Gemeinschaftsökologie und Diversität tropischer Kaulquappen

Two of the central questions of community ecology are whether there are forces influencing diversity and composition of species communities and which measure of diversity provides useful information on a community. Communities of tropical regions, such as the world’s most species rich tadpole communities from Madagascar, are attractive models to face these questions. In two consecutive wet seasons and a dry season (2007-2008) we have repeatedly sampled >30 communities and identified species by DNA barcoding. We analysed patterns of species richness and composition and their correlations with environmental variables. We also tested the performance of three measures of diversity (species richness [SR], functional diversity [FD], and phylogenetic diversity [PD]) also with special focus on seasonality. These measures were used to test whether environmental filters or competition are of importance for tropical stream tadpole communities. We could show that Madagascan streams are of outstanding importance for frog reproduction. Species richness (up to 22 species per community) mainly depended on stream (tadpole) habitat and not on forest (adult) habitat. However, species composition was largely determined by forest characteristics. We could show that during the wet season communities are characterised by functional redundancy and weak low FD. The latter points out that environmental filters may act on communities. In contrast, the less species rich communities of the dry season show a strong pattern of high FD (species less similar than expected). They are shaped by competition. Analyses using PD revealed a contrasting pattern. During the dry season species are closer related than expected (low PD). We could therefore show that all three applied measures of diversity contain important information and they are not interchangeable. In a rather descriptive chapter, species-species and species-habitat associations of all species and functional species groups are summarised.Das Erkennen von Umweltvariablen, die Artenreichtum und -zusammensetzung von Gemeinschaften beeinflussen und die Suche nach einem Diversitätsmaß, das Artengemeinschaften informativ beschreibt, gehören zu den Kernpunkten der Gemeinschaftsökologie. Als Modellsysteme bieten sich besonders tropische Gemeinschaften an, wie z.B. die artenreichsten Kaulquappengemeinschaften der Welt auf Madagaskar. Von 2007 bis 2008 (Regen- & Trockenzeit) haben wir wiederholt Daten von >30 Gemeinschaften erhoben, wobei Arten mittels DNA-barcoding bestimmt wurden. Wir korrelierten Muster von Artenreichtum und -zusammensetzung mit Umweltvariablen und testeten das Verhalten dreier Diversitätsmaße (Artenreichtum, funktionale Diversität [FD] und phylogenetische Diversität [PD]), wobei besonders Auswirkungen von Saisonalität betrachten wurden. Diese Maße erlauben ebenso Aufschlüsse auf die Bedeutung von Umweltfiltern oder Konkurrenz für die Zusammensetzung tropischer Kaulquappengemeinschaften. Wir konnten zeigen, welch hohe Bedeutung Fließgewässer für die Reproduktion madagassischer Anuren haben. Der Artenreichtum der Gemeinschaft (bis 22 Arten) wurde primär durch Gewässermerkmale bestimmt, während die Artenzusammensetzung auch vom umliegenden Wald (Habitat der Adulten) abhing. Während der Regenzeit wiesen die Gemeinschaften neben funktionaler Redundanz auch Muster niedriger FD auf, was auf die Wirkung von Umweltfiltern hindeutet. Im Gegensatz dazu fanden wir in der Trockenzeit sehr hohe FD: Arten einer Gemeinschaft wahren verschiedener voneinander als erwartet. Hier spielte Konkurrenz eine Rolle. PD wiederum zeigte ein gegenteiliges Muster: Arten waren näher miteinander verwandt als erwartet. Damit konnten wir zeigen, dass alle drei Maße wichtige Informationen bieten und mitnichten untereinander austauschbar sind. In einem eher beschreibenden Kapitel stellen wir Assoziationen von Arten miteinander und Habitatmerkmalen dar

The world's richest tadpole communities show functional redundancy and low functional diversity: ecological data on Madagascar's stream-dwelling amphibian larvae

<p>Abstract</p> <p>Background</p> <p>Functional diversity illustrates the range of ecological functions in a community. It allows revealing the appearance of functional redundancy in communities and processes of community assembly. Functional redundancy illustrates the overlap in ecological functions of community members which may be an indicator of community resilience. We evaluated patterns of species richness, functional diversity and functional redundancy on tadpole communities in rainforest streams in Madagascar. This habitat harbours the world's most species-rich stream tadpole communities which are due to their occurrence in primary habitat of particular interest for functional diversity studies.</p> <p>Results</p> <p>Species richness of tadpole communities is largely determined by characteristics of the larval habitat (stream structure), not by adult habitat (forest structure). Species richness is positively correlated with a size-velocity gradient of the streams, i.e. communities follow a classical species-area relationship. While widely observed for other taxa, this is an unusual pattern for anuran larvae which usually is expected to be hump-shaped. Along the species richness gradient, we quantified functional diversity of all communities considering the similarity and dissimilarity of species in 18 traits related to habitat use and foraging. Especially species-rich communities were characterised by an overlap of species function, i.e. by functional redundancy. By comparing the functional diversity of the observed communities with functional diversity of random assemblages, we found no differences at low species richness level, whereas observed species-rich communities have lower functional diversity than respective random assemblages.</p> <p>Conclusions</p> <p>We found functional redundancy being a feature of communities also in primary habitat, what has not been shown before using such a continuous measure. The observed species richness dependent pattern of low functional diversity indicates that communities with low species richness accumulate functional traits randomly, whereas species in species-rich communities are more similar to each other than predicted by random assemblages and therefore exhibit an accumulation of stream-specific functional traits. Beyond a certain species richness level, therefore, stream-specific environmental filters exert influence whereas interspecific competition between species does not influence trait assemblage at any species richness level.</p

Site structure analysis and optimization

The article contains information about current situation of site development, reasons why sites are so essential for activity of organizations and why researches of their structure improvement are so important. Short analysis of previous researches is provided, with their negative features and ways for further researches being exposed. Several ways to formulate recommendations and requirements for site structure are suggested, as well as methods for its optimization. A method for implementation of research results as software product is proposed. The information about an example of such software which performs analysis of sites of educational institution is provided too

Article Description of tadpoles of five frog species in the subgenus Brygoomantis from Madagascar (Mantellidae: Mantidactylus)

Abstract We describe the larval stages of five frog species classified in the Madagascan subgenus Brygoomantis of the genus Mantidactylus, which were identified by DNA barcoding: Mantidactylus alutus, Mantidactylus curtus, and three taxonomically undescribed species here named Mantidactylus sp. aff. biporus &quot;Ranomafana&quot;, M. sp. aff. biporus &quot;Marojejy&quot;, and M. sp. aff. curtus &quot;Ankaratra&quot;. The larvae of M. alutus, and of M. sp. aff. curtus &quot;Ankaratra&quot;, had been described before, and we confirm and complement the previous studies. Our data confirm that Brygoomantis tadpoles are benthic, of a rather generalized body shape and oral disc morphology. All species for which tadpoles are known so far have a large dorsal gap of marginal papillae, a labial tooth row formula of 3-5 rows on the anterior labium of which only the first is continuous and the others have distinct medial gaps, and three rows of labial teeth on the posterior labium of which the first usually has a very small medial gap which however can sometimes be undetectable. Total number of marginal and submarginal papillae ranges from 50 to 103 and density of labial teeth (on the second upper row) from 19 to 76 per mm

Comparative Analysis of Mesenchymal Stem Cell Cultivation in Fetal Calf Serum, Human Serum, and Platelet Lysate in 2D and 3D Systems

In vitro two-dimensional (2D) and three-dimensional (3D) cultivation of mammalian cells requires supplementation with serum. Mesenchymal stem cells (MSCs) are widely used in clinical trials for bioregenerative medicine and in most cases, in vitro expansion and differentiation of these cells are required before application. Optimized expansion and differentiation protocols play a key role in the treatment outcome. 3D cell cultivation systems are more comparable to in vivo conditions and can provide both, more physiological MSC expansion and a better understanding of intercellular and cell-matrix interactions. Xeno-free cultivation conditions minimize risks of immune response after implantation. Human platelet lysate (hPL) appears to be a valuable alternative to widely used fetal calf serum (FCS) since no ethical issues are associated with its harvest, it contains a high concentration of growth factors and cytokines and it can be produced from expired platelet concentrate. In this study, we analyzed and compared proliferation, as well as osteogenic and chondrogenic differentiation of human adipose tissue-derived MSCs (hAD-MSC) using three different supplements: FCS, human serum (HS), and hPL in 2D. Furthermore, online monitoring of osteogenic differentiation under the influence of different supplements was performed in 2D. hPL-cultivated MSCs exhibited a higher proliferation and differentiation rate compared to HS- or FCS-cultivated cells. We demonstrated a fast and successful chondrogenic differentiation in the 2D system with the addition of hPL. Additionally, FCS, HS, and hPL were used to formulate Gelatin-methacryloyl (GelMA) hydrogels in order to evaluate the influence of the different supplements on the cell spreading and proliferation of cells growing in 3D culture. In addition, the hydrogel constructs were cultivated in media supplemented with three different supplements. In comparison to FCS and HS, the addition of hPL to GelMA hydrogels during the encapsulation of hAD-MSCs resulted in enhanced cell spreading and proliferation. This effect was promoted even further by cultivating the hydrogel constructs in hPL-supplemented media

Multi-dimensional modeling and simulation of semiconductor nanophotonic devices

Self-consistent modeling and multi-dimensional simulation of semiconductor nanophotonic devices is an important tool in the development of future integrated light sources and quantum devices. Simulations can guide important technological decisions by revealing performance bottlenecks in new device concepts, contribute to their understanding and help to theoretically explore their optimization potential. The efficient implementation of multi-dimensional numerical simulations for computer-aided design tasks requires sophisticated numerical methods and modeling techniques. We review recent advances in device-scale modeling of quantum dot based single-photon sources and laser diodes by self-consistently coupling the optical Maxwell equations with semiclassical carrier transport models using semi-classical and fully quantum mechanical descriptions of the optically active region, respectively. For the simulation of realistic devices with complex, multi-dimensional geometries, we have developed a novel hp-adaptive finite element approach for the optical Maxwell equations, using mixed meshes adapted to the multi-scale properties of the photonic structures. For electrically driven devices, we introduced novel discretization and parameter-embedding techniques to solve the drift-diffusion system for strongly degenerate semiconductors at cryogenic temperature. Our methodical advances are demonstrated on various applications, including vertical-cavity surface-emitting lasers, grating couplers and single-photon sources

Diversity of the strongly rheophilous tadpoles of Malagasy tree frogs, genus Boophis (Anura, Mantellidae), and identification of new candidate species via larval DNA sequence and morphology

This study provides detailed morphological descriptions of previously unknown tadpoles of the treefrog genus Boophis Tschudi and analyses of habitat preferences of several of these tadpoles in Ranomafana National Park. A total of twenty-two tadpoles determined via DNA barcoding are characterized morphologically herein, fourteen of them for the first time. Twelve of these tadpoles belong to taxonomically undescribed candidate species which in several cases are so far only known from their larval stages. Our data show that the larvae of some of these candidate species occur syntopically yet maintaining a clearly correlated genetic and morphological identity, suggesting that they indeed are true biological and evolutionary species. Tadpoles considered to belong to the “adherent” ecomorphological guild inhabit fast-running waters and their oral disc is commonly to continuously attached to the rocky substrate, supposedly to keep their position in the water current. Some of these species are characterized by the presence of a dorsal gap of papillae and the absence of an upper jaw sheath. This guild includes the tadpoles of the B. albipuncatus group (B. ankaratra, B. schuboeae, B. albipunctatus, B. sibilans, B. luciae), and of the B. mandraka group (B. sambirano and six candidate species related to this species and to B. mandraka). Tadpoles considered belonging to the “suctorial” guild inhabit fast-running waters where they use frequently their oral disc to attach to the substrate. They have an enlarged oral disc without any dorsal gap, including two nominal species (B. marojezensis, B. vittatus), and five candidate species related to B. marojezensis. An ecological analysis of the tadpoles of B. luciae, B. schuboeae and B. marojezensis [Ca51 JQ518198] from Ranomafana National Park did not provide evidence for a clear preference of these tadpoles to the fast flowing microhabitat sections of the stream, although the tadpoles discussed in this study are typically caught in this habitat

Nidicolous tadpoles rather than direct development in Malagasy frogs of the genus Gephyromantis

Frogs in the genus Gephyromantis from Madagascar were assumed to have a direct developmental mode, i.e. the complete embryonic and larval development within the egg, but recently free-swimming, exotrophic tadpoles of a few species have been found. Herein we provide detailed morphological descriptions of the tadpoles of five more species of this genus, indicating a developmental mode other than direct development in species of Gephyromantis. Tadpoles of Gephyromantis granulatus, G. sculpturatus, G. tschenki, and G. ventrimaculatus were found free-swimming in streams, and tadpoles of G. sp. aff. blanci were raised after hatching from clutches found in the leaf litter. All tadpoles were identified by DNA barcoding. The oral discs of all five species are characterized by the lack of many typical morphological traits of exotrophic tadpoles (such as oral papillae and keratodonts). This indicates that these tadpoles are either non-feeding (endotrophic) or only facultatively feeding tadpoles. We classify these tadpoles as nidicolous based on the observation that the larvae of G. sp. aff. blanci stayed after hatching in the jelly nest until metamorphosis. It remains unclarified whether all species have strictly nidicolous tadpoles, and the larvae of the four species found in the streams were just accidentally washed into these streams; alternatively, some of these tadpoles might be nidicolous at first but in some species need to live in free water at later stages. © 2011 Copyright Taylor and Francis Group, LLC

Formation of three-dimensional tubular endothelial cell networks under defined serum-free cell culture conditions in human collagen hydrogels

Abstract Implementation of tubular endothelial cell networks is a prerequisite for 3D tissue engineering of constructs with clinically relevant size as nourishment of cells is challenged by the diffusion limit. In vitro generation of 3D networks is often achieved under conditions using serum containing cell culture medium and/or animal derived matrices. Here, 3D endothelial cell networks were generated by using human umbilical vein endothelial cells (HUVECs) in combination with human adipose tissue derived stromal cells (hASCs) employing human collagen I as hydrogel and decellularized porcine small intestinal submucosa as starter matrix. Matrigel/rat tail collagen I hydrogel was used as control. Resulting constructs were cultivated either in serum-free medium or in endothelial growth medium-2 serving as control. Endothelial cell networks were quantified, tested for lumen formation, and interaction of HUVECs and hASCs. Tube diameter was slightly larger in constructs containing human collagen I compared to Matrigel/rat tail collagen I constructs under serum-free conditions. All other network parameters were mostly similar. Thereby, the feasibility of generating 3D endothelial cell networks under serum-free culture conditions in human collagen I as hydrogel was demonstrated. In summary, the presented achievements pave the way for the generation of clinical applicable constructs