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A 5000-year pollen and plant macrofossil record from the Osogovo Mountain, Southwestern Bulgaria: Vegetation history and human impact
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Abstract Pollen and plant macrofossil analyses were performed on a sequence 105 cm deep obtained from a peat bog (1750 m) that is located above the present timber-line in the Osogovo Mountain, Southwestern Bulgaria. The palaeovegetation reconstruction, supported by a radiocarbon chronology, revealed the vegetation dynamics and human impact during the last 5000 years. The peat bog formed when a coniferous belt of Abies alba and Pinus (Pinus sylvestris, Pinus nigra) covered the high mountain slopes. Charcoal fragments indicate the presence of a broad-leaved tree community composed of Quercus, Corylus, Carpinus, Tilia, Acer and Ulmus at lower altitudes. Stands of Fagus sylvatica in places with higher air and soil humidity, like river valleys and deep ravines, became established. The pollen assemblages after c. 3200 cal. \BP\ record an important change in the forest composition that led to the replacement of the conifers, mostly A. alba, by the invading communities of F. sylvatica. The reasons for this replacement included factors related to both climate change and anthropogenic disturbance. During the last centuries a large-scale degradation of the woodlands in the mountain has occurred. On a regional scale the palaeoecological evidence is compared with information from palynological, archaeological and historical sources in Southwestern Bulgaria.
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Origin of the forest steppe and exceptional grassland diversity in Transylvania (central-eastern Europe)
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Aim The forest steppe of the Transylvanian Plain is a landscape of exceptionally diverse steppe-like and semi-natural grasslands. Is this vegetation a remnant of a once continuous temperate forest extensively cleared by humans, or has the area, since the last glacial, always been a forest steppe? Understanding the processes that drive temperate grassland formation is important because effective management of this biome is critical to the conservation of the European cultural landscape. Location Lake Stiucii, north-western Romania, central-eastern Europe. Methods We analysed multi-proxy variables (pollen, coprophilous fungi, plant macroremains, macrocharcoal) from a 55,000 year discontinuous sequence (c. 55,000–35,000; 13,000–0 cal. yr bp), integrating models of pollen-based vegetation cover, biome reconstruction, global atmospheric simulations and archaeological records. Results Needleleaf woodland occurred during glacial Marine Isotope Stage (MIS) 3, but contracted at the end of this period. Forest coverage of c. 55% (early Holocene) and 65% (mid-Holocene) prevailed through the Holocene, but Bronze Age humans extensively cleared forests after 3700 cal. yr bp. Forest coverage was most widespread between 8600 and 3700 cal. yr bp, whereas grasses, steppe and xerothermic forbs were most extensive between 11,700 and 8600 cal. yr bp and during the last 3700 cal. yr bp. Cerealia pollen indicate the presence of arable agriculture by c. 7000 cal. yr bp. Main conclusions We have provided the first unequivocal evidence for needleleaf woodland during glacial MIS 3 in this region. Extensive forests prevailed prior to 3700 cal. yr bp, challenging the hypothesis that the Transylvanian lowlands were never wooded following the last glaciation. However, these forests were never fully closed either, reflecting dry growing season conditions, recurrent fires and anthropogenic impacts, which have favoured grassland persistence throughout the Holocene. The longevity of natural and semi-natural grasslands in the region may explain their current exceptional biodiversity. This longer-term perspective implies that future climatic warming and associated fire will maintain these grasslands.
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Pollen analysis of 15th century cesspits from the palace of the dukes of Burgundy in Bruges (Belgium): evidence for the use of honey from the western Mediterranean
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A phylogeny of Cichlidogyrus species (Monogenea, Dactylogyridea) clarifies a host switch between fish families and reveals an adaptive component to attachment organ morphology of this parasite genus
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Background: Parasite switches to new host species are of fundamental scientific interest and may be considered an important speciation mechanism. For numerous monogenean fish parasites, infecting different hosts is associated with morphological adaptations, in particular of the attachment organ (haptor). However, haptoral morphology in Cichlidogyrus spp. (Monogenea, Dactylogyridea), parasites of African cichlids, has been mainly linked to phylogenetic rather than to host constraints. Here we determined the position of Cichlidogyrus amieti, a parasite of species of Aphyosemion (Cyprinodontiformes, Nothobranchiidae) in the phylogeny of its congeners in order to infer its origin and assess the morphological changes associated with host-switching events. Methods: The DNA of specimens of C. amieti isolated from Aphyosemion cameronense in Cameroon was sequenced and analyzed together with that of Cichlidogyrus spp. from cichlid hosts. In order to highlight the influence of the lateral transfer of C. amieti on the haptoral sclerotised parts we performed a Principal Component Analysis (PCA) to compare the attachment organ structure of C. amieti to that of congeners infecting cichlids. Results: Cichlidogyrus amieti was found to be nested within a strongly supported clade of species described from Hemichromis spp. (i.e. C. longicirrus and C. dracolemma). This clade is located at a derived position of the tree, suggesting that C. amieti transferred from cichlids to Cyprinodontiformes and not inversely. The morphological similarity between features of their copulatory organs suggested that C. amieti shares a recent ancestor with C. dracolemma. It also indicates that in this case, these organs do not seem subjected to strong divergent selection pressure. On the other hand, there are substantial differences in haptoral morphology between C. amieti and all of its closely related congeners described from Hemichromis spp.. Conclusions: Our study provides new evidence supporting the hypothesis of the adaptive nature of haptor morphology. It demonstrates this adaptive component for the first time within Cichlidogyrus, the attachment organs of which were usually considered to be mainly phylogenetically constrained.
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Revision of the genus Frechastraea Scrutton, 1968 (Rugosa) in the Upper Frasnian of Belgium
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Multimodal defensive strategies in larvae of two Hemichroa sawfly species
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Diversity of ostracod communities (Crustacea, Ostracoda) across hierarchical spatial scales in a tropical floodplain
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Association of body size and behavior of freshwater ostracods (Crustacea, Ostracoda) with aquatic macrophytes
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New exceptionally well-preserved specimens of “Zangerlia”neimongolensis from Bayan Mandahu, Inner Mongolia, andtheir taxonomic significance
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Two exceptionally well-preserved specimens of “Zangerlia” neimongolensis provide addi-tional information on the structure of the skull, shell and limbs of this taxon. Thesespecimens show that the carapace is more similar to that of Hanbogdemys than was previ-ously recognized. A PAUP analysis results in a single most parsimonious cladogram in whichthe type species of Zangerlia, Zangerlia testudinimorpha is separated from other speciesthat have been included in that genus while “Z.” neimongolensis, “Zangerlia” ukaachelysand “Zangerlia” dzamynchondi and Jiangxichelys are grouped together. Both specimens areexceptional in being preserved in a life-like position: one is preserved with the skull ina retracted position; the other with the head and left forelimb both protracted and in araised position. These positions suggest that they were entombed while still alive. Thusthese specimens provide additional examples of rapid burial of vertebrates in the BayanMandahu locality, most likely from either by sand storms that dumped massive amountsof sand over a short period of time or by collapse of individuals in burrows.
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Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia
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