Phenotypic variation in Galerida larks in Morocco: the role of history and natural selection

The relative influences of history, natural selection and hybridization in shaping phenotypic variation in closely related taxa is a crucial issue in current evolutionary biology. In this study, we used as a model two sibling but paradoxically highly variable species of larks (Galerida theklae and Galerida cristata) of Morocco to separate the impacts of these evolutionary forces. In the former species, variation is manifested mainly in colouration, while in the latter, variation also encompasses bill size and shape. Mitochondrial and nuclear DNA sequencing were used to identify the historical relationships among the subspecies and species. According to our analyses, G. cristata and G. theklae diverged about 3.7 million years ago (Ma), and we found no evidence for a role of hybridization in maintaining their similarity. In G. theklae, there was no further subdivision, while in G. cristata two major mtDNA groups were identified (divergence approximately 1.1 Ma). These two lineages are parapatric and regroup, respectively, the three short-billed subspecies [G. (cristata) cristata] and the two long-billed subspecies [G. (cristata) randonii]. Patterns of morphological variation were then contrasted to this pattern of neutral relationships: we found that G. (c.) cristata was morphologically more similar to G. theklae than to G. (c.) randonii. Overall, these results point towards the prominent role of (i) natural selection and/or phenotypic plasticity in adapting the plumage to local conditions and (ii) natural selection in combination with historical isolation in driving the divergence in size and bill morphology in the crested larks.     

Life cycle assessment of energy self-sufficiency systems based on agricultural residues for organic arable farms

The agricultural industry today consumes large amounts of fossil fuels. This study used consequential life cycle assessment (LCA) to analyse two potential energy self-sufficient systems for organic arable farms, based on agricultural residues. The analysis focused on energy balance, resource use and greenhouse gas (GHG) emissions. A scenario based on straw was found to require straw harvest from 25% of the farm area; 45% of the total energy produced from the straw was required for energy carrier production and GHG emissions were reduced by 9% compared with a fossil fuel-based reference scenario. In a scenario based on anaerobic digestion of ley, the corresponding figures were 13%, 24% and 35%. The final result was sensitive to assumptions regarding, e.g., soil carbon content and handling of by-products.     

Does food play a prominent role in visual attention to disgusting stimuli?

Journal of Ethology - Disgust is a basic emotion which protects individuals from potential contamination. It is hypothesized that disgust evolved primarily as a mechanism against oral contamination...     

A planktivorous specialist turns rapacious: piscivory in invading vendace Coregonus albula

Following invasion and establishment in a subarctic watercourse, small-sized vendace Coregonus albula were surprisingly found to include fish prey in their diet. The zooplankton resource was severely depleted and only made a minor dietary contribution.     

Is information a proper observable for biological organization?

In the last century, jointly with the advent of computers, mathematical theories of information were developed. Shortly thereafter, during the ascent of molecular biology, the concept of information was rapidly transferred into biology at large. Several philosophers and biologists have argued against adopting this concept based on epistemological and ontological arguments, and also, because it encouraged genetic determinism. While the theories of elaboration and transmission of information are valid mathematical theories, their own logic and implicit causal structure make them inimical to biology, and because of it, their applications have and are hindering the development of a sound theory of organisms. Our analysis concentrates on the development of information theories in mathematics and on the differences between these theories regarding the relationship among complexity, information and entropy.     

Cecropins as a marker of Spodoptera frugiperda immunosuppression during entomopathogenic bacterial challenge

An antimicrobial peptide (AMP) of the cecropin family was isolated by HPLC from plasma of the insect pest, Spodoptera frugiperda. Its molecular mass is 3910.9 Da as determined by mass spectrometry. Thanks to the EST database Spodobase, we were able to describe 13 cDNAs encoding six different cecropins which belong to the sub-families CecA, CecB, CecC and CecD. The purified peptide identified as CecB1 was chemically synthesized (syCecB1). It was shown to be active against Gram-positive and Gram-negative bacteria as well as fungi. Two closely related entomopathogenic bacteria, Xenorhabdus nematophila F1 and Xenorhabdus mauleonii VC01(T) showed different susceptibility to syCecB1. Indeed, X. nematophila was sensitive to syCecB1 whereas X. mauleonii had a minimal inhibitory concentration (MIC) eight times higher. Interestingly, injection of live X. nematophila into insects did not induce the expression of AMPs in hemolymph. This effect was not observed when this bacterium was heat-killed before injection. On the opposite, both live and heat-killed X. mauleonii induced the expression of AMPs in the hemolymph of S. frugiperda. The same phenomenon was observed for another immune-related protein lacking antimicrobial activity. Altogether, our data suggest that Xenorhabdus strains have developed different strategies to supplant the humoral defense mechanisms of S. frugiperda, either by increasing their resistance to AMPs or by preventing their expression during such host-pathogen interaction.     

Vaccines against botulism

The clostridial neurotoxins (CNTs) are the most toxic proteins for humans and include botulinum neurotoxins (BoNT) and tetanus neurotoxin (TeNT). CNT neurotropism is based upon the preferred binding and entry into neurons and specific cleavage of neuronal SNARE proteins. While chemically inactive TeNT toxoid remains an effect vaccine, the current pentavalent vaccine against botulism is in limited supply. Recent advances have facilitated the development of the next generation of BoNT vaccines, utilizing non-catalytic full-length BoNT or a subunit vaccine composed of the receptor binding domain of BoNT as immunogens. This review describes the issues and progress towards the production of a vaccine against botulism that will be effective against natural BoNT variants.     

A modelling study of the respective role of hydrodynamic processes and larval mortality on larval dispersal and recruitment of benthic invertebrates: example of Pectinaria koreni (Annelida: Polychaeta) in the Bay of Seine (English Channel)

The dispersal of Pectinaria koreni larvae released from theeastern Bay of Seine (English Channel) was studied using a two-dimensionalhydrodynamic model which integrates tides, wind-driven currentsand eddy diffusion, in order to examine the influence of environmentalforcing and mortality on larval population dynamics. A broadagreement between predicted larval dispersal for two spawningevents observed in 1987 and field data suggests that numericalmodelling may be useful to analyse processes involved in thetransport and the dynamics of larval populations. Larval mortalitymay be as important as hydrodynamic processes on larval lossesfor the adult population. Tides and eddy diffusion had someeffects on larval dispersal, but wind forcing and the timingof spawning in relation to the meteorological environment arepredicted to be the main source of variability in larval dispersalrates. Although wind-induced larval transport may produce interannualvariations in larval retention and recruitment, predicted retentionrates were always sufficient to ensure the maintenance of theadult population, regardless of hydrodynamic conditions. Thelong-range transport of larvae from the eastern Bay of Seineto distant populations was conditioned by constant strong winds,lasting 15 consecutive days, and should be considered an extremelyrare event.