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Wesche K.,Senckenberg Museum of Natural History Gorlitz | Krause B.,University of Gottingen | Culmsee H.,Heritage Foundation | Leuschner C.,University of Gottingen
Biological Conservation | Year: 2012

There is growing concern that biodiversity loss in European agricultural landscapes is having negative effects on functional trait diversity. Long-term studies examining vegetation changes from the period before agricultural industrialisation are however rare. Here, we ask how management intensification and increased nutrient input initiated in the 1950/1960s have altered grassland plant community composition, species diversity and functional trait composition using comprehensive datasets from five floodplain regions (plus one protected reference region) in northern Germany. Sites with available historical relevés and vegetation maps (1950/1960s, 1990s) were resampled in 2008 to facilitate the analysis of a period spanning four to five decades.Plant community composition changed tremendously in all study regions during the 50. year period, which was related to increasing Ellenberg indicator values for nutrient availability. Species richness at the plot-level fell by 30-50% over the period, and losses in functional diversity were equally large. A non-formal comparison with the results from the protected reference study region indicates that the changes may mostly be attributable to local nutrient input rather than to supra-regional climate change. Our results indicate a consistent trend towards much more species-poor communities dominated by mow-tolerant, N-demanding competitive grasses, whereas species with more ruderal strategies, species flowering early in the season and, in particular, insect-pollinated herbs have all decreased. The substantial loss of nectar-producing grassland herbs is likely to have negative effects on the abundance of pollinating insects, with consequences for the grassland animal communities. This highlights the growing need for adequate grassland management schemes with low N input to preserve high-nature-value grassland. © 2012 Elsevier Ltd.

Schuch S.,University of Gottingen | Wesche K.,Senckenberg Museum of Natural History Gorlitz | Schaefer M.,University of Gottingen
Biological Conservation | Year: 2012

Landscapes in Central Europe have changed considerably during the last five decades, while nature reserves have been less affected. However, there is growing concern that species richness and population size of animals in reserves may decrease even under protection.We performed a comparative study of the development in auchenorrhynchan communities of governmentally protected dry grasslands in Eastern Germany and tested whether reserves were effective in maintaining insect communities. The historical surveys are from 1963 to 1967. Between 2008 and 2010 we revisited 26 of the original sites and sampled leafhoppers and planthoppers by applying the same sampling technique as in the 1960s. Thus, we were able to perform a 40-year-comparison for auchenorrhynchan species richness and abundance. Comparisons capturing three successive years of each period allowed us to assess interannual variability in abundance.Species richness hardly differed between the two periods. However, some new species were found, and therefore species composition changed. Species abundance and overall numbers of individuals declined. Mainly species known to be very common dry grassland specialists exhibited strong declines in abundance. On average, only 27% of auchenorrhynchan numbers caught from 1964 to 1966 were recorded for the years 2008 to 2010.The results suggest that weather conditions and climate change are minor factors in the decline in auchenorrhynchan populations in recent years. Although the studied areas were under protection during the last 50. years, air-borne nitrogen deposition, the introduction of modern intense land use practices and alterations in plant communities, are likely to have influenced auchenorrhynchan abundance to a large extent. © 2012 Elsevier Ltd.

Meyer S.,University of Gottingen | Wesche K.,Senckenberg Museum of Natural History Gorlitz | Krause B.,University of Gottingen | Leuschner C.,University of Gottingen
Diversity and Distributions | Year: 2013

Aim: To assess the consequences of agricultural intensification since the 1950s for Central Europe's plant communities of arable plants. Location: Central Germany. Methods: We employed a semipermanent plot design to analyse changes in 392 field interiors for 10 study regions, including sandy, limestone and loamy sites between the 1950s/60s and 2009. Results: The analysis revealed a reduction in the regional species pool during the 50-year period of 23% (from 301 to 233 vascular species) and dramatic losses in plot-level diversity (from medians of 24 to 7). Median cover of spontaneously growing arable plants decreased from 30% to 3%. Losses were disproportionally larger on limestone sites while sandy sites maintained a larger fraction of the original diversity. Archaeophytes, neophytes and most Poaceae (including some aggressive weeds) showed similarly strong losses as indigenous plants. This contradicts the assumption that grasses and neophytes are generally profiting from agricultural intensification. Crop diversity decreased from 25 crop plants present in the 1950s/60s to only 16 in 2009, while crop cover generally increased. Winter cereals, oilseed rape and maize are dominant today, while all other crop types showed strong declines. Main conclusions: Vegetation change over time depended on soil substrate with once markedly different arable communities now showing more homogenized community structure. Increasing Ellenberg indicator values for nitrogen and pH point to N fertilization as a major driver of change. New conservation measures such as the establishment of field flora reserves and agri-environment schemes with less intensive land use are thus urgently needed especially on limestone substrates to bring an end to the decline of this functionally distinct and increasingly threatened component of the Central European flora. © 2013 John Wiley & Sons Ltd.

Ritz C.M.,Senckenberg Museum of Natural History Gorlitz | Wissemann V.,Justus Liebig University
Journal of Heredity | Year: 2011

Dogroses are characterized by a unique meiosis system, the so-called canina meiosis, which facilitates sexual reproduction at odd-number ploidy. The mostly pentaploid somatic level of dogroses is restored by a merger of haploid sperm cells and tetraploid egg cells. We analyzed experimental hybrids between different dogrose species using microsatellites to determine pollen-transmitted alleles. This information was used to reconstruct the putative hybridogenic origin of Rosa micrantha and R. dumalis and to estimate the frequency of spontaneous hybridization in a natural population. We found no evidence for the hybrid origin of R. dumalis, but our data suggest that R. micrantha presumably arose by hybridization between R. rubiginosa and R. canina or R. corymbifera. We observed only hexaploid individuals of R. micrantha, thus the establishment of this hybridogenic species was favored when unreduced gametes contributed to their origin. We demonstrate that spontaneous hybrids originated infrequently from the parental species in a natural population, but hybridization was often associated with the formation of unreduced gametes. We postulate that unreduced gametes play a major role in the evolutionary success of dogrose hybrids because they provide highly homologous chromosomes crucial for bivalent formation during canina meiosis and thus ensuring this unique form of sexual reproduction. © 2011 The American Genetic Association. 2011. All rights reserved.

Seifert B.,Senckenberg Museum of Natural History Gorlitz
Ecological Entomology | Year: 2010

1. The syndrome of intranidal mating, morpho-ethological gyne polymorphism, and polygyny is found in less than 5% of European ant species, but is considered as an important precondition for sympatric and parapatric speciation. 2. This idea is discussed in three cases that represent example of evolution below the species level: (1) the polygynous - polydomous form of Lasius turcicus as a model of how speciation of the supercolonial Lasius neglectus could have taken place; (2) the microgyne form of Myrmica rubra as a model for sympatric speciation of socially parasitic species; and (3) hybridisation and rapid genotype selection in supercolonial wood ants of the Formica rufa group as a model for hybrid speciation. 3. The first step of the evolutionary scenario is transition to polygyny followed by development of morpho-ethological gyne polymorphism: smaller gynes with weaker wing muscles and body reserves shift to intranidal mating and reduce dispersal flight, while larger gynes with bigger wing muscles and body reserves retain nuptial and dispersal flight. This scenario leads to mating place separation and facilitates further genotype divergence. 4. There is much less gene flow between conspecific supercolonies of Formica rufa group ants with dominance of intranidal or intracolonial mating than between conspecific monogynous colonies performing a nuptial flight. If two supercolonial species occasionally hybridise and if landscape structure provides some isolation of the resulting hybrid supercolony, very strong selection for genotypes takes place within this cohesive system of thousands of reproductive females eventually leading to novel genotypes and new species. © 2010 The Royal Entomological Society.

The South Australian members of the flat-millipede genera Oncocladosoma Jeekel, 1985 and Somethus Chamberlin, 1920 are revised using an integrative approach incorporating sequence data and morphology. The partial mitochondrial cytochrome c oxidase subunit I (COI) barcoding gene and partial nuclear ribosomal 28S rRNA were amplified and sequenced for 15 Oncocladosoma specimens and 10 Somethus specimens and the datasets were used for molecular phylogenetic analysis and genetic distance determination. Both morphology and molecular data indicate that all species of Oncocladosoma fall within Somethus, and therefore, Oncocladosoma is synonymised with Somethus. Within those species supported by molecular data, features of the solenomere tip are relatively stable and useful for species identification. 28S rRNA has proven to provide sufficient nucleotide variation to provisionally discriminate species. Oncocladosoma castaneum ingens Jeekel, 1985, O. clavigerum Jeekel, 1985 and O. conigerum Jeekel, 1985 are junior synonyms of Somethus castaneus, comb. nov., and Somethus modicus Jeekel, 2002 is a synonym of S. scopiferus Jeekel, 2002. New records and electron scanning micrographs of gonopods are provided for S. castaneus, comb. nov., S. inflatus (Jeekel, 2002), comb. nov., S. lancearius Jeekel, 2002, S. scopiferus Jeekel, 2002, and Somethus grossi Jeekel, 1985, together with a key to the South Australian species of Somethus. © The authors 2016.

This study documents the first detailed phylogenetic analysis of an Australian paradoxosomatid millipede genus. Two mitochondrial genes (partial COI and 16S) as well as partial nuclear 28S rDNA were amplified and sequenced for 41 individuals of the southeastern Australian genus Pogonosternum Jeekel, 1965. The analysis indicates that five species groups of Pogonosternum occur across New South Wales, Victoria and Tasmania: P. nigrovirgatum (Carl, 1912), P. adrianae Jeekel, 1982, P. laetificum Jeekel, 1982 and two undescribed species. P. coniferum (Jeekel, 1965) specimens cluster within P. nigrovirgatum. Most of these five species groups exhibit a pattern of high intraspecific genetic variability and highly localized haplotypes, suggesting that they were confined to multiple Pleistocene refugia on the southeastern Australian mainland. The phylogenetic data also show that northwestern Tasmania was colonized by P. nigrovirgatum, probably from central Victoria, and northeastern Tasmania by an as yet undescribed species from eastern Victoria. © Peter Decker.

Dreijers E.,Senckenberg Museum of Natural History Gorlitz | Reise H.,Senckenberg Museum of Natural History Gorlitz | Hutchinson J.M.C.,Senckenberg Museum of Natural History Gorlitz
Journal of Molluscan Studies | Year: 2013

The large slug known as Arion lusitanicus (or A. vulgaris) is an important pest that is spreading through much of Europe. Arion rufus disappears at sites where A. lusitanicus has established strong populations. The finding of morphological intermediates suggests that A. lusitanicus hybridizes with A. rufus, but interspecific mating had not been proved. Considering the marked differences in their genitalia, it has been hard to envisage how mixed couples might transfer sperm. Arion lusitanicus and A. rufus were collected from pure populations near Görlitz, Germany, and used for laboratory mating trials involving either two individuals of A. rufus (henceforth RR), two of A. lusitanicus (LL) or one of each species (mixed). Matings were video recorded and some couples were killed during or after copulation to study spermatophore transfer and genital anatomy during mating. Three mixed pairs copulated. However, mixed pairs were significantly less likely to copulate than either RR or LL pairs (7% vs 52 and 36%). At each stage of mating, the probability of proceeding further was lower in mixed pairs than predicted from rates in RR and LL pairs, but this effect was strongest for yin-yang formation and initiating copulation. One problem was that A. lusitanicus tried to circle after yin-yang formation, whereas A. rufus remained stationary. In this respect, and in the repositioning of its everted oviduct, it was A. lusitanicus that compromised. LL copulations lasted over twice as long as RR copulations, but spermatophore formation took similar times, permitting reciprocal spermatophore exchange in mixed couples even though their copulations ended much earlier than in LL pairs. Our observations of mating behaviour of intraspecific pairs largely agree with previous descriptions of A. rufus, but we discuss some discrepancies between our findings and the fuller descriptions available for A. lusitanicus. © 2013 The Author.

Wesche K.,Senckenberg Museum of Natural History Gorlitz | Von Wehrden H.,Lüneburg University
Applied Vegetation Science | Year: 2011

Question: How do standard multivariate classification algorithms perform for Mongolian dryland vegetation characterized by low diversity and very long floristic gradients? Location: Southern Mongolian Gobi. Methods: We compared several widely used classification methods based on 1231 relevés obtained with a similar sampling method. We applied agglomerative cluster algorithms (flexible beta/FLEX, average linkage/UPGMA, weighted linkage/WPGMA, complete linkage, Ward's clustering) and a divisive classification technique (TWINSPAN); data were reduced to presence/absence. We compared results against a published phytosociological classification (PHYTO), against environmental background data, and with respect to the presence of significant indicator species. Results: Complete linkage was inferior to other methods. TWINSPAN, UPGMA, flexible beta and WPGMA gave partly similar clusters, with FLEX and WARD showing the highest pair-wise similarity. Classifications of all methods except CL partly agreed with PHYTO classification. Clusters of all methods had significant indicator species, but Ward's method had the highest number of indicator species, followed by the PHYTO classification and FLEX, TWINSPAN, UPGMA and WPGMA. The latter four methods all yielded clusters that differed in terms of precipitation, but TWINSPAN, FLEX and Ward's method performed best under this criterion. PHYTO and CL ranked last in partitioning the precipitation gradient. Comparisons with ordinations indicated that classification algorithms capture the main floristic gradient but were less successful than the phytosociological approach to elucidate the finer structures. Conclusion: Performance of classification methods differed depending on the applied validation approach and we thus caution against uncritically adopting a single evaluation/validation criterion. Most numerical approaches can aid sorting of large data sets, while details of manual syntaxonomic classifications are not easily reproduced. Choice of the most appropriate classification and validation method thus clearly depends on the overall aim of a given study. © 2011 International Association for Vegetation Science.

Pilz M.,Senckenberg Museum of Natural History Gorlitz | Hohberg K.,Senckenberg Museum of Natural History Gorlitz
Soil Biology and Biochemistry | Year: 2015

This study focuses on the CO2-tolerance of soil nematodes from natural CO2 springs (mofette fields). In laboratory experiments, we compared survival, reproduction, activity and reactivation of a CO2-sensitive species with a CO2-tolerant species. Both species survived even 100% CO2, but in an inactive state. The higher the CO2 concentration the more individuals entered inactivity. We found significant differences between the two species: more adults of the CO2-tolerant species maintained activity and reproduction at higher CO2 concentrations. Moreover, reactivation after inactivity was faster. Together with a higher juvenile mortality of the CO2-sensitive species, these interspecific differences are conclusive to explain the niche separation of the two species that was observed in the mofette field. © 2015 Elsevier Ltd.

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