Mountain slopes are known to promote the diversity and endemism of most taxa. Consequently, turnover of species is expected to be increased along elevational gradients compared to more uniform lowland areas of tropical forests. Mt. Wilhelm, the highest peak of Papua New Guinea, represents one of the last complete altitudinal forest transects with high-levels of biodiversity and pristine forests all along. We studied species diversity and distribution of the Mt. Wilhelm ant communities from 200 m a.s.l. up to tree line at 3700 m a.s.l., using a wide scope of sampling techniques. For the first time, the ants were sampled across different forest strata and at equally spaced elevational bands (500 m a.s.l.) along the complete gradient (257 species in total). The ants occurred up to 2700 m a.s.l. with general decline of their abundance and species richness with altitude, but not in the same way across forest strata. While the species occurrences linearly declined on the ground, they were highest at mid elevations on the vegetation. Species richness peaked at mid altitudes in all strata. Species composition varied both with sampled stratum and elevation, and there was an increase of soil-nesting species sampled on vegetation with increasing altitude. Most species occurred only in one or two elevational sites and there was no difference in the mean elevational range between ground-nesting and arboreal-nesting species. A simple model based on the species accumulation curves suggested that the Mt. Wilhelm ant species richness is two-fold increased, if rarefied to and compared with the same number of individuals as sampled in the lowlands. Our study demonstrates that pristine rainforests of Mt. Wilhelm considerably boost species diversity and endemism, and as such they should be of high conservation priority.
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RBINS Staff Publications 2019
Connectivity throughout the life cycle of flatfish remains an open question, especially at the early life stages. The case of sole (Solea solea) is of particular interest because it is one of the most valuable commercial species in the North Sea. It is crucial to understand how the spawning grounds and nurseries are connected and what are the processes influencing larval retention and dispersal in order to propose appropriate management measures. Especially, dispersal during the larval stage is still poorly known. The transport of sole larvae from the spawning grounds to the nurseries is driven by hydrodynamic processes but the final dispersal pattern and larval abundance at nurseries might be affected by biological processes and environmental factors. Larval Transport Models (LTMs) coupled to Individual-Based Models (IBMs) are more and more commonly used to assess the relative contribution of these processes on the larval dispersal. IBMs allow to take into account growth to estimate the duration of dispersal based on environmental conditions met by the larvae. These models may be sensitive to process parametrization and may give different results for parametrizations derived from the same data set. The Larvae&Co model (Lacroix et al., 2013) used in the frame of B-FishConnect project couples the 3D hydrodynamic model Coherens with an IBM of sole larvae. It is used here to investigate the impact of parametrization of the stage duration on the dispersal of sole larvae in the North Sea. In this study, we compare two parametrizations (Rochette et ai, 2012 and Lacroix et ai, 2013) of the stage duration (temperature dependent) derived from the same data set (mainly Fonds, 1979). We show that only small differences of the stage duration parametrization may induce significant differences of the dispersal pattern, connectivity and larval recruitment at nursery. This highlights the importance to parametrize biological processes with accuracy and the need to collect sufficient data (samples, genotypes and otoliths) and conduct experimental studies to derive biological processes parametrizations in order to improve model’s reliability.
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In last decades, scholars have highlighted the usefulness of birds, as part of the small game, to help understanding complex human behaviour and choices during the Prehistory. While the exploitation of birds has been documented in several sites in eastern or southern Europe, what happened in north-western Europe is still largely unknown due to a lack in the preservation and in the study of bird material. In this context, archaeological assemblages from Belgium offer a great opportunity to better understand the exploitation of birds in this part of Europe, because of the good conditions of preservation offered by its partially karstic subsoil. Here, we present the results of the study of the bird material from the largest Late Magdalenian assemblage of Belgium, the cave site of the Trou de Chaleux. Archaeological excavations at the Trou de Chaleux at the end of the 19th century yielded a vast assemblage of lithic and bone material as well as figurative art, characteristic of the Late Magdalenian. AMS dates with calibrated ages range from 15,733 cal BP to 14,134 cal BP, situating the main archaeological deposit from the Trou de Chaleux at the transition of Greenland Stadial-2 to Greenland Interstadial-1 (Bølling-Allerød Interstadial). Among the archaeozoological material, more than 500 bird bones have been isolated, which had never been studied. We performed the taxonomic and skeletal identification of the material and we examined in detail the surface of the bones in search of human modifications such as tool marks, fire traces or pigment deposits. Surface alterations were investigated based on a macro- and microscopic analysis, including an analysis of wear traces and elementary composition. More than 30 bird bones display traces of human intervention, mainly tool marks. The traces observed indicate an intense exploitation of birds for food, technical but also symbolic purposes. Ptarmigans, ducks, snowy owl and northern raven were consumed. The bones of the largest taxa such as geese, swan or loon were used as raw material to produce tubes and needles. Feathers were also extracted. Finally, talons of golden eagle, northern raven and snowy owl have been sought after for non-utilitarian purposes. The study of the bird material from the Trou de Chaleux helps precising exploitation patterns of animal in north-western Europe and allow comparisons with other regions. The strong interest observed for geese could be a regional particularity.
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