The excavation campaign in 2011 focussed mainly on investigating the flatland settlement at the foot of the tell ‘‘Magura Gorgana’’. Three trenches respectively were explored in the area northeast and west of the settlement mound. Trenches H, L and P lie ca. 80 northeast of the centre of the tell, and trenches N1, N2 and N3 are located west of that midpoint. They yielded the hitherto oldest excavated material, which has already been radiocarbon dated. Excavations in the outer settlement of Pietrele have brought forth surprising and new perspectives. The oldest settlement attested until now can be dated to the end of the 6th millennium BC, and thus perhaps even to the Middle Neolithic. While a duration of 300 years (4250 to 4550 cal BC) has been confirmed for habitation of the tell, yet without reaching the native soil, find contexts from the end of the 6th and the first half of the 5th and end of the 5th millennium BC have come to light in the flatland settlement. Neolithic and Copper Age settlement remains are present in the immediate vicinity, which is not surprising for a site that was inhabited for a longer time. Hence, in Pietrele the possibility presents itself to research the horizontal stratigraphy of the flatland settlement, link it with the vertical stratigraphy of the tell settlement, and with that to control and render precise the chronological system for the Neolithic. At this point it can already be stated that the boundaries of the flat extended settlement were not reached by geophysical prospection in 2005, neither to the north nor to the west of the tell. Furthermore, geomorphological investigations have already gone far beyond the immediate area of the tell. More than 130 core drillings allow the conclusion that in the course of millennia flowing and standing bodies of water discharged into the Danube meadows. These meadows were covered by a large lake during the time of the tell’s habitation. Initial results of geochemical analyses confirm the existence of this expansive palaeolake before 4600 BC. The basic characteristics of the lake sediments include several massive phases of dark deposits, each a few decimetres in thickness, which are designated as ‘‘dark layers’’ (DL). They mark drastic events in the development of the lake. The lowermost layer, DL I, can be dated by the AMS-14C dating method to the 5th millennium BC, that is, the time of the tell’s habitation. Still to clarify is whether the introduction of organic material through settlement activities and land use had an adverse effect upon the quality of the water.
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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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