Bathysabellaria neocaledoniensis, a new genus and species of Sabellariidae (Annelida, Polychaeta) from bathyal zones off New Caledonia (Southwest Pacific Ocean)

A new genus and species of Sabellariidae is described from deep water off New Caledonia and compared with other sabellariids having four parathoracic segments.     

Quantifying the effects of temperature and flow regime on the abundance of 0+ cyprinids in the upper River Rhone using Bayesian hierarchical modelling

1. Assuming that recruitment variation is one of the main sources of fish population and assemblage changes, it is necessary to understand how natural variations in the environment influence 0+ fish abundance. Temperature regimes play an important role in enhancing both spawning activity and survival during early larval fish development. Flow regime variation, which is a powerful source of stream disturbance, is another factor to be taken into account. 2. Responses to these variables need to be assessed using long‐term datasets, since standard statistical approaches fail to provide a causal structure or to quantify the different effects. We therefore used a 26‐year dataset to evaluate the respective effects of seven derived independent variables describing the effects of temperature and flow regimes on the 0+ juvenile abundance of eight fish species in the River Rhone. 3. A clustering procedure using the Kendall tau rank correlation coefficient was implemented and identified three groups of fish according to their synchronic variations in juvenile abundance; i.e. varying with decreasing juvenile abundance, slightly increasing juvenile abundance and increasing juvenile abundance. These clusters provided the basis for building hierarchical log‐Poisson generalized linear models. The Bayesian paradigm gives a reliable framework for model selection, and the best model was determined using the Bayes Factor. 4. The posterior distribution of the regression parameters was coherent with what was expected based on knowledge of the biology of the different species. It indicates that temperature regime drives 0+ juvenile abundance but that flow regime also plays an important regulating role. The models thus detected evidence of the consequences of specific flow events such as larval drift and an increase in available habitat during higher flow discharges. 5. Our study illustrates the advantages of using a hierarchical modelling approach to quantify ecological effects by improving discrimination between the different sources of uncertainty, leading to better precision when estimating regression parameters.     

Species richness of insect herbivore communities on Ficus in Papua New Guinea

Insect herbivores were sampled from the foliage of 15 species of Ficus (Moraceae) in rainforest and coastal habitats in the Madang area, Papua New Guinea. The collection included 13 193 individuals representing 349 species of leaf-chewing insects and 44 900 individuals representing 430 species of sap-sucking insects. Despite a high sampling intensity, the species accumulation curve did not reach an asymptote. This pattern was attributed to the highly aggregated distribution of insects on individual host trees. The number of insect species collected on a particular Ficus species ranged from 34 to 129 for leaf-chewing and from 51 to 219 for sap-sucking insects. Two Ficus species growing on the seashore sustained less speciose insect communities than their counterparts growing in forest. For the forest figs, significant predictors of insect species richness included leaf palatability and leaf production for leaf-chewing insects (40% of the variance explained), and tree density and leaf expansion for sap-sucking insects (75%). The high faunal overlap among Ficus communities and the importance of local resources for insect herbivores suggest that highly specialized interactions between insect herbivores and Ficus in Papua New Guinea have not been conserved in evolutionary time. This is at variance with the dogma of old, extremely specialized and conservative interactions between insect herbivores and their hosts, providing numerous ecological niches in the floristically rich tropics.     

Molecular systematics and evolution of the subgenus Mesocarabus Thomson, 1875 (Coleoptera: Carabidae: Carabus), based on mitochondrial and nuclear DNA

The subgenus Mesocarabus Thomson, 1875 is a western Palaearctic group that currently includes five species: four of them inhabiting western Europe (Carabus lusitanicus Fabricius, 1801, Carabus problematicus Herbst, 1786, Carabus dufourii Dejean & Boisduval, 1829, and Carabus macrocephalus Dejean, 1826) and one found in the Rif Mountains in northern Morocco (Carabus riffensis Fairmaire, 1872). Representatives of Mesocarabus have been included in previous molecular phylogenetic studies, but taxon‐ or gene‐sampling limitations yielded inconclusive results regarding its monophyly and sister relationship. Here we perform molecular phylogenetic analyses based on five mitochondrial (3625 nt) and eight nuclear (5970 nt) genes sequenced in many Mesocarabus populations, and in related western Palaearctic Carabus Linnaeus, 1758. We conducted parsimony, maximum‐likelihood, and Bayesian analyses and found a well‐supported sister relationship between a monophyletic Mesocarabus with Iberian species of the subgenus Oreocarabus Géhin, 1876. Within Mesocarabus, the European species form a monophyletic lineage sister to Moroccan C. riffensis. A time‐calibrated phylogeny suggests the split between Mesocarabus and Oreocarabus occurred at 11.8 Mya (95% highest posterior density, HPD, 8.7–15.3 Mya), and the divergence between C. riffensis and European Mesocarabus at 9.5 Mya (95% HPD 7.0–12.5 Mya). The early diversification of Mesocarabus and related subgenera during the Miocene, and alternative hypotheses concerning the origin of Mesocarabus in the Iberian Peninsula and the Betic‐Riffian plate are discussed using calibration data and dispersal–vicariance biogeographic analyses. Finally, we found instances of incongruence between mitochondrial DNA and nuclear‐based phylogenies of Mesocarabus, which are hypothesized to be the result of introgressive hybridization. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 787–804.     

Different stresses, similar morphogenic responses: integrating a plethora of pathways

Exposure of plants to mild chronic stress can cause induction of specific, stress-induced morphogenic responses (SIMRs). These responses are characterized by a blockage of cell division in the main meristematic tissues, an inhibition of elongation and a redirected outgrowth of lateral organs. Key elements in the ontogenesis of this phenotype appear to be stress-affected gradients of reactive oxygen species (ROS), antioxidants, auxin and ethylene. These gradients are present at the the organismal level, but are integrated on the cellular level, affecting cell division, cell elongation and/or cell differentiation. Our analysis of the literature indicates that stress-induced modulation of plant growth is mediated by a plethora of molecular interactions, whereby different environmental signals can trigger similar morphogenic responses. At least some of the molecular interactions that underlie morphogenic responses appear to be interchangeable. We speculate that this complexity can be viewed in terms of a thermodynamic model, in which not the specific pathway, but the achieved metabolic state is biologically conserved.     

Putative speciation events in Lamellodiscus (Monogenea: Diplectanidae) assessed by a morphometric approach

In the present study, we used morphometry as a proxy to study the microevolution of generalist Lamellodiscus (Monogenea, Diplectanidae) species, comprising gill parasites of sparid fish. We investigated 147 individuals, belonging to nine described species, regrouped in four morphotypes. Morphometric measurements were taken on sclerotized parts of the attachment organ. The formation of groups on the basis of the global morphometry within a host species, or between several host species, was assessed using both exploratory analyses (principal component analysis and clustering analysis) and statistical tests. We showed that: (1) for three out of four morphotypes, the global morphometry was significantly different according to host species used, and (2) the coexistence of two populations of Lamellodiscus elegans on Diplodus sargus could reflect an ongoing intra‐host speciation event. We suggest that generalist Lamellodiscus are undergoing specialization on their different hosts, which may lead to speciation. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 559–569.     

Functional diversity is positively associated with biomass for lake diatoms

1. Recent work has emphasised the benefit of using functional measures when relating biodiversity to ecosystem functioning. In this study, we investigated the extent to which functional and taxonomic diversity might be related to summed biovolume in community assemblages of 212 species of diatoms collected from 65 temperate lakes in western and central Quebec, Canada. 2. We quantified functional diversity as both the total path‐length of a functional dendrogram (FD) and the variance in species traits (TV) for a given community. Selected traits included both size and responses to a set of environmental variables known to be influential for diatom communities. 3. Species richness, as well as both FD and TV, was positively associated with total diatom biovolume at the level of the entire diatom community, suggesting that diversity in response types (particularly to total phosphorus and pH) is important for diatom community production. 4. Although functional measures of diversity did not provide enhanced explanatory power over species richness, we argue that an exploration of functional traits potentially allows greater insight into the mechanisms underlying biodiversity–ecosystem functioning relations, indicating which traits might be most influential in driving community biomass production.