitats. Since multiple aspects of agrarian land-use change will affect not only species richness but all levels of biodiversity such as genes, individuals, populations, communities, landscapes and ecosystems in specific ways and act across different spatial scales, a detailed knowledge about the relative effects on particular dimensions of biodiversity is important for ecological theory and biodiversity research. The principal objective of this thesis is to explore the relative effects of scale and land-use changes on major organisational levels of biodiversity in European agricultural landscapes. Therefore, this thesis deals with three different aspects of biodiversity realised in the same landscapes: genetics, populations and communities. The first part deals with the spatial genetic structure of the land snail Cepaea nemoralis (L.) in a medium fragmented landscape at the local and landscape scale. The second part focuses on habitat modelling relating occurrence patterns in populations of the butterfly Pararge aegeria (L.) to environmental variables. The third part analyses two aspects of communities. Firstly, we related the similarities among local plant and arthropod communities to land-use variables at the landscape scale while controlling for local effects. We used similarities to consider species identities and abundances. Secondly, the relative effects of land-use factors at three spatial scales (region, landscape, local) on compositional and ecological aspects of local arthropod communities were investigated. Our studies emphasise that environmental change will affect biodiversity significantly at all major organisational levels. Population genetics, population structure, species richness, community similarity, community composition and ecological community characteristics, all responded to environmental factors but in a specific way. In order to address the fundamental question of which factors determine certain biodiversity levels, we disentangled the relative effects of single environmental factors that act on different spatial scales. All three analysed levels of biodiversity (genetics, populations, communities) revealed a clear trend of increasing importance of scale from the local level to the landscape and finally to the region. The genetic diversity of the land snail Cepaea nemoralis was not affected by local features such as patch size or habitat diversity, whereas the observed metapopulation structure indicated a pronounced effect of landscape features. The population response of the butterfly Pararge aegeria was a bit more complex. Under beneficial environmental conditions the impact of local and landscape-scale factors was similar but low. However, adverse conditions revealed an increasing effect of scale from local factors (suitable habitat) to landscape features (number of woody patches) and finally to regional factors (climate). Likewise, the analysis of community turnover, species composition and ecological groups supported these findings and were remarkably similar even between arthropod groups that differ markedly in their ecology. The analysis of biodiversity in agricultural landscapes across organisational levels and spatial scales supported a top-down hierarchical theory of biodiversity. It predicts that local communities are assembled from a regional species pool, which is modulated by large-scale factors such as climate or evolutionary and biogeographical history, through a series of hierarchical filters at the landscape scale and, to a lower extent, at the local scale according to both dispersal- and niche-assembly processes. Dispersal is suggested to be one of the main drivers of biodiversity at the landscape scale. Consequently, land-use change that affects the connectivity of habitats will significantly affect biodiversity by diminishing or even disrupting genetic, population and community processes. However, real species are not entirely neutral as the effects of niche-assembly related processes showed. This calls for a further unification of biodiversity theories that should consider species identities and their ecological role as well as their dispersal ability and spatial patterns across a variety of spatial and temporal scales if one wants to understand the multifaceted manifestations of live

Lebenszeit-Mortalität von Männern mit normalen und subnormalen Spermienkonzentrationen

Die Spermatogenese ist ein komplexer Prozess und stellt eines der wenigen Beispiele kontinuierlicher Proliferation von hochdifferenzierten und hochspezialisierten Zellen im menschlichen Organismus dar. Sie reagiert auf Grund ihrer raschen Reproduktion und dem hohen Differenzierungsgrad ihrer Zellen empfindlich auf Noxen und Stressoren. Der durchgeführten Studie liegt die Überlegung zu Grunde, dass die Spermatogenese bzw. deren Störungen ein Anzeichen für die Belastung des männlichen Organismus mit Noxen darstellen könnten. Werden gewisse Vorerkrankungen ausgeschlossen, so könnte eine Beeinträchtigung der Spermatogenese, ausgedrückt durch subnormale Spermienkonzentrationen, als Indikator für den Gesundheitszustand des männlichen Organismus angesehen werden. Entsprechend sollten Männer mit Spermatogenesestörungen aufgrund ihres schlechteren allgemeinen Gesundheitszustandes früher versterben als Männer ohne solche Störungen. Es sollte sich ein Zusammenhang zwischen der Spermienkonzentration und der Lebensdauer eines Individuums, also der Lebenszeit-Mortalität, finden lassen. Datengrundlage waren Krankenakten von Patienten der Andrologischen Sprechstunde des Universitätsklinikums Marburg, welche in den Jahren 1949 bis 1985 – meist aufgrund eines unerfüllten Kinderwunsches – eine Spermiogramm-Analyse durchführen ließen. Mittels Recherche in Einwohnermeldeämtern und der hessischen Zentraldatei einer gesetzlichen Krankenkasse wurden der Vitalstatus (lebend vs. verstorben) bzw. die Sterbedaten von 601 ehemaligen Patienten ermittelt. Der zuletzt ausgeübte Beruf diente als Indikator für den sozioökonomischen Status. Die Fälle wurden in Abhängigkeit von der angegebenen Spermienkonzentration nach Empfehlungen der WHO in 3 Fertilitätsklassen eingeteilt: normozoosperm (Spermienkonzentration &#8805; 20 Mio./ml), oligozoosperm (< 20 Mio./ml) und azoosperm (keine Spermien im Ejakulat). Eine Sterbetafel-Analyse ermöglichte die Darstellung der Überlebensfunktionen der Fertilitätsklassen und ermittelte eine höhere Mortalität für oligozoosperme als für normozoosperme Fälle. Die semi-parametrische Cox-Regression sowie weitere parametrische Regressionsverfahren, u.a. das Gompertz-Makeham-Modell, erlaubten, diesen Unterschied zu quantifizieren und unter Kontrolle verschiedener Variablen die Lebenszeit-Mortalität in Abhängigkeit vom Fertilitätsstatus modellieren. Es zeigte sich hier, dass die oligozoospermen Fälle ein doppelt so hohes Mortalitätsrisiko wie die normozoospermen Männer hatten. Die Sterblichkeit der Azoospermen hingegen war weder gegenüber jener der Normo- noch gegenüber jener der Oligozoospermen erhöht. Hinsichtlich der Spermienkonzentration wiesen die Regressionsmodelle keinen Zusammenhang mit der Lebenszeit-Mortalität der Individuen nach. Dies lässt den Schluss zu, dass sich der Zusammenhang zwischen Spermatogenese und Mortalität nicht in quantitativer Form als direkte Dosis-Wirkungs-Beziehung, sondern eher in qualitativer Form als niedrigeres bzw. höheres Sterberisiko bei „besserer“ bzw. „schlechterer“ reproduktionsphysiologischer Funktion zeigt. Zur Begründung einer höheren Sterblichkeit der Fälle mit subnormalen Spermienkonzentrationen werden verschiedene Erklärungsansätze diskutiert. (1) Auswirkungen von Kinderlosigkeit auf die Gesundheit und Mortalität: (Ungewollte) Kinderlosigkeit erhöht das Risiko für eine Scheidung, ist assoziiert mit ungesünderem Lebensstil, geringerer sozialer Unterstützung und erhöhter Morbidität. (2) Bedingungen in utero und im frühen Kindesalter: Nachteilige Konditionen können sich gleichzeitig negativ auf die Gesundheit im Allgemeinen und auf reproduktionsphysiologische Funktionen, z.B. die Spermatogenese, auswirken. (3) genetische Dispositionen, welche einen Zusammenhang zwischen verminderter Fertilität einerseits und erhöhter Mortalität andererseits moderieren

Insects Overshoot the Expected Upslope Shift Caused by Climate Warming

Along elevational gradients, climate warming may lead to an upslope shift of the lower and upper range margin of organisms. A recent meta-analysis concluded that these shifts are species specific and considerably differ among taxonomic lineages. We used the opportunity to compare upper range margins of five lineages (plants, beetles, flies, hymenoptera, and birds) between 1902-1904 and 2006-2007 within one region (Bavarian Forest, Central Europe). Based on the increase in the regional mean annual temperature during this period and the regional lapse rate, the upslope shift is expected to be between 51 and 201 m. Averaged across species within lineages, the range margin of all animal lineages shifted upslope, but that of plants did not. For animals, the observed shifts were probably due to shifts in temperature and not to changes in habitat conditions. The range margin of plants is therefore apparently not constrained by temperature, a result contrasting recent findings. The mean shift of birds (165 m) was within the predicted range and consistent with a recent global meta-analysis. However, the upslope shift of the three insect lineages (>260 m) exceeded the expected shift even after considering several sources of uncertainty, which indicated a non-linear response to temperature. Our analysis demonstrated broad differences among lineages in their response to climate change even within one region. Furthermore, on the considered scale, the response of ectothermic animals was not consistent with expectations based on shifts in the mean annual temperature. Irrespective of the reasons for the overshooting of the response of the insects, these shifts lead to reorganizations in the composition of assemblages with consequences for ecosystem processes

Evaluation of two rapid commercial assays for detection of Streptococcus agalactiae from vaginal samples

IntroductionStreptococcus agalactiae, also known as group B streptococci (GBS), is associated with invasive infections in neonates. Identification of GBS vaginal colonization in pregnant women before delivery is essential for treatment with antibiotics to prevent intrapartum vertical transmission to the newborn. This study was designed to evaluate applicability of two rapid real‐time PCRs in comparison to standard culture identification.Material and methodsWe compared the Xpert GBS assay, hereafter referred to as Xpert, and GenomEra GBS PCR, hereafter referred to as GenomEra. The standard culture identification consisted of two different agar plates as well as an enrichment broth.ResultsWe analyzed vaginal samples of 260 pregnant women; 42 samples were tested GBS‐positive by using standard culture as a gold standard, 30 by Xpert, and 37 by GenomEra. Xpert and GenomEra assays performed with sensitivities of 71.4% and 88.1% as well as specificities of 98.6% and 99.1%, respectively. Twelve vaginal samples were false‐negative by Xpert and five samples by GenomEra. Interestingly, three negative Xpert results of standard culture‐positive samples exhibited high Ct‐values indicating the presence of GBS. If higher Ct‐values are taken into consideration, the sensitivity of Xpert increases up to 78.6%. Moreover, only three Xpert PCRs had to be repeated, whereas two Genomera were invalid even after repetition and further 15 GenomEra PCRs were repeated because of borderline results or inhibition of the PCR test.ConclusionsIn this study, GenomEra assay performed with a higher sensitivity than the Xpert PCR. On the other hand, the Xpert assay needs less hands‐on‐time for a sample preparation and requires approximately four‐fold less repetitions as compared to the GenomEra assay. This robust performance of the Xpert assay make it applicable as a rapid intrapartum point‐of‐care test, although a higher sensitivity would be desirable. Therefore, culture in the 35–37 week of gestation remains the gold standard to detect vaginal colonization

The Predictability of Phytophagous Insect Communities: Host Specialists as Habitat Specialists

The difficulties specialized phytophagous insects face in finding habitats with an appropriate host should constrain their dispersal. Within the concept of metacommunities, this leads to the prediction that host-plant specialists should sort into local assemblages according to the local environmental conditions, i.e. habitat conditions, whereas assemblages of host-plant generalists should depend also on regional processes. Our study aimed at ranking the importance of local environmental factors and species composition of the vegetation for predicting the species composition of phytophagous moth assemblages with either a narrow or a broad host range. Our database consists of 351,506 specimens representing 820 species of nocturnal Macrolepidoptera sampled between 1980 and 2006 using light traps in 96 strict forest reserves in southern Germany. Species were grouped as specialists or generalists according to the food plants of the larvae; specialists use host plants belonging to one genus. We used predictive canonical correspondence and co-correspondence analyses to rank the importance of local environmental factors, the species composition of the vegetation and the role of host plants for predicting the species composition of host-plant specialists and generalists. The cross-validatory fit for predicting the species composition of phytophagous moths was higher for host-plant specialists than for host-plant generalists using environmental factors as well as the composition of the vegetation. As expected for host-plant specialists, the species composition of the vegetation was a better predictor of the composition of these assemblages than the environmental variables. But surprisingly, this difference for specialized insects was not due to the occurrence of their host plants. Overall, our study supports the idea that owing to evolutionary constraints in finding a host, host-plant specialists and host-plant generalists follow two different models of metacommunities: the species-sorting and the mass-effect model