Search publications of the members of the Royal Belgian institute of natural Sciences
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Total suspended matter maps from chris imagery of a small inland water body in oostende (Belgium)
- It has been already established that total suspended matter (TSM) can be retrieved from CHRIS imagery for turbid coastal waters, but what about inland waters? Because of the high resolution of CHRIS/PROBA images, inland waters not visible by sensors like SeaWiFS, MERIS and MODIS become detectable and are expected to become a key new application domain for optical remote sensing. In the Oostende test site there is a small (800m* 1400m) inland water body with an average depth of 1.5m called the Spuikom. On 6 July 2004, a cloud free CHRIS acquisition of the Oostende test site occurred with simultaneous in situ measurements. The reprocessed dataset is evaluated and analyzed. Data from CHRIS show abnormally high near infrared (NIR) reflectance in the lake, especially near the borders. This does not significantly affect TSM maps but does contaminate the chlorophyll maps deduced from CHRIS imagery. This high NIR reflectance is probably caused by adjacency effects, although the possibility of bottom reflection must also be assessed. In the summer of 2005 a measurement campaign is planned to investigate further the influence of nearby land and bottom reflection in order to provide a benchmark dataset for testing of algorithms to detect and correct for such effects. CHRIS images will be an important component of this dataset.
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Molecular systematics of the endemic Leptaxini (Gastropoda: Pulmonata) on the Azores islands
- The Azorean representatives of the Leptaxini (Pulmonata) are single island endemics, where a high-spired shell distinguishes the monotypic genus Helixena from two slightly different low-spired forms within Leptaxis (azorica and caldeirarum type). We studied the evolutionary history of putative taxa and the three shell-types using 12 allozyme loci and sequences of nuclear (ITS-1 and ITS-2) and mitochondrial DNA (COI and 16S rRNA). While little variation was found in both ITS genes, allozyme and mtDNA divergence was among the highest reported for pulmonate land snails. Generally, phylogeographic patterns are indicative of allopatric differentiation via the successive colonization of (younger) islands, while a major role for adaptive evolution is not supported. The azorica shell-type is monophyletic and has no common history with other sympatric shell-types on the same islands. The (ambiguous) position of Helixena sanctaemariae makes Leptaxis paraphyletic on the Azores and possibly also the caldeirarum shell-type. Helixena can therefore not be distinguished as a separate genus on the Azores. Following a lineage-based concept, representatives on all (ancient) islands should be considered distinct species. © 2005 Elsevier Inc. All rights reserved.
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A micro- and macrobotanical study of two Middle Weichselian, fluviatile deposits in the loam area of middle Belgium
- A palynological study of Middle Weichselian fluviatile deposits, lying at the base of a bipartite loam cover at Soignies and Courcelles, revealed an open landscape with some scattered trees or shrubs of Pinus, Betula and Salix except for the lowermost channel at Soignies, where a boreal forest composed of Alnus, Pinus, Betula and Salix could be reconstructed. The diaspores appear to have been derived from plant communities representing a diversity of habitats, i.e., fully aquatic communities (Charetea, Potametea), swamps and mires (Phragmitetea, Parvocaricetea, Molinio-Arrhenatheretea) and pioneers of bare ground (Bidentetea). The abundance of leaves from Salix herbacea, retrieved from both sites, confirms the arctic climatic conditions. © Royal Botanical Society of Belgium.
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The Middle Holocene shell mound of El Gouna on the Red Sea (Egypt)
- In the El Gouna (Hurghada) area on the Red Sea of Egypt, a Middle Holocene shell mound from around 5800 B.P. (uncalibrated radiocarbon years before A.D. 1950) has been tested by a restricted excavation. Collection of shellfish on the Red Sea shore provided subsistence opportunities for Middle Holocene groups coeval with the Early Predynastic Tasian of the Nile Valley. The El Gouna site demonstrates for the first time that prehistoric shell mounds exist near the Egyptian Red Sea shore.
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Linking science and policy for biodiversity
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The continuous exploitation of wild animal resources in the archaeozoological record of Ghana
- The paper provides a critical review of the archaeozoological information from Ghanaian sites published up to now and summarizes the new faunal analysis of several Gonja and Asante sites. The data suggest the persistence of the use of the various wild animal resources available and limited reliance on domestic animals since late prehistoric times up to today, although certain resources such as molluscs, insects etc. may have limited or no visibility. Intensive utilisation of edible wild resources may be prevalent in African woodlands.
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Post-storm surveys reveal large-scale spatial patterns and influences of site factors, forest structure and diversity in endemic bark-beetle populations
- The storm that struck France on december 26th and 28 th 1999 felled 140 million m3 of timber and had a high economic, social and landscape impact. This event offered the opportunity to study large-scale patterns in populations of forest insect pests that would benefit from the abundant breeding material. A large-scale survey was carried out in France in 2000 to sample the most frequently observed species developing on spruce (Ips typographus, Pityogene schalcographus) and pine (Tomicus piniperda, Ips sexdentatus) in 898 locations distributed throughout wind-damaged areas. The local abundance of each species scored on a 0 to 5 scale was analysed using geostatistical estimators to explore the extent and intensity of spatial autocorrelation, and was related to site, stand, and neighbourhood landscape metrics of the forest cover (in particular the interconnection with broadleaf forest patches) found within dispersal distance. All species but I. sexdentatus, which was much less abundant, displayed large-scale spatial dependence and regional variations in abundance. Lower infestation levels per tree (windfalls and standing trees) were observed in stands with a high proportion of wind-damaged trees, which was interpreted as the result of beetles distributing themselves among the available breeding material. More infestations were observed in wind-broken trees as compared to wind-felled trees. More importantly, populations showed significant relationships with the structure of coniferous stands (in particular with the number of coniferous patches). T. piniperda population levels were negatively correlated to the amount of coniferous edge shared with broadleaf forest patches, possibly because of the disruptive effect of non-host volatiles on host-finding processes at the landscape-scale. The differences observed between species regarding patterns and relationships to site, stand, and forest cover characteristics are discussed in relation to the ecological characteristics of each species. © Springer 2005.
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Imitation systems, monkey vocalization, and the human language
- In offering a detailed view of putative steps towards the emergence of language from a cognitive standpoint, Michael Arbib is also introducing an evolutionary framework that can be used as a useful tool to confront other viewpoints on language evolution, including hypotheses that emphasize possible alternatives to suggestions that language could not have emerged from an earlier primate vocal communication system.
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Villala Goemans and O'Brien, a new genus of Fulgoridae (Hemiptera, Fulgoromorpha) with three new species from Mexico, Belize, Guatemala, Honduras, and Costa Rica
- A new genus of Fulgoridae, Villala, with a long head projection, is described with three new species: V. canoi Goemans from Guatemala, Costa Rica, Belize, and Honduras; V. angelica O'Brien from Costa Rica, and V. platyrhina O'Brien from Mexico. A key to the species and comparative notes are included. © Taylor & Francis.
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The loess-palaeosol succession of Kurtak (Yenisei basin, Siberia): A reference record for the Karga Stage (MIS 3)
- The loess-palaeosol succession of Kurtak, along the western slope of the Yenisei Valley, is one of the best documented Late Pleistocene sequences in southern Central Siberia. The present paper deals with the Kurtak Pedocomplex and with the Chani Bay Complex preserved on the plateau and in a lateral depression respectively, which corre pond to the Karga Stage (MIS 3). For this sequence we obtained a detailed palaeoclimatic succession based on pedological and palynological data recording 14 short interstadial periods. The chronology of this record is well established by ca 100 radiocarbon dates on charcoal and wood remains, ranging from 42,520 to 25,710 BP. Botanical analysis shows a steppe-like vegetation with small tree populations (spruce, pine, birch) in lateral valleys during the colder periods. During the interstadial episodes spruce populations grew denser in the valleys, while scattered spruce, larch and pine trees expanded on the plateau. Therefore, the Kurtak Pedocomplex and Chani Bay Complex provide a unique climatic record for MIS 3, similar to the middle pleniglacial succession of the Dinkel Valley in the Netherlands and to loess-palaeosol records of Eastern and Central Europe. This means that the Siberian record shows a climatic sequence of global significance, and that the environmental conditions during MIS 3 were highly unstable at the Eurasian continent.
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Exploitation of kairomones and synomones by Medetera spp. (Diptera: Dolichopodidae), predators of spruce bark beetles
- The semioehemical relationships in a predator-prey-host plant system were studied by a series of multiple-choice field assays. The studied system included predatory flies of the genus Medetera (Diptera: Dolichopodidae), the bark beetles Ips typographus and Pityogenes chalcographus (Coleoptera: Curculionidae: Scolytinae) as prey and Norwegian spruce (Picea abies) as the host plant. Of the nine species of predators collected, only M. setiventris and M. melancholica provided sufficient data for statistical analysis. The response of the predators to monoterpenic products of the host (alpha-pinene, limonene, camphor), pheromone compounds of I. typographus (S-cis-verbenol and 2-methyl-3-buten-2-ol) and a mixture of the pheromones of I. typographys and P. chalcographus were investigated. Our field trials revealed that tree volatiles plus pheromones of the prey, and a pheromone mixture of both prey species were considerably more attractive to M. setiventris and M. melancholica than the individual chemicals. Medetera seem to respond to the stage of tree decay and the intensity of bark beetle infestation via the ratios of tree volatiles and/or prey pheromones.
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Mate choice in the hermaphroditic land snail Succinea putris (Stylommatophora: Succineidae)
- Internally fertilizing hermaphroditic animals show a bewildering variety of mating behaviours and mechanisms and many species have reciprocal sperm exchange. When matings are frequent and costly, partners are predicted to donate more sperm when they receive more sperm (i.e. conditional sperm exchange), but this has been shown experimentally only in sea slugs, free-living flatworms and possibly cestodes. We studied mate choice and sperm reciprocity patterns in the hermaphroditic land snail Succinea putris. Mate choice was random with respect to shell size. However, in matings where the partners were of unequal size, significantly more matings were observed where a small active individual mated on top of a larger inactive individual than the reverse. We suggest that this may be the result of mating on a vertical substrate or hanging underneath a horizontal substrate, because under these conditions it may be easier for a larger, inactive individual to carry a smaller, active one, than vice versa. The number of sperm transferred during mating was highly variable and was not related to the size of the donor, the size of the recipient, the size difference between the two partners or mating duration. Twelve of the 87 matings involved unilateral sperm exchange. There was no evidence for conditional sperm digestion. There was a significant, but weak positive relation between the numbers of sperm donated by the two partners. Hence, it remains unclear whether sperm exchange in S. putris is conditional or not. © 2005 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
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Molecular phylogeny of coral-reef sea cucumbers (Holothuriidae: Aspidochirotida) based on 16S mitochondrial ribosomal DNA sequence
- Members of the Holothuriidae, found globally at low to middle latitudes, are often a dominant component of Indo-West Pacific coral reefs. We present the first phylogeny of the group, using 8 species from the 5 currently recognized genera and based on approximately 540 nucleotides from a polymerase chain reaction-amplified and conserved 3′ section of 16S mitochondrial ribosomal DNA. Parsimony and likelihood analyses returned identical topologies, permitting several robust inferences to be drawn. Several points corroborated the Linnean classification. Actinopyga and Bohadschia each appear monophyletic and Pearsonothuria is sister to Bohadschia. Other aspects of our phylogeny, however, were not in accord with the taxonomy of Holothuriidae or previous speculations about the group's evolutionary history. Most notably, the genus Holothuria appears paraphyletic. Actinopyga and Bohadschia, sometimes held to be closely related to one another because of certain morphologic similarities, are only distantly related. The morphologically distinct Labidodemas, even thought to warrant separation at the family level, is nested well within Holothuria. A maximum parsimony reconstruction of ancestral ossicle form on the phylogeny indicated that, in addition to a probable bout of elaboration in ossicle form (the modification of rods or rosettes to holothuriid-type buttons), at least 2 rounds of ossicle simplification also transpired in which buttons reverted to rods or rosettes. Cuvierian tubules, defensive organs unique to numerous members of Holothuriidae, were probably present before the initial radiation of the family, but the reconstruction is ambiguous as to their ancestral function. © Springer Science+Business Media, Inc. 2005.
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New metallothionein mRNAs in Gobio gobio reveal at least three gene duplication events in cyprinid metallothionein evolution
- This paper reports the identification and analysis of the primary structure of three novel metallothionein cDNA sequences in the gudgeon, Gobio gobio (Cyprinidae). Two different 180 bp coding regions were identified, resulting in two MT isoforms differing in one amino acid. The primary structure of the amino acid sequence was compared to other cyprinid MT sequences. Furthermore, two differently sized cDNAs were discovered in one of the two transcripts. We present a phylogenetic comparison of our sequences to other, previously published cyprinid MT gene sequences. Our analysis reveals an unexpected complexity in cyprinid MT evolution, with at least three gene duplication events. Differences and homologies between the evolution of cyprinid MT genes are compared to other teleost families. Finally, possible implications for metallothionein classification are discussed. © 2005 Elsevier Inc. All rights reserved.
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Paracrenhydrosoma oceaniae sp. nov. (Copepoda: Harpacticoida), from Kongsfjorden, Northwest Svalbard (Arctic)
- Both sexes of a new species of Cletodidae belonging to the Acrenhydrosoma-lineage are described from material collected at Kongsfjorden (Svalbard) and attributed to the genus Paracrenhydrosoma Gee, 1999. Paracrenhydrosoma oceaniae sp. nov. is easily distinguished from its congeners by the reduced setal formula of the natatorial legs, lacking the inner subdistal seta on segment 3 of legs 3 and 4. Several other characteristics viz. antennular and antennal armature, and the free leg 5 exopodite in both sexes, are indications of its basal position in the genus.
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An assessment of animal species diversity in continental waters
- There is a need for monitoring the status and trends of freshwater biodiversity in order to quantify the impacts of human actions on freshwater systems and to improve freshwater biodiversity conservation. Current projects carrying assessment of freshwater biodiversity focus mainly on leading-better-known groups such as fish, or identify keystone species and/or endemic freshwater systems for conservation purposes. Our purpose is to complete these existing projects by providing quantitative estimates of species number for all freshwater groups on each continent and/or major eco-regions. This article present the results of the first implementation phase carried out from September 2002 to June 2003 and which addressed only freshwater animal species. The project consisted of: (1) compiling existing data from literature, web sites and museum collections; (2) contacting scientific experts of each group to provide a 'to the best of their knowledge, estimates of species numbers. In this study, we consider as true freshwater species, those that complete part or all of their life cycle in freshwater, and water-dependant species those that need freshwater for food or that permanently use freshwater habitats. The current order of magnitude for known freshwater animal species world wide is 100 000, of which half are insects. Among other groups, there are some 20 000 vertebrate species; 10 000 crustacean species and 5000 mollusc species that are either true freshwater or water-dependant species. The study highlighted gaps in the basic knowledge of species richness at continental and global scales: (1) Some groups such as Protozoa, nematodes or annelids have been less studied and data on their diversity and distribution is scarce. Because current richness estimates for these groups are greatly biased by knowledge availability, we can expect that real species numbers might be much higher. (2) Continents are not equal in the face of scientific studies: South America and Asia are especially lacking global estimates of species richness for many groups, even for some usually well-known ones such as molluscs or insects. The second phase of the project will address freshwater plants and algae. The present status should be considered as a first sketch of the global picture of freshwater biodiversity. We hope that this project will initiate interactive exchange of data to complete and update this first assessment. © Springer 2005.
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Taxonomy and systematics in biodiversity research
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Revision of the genus Thambemyia Oldroyd (Diptera: Dolichopodidae) with description of a new subgenus
- The genus Thambemyia Oldroyd is revised. Five species are recognized. Three new species - T. bisetosa, T. bruneiensis and T. hui - are described, and T. pagdeni Oldroyd, 1956 is redescribed. A new subgenus is founded for one new Japanese species, T. (Prothambemyia) japonica. A key to all known species of the genus is provided. Their distributions are also discussed. © 2005 The Entomological Society of Japan.
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The female reproductive organ in podocopid ostracods is homologous to five appendages: Histological evidence from Liocypris grandis (Crustacea, Ostracoda)
- The giant ostracod, Liocypris grandis, found in South African temporary pools, has five pairs of additional appendage-like structures, seemingly associated with the Female Reproductive Organ (FRO). Original investigations of these structures by light and scanning electron microscopy could not unequivocally determine whether or not these structures are homologous to genuine appendages and if so, to how many. The present paper investigates morphology and attachment of these structures by frontal and transversal micro-sectioning (thickness = 1 μ m) of the caudal soft parts of mature females of L. grandis. It is found that all five appendages (R1-R5) have one individual attachment point where they enter into the FRO. Also R3(I) and R3(II) have a single attachment only, these two parts thus represent one single appendage. Whereas R1-R4 have clear lateral insertions, R5 is caudally positioned. The fusion of this latter appendage with the FRO occurs internally, at the posterior edge of the bulge of the FRO and is not externally visible. It is herewith thus accepted that R1-R5 are genuinely endogenous structures (and not, for example, exogenous parasites), that the five structures are homologous to five appendages, and not for example to parts of biramous appendages. It follows from this that the female reproductive organ is homologous to at least five, not to one segment. This would bring the number of (original) thoracic segments in podocopid ostracods to at least 8. An additional pair of triangular structures, inserted in between the two FRO is here described as structures 'X'. Their homology and function remain unknown. © Springer 2005.
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A new species of Glochinema (Epsilonematidae: Nematoda) from the oxygen minimum zone off Baja California, NE Pacific and phylogenetic relationships at species level within the family
- Glochinema spinithorni sp. nov. is described from muddy, bathyal sediments of the oxygen minimum zone (OMZ) of the north eastern Pacific Ocean off Baja California. It is characterized by a rather large body length (over 1 mm), a large number of body rings (242-282), sexual dimorphism in the number and position of pharyngeal thorns near the head region, cuticular ornamentation with numerous hairy spines and two sets of stronger spines ventrally in the anterior body half, mid-sized spiral amphids, and by the number and arrangement of ambulatory setae and long spicules (over 100 μm). The finding of a second OMZ Glochinema species with similar morphological characteristics supports the presumption that OMZs function as isolated habitats promoting endemism at low taxonomic levels. Results of phylogenetic analyses at the species level restricted to the Glochinematinae and Keratonematinae suggest that both OMZ species form a monophyletic group. An attempt was made to recognize phylogenetic relationships at species level within the family. The phylogenetic analyses were based upon a data matrix of 96 ingroup taxa and 25 characters. The results support the monophyly of the genera Leptepsilonema, Metepsilonema, Perepsilonema and Polkepsilonema (with or without Pternepsilonema).
