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Holland V.,Biodiversity and Climate Research Center ankfurt | Holland V.,Goethe University Frankfurt | Fragner L.,University of Vienna | Jungcurt T.,Goethe University Frankfurt | And 3 more authors.
Photosynthetica | Year: 2016

Metabolite changes and senescence behaviour after mechanical phloem girdling were studied in leaf tissue of Quercus pubescens. Sugar accumulation is not only considered to be an important part of several developmental signalling pathways, but is also seen as one of the basic triggers for senescence induction, or at least an obligatory accessory phenomenon. Our survey showed that an accumulation of the soluble sugars, glucose and fructose, was not on its own obligatorily connected with the induction of leaf senescence, since no indication or even an onset of senescence could be observed during the course of the experiment. Instead, we observed an inhibition of leaf development with a decrease of photosynthesis and a slow-down of development in nearly all chlorophyll a fluorescence analysis parameters using the JIP-test. We detected a change of metabolites linked to oxidative stress, possibly due to an overexcitation of the developmentally inhibited photosynthetic apparatus. © 2016 The Institute of Experimental Botany


Huwer A.,Biodiversity and Climate Research Center ankfurt | Wittig R.,Institute of Ecology
Phytocoenologia | Year: 2012

To date, studies on the effects of climate change on European vegetation have primarily been conducted at northern or altitudinal boundaries of species ranges. The objective of this study was to determine if and in what man- ner climate change has affected plant associations in the central European lowland. Using a total of 200 relevés col- lected in 1976, 1983, 1996 and 2008, and relevant climate data from 1970 to 2008, we attempted to identify the effects of recent climate change on herbaceous species composition in a distinct type of beech forest (Oxali-Fagetum) in North Rhine-Westphalia (Germany). Both temperature and precipitation in the study area increased over the period under investigation. These climatic changes were accompanied by slight shifts in herbaceous species composition, expressed as a temporal break between the fi rst and last two sampling years within ordination plots generated by nonmetric multidimensional scaling. The observed fl oristic changes consisted primarily of changes in the relative distribution of species within the community but did not indicate changes in community composition. © 2012 Gebrüder Borntraeger, 70176 Stuttgart, Germany.


Klostermann L.,Goethe University Frankfurt | Gischler E.,Goethe University Frankfurt | Storz D.,Biodiversity and Climate Research Center ankfurt | Hudson J.H.,Reef Technology Inc.
Marine Geology | Year: 2014

Six Holocene sedimentary events (ranging in age from 420-890, 890-1560, 2040-2340, 2420-3380, 3890-4330, and 5480-5760. yrs. BP) have been identified in the lagoon of Rasdhoo Atoll (Maldives; 4°N, 73°W), thereby underlining the importance of atoll lagoons as potential archives of environmental change. Holocene coastal sediments have been studied as archives for past tsunami and storm events but comparable sedimentological studies of mid-ocean atoll lagoons are rare. In ten vibracores covering the past 6.5. kyrs that are characterized by mudstone, wackestone, and floatstone background sedimentation, we found two types of event deposits: (1) several cm thick rudstone layers with redeposited corals like Acropora sp. and Seriatopora sp., which derive from the marginal and/or lagoonal reefs and have been transported into the lagoon and (2) thin (several mm) layers of wackestone, floatstone, and rudstone consisting of reef-derived components like coralline red algae, reef foraminifera (e.g., Amphistegina spp., Calcarina sp.), and redeposited coral fragments. Both types of event layers may be correlated among several cores, which we interpret as tsunami deposits. Five of the six events have temporal counterparts identified at the coasts of Thailand, Sumatra, and India. In the Maldives, close to the equator, no category 1-5 typhoons were recorded, but only tropical depressions and storms as potential triggers of event sedimentation have occurred rarely. Major earthquakes off western Indonesia and generated tsunamis, which potentially reach most parts of the Indian Ocean, are common. © 2013 Elsevier B.V.


Storz D.,Biodiversity and Climate Research Center ankfurt | Gischler E.,Goethe University Frankfurt | Parker J.,University of Western Australia | Klostermann L.,Goethe University Frankfurt
Marine Micropaleontology | Year: 2014

This study presents the first high-resolution Holocene records of diversity and assemblages of benthic foraminifera from tropical reef environments in the Indian Ocean. Two 3.2. m and 4.4. m long cores from the lagoon of Rasdhoo Atoll (4°N/73°W) in the central Maldives, were sampled at ~. 250. yr intervals. Core #16 covers most of the Holocene (10.32-0. kyr BP) and was taken in the deep lagoon of the atoll (35. m water depth). Core #19 covers the time span 7.375-0. kyr BP and is from a sublagoon (14. m water depth) on the northern margin of the atoll. In Core #16, an early colonization phase during Holocene sea-level rise is characterized by an Ammonia sp. 1 dominated assemblage until ~. 7. kyr BP. The slowdown of sea-level rise in the Mid Holocene (~. 4. kyr BP) marks the onset of a phase of stable environmental conditions in the deep lagoon with high diversity. A shift toward lower diversity and the dominance of Textularia foliacea has occurred from ~. 4-1. kyr BP, which may be explained with the Intermediate Disturbance Hypothesis. An environmental change at ~. 1.4. kyr has caused a distinct faunal change, the decrease of T. foliacea and an increased recovery in diversity. In Core #19, a significant faunal change at ~. 4.0. kyr BP from an Ammonia sp. 2 dominated fauna to a fauna with Ammonia sp. 1, miliolid taxa and a higher diversity might be related to the formation of a sand spit that separates the sublagoon from the main lagoonal basin. The westward extension of the sand spit during the Late Holocene could have changed the restricted bottom water circulation in the main lagoon and caused longer residence times of water and the build-up of lower oxygen and higher nutrient concentrations. This study underlines the importance of the factor time on diversity and the significance of lagoon circulation and bottom water residence times on assemblages and diversity of benthic foraminifera. © 2013 Elsevier B.V.


Holland V.,Biodiversity and Climate Research Center ankfurt | Holland V.,Goethe University Frankfurt | Koller S.,Biodiversity and Climate Research Center ankfurt | Bruggemann W.,Biodiversity and Climate Research Center ankfurt | Bruggemann W.,Goethe University Frankfurt
Plant Biology | Year: 2014

Climate change is one of the major issues nowadays, and Mediterranean broadleaf species have been suggested to fill possible future gaps created by climate change in Central European forests. To provide a scientific-based foundation for such practical strategies, it is important to obtain a general idea about differences and similarities in the physiology of Central European and Mediterranean species. In the present study, we evaluated the onset of leaf senescence of a broad spectrum of oak species under the Central European climate in a common garden experiment. Degradation of the photosynthetic apparatus of evergreen (Quercus ilex, Q. suber), semi-evergreen (Q. × turneri, Q. × hispanica) and deciduous oaks (Q. robur, Q. cerris, Q. frainetto, Q. pubescens) was monitored as chlorophyll content and analysed chlorophyll fluorescence induction transients. In the deciduous species, a significant decline in chlorophyll content was observed during autumn/winter, with Q. pubescens showing the slowest decline. Analysis of fluorescence induction transients revealed a significant decline in quantum efficiency of the primary photochemistry and reaction centre density and later, a decrease in quantum efficiency of end acceptor reduction. Alterations in fluorescence parameters were compared to the decline in chlorophyll content, which occurred much more slowly than expected from the fluorescence data. The evergreen species showed no decline in chlorophyll content, nor different chlorophyll a fluorescence induction behaviour despite temperature falling below 0 °C. The hybrids showed intermediate behaviour between their parental evergreen and deciduous taxa. © 2014 German Botanical Society and Royal Botanical Society of the Netherlands.


Malkowsky Y.,Biodiversity and Climate Research Center ankfurt | Malkowsky Y.,Goethe University Frankfurt | Gotze M.-C.,Biodiversity and Climate Research Center ankfurt | Gotze M.-C.,Goethe University Frankfurt
Organisms Diversity and Evolution | Year: 2014

Pectinidae, a large group of marine bivalves comprising more than 300 species worldwide, inhabit a diverse array of habitats, enabling an enormous radiation, and yielding many different life forms and adaptations. This apparent diversity led to the distinction of ecotypes based on shell morphology and lifestyle. Eyes in Pectinidae (Bivalvia, Pteriomorphia) have long sparked scientific interest and have been described for various species over the past two centuries. These eyes are morphologically and functionally highly complex. Despite this complexity, studies have focused mostly on functional aspects with only few examining the relationships associated with different environmental or evolutionary traits. Here, the pallial eye structure within the Pectinidae was examined using Masson Goldner Trichrom staining, and ancestral character estimation with BayesTraits was performed to reconstruct macro-evolutionary patterns. To evaluate the connection of substrate type and lifestyle to the evolution of eyes, we compared eyes within the major subgroups of Pectinidae while considering the different lifestyles and substrate types as well as different depth ranges. The results indicate a tendency towards a taxon-/clade-specific evolution in respect to characters such as the cornea and lens while depth specific adaptations occur mainly in the light sensitive compartments of the retina. Successive reduction of eyes seems to occur from shallow to deep water species and ends in a total reduction of all structures in deep sea species. © 2014 Gesellschaft für Biologische Systematik.


Malkowsky Y.,Biodiversity and Climate Research Center ankfurt | Malkowsky Y.,Goethe University Frankfurt | Klussmann-Kolb A.,Goethe University Frankfurt
Systematics and Biodiversity | Year: 2012

Phylogenetic relationships within Pectinidae (Bivalvia, Pteriomorphia) have been investigated primarily for Pacific and Western Atlantic or commercially valuable taxa. Most molecular phylogenetic studies have revealed monophyly of pectinid bivalves but interrelationships of the different clades are still inconsistent. However, non-commercial European Pectinidae has mostly been neglected in earlier investigations and therefore the evolution and radiation of the European Pectinidae is poorly understood. Since the fossil record of this group is well investigated, the evolutionary age of phylogenetic diversification and radiation events within this group can be dated. Thus, the connection of geological and climatic changes to radiation events within this group can be assessed. We investigated the phylogenetic relationships within European Pectinidae using mitochondrial (12S and 16S) and nuclear (18S, 28S and H3) gene markers and performed relaxed molecular clock approaches to gain information on the evolutionary age and the connection between Cenozoic climatic changes and diversification within this group. The results show concordance of radiation events with the Middle Miocene cooling event and the following climatic period with slowly decreasing temperatures. However, geological changes such as the uplift of the Gomphotherium Landbridge or the closure and re-opening of the Strait of Gibraltar also had great impact on diversification and distribution patterns within European Pectinidae. © 2012 The Natural History Museum.


Holland V.,Biodiversity and Climate Research Center ankfurt | Holland V.,Goethe University Frankfurt | Koller S.,Biodiversity and Climate Research Center ankfurt | Koller S.,Goethe University Frankfurt | And 3 more authors.
Trees - Structure and Function | Year: 2016

Key message: Different environmental conditions affect tree senescence by different patterns of carbohydrate concentrations and have specific impact on the dissection of the photosynthetic apparatus. Abstract: A proactive cultivation of Mediterranean broadleaf species, including oaks, has been suggested to fill possible temporal and spatial gaps in forestry created by Climate Change in Central Europe in the future. Climate can affect trees in several different ways, e.g., by modulating the course of leaf senescence. Senescence-associated processes, like regulation of carbohydrates and changes in chlorophyll fluorescence under drought stress conditions were studied with leaf tissue of drought-tolerant downy oak (Quercus pubescens). Two months of consistent drought stress in a frost-free greenhouse led to significantly earlier senescence and significant increased amounts of soluble sugars in the leaves of the drought-stressed group in comparison to a well-watered control group. Similar sugar accumulation was observed in trees outdoors, after exposure to frost. In contrast to monocarpic plants the accumulation of free sugars is neither triggering leaf senescence, nor is it a side effect of age-depending changes in Q. pubescens. Instead, sugar accumulation is induced by abiotical factors, like drought and frost. Furthermore, we suggest that the senescence process in the absence of drought stress or frost depends on the source status of the leaf, which, in term, is a function of light (through photosynthesis) and night temperature (through respiration). Contents of the storage metabolite starch decreased during late summer in all three groups. Drought-stressed plants showed a decline of the connectivity of photosystem II antenna, reflected as the L-band in the chlorophyll fluorescence induction curves, and stronger correlations between the declines in the capacity of photosynthetic dark reactions and electron transport-associated chlorophyll fluorescence parameters. We conclude that the disassembly of single parts of the photosynthetic apparatus during leaf senescence is a uniform process, but the onset of this process depends on abiotical environmental factors. © 2015, Springer-Verlag Berlin Heidelberg.


Malkowsky Y.,Biodiversity and Climate Research Center ankfurt | Malkowsky Y.,Goethe University Frankfurt | Jochum A.,Goethe University Frankfurt
Acta Zoologica | Year: 2015

Recent methodological and technical developments in comparative morphology have broadened understanding of evolutionary traits in molluscs. Scientists are capable of reconstructing organ systems and entire architectural physiologies with utmost precision. The pallial eyes of Pectinidae are amongst the most complex visual systems found in molluscs and have aroused scientific curiosity for decades. This investigation presents the most comprehensive description of pallial eye morphology in four major groups of Pectinidae: Aequipectini group, Pectininae, Chlamydinae and Palliolinae. The cornea, lens, retinae and branching of the optic nerve are depicted in topographic detail. Three-dimensional reconstructions of microtome sections enable the comparison of whole eyes and structures in contrast to single-section analysis. Here, we demonstrate two significant findings: (i) the morphology of corneae and lenses varies in scallop species and (ii) the retinae are innervated in different ways in different species. Moreover, we show how morphological characteristics such as the hyperbolic shape of the lens can be overlooked if only single sections are investigated. © 2014 The Royal Swedish Academy of Sciences.

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