Invaders or endemics? Molecular phylogenetics,biogeography and systematics of Dreissena in the Balkans

1. Zebra mussels and their relatives (Dreissena spp.) have been well studied in eastern, central and western Europe as well as in North America, because of their invasiveness and economic importance. Much less is known about the biology and biogeography of indigenous (endemic) taxa of Dreissena, in the Balkans. A better knowledge of these taxa could help us (i) understand the factors triggering invasiveness in some taxa and (ii) identify other potentially invasive species. 2. Using a phylogenetic approach (2108 base pairs from three gene fragments), Dreissena spp. from natural lakes in the Balkans were studied to test whether invasive Dreissena populations occur in such lakes on the Balkan Peninsula, whether Dreissena stankovici really is endemic to the ancient Lakes Ohrid and Prespa, and to infer the phylogenetic and biogeographical relationships of Balkan dreissenids. 3. No invasive species of Dreissena, such as Dreissena polymorpha, were recorded. The supposedly ‘endemic’D. stankovici is not restricted to the ancient Lakes Ohrid and Prespa, but is the most widespread and dominant species in the west‐central Balkans. Its southern sister taxon, Dreissena blanci, occurs sympatrically with D. stankovici in Lakes Prespa, Mikri Prespa and Pamvotis. Both species are classified into the subgenus Dreissena (Carinodreissena) of which the subgenus Dreissena (Dreissena) (which includes the invasive D. polymorpha) is the sister taxon. Dreissena blanci and D. stankovici are considered to represent distinct species. 4. On a global scale, the two Balkan species have small ranges. An early Pliocene time frame for the divergence of the subgenera Carinodreissena and Dreissena is discussed, as well as potential colonization routes of the most recent common ancestor of Carinodreissena spp. 5. The ambiguous taxonomy of dreissenids in the Balkans is addressed. As nominal D. blanci presbensis from Lake Prespa has nomenclatural priority over D. stankovici, the correct name for the latter taxon should be Dreissena presbensis.     

Tuberculation in spatangoid fascioles: Delineating plausible homologies

The existing definition of spatangoid fascioles as a narrow band of minute tubercles (miliaries) is inadequate. One reason is that many intermediates between the presence of indisputable fascioles and their total absence are known. Although fascioles are widely used in the classification of spatangoids, diversity of fasciole tuberculation has largely been ignored. We examine fascioles in about 100 spatangoid species, focusing on the earliest manifestations of fascioles (both developmentally and phylogenetically) and on their variable tuberculation. Qualitative observations are complemented by quantitative analyses (ANOVA and PCA) of 21 species. Three types of fascioles are defined according to tubercle pattern: protofascioles for localized concentrations of miliaries; parafascioles for bands of miliaries with a progressive transition to the surrounding tuberculation; orthofascioles for strongly differentiated, well-circumscribed bands of miliaries. Ontogenetic, architectural, ecological, and taxonomic variations of these three patterns are qualitatively and quantitatively investigated. We attempt to delineate plausible homologies, origins, and subsequent evolution of the different kinds of fascioles.     

Evolution to the extreme: origins of the highly modified apical system in pourtalesiid echinoids

The apical system of the genus Pourtalesia displays a plate architecture that falls so far outside that typical of other echinoids that plate homologies remain problematic. A new approach using the Extraxial–Axial Theory (EAT) that develops homologies for the Echinodermata is proposed. The exploration of apical plate patterns throughout ontogenetic sequences shows that the typical holasteroid pattern found in the youngest specimens undergoes a series of disturbances that result in a multiple disjunction accompanied by isolation or disappearance of certain genital plates. We propose a new interpretation of the apical architecture of the genus that agrees with: (1) the plate addition processes as predicted by the EAT; (2) patterns observed in other genera of the Pourtalesiidae as well as in its sister‐group (plexechinids); and (3) the patterns known from Palaeocene holasteroids. In the context of the EAT, the genus Pourtalesia appears to represent the extreme in a reduction of the extraxial part of the body wall. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140 , 137–155.     

POPULATION GENETICS OF EUROPEAN ANODONTINAE (BIVALVIA: UNIONIDAE)

Enzyme electrophoresis was used to study population geneticsand molecular differentiation of European Anodontmae. The existenceof two genera (Anodonta Lamarck 1799 and Pseudanodonta Bour-guignat1876) is supported by the number of diagnostic loa (4) and Net'sD > 0.463 in all cases. In western and central Europe thereare two species of Anodonta, A. anatina (Linnaeus 1758) andA cygnea (Linnaeus 1758) while two other taxa of still uncertainrank were identified in the Mediterranean area. An estimatedmedium level of gene flow and pronounced genetic differentiationbetween-the taxa support this view. Data on genetic distancessuggest that the diversification of European Anodontinae tookplace in the middle-late Pleistocene (Received 15 August 1995; accepted 5 February 1996)     

Sequestration and turnover of bacterial- and fungal-derived carbon in a temperate grassland soil under long-term elevated atmospheric pCO2

Temperate grasslands contribute about 20% to the global C budget. Elevation of atmospheric CO₂ concentration (pCO₂) could lead to additional C sequestration into these ecosystems. Microbial‐derived C in the soil comprising about 1–5% of total soil organic carbon may be an important ‘pool’ for long‐term storage of C under future increased atmospheric CO₂ concentrations. In our study, the impact of elevated pCO₂ on bacterial‐ and fungal‐derived C in the soil of Lolium perenne pastures was investigated under free air carbon dioxide enrichment (FACE) conditions. For 7 years, L. perenne swards were exposed to ambient and elevated pCO₂ (36 and 60 Pa pCO₂, respectively). The additional CO₂ in the FACE plots was depleted in ¹³C compared with ambient plots, so that ‘new’ (<7 years) C inputs in the form of microbial‐derived residues could be determined by means of stable C isotope analysis. Amino sugars in soil are reliable organic biomarkers for indicating the presence of microbial‐derived residues, with particular amino sugars indicative of either bacterial or fungal origin. It is assumed that amino sugars are stabilized to a significant extent in soil, and so may play an important role in long‐term C storage. In our study, we were also able to discriminate between ‘old’ (> 7 years) and ‘new’ microbial‐derived C using compound‐specific δ¹³C analysis of individual amino sugars. This new tool was very useful in investigating the potential for C storage in microbial‐derived residues and the turnover of this C in soil under increased atmospheric pCO₂. The ¹³C signature of individual amino sugars varied between ?17.4‰ and ?39.6‰, and was up to 11.5% depleted in ¹³C in the FACE plots when compared with the bulk δ¹³C value of the native C3 L. perenne soil. New amino sugars in the bulk soil contributed up to 16% to the overall amino sugar pool after the first year and between 62% and 125% after 7 years of exposure to elevated pCO₂. Amounts of new glucosamine increased by the greatest amount (16–125%) during the experiment, followed by mannosamine (?9% to 107%), muramic acid (?11% to 97%), and galactosamine (15–62%). Proportions of new amino sugars in particle size fractions varied between 38% for muramic acid in the clay fraction and 100% for glucosamine and galactosamine in the coarse sand fraction. Summarizing, during the 7‐year period, amino sugars constituted only between 0.9% and 1.6% of the total SOC content. Therefore, their absolute significance for long‐term C sequestration is limited. Additionally new amino sugars were only sequestered in the silt fraction upon elevated pCO₂ exposure while amino sugar concentrations in the clay fraction decreased. Overall, amino sugar concentrations in bulk soil did not change significantly upon exposure to elevated pCO₂. The calculated mean residence time of amino sugars was surprisingly low varying between 6 and 90 years in the bulk soil, and between 3 and 30 years in the particle size fractions, representing soil organic matter pools with different but relatively low turnover times. Therefore, compound‐specific δ¹³C analysis of individual amino sugars clearly revealed a high amino sugar turnover despite more or less constant amino sugar concentrations over a 7 years period of exposure to elevated pCO₂.     

RICIN-BINDING PROTEINS ALONG THE ENDOCYTIC PATHWAY: THE MAJOR ENDOSOMAL RICIN-BINDING PROTEIN IS ENDOSOME-SPECIFIC

Ricin is internalized after binding at the cell surface via lectin activity of the B-chain recognizing terminal galactose residues. Ricin-A chain is then translocated to the cytosol from various endocytic structures. Cell death is the result of catalytic inactivation of protein synthesis. Using ¹²⁵I-ricin overlays, we examined the distribution of ricin binding-proteins within highly purified preparations of plasma membrane vesicles, endosomes and lysosomes from lymphocytes. All compartments of the endocytic pathway had distinct profiles; some ricin-binding proteins were present throughout the pathway; others were restricted to the plasma membrane and endosomes. The major endosomal protein recognized by ¹²⁵I-ricin, a 166kDa glycoprotein, was endosome-specific. When endosomal proteins were solubilized before chromatography onto ricin-agarose this protein was also by far the major specifically-bound glycoprotein. This 166 kDa glycoprotein might be involved in ricin translocation from this compartment.     

YOLDIELLA SEGUENZAE, A NEW SPECIES OF NUCULANIDAE (BIVALVIA; NUCULOIDA) FROM THE MEDITERRANEAN SEA

A new species, Yoldiella seguenzae (Bivalvia, Nucu-loida), froma deep sea community off the north east coast of Sardinia (MediterraneanSea), is described. Morphometrical and statistical comparisonwith the very similar Yoldiella philippiana (Nyst, 1845), andgeneral morphological comparison with other Mediterranean andAtlantic species support the distinc-tivness of Y. seguenzaewhich is distributed in deep waters of the Central MediterraneanSea, Alboran Sea and the Atlantic Ocean. (Received 21 October 1993; accepted 1 July 1994)     

Mathematical modeling of soil carbon turnover in natural Podocarpus forest and Eucalyptus plantation in Ethiopia using compound specific δ13C analysis

Forest soils exhibit huge potential in storing carbon, but may also release large amounts of it if they undergo major changes in land use and environmental conditions. Biogeochemical processes controlling accumulation and release of soil organic carbon (SOC) are not yet sufficiently understood. We investigate the dynamics of SOC depending on its chemical composition below a natural forest (Podocarpus falcatus dominated) and a plantation (Eucalyptus saligna) growing on Nitisols in southern Ethiopia. Soils at the study‐site show a huge shift to less negative δ¹³C values at a depth of 20–30 cm, indicating a change from C4 savanna to C3 forest during the late Holocene. Total organic carbon (TOC), black carbon (BC), and sugars from microbial (rhamnose, fucose) and plant origin (xylose, arabinose) are subjected to compound‐specific stable isotope analysis. Turnover characteristics are calculated using a numerical advection–diffusion–decomposition model. Our measurements show significant differences in carbon storage (P<0.05) for both sites (Podocarpus 23.5 ± 3.2 kg SOC m^?3; Eucalyptus 18.6 ± 2.7 kg SOC m^?3). These differences can be explained with an initial loss of 15–26% of TOC about 50 years ago, induced by clearing the natural forest. After canopy closure, the carbon input below Eucalyptus is 15–34% less than below natural forest. At present, mean residence times (MRTs) of the investigated compounds do not differ between both stands. Sugars show the shortest MRTs in the topsoil with 2–7 years (xylose) and 5–13 years (arabinose) and have been affected the most by clear‐cutting. TOC and BC show MRTs of 13–25 years and 20–34 years, respectively. Old C4 carbon below 20 cm has merely been affected by the land use change. Contrary to expectation, our study does not indicate a pronounced recalcitrance of BC.     

Evolution of ontogenetic allometry shaping giant species: a case study from the damselfish genus Dascyllus (Pomacentridae)

The evolution of body size, the paired phenomena of giantism and dwarfism, has long been studied by biologists and paleontologists. However, detailed investigations devoted to the study of the evolution of ontogenetic patterns shaping giant species are scarce. The damselfishes of the genus Dascyllus appear as an excellent model for such a study. Their well understood phylogeny reveals that large‐bodied species have evolved in two different clades. Geometric morphometric methods were used to compare the ontogenetic trajectories of the neurocranium and the mandible in both small‐bodied (Dascyllus aruanus and Dascyllus carneus; maximum size: 50–65 mm standard length) and giant (Dascyllus trimaculatus and Dascyllus flavicaudus; maximum size: 90–110 mm standard length) Dascyllus species. At their respective maximum body size, the neurocranium of the giant species is significantly shorter and have a higher supraoccipital crest relative to the small‐bodied species, whereas mandible shape variation is more limited and is not related to the ‘giant’ trait. The hypothesis of ontogenetic scaling whereby the giant species evolved by extending the allometric trajectory of the small‐bodied ones (i.e. hypermorphosis) is rejected. Instead, the allometric trajectories vary among species by lateral transpositions. The rate of shape changes and the type of lateral transposition also differ according to the skeletal unit among Dascyllus species. Differences seen between the two giant species in the present study demonstrate that giant species may appear by varied alterations of the ancestor allometric pattern. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 99–117.