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Simonneau M.,Groupe detude des invertebres armoricains | Courtial C.,Groupe detude des invertebres armoricains | Petillon J.,CNRS Biodiversity and Territory Management Laboratory
Comptes rendus biologies | Year: 2016

Spiders are known to commonly use aerial dispersal, so-called ballooning, especially at juvenile stages. They produce a silk thread that allows them to rise up in the air to disperse, which serves as inbreeding avoidance or to find an optimal over-winter habitat. Studies of phenology, species and meteorological factors associated with aerial dispersal have been limited to laboratory settings, with few data obtained under natural settings and no studies to date executed in France. To understand aerial dispersal, we conducted daily sampling between 2000 and 2002 at a height of 12m. For adults, high proportions of "ballooners" were observed during four seasonal peaks, with dispersal most prevalent during summer, while for juveniles dispersal was protracted across summer and fall. Linyphiidae is the most abundant family among the 10,879 individuals caught. We show a significant and negative influence of high wind speeds on ballooning, an effect that increased even under low temperatures (<19°C). At wind speeds greater than 4m·s(-1) dispersal becomes difficult, and is almost impossible beyond 5.5m·s(-1). Ballooning ability is reported for the first time for several species. This study increases our knowledge on aerial dispersal in spiders in an agricultural context. Such behaviour can be seen as a survival strategy to escape from a disturbed and unstable landscape. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.


Valery L.,CNRS Biodiversity and Territory Management Laboratory | Radureau A.,French National Institute for Agricultural Research | Lefeuvre J.-C.,CNRS Biodiversity and Territory Management Laboratory
Journal of Coastal Conservation | Year: 2016

Contrary to many estuaries where the increase in inputs of nitrogenous nutrients results in a macro-algal or phytoplanktonic bloom, no proliferation of this kind has ever been observed in the waters of Mont-Saint-Michel bay (north-western France) owing to a very high turbidity which greatly limits light penetration. On the other hand, it is well known that the factor that usually limits the growth of vascular plants in salt marshes is not the light resource but nitrogen availability; these plant species are therefore able to benefit fully from the enrichment of water by nitrogenous compounds. This seems to be the case of the sea couch grass Elymus athericus that has spread very rapidly on the salt marshes of this site since the mid-1980s. Firstly, the present study (i) accurately documents, from a compilation of data from administrative archives, the changes in agricultural land use in the major watersheds during the period 1970–2010, together with related changes in the nitrate contents of the rivers flowing into the bay; (ii) quantifies the spatial spread of sea couch grass between 1984 and 2013 from the five maps made during this period. In the second part, using in-depth analysis based on the findings of previous studies, it shows that the expansion of this native grass corresponds to a biological invasion phenomenon, for which nitrogen enrichment of the bay seems to be the only plausible explanation. © 2016 Springer Science+Business Media Dordrecht


Gallon R.K.,French Natural History Museum | Robuchon M.,CNRS Systematics, Biodiversity and Evolution Institute | Robuchon M.,French National Center for Scientific Research | Leroy B.,CNRS Biodiversity and Territory Management Laboratory | And 4 more authors.
Journal of Biogeography | Year: 2014

Aim: To assess environmental changes within a marine biogeographical transition zone and how they have affected seaweed assemblages and distributions over the past two decades. Location: Brittany (western France, Europe) - a biogeographical transition zone between cold-temperate and warm-temperate regions. Methods: We assessed spatio-temporal variation for three environmental parameters [sea-surface temperature (SST), suspended inorganic matter and chlorophyll a] between 1992 and 2012 in five adjoining regions using generalized linear models. To investigate changes in assemblages and distributional patterns of red seaweeds based on sampling surveys conducted during two separate periods (1992-1998 and 2010-2012), we used two complementary approaches, multivariate data analysis and species distribution models (SDMs) with a set of modelling procedures. Results: Coastal water temperature in Brittany has increased by 0.7 °C on average over the past two decades (0.35 °C per decade). At a finer scale, changes in SST showed that Brittany constitutes a mosaic of contrasting conditions, with the western and north-western regions being colder and less affected by climate change than the other three regions. Our results suggest that increasing SST caused significant changes in subtidal red seaweed assemblages over the 20-year period. Between the two periods, SDMs predicted significant species shifts for seven out of ten representative species, and reductions in the distribution ranges of most species. Main conclusions: Our study confirmed important differences across the different regions of the studied biogeographical transition zone. Changes in abiotic parameters and red seaweed assemblages are expected to occur at varying extremes across these regions, with western and north-western Brittany representing the most stable zones that might constitute a potential refuge for certain species when responding to global changes. © 2014 John Wiley & Sons Ltd.


PubMed | Ludwig Maximilians University of Munich, Memory of Time, CNRS Sophia Agrobiotech Institute, CNRS Biodiversity and Territory Management Laboratory and CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments
Type: Journal Article | Journal: Arthropod structure & development | Year: 2016

A new fossil lobster from the Cretaceous of Lebanon, Charbelicaris maronites gen. et sp. nov., is presented here, while the former species Cancrinos libanensis is re-described as Paracancrinos libanensis comb. nov. P. libanensis is shown to be closer related to the contemporary slipper lobsters than to Cancrinos claviger (lithographic limestones, Jurassic, southern Germany). A finely-graded evolutionary scenario for the slipper-lobster morphotype is reconstructed based on these fossil species and extant forms. The evolutionary changes that gave rise to the current plate-like antennae of Scyllaridae, a key apomorphy of this group, are traced back through time. The antenna of what is considered the oldest slipper lobster became petaloid and consisted of about 20 fully articulated elements. For this group the name Scyllarida sensu lato tax. nov. is introduced. In a next evolutionary step, the proximal articles became conjoined and a lateral extension appeared on peduncle element 3. The entire distal petaloid region is conjoined already at the node of Verscyllarida tax. nov. In modern slipper lobsters, Neoscyllarida tax nov., the distal region is no longer petaloid in shape but asymmetrical. The study also emphasizes that exceptionally preserved fossils need to be documented with optimal documentation techniques to obtain all available information.


PubMed | University Claude Bernard Lyon 1, CNRS Biodiversity and Territory Management Laboratory and CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments
Type: Journal Article | Journal: Arthropod structure & development | Year: 2016

Polychelidan lobsters are fascinating crustaceans that were known as fossils before being discovered in the deep-sea. They differ from other crustaceans by having four to five pairs of claws. Although recent palaeontological studies have clarified the systematics and phylogeny of the group, the biology of extant polychelidans and--first of all--their anatomy are poorly documented. Numerous aspects of the evolutionary history of the group remain obscure, in particular, how and when polychelidans colonized the deep-sea and became restricted to it. Surprisingly, the biology of extant polychelidans and the anatomy of all species, fossil and recent, are poorly documented. Here, X-ray microtomography (XTM), applied to an exceptionally well-preserved specimen from the La Voulte Lagersttte, reveals for the first time vital aspects of the external and internal morphology of Voulteryon parvulus (Eryonidae), a 165-million-year-old polychelidan: 1) its mouthparts (maxillae and maxillipeds), 2) its digestive tract and 3) its reproductive organs. Comparisons with dissected specimens clearly identify this specimen as a female with mature ovaries. This set of new information offers new insights into the feeding and reproductive habits of Mesozoic polychelidans. Contrasting with other Jurassic polychelidans that lived in shallow-water environments, V. parvulus spawned in, and probably inhabited, relatively deep-water environments, as do the survivors of the group.


PubMed | CNRS Ecosystems, Biodiversity, and Evolution Laboratory, University Claude Bernard Lyon 1, CNRS Biodiversity and Territory Management Laboratory and University of Rennes 1
Type: | Journal: Journal of insect physiology | Year: 2016

In salt marshes, the alternation of low and high tides entails rapid shifts of submersion and aerial exposure for terrestrial communities. In these intertidal environments, terrestrial species have to deal with an osmotic loss in body water content and an increase in sodium chloride concentration when salt load increases. In salt marshes, spiders represent an abundant arthropod group, whose physiological ecology in response to variations of soil salinity must be further investigated. In this study, we compared the effect of salinity on the survival and physiology of three species of Lycosidae; two salt marsh species (Arctosa fulvolineata and Pardosa purbeckensis) and one forest species (P. saltans). Spiders were individually exposed at three salinity conditions (0, 35 and 70) and survival, changes in body water content, hemolymph ions (Na(+), Ca(2+), Mg(2+), K(+); ICP-MS technique) and metabolites (mainly amino acids, polyols, sugars; LC and GC techniques) were assessed. The survival of the forest species P. saltans was very quickly hampered at moderate and high salinities. In this spider, variations of hemolymph ions and metabolites revealed a quick loss of physiological homeostasis and a rapid salt-induced dehydration of the specimens. Conversely, high survival durations were measured in the two salt-marsh spiders, and more particularly in A. fulvolineata. In both P. purbeckensis and A. fulvolineata, the proportion of Na(+), Ca(2+), Mg(2+), K(+) remained constant at the three experimental conditions. Accumulation of hemolymph Na(+) and amino acids (mainly glutamine and proline) demonstrated stronger osmoregulatory capacities in these salt-marsh resident spiders. To conclude, even if phylogenetically close (belonging to the same, monophyletic, family), we found different physiological capacities to cope with salt load among the three tested spider species. Nevertheless, physiological responses to salinity were highly consistent with the realized ecological niches of the spiders.


Ruhland F.,French National Center for Scientific Research | Petillon J.,CNRS Biodiversity and Territory Management Laboratory | Trabalon M.,French National Center for Scientific Research
Journal of Insect Physiology | Year: 2016

Many arachnids like other terrestrial arthropods, provide extensive maternal care. Few studies have quantified the underlying physiological costs of maternal care. We investigated how maternal care affects the free-moving wolf spider's (Pardosa saltans) energy requirements. We described in detail their basic reproduction biology (i.e. carrying cocoon and young) and we evaluated the variation in the females’ energy reserves during maternal care. Our results show that mothers guard eggs until hatching and then guard their spiderlings for 27–30 more days. Laboratory observations indicated that spiderlings start leaving the maternal abdomen gradually 5–7 days after hatching. Females carry an egg sac (cocoon) that can weigh up to 77% of their post-reproduction weight and carry young that weigh 87–100% of their body mass. Females lost weight over time despite regular food intake, while carrying cocoon and young; but their weights increased gradually during the dispersal of young. The contributions of proteins, glucose and triglycerides to maintain females’ energy were calculated. Their energetic state varied during maternal care, in particular lipid levels declined, during the care of spiderlings when the females’ predatory behaviour was inhibited. Our results show that the maternal care provided by P. saltans females is particularly costly physiologically, during the 30 days following egg sac formation and development of spiderlings, even when food is available. © 2016 Elsevier Ltd


Lafage D.,CNRS Biodiversity and Territory Management Laboratory | Lafage D.,University of Angers | Petillon J.,CNRS Biodiversity and Territory Management Laboratory
Basic and Applied Ecology | Year: 2016

In Europe, agri-environment schemes (AES) have been implemented to counteract the effects of agricultural intensification. Studies investigating the role of management improvement induced by AES are quite numerous, but rarely take into account the effect of natural perturbations such as flooding, although severe disturbances are well known to shape community structure. Here we investigated the relative importance of management improvement and flooding to explain community parameters of two dominant arthropod groups and vegetation in alluvial meadows.Sampling took place in 2013, using suction samplers for arthropods and phytosociological relevés for vegetation, in 83 meadows distributed along 200. km of the Loire Valley (France). Pair-matched approach (by R-ANOVA) was used to assess overall effects of AES whereas a gradient analysis (GLM) was carried out to assess the impact of AES prescriptions (fertilisation and cutting-date) together with indirect (long-term) and direct (short-term) effects of flooding.No significant effect of AES was found on arthropod and plant assemblages, abundance/productivity or diversity (both α and β), but the number of rare plant species was higher in sites under AES. Prescriptions had little impact on most response variables considered; the only significant impact being the positive effect of high-amounts of fertilisers on spider α- and β-diversities. Conversely, systematic long-term effects of flooding were found on all response variables of spiders, carabids and plants, underlining the key role of this factor in alluvial meadows. Our study demonstrates that maintaining or enhancing hydrological functioning of ecosystems is even more important than regulating both the cutting-dates and the low input of fertilisers for conservation purposes in flooded, already naturally nutrient rich, meadows. In Europa wurden Agrar-Umwelt-Programme (AES) begonnen, um den Einflüssen einer intensivierten Landwirtschaft entgegenzuwirken. Untersuchungen zu Verbesserungen durch AES sind recht zahlreich, aber selten berücksichtigen sie den Einfluss natürlicher Störungen (z.B. Überflutungen), obwohl schwere Störungen bekanntlich die Gemeinschaftsstruktur formen können. Wir untersuchten die relative Bedeutung von Verbesserungen durch Bewirtschaftung und Überflutung, um die Gemeinschaftsparameter von zwei Arthropodengruppen sowie der Vegetation in Flussauen zu erklären. Die Probenahmen erfolgten 2013 mit Saugfängen für Arthropoden und vegetationskundlichen Aufnahmen auf 83 Wiesen entlang eines 200. km-Abschnitts der Loire (Frankreich). R-ANOVA wurde benutzt, um die globalen Effekte von AES abzuschätzen, während Gradientenanalysen durchgeführt wurden, um den Einfluss von AES-Vorschriften (Düngung und Mähzeitpunkt) zusammen mit indirekten (langfristigen) und direkten (kurzfristigen) Effekten der Überflutung zu bestimmen. Wir fanden keinen signifikanten Effekt von AES auf die Arthropoden- und Pflanzengemeinschaften, auf Abundanz/Produktivität oder α- oder β-Diversität, aber die Anzahl seltener Pflanzenarten war unter AES erhöht. Die Vorschriften hatten wenig Einfluss auf die meisten der untersuchten abhängigen Variablen; der einzige signifikante Einfluss war der positive Effekt von Düngung auf die α- und β-Diversität der Spinnen. Umgekehrt fanden wir, dass systematische Langzeiteffekte der Überflutung bei allen die Spinnen, Laufkäfer und die Vegetation betreffenden abhängigen Variablen auftraten, was die Schlüsselrolle dieses Faktors in Flussauen unterstreicht. Unsere Untersuchung zeigte, dass Erhalt oder Stärkung des hydrologischen Funktionierens von Ökosystemen noch wichtiger ist, als für Naturschutzzwecke Mähzeiten und Düngergaben in ohnehin nährstoffreichen überflutungswiesen zu regulieren. © 2016 Gesellschaft für Ökologie.


PubMed | Groupe detude des invertebres armoricains and CNRS Biodiversity and Territory Management Laboratory
Type: Journal Article | Journal: Comptes rendus biologies | Year: 2016

Spiders are known to commonly use aerial dispersal, so-called ballooning, especially at juvenile stages. They produce a silk thread that allows them to rise up in the air to disperse, which serves as inbreeding avoidance or to find an optimal over-winter habitat. Studies of phenology, species and meteorological factors associated with aerial dispersal have been limited to laboratory settings, with few data obtained under natural settings and no studies to date executed in France. To understand aerial dispersal, we conducted daily sampling between 2000 and 2002 at a height of 12m. For adults, high proportions of ballooners were observed during four seasonal peaks, with dispersal most prevalent during summer, while for juveniles dispersal was protracted across summer and fall. Linyphiidae is the most abundant family among the 10,879 individuals caught. We show a significant and negative influence of high wind speeds on ballooning, an effect that increased even under low temperatures (<19C). At wind speeds greater than 4ms(-1) dispersal becomes difficult, and is almost impossible beyond 5.5ms(-1). Ballooning ability is reported for the first time for several species. This study increases our knowledge on aerial dispersal in spiders in an agricultural context. Such behaviour can be seen as a survival strategy to escape from a disturbed and unstable landscape.


Audo D.,CNRS Biodiversity and Territory Management Laboratory | Audo D.,CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2016

Polychelidan lobsters are decapod crustaceans characterized by a peculiar morphology: four to five pairs of claws and a flattened body. They were first discovered as fossils long before being discovered in modern deep sea environments. Many aspects of fossil and extant polychelidan biodiversity and ecology still remain poorly understood. This paper documents a new species and genus of polychelidan lobster, Tonneleryon schweigerti n. gen., n. sp. from the Toarcian of Holzmaden (Baden Württemberg, Germany). It also re-describes ?Coleia sinuata Beurlen, 1928, which was confused until now with the new species. Actually, ?Coleia sinuata was described on the basis of a single, poorly preserved, juvenile specimen. Tonneleryon schweigerti is characterized by large eyes, which suggest its vision played an important role in its life-habits. Specimens of Tonneleryon schweigerti are generally preserved in cluster of several individuals, a characteristic unique to this species. All specimens in these accumulation are of similar size and do not possess the characteristics of exuviae such as a split median line or disjunction of carapace and first pleonite. They therefore probably represent a mass-mortality assemblage and suggest this species was gregarious. © 2016 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

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