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The dynamics of ant mosaics in tropical rainforests characterized using the Self-Organizing Map algorithm
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Ants, the most abundant taxa among canopy-dwelling animals in tropical rainforests, are mostly represented by territorially-dominant arboreal ants (TDAs) whose territories are distributed in a mosaic pattern (arboreal ant mosaics). Large TDA colonies regulate insect herbivores, with implications for forestry and agronomy. What generates these mosaics in vegetal formations, which are dynamic, still needs to be better understood. So, from empirical research based on three Cameroonian tree species (Lophira alata, Ochnaceae; Anthocleista vogelii, Gentianaceae; and Barteria fistulosa, Passifloraceae), we used the Self-Organizing Map (SOM, neural network) to illustrate the succession of TDAs as their host trees grow and age. The SOM separated the trees by species and by size for L. alata, which can reach 60 m in height and live several centuries. An ontogenic succession of TDAs from sapling to mature trees is shown, and some ecological traits are highlighted for certain TDAs. Also, because the SOM permits the analysis of data with many zeroes with no effect of outliers on the overall scatterplot distributions, we obtained ecological information on rare species. Finally, the SOM permitted us to show that functional groups cannot be selected at the genus level as congeneric species can have very different ecological niches, something particularly true for Crematogaster spp. which include a species specifically associated with B. fistulosa, non-dominant species and TDAs. Therefore, the SOM permitted the complex relationships between TDAs and their growing host trees to be analyzed, while also providing new information on the ecological traits of the ant species involved. This article is protected by copyright. All rights reserved.
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RBINS Staff Publications
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The dynamics of ant mosaics in tropical rainforests characterized using the Self-Organizing Map algorithm
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RBINS Staff Publications 2016
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The earliest Eocene mammal fauna of the Erquelinnes Sand Member near the French-Belgian border
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The earliest Eocene Erquelinnes site was discovered in 1880, but its mammal fauna has been frequently ignored. This paper provides the first detailed overview of the Erquelinnes mammals since 1929. The new faunal list doubles the known diversity at Erquelinnes to a total of 16 species, now also including amphilemurids, hyaenodontids, mesonychids, louisinids, equids and diacodexeids. The majority of the Erquelinnes species is also present in the earliest Eocene Dormaal MP7 reference fauna, with as most notable exceptions the presence of a potentially dwarfed specimen of Dissacus, and of two perissodactyl taxa at Erquelinnes. The ceratomorph perissodactyl Cymbalophus cuniculus is also known from the earliest Eocene of England, but a specimen identified as cf. Sifrhippus sandrae is closely similar to contemporaneous primitive North American equids. This specimen represents the oldest unambiguous European equid and highlights faunal similarities between Europe and North America during this time interval. Faunal differences between Erquelinnes and Dormaal seem mostly due to depositional differences, and the Erquelinnes fauna represents a typical earliest Eocene fauna, closely similar to other MP7 and PEI faunas in Europe.
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The earliest evidence for deformation of livestock horns: The case of Predynastic sheep from Hierakonpolis, Egypt
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Archaeozoological evidence for the modification of sheep horns during Egypt's Predynastic period was uncovered at Hierakonpolis, Upper Egypt. At HK6, the site's so-called elite cemetery, a grave, which was part of a larger mortuary complex dated to around 3700 BC, contained at least 6 large, castrated male sheep. One individual was polled, while four others were of the corkscrew-horn type, but their horns were not oriented in the natural, lateral direction. Instead, the horns had been intentionally manipulated to grow upwards and in three cases this resulted in upright, parallel horns. While comparable practices are well documented in Africa in cattle through both modern ethnographic observations and archaeozoological studies of material from third millennium BC Nubia (in Kerma, Sudan), the Hierakonpolis sheep provide the oldest evidence for horn modification of livestock, and the first demonstration of the practice applied to sheep. When describing the skulls particular attention is paid to the pathological traces and deformities, i.e. constrictions on the horn cores, holes at the horn core bases, and deformations of the frontals. In order to assess the possible methods used in Predynastic Hierakonpolis to redirect the horns, these observations are compared with ethnographic and archaeozoological data from the literature. Finally, the possible reasons why these sheep were modified are also discussed. This study indicates that Predynastic Egyptians were already familiar with horn modelling techniques and confirms that this practice has a long history in the Nile Valley.
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RBINS Staff Publications 2024
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The Early Carboniferous progymnosperm Protopitys: new data on vegetative and fertile structures, and on its geographic and stratigraphic distribution
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We review progress made during the last 25 years in our understanding of the Protopityales, Early Carboniferous plants belonging to the extinct group of the progymnosperms. Recent studies support previous observations that the only genus of this order, Protopitys, included large arborescent plant with trunks up to 1 m in diameter. All branch orders had an oval eustele, secondary xylem with small rays and tracheid pitting ranging from circular bordered to scalariform bordered, and vascular traces to lateral appendages emitted in an alternate to subopposite distichous arrangement. Leaf morphology remains unknown. New material also confirms that fertile organs of Protopitys consist of branching systems bearing elongated sporangia terminally. Spores have a perispore and range in two size groups, which has been interpreted as a primitive stage of heterospory. The dense wood and fertile parts of Protopitys are comparable to those of the aneurophytalean progymnosperms of the Devonian, but Protopitys is distinct by its eustelic primary vascular system, and its affinities are still uncertain. The genus is now documented from at least nine localities in Europe, North America and Australia. Recent discoveries also indicate that it was present through the whole Mississippian, from the middle Tournaisian to the Serpukhovian.
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The Early Miocene odontocete Araeodelphis natator Kellogg, 1957 (Cetacea; Platanistidae), from the Calvert Formation of Maryland, U.S.A.
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RBINS Staff Publications 2017
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The ecological role of ponds in a changing world
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RBINS Staff Publications
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The ecological role of ponds in a changing world. Hydrobiologia
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RBINS Staff Publications
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The Ecology and Feeding Habits of the Arboreal Trap-Jawed Ant Daceton armigerum
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RBINS Staff Publications
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The ecology of benthopelagic fishes at offshore wind farms: a synthesis of 4 years of research.
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RBINS Staff Publications