Co-evolution between parthenogenesis-inducing Wolbachia and its hosts.

Wolbachia are intracellular, symbiotic bacteria, known for their ability to manipulate the reproduction mechanism of their arthropod hosts, for example by inducing parthenogenesis. In this thesis, I studied the causes, consequences and dynamics of a parthenogenesis-inducing (PI) Wolbachia infection in two hosts, the parasitoid wasps Tetrastichus coeruleus (Hymenoptera: Eulophidae) and Asobara japonica (Hymenoptera: Braconidae). Interestingly, both T. coeruleus and A. japonica have Wolbachia-infected parthenogenetic populations and uninfected sexual populations. The main conclusions of this thesis are as follows. First, different scenarios may occur for the spread of PI-Wolbachia infection in different host species. Wolbachia has spread via vertical transmission through populations of T. coeruleus, whereas in A. japonica Wolbachia has spread via horizontal transmission. Second, different barriers may prevent migration and gene flow between Wolbachia-infected and uninfected populations in different host species. In T. coeruleus the different populations occur in different ecological environments, whereas in A. japonica there seems to be a geographical barrier between the different populations. Third, different ages of the PI-Wolbachia infection may have different consequences for the host species. The occasional male production by Wolbachia-infected A. japonica might be explained by the relatively young age of the infection. The Wolbachia infection in T. coeruleus seems to be older. Last, a PI-Wolbachia infection can have severe consequences for the sexual functionality of infected males and females. PI-Wolbachia seems to induce cytoplasmic incompatibility in infected A. japonica males. PI-Wolbachia-infected T. coeruleus females exhibited a degradation of receptivity to matings and of spermathecal morphology.LEI Universiteit LeidenNetherlands Organization for Scientific Research division Earth and Life Sciences (NWO-ALW), J.E. Jurriaanse Stichting Rotterdam.Dierenecologi

Triassic Isopoda – three new species from Central Europe shed light on the early diversity of the group

Despite its vernacular names (e.g. ‘woodlice’) Isopoda is a group with mostly aquatic species, with most species living in marine environments. The fossil record for isopods compared to other groups of Eucrustacea is relatively sparse. This applies even more for the Triassic. While in the Jurassic Isopoda is relatively well represented by fossils, only eight species have previously been described from the Triassic. In this study three new species of Isopoda are described from two field sites in Europe: Obtusotelson summesbergeri sp. nov. and Discosalaputium aschauerorum sp. nov. from Polzberg (Gaming, Lower Austria, Austria) and Gelrincola winterswijkensis sp. nov. from Winterswijk (Gelderland, Netherlands). All three new species are interpreted as representatives of Scutocoxifera (ingroup of Isopoda). The species Gelrincola winterswijkensis sp. nov. is further interpreted to be a representative of Cymothoida (ingroup of Scutocoxifera). Most of the oldest fossils of Isopoda belong to Phreatoicidea, which is supposed to be the sistergroup to all remaining Isopoda. Nowadays, Phreatoicidea is a small relic group, its representatives living in freshwater environments. The new species herein presented contribute to our understanding of the diversity of Isopoda in the Triassic and support the assumption that the transition from a dominance of Phreatoicidea towards the dominance of the remaining lineages of Isopoda happened quite early (likely prior to the Triassic)

-A calf-dominated mammoth age profile from the 27 kyBP stadial Krems- Wachtberg site in the middle Danube valley -in

A short rescue-excavation in 1930 at a c.15 m 2 encampment area recovered remains from at least eight individual mammoths (Mammuthus primigenius), six wolves (Canis lupus), four red foxes (Vulpes vulpes), one arctic fox (Alopex lagopus), three wolverines (Gulo gulo), and single remains from reindeer (Rangifer tarandus), red deer (Cervus elaphus), ibex (Capra ibex), and musk ox (Ovibos moschatus). The body part representation and the bone modification patterns of the species are studied, and the death age profile of the mammoth bone sample is figured. The archeological documentation of the site, the preservation state of the bones, and the evidence of delicate bone fragments support a geologically short-time generated origin of the sample with only light disturbance by carnivores. The remains of at least four calves of suckling age, as well as two subadults, and two adults, at least one bull, may be caused by the exploitation of a mammoth family group. Within the body parts of the juveniles, heads including isolated milk teeth are overrepresented. The osteological patterns of the proboscidean finds indicate the utilization of head, back, and foot parts, as well as long bone and rib internals. Cortical bone fragments were used for works and tools. By ethological analogy the death age profile pleads for a proliferating mammoth population. The second main property of the sample is the extraordinary high carnivore representation, which is over 50 % of the minimal number of individuals, and the evidence of their butchering. Under three models about the procurement strategy, the task independent model, the natural cooccurrence model, and the co-occurrence exploiting model, this last one is favoured: The Pavlovian people confronted family herd-units, using any ambush place within the multiformity of the regional landscape, and selectively brought carcass parts back to the residential camp. The prey spectrum and the multiform landscape reflect a variety of potential forage grounds. This and the postulated healthy mammoth herd structure, suggest high yield environmental conditions, and a stable supply position of the Pavlovian people. Site occupation, interpreted from the mammoth calf ages, and from the osteological patterning of the medium-sized herbivore and carnivore carcasses, was probably during the winter months. The contextual occurrence of the zoomorphous burnt clay figurines and the animal parts may reflect a non-subsistential set of human behavior

Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy

We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1–100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc

A leatherback turtle (Testudines, Dermochelyidae) from the Miocene of the Westerschelde, the Netherlands

The Westerschelde Estuary in The Netherlands is known for its rich vertebrate fossil content. In a recent trawling campaign aimed at sampling a late Miocene marine vertebrate assemblage, over 5000 specimens were retrieved, all currently stored in the Natuurhistorisch Museum Rotterdam. One specimen is a well preserved fragment of a dermochelyid sea-turtle carapace. The Westerschelde specimen is an addition to the scant hypodigm of dermochelyids from the Miocene North Sea. The carapace fragment is described and identified as Psephophorus polygonus. The various secondary marks present on the fragment are suggestive of both predatory and scavenging origin. Based on the assumption that P. polygonus had a similar carapace structure as recent D. coriacea, the minimal size of the complete carapace is estimated to have been 168 x 126 cm. Furthermore, based on the physical traits of the Westerschelde specimen and a reexamination of P. polygonus specimens, including the neotype stored at the Naturhistorisches Museum Wien (Austria), it is argued that previously assigned characteristics cannot be used as discriminative taxonomic properties of dermochelyids in general, and of P. polygonus in particular. An improved cladistic analysis on dermochelyids is performed based on previously defined and new taxonomic characters. Using this analysis it is argued that Psephophorus calvertensis is a junior synonym of P. polygonus. Hence, a new diagnosis of Psephophorus polygonus is defined. The ‘addition’ of P. calvertensis to the species P. polygonus confirms its presence on both sides of the Atlantic Ocean. Therefore, we suggest P. polygonus to have had a cosmopolitan distribution, similar to the extant species Dermochelys coriacea

A non-marine horseshoe crab from the Middle Triassic (Anisian) of the Netherlands

Horseshoe crabs (Xiphosura) have a long evolutionary history starting in the Ordovician, but they have rarely been reported from the Netherlands. We report on the first Triassic horseshoe crab from the Netherlands identifiable to the species level, a specimen of the limulid Limulitella bronnii.We provide the first diagnosis for this species and refigure the holotype. The new specimen was found in the Middle Triassic (Anisian) Muschelkalk sediments of the Vossenveld Formation, in the Illyrian part of the stratigraphic profile of the Winterswijk quarry complex. The Winterswijk specimen represents the youngest occurrence of L. bronnii. The inferred nonmarine habitat of this horseshoe crab species elsewhere in conjunction with occurrences of plant and insect remains within the same layer at Winterswijk suggest the specimen herein most probably did not live in marine conditions either. This species has previously been found in non-marine sediments in France and Germany, expanding its geographic range northward. Several faunal elements from Winterswijk including L. bronnii show resemblance to the roughly co-eval non-marine components of the Anisian Grès à Voltzia Formation in NE France, suggesting a paleobiogeographic connection between these regions in Western Europe

Investigating seasonal mobility in Irish giant deer Megaloceros giganteus (Blumenbach, 1799) through strontium isotope (87Sr/86Sr) analysis

Giant deer Megaloceros giganteus (Blumenbach, 1799) fossils are commonly found in Lateglacial deposits throughout Ireland. While their migrational behaviour has been suggested, it has never been researched. We hypothesise that giant deer underwent seasonal migrations, specifically during Late Pleistocene cold periods as a behavioural adaptation. Giant deer required a high nutrient uptake and were maladapted to the cold‐dry steppe of the Pleistocene glacials. Migration allowed for optimal nutrient uptake during summer, while avoiding the harsh winter conditions of the glacials by moving to sheltered, low‐lying areas. In this study strontium isotope analysis (87Sr/86Sr) of sequentially sampled dental enamel is conducted for the first time on giant deer that were previously sampled in the same manner for δ13C and δ18O, allowing correlations between the isotope data sets. One specimen from Ballybetagh, Dublin generated results indicating seasonal mobility behaviour. This individual was perhaps pushed to migrate at the Younger Dryas stadial onset as the vegetation giant deer depended on disappeared in Ireland. Adaptive mobility behaviour in response to climate was perhaps imperative to their survival through previous glacial periods, but other Eurasian populations would need to be analysed to make such a general conclusion