Phytoplancton du lac Ichkeul (Tunisie): Composition,structure et activité photosynthétique Phytoplankton of Lake Ichkeul (Tunesia): Composition,Structure and Photosynthetic Activity

Phytoplankton evolution was established during a study carried out on lake Ichkeul (Tunisia) from January 1985 to June 1988. During this period, the flora, composed of 51 species is distributed principally between Diatomophyceae and Chlorophyceae. Succesional changes of phytoplankton were often unpredictable and characterized by populations with monospecific trend. Photosynthetic activity and the parameters A_opt and I_K were studied regularly along the year 1985 by oxygen method (GOLTERMANN , 1969). The relations between phytoplankton composition and photosynthetic activity were discussed.     

Interaction du photopériodisme et des effets de la zéatine, du saccharose et de ľeau dans la floraison du Chenopodium polyspermum

Interaction of photoperiodism and zeatin, sucrose and water effects on the flowering of Chenopodium polyspermum Root removal in Chenopodium polyspermum, a quatitative short-day plant, enhances flowering under non-inductive conditions. Presence of roots may be mimicked by zeatin applications on buds. Induction of flowering by short days may be counteracted by applications of zeatin, and appearance of flowers depends on the balance between number of inductive short days and zeatin quantity applied. Sucrose added in the culture medium or applied on buds acts as zeatin. Applications of water on buds may also delay flowering. These results show the plurifactorial regulation of the floral development of this plant. The relations between the non-specificity of the induction and the specificity of the morphogenetic response are discussed.     

Évolution temporelle de la diversité génétique de Chaerophyllum bulbosum : conséquences sur la gestion des ressources génétiques

To increase the germplasm necessary for varietal improvement of tuberous-rooted chervil, a food apiaceae of increasing importance, two successive surveys of wild populations were carried out in Germany, in the Rhine and the Weser River basins. These mainly riparian populations are likely to be shaped by changes in hydrographic networks that characterize their habitat. Molecular studies have shown a strong structuration between wild populations (G_ST ∼ 32 %), but did not reveal any structuring effect of the hydrographic network on diversity or any global phenomenon of genetic erosion. A discussion about the strategy for maintaining the diversity of this species on a long-term period is proposed.     

Entomophages et maladies des insectes

Summary Without discussing the problem of the particular role of Epizootics in natural populations, the author examines the different types of relations existing between entomophagous insects and diseases of their hosts. The consequence for parasites and predators of a possible use of pathogenes as a method of Biological Control of pests is examined with more detail in the case ofP. brassicae L. submitted to sprays with a suspension of spores ofB. thuringiensis Berliner. It is shown that two hymenopterous parasites (Apanteles glomeratus L. Anilastus ebeninus Grav). can survive the death of their host, under certain circumstances. The survival ofA. glomeralus is conditionned by its being in the last larval instar on the day of treatment. The consequence of the disease of the host caterpillar is a shortening of the endoparasitic life of the Braconid. A similar effect can be observed whenP. brassicae caterpillars are treated with a contact insecticide, but in this case,Apanteles larvae are killed by residues on their emergence from the host. There is no direct effect of spore suspensions on the larvae of the parasite. It seems thus possible to adopt bacterial control measures preserving a part of the entomophagous populations.

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I.N.R.A., Laboratoire de lutte biologique de La Minière.     

Variabilité et homogénéité des modes de débitage en Chine entre 300 000 et 50 000 ans

The position of lithic industries of Chinese Paleolithic in comparison with those of other regions in the world is always a controversial topic. The typological analysis has made Chinese prehistorians reveal some variability between lithic industries of different regions of China in terms of technical tradition and industrial structure. But this recognition, based upon some morphological characters of stone artifacts, failed to define systematically the modes of production that exist in each site. To answer these problematic some new methods need to be applied. So the lithic materials from 8 Chinese sites dated from 300 ka to 50 ka B.P. were selected and analyzed by means of lithic technological analysis and a new approach for analyzing the structures of cores. This paper presents principally the analytical results of modes of débitage and revealed that the modes of débitage during this period were characterized essentially by system C (“simple débitage”) and E (discoid) and that the concept Levallois was absent during this period in technical systems of lithic production in China. The Chinese lithic industries between 300 ka and 50 ka B.P. saw some homogeneity in the scale of the continent and remarkable difference from those of other regions in the world. So a stable, continuous but independent even isolated evolution in comparison with those of other regions was observed in this period. In addition, despite of apparent homogeneity, some variability exists also between these industries.     

Les hommes du Paléolithique supérieur d’Afalou Bou Rhummel (Bedjaia, Algérie). Interprétation nouvelle des cinétiques cranio-faciales et des effets de l’avulsion dentaire. Malformations crâniennes, troubles de la croissance, anomalies et maladies alvéolo-dentaires

New research lines by the author favours interpretation tracks and analytics investigation fields that were not considered in traditional paleoanthropology. New readings of biodynamic morphogenesis supported by digitised architectural analysis emphasize not only the dynamic of different cranio-facial kinetics but also the determination when this is possible from causes and effects. To say the approach which study is the analysis of deep structure of skull unveils in some sense the state of the structure whether it is normal, abnormal or pathologic. The study of relations between Afalou’s humans numerous cranio-facial anomalies and maxillo-mandibular dysmorphosis and malocclusions gives an account of the interest played by biodynamic morphogenesis and cranio-facial architecture in the morpho-functional interpretation of relations skull/face/tooth. In this context, the dental extraction of upper incisors, ritual which was operated not only adolescents but also on temporary dentition children, was in part responsible for the development first of an hypomaxillie then the inbalance of sphenoidal and occipital complexes. In addition to the mutilated nature of anterior dentitions, the study of about thirty skulls emphasized numerous craniofacial malformations showing different kind of asymetries (rotation lateral flexion, torsion, plagiocephaly).     

A lepidopteran (<Emphasis Type="Italic">Imbrasia belina</Emphasis>) might influence tree-grass balance of <Emphasis Type="Italic">Colophospermum mopane</Emphasis> savanna

Traditional explanations of tree-grass coexistence in African savannas are based on competition between these growth forms or demographic bottlenecks of trees maintained by fire or mammalian browsers. Perturbation of their “balance” may result in an alternate system state of woody encroachment. Invertebrate herbivory has never been offered as an explanation. We developed a consumer-resource model which illustrated that annual irruptions of a lepidopteran (Imbrasia belina), known as mopane worm, can determine the tree-grass balance of semi-arid Colophospermum mopane savanna in southern Africa. Model performance was sensitive to the abundance, hence mortality, of mopane worms, owing to their complete defoliation of tree leaf biomass resulting in altered competitive relations between trees and grasses. Invertebrate herbivores have been recognized in other systems as agents for effecting a state change of host tree populations; this modeling study offers a first indication of such a role for the well-researched tree-grass relations of African savannas.     

Sex‐ and age‐biased mortality in wild Grey Partridge Perdix perdix populations

Differing reproductive effort, individual qualities and local environmental conditions can lead to uneven mortality risk among individuals within populations and may result in survival differences according to age and sex. Identification of factors contributing to unequal operational sex ratios has been important for understanding population dynamics and conservation management. In this study, sex‐ and age‐specific mortality was estimated in three wild Grey Partridge populations from analysis of year‐round radiotracking data from 168 individuals. Survival days were counted in three periods defined individually for each bird: the pairing period (covey break‐up to laying of the first egg); the nesting period (between clutch initiation date and failure of the last nesting attempt, or the date when chicks were 14 days old); and the covey period (the end of the nesting period or joining a group until covey break‐up). Predation was the main cause of mortality. A significant effect of age on survival was found during the pairing period, when older individuals paired off faster and survived better. The highest mortality risk overall was found during the nesting period. Furthermore, significantly higher mortality of females was recorded during the nesting period, suggesting that greater investments in reproduction, behaviour at the nest or the quality of nesting habitats can decrease survival of females and cause a male‐skewed sex ratio. No significant effect of age or sex was found during the covey period, or for the year as a whole, but there was a significant difference in annual mortality rates between the three study populations. Our results confirm age‐ and sex‐specific variation of adult mortality in a ground‐nesting bird with biparental care during the annual cycle, documenting differing sensitivities of various population cohorts to predation.     

Infanticide and social flexibility in the genus <Emphasis Type="Italic">Gorilla</Emphasis>

Based on the cases of infanticide by male mountain gorillas reported from the Virunga volcanic region, the socioecological and life history features of gorillas satisfy the conditions for which infanticide may be expected. However, there are considerable variations in the occurrence of infanticide between habitats. We analyze the recent reports of infanticides that were directly observed or are suspected based on field evidence in two populations of eastern and western lowland gorillas (Kahuzi and Mbeli Bai, respectively) along with previous reports on mountain gorillas, and consider which social features are linked with and which factors influence the occurrence of infanticide in the gorilla populations. All victims were suckling infants and most of them were killed by males who seemed unrelated to them. Dependent infants are most vulnerable to infanticide when the protector male (its putative father in most cases) is absent, and so male protection ability seems to be important in determining female transfer decisions. Two cases observed in Kahuzi suggest that the infanticidal male may discriminate between infants to accept and those to kill according to his previous interactions with their mothers. Mating for a prolonged period prior to parturition is necessary for immigrant females to avoid infanticide by the new male of the group that they join. Infanticide was usually associated with female transfer, and the patterns of female association at transfer may shape variations in social structure between populations. Female mountain gorillas prefer large groups with multiple males and tend to transfer alone in order to seek more protection against infanticide in Virunga. By contrast, female eastern and western lowland gorillas tend to transfer with other females to small groups or solitary males, and maturing silverbacks take females to establish new groups through group fission in Kahuzi and Mbeli Bai. These differences may result in more multi-male and larger groups in the Virungas than in Kahuzi and Mbeli Bai. Rapid changes in density of gorilla social units and their relations following drastic environmental changes caused by recent human disturbances may also increase the probability of infanticide.     

Correspondence regarding Zhong et al., BMC Bioinformatics 2013 Mar 7;14:89

Computational expression deconvolution aims to estimate the contribution of individual cell populations to expression profiles measured in samples of heterogeneous composition. Zhong et al. recently proposed Digital Sorting Algorithm (BMC Bioinformatics 2013 Mar 7;14:89) and showed that they could accurately estimate population-specific expression levels and expression differences between two populations. They compared DSA with Population-Specific Expression Analysis (PSEA), a previous deconvolution method that we developed to detect expression changes occurring within the same population between two conditions (e.g. disease versus non-disease). However, Zhong et al. compared PSEA-derived specific expression levels across different cell populations. Specific expression levels obtained with PSEA cannot be directly compared across different populations as they are on a relative scale. They are accurate as we demonstrate by deconvolving the same dataset used by Zhong et al. and, importantly, allow for comparison of population-specific expression across conditions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-014-0347-5) contains supplementary material, which is available to authorized users.     

Detection and resolution of genetic loci affecting circadian period in <Emphasis Type="Italic">Brassica oleracea</Emphasis>

Circadian rhythms regulate many aspects of plant growth, fitness and vigour. The components and detailed mechanism of circadian regulation to date have been dissected in the reference species Arabidopsis thaliana. To determine the genetic basis and range of natural allelic variation for intrinsic circadian period in the closest crop relatives, we used an accurate and high throughput data capture system to record rhythmic cotyledon movement in two immortal segregating populations of Brassica oleracea, derived from parent lines representing different crop types. Periods varied between 24.4 and 26.1 h between the parent lines, with transgressive segregation between extreme recombinant lines in both populations of ∼3.5 h. The additive effect of individual QTL identified in each population varied from 0.17 to 0.36 h. QTL detected in one doubled haploid population were verified and the mapping intervals further resolved by determining circadian period in genomic substitution lines derived from the parental lines. Comparative genomic analysis based on collinearity between Brassica and Arabidopsis also allowed identification of candidate orthologous genes known to regulate period in Arabidopsis, that may account for the additive circadian effects of specific QTL. The distinct QTL positions detected in the two populations, and the extent of transgressive segregation suggest that there is likely to be considerable scope for modulating the range of available circadian periods in natural populations and crop species of Brassica. This may provide adaptive advantage for optimising growth and development in different latitudes, seasons or climate conditions.     

Le Paléolithique ancien de l’Europe orientale et du Caucase

Currently, only Tréhougol’naya Cave has reliably dated evidence for human settlement in Eastern Europe and Caucasus, from the beginning through the middle of the Middle Pleistocene. In Eastern Europe, assemblages from Khriatchi and Mikhailovskoé, and possibly Darvagchai I, appear to be the only stratified locations that tentatively can be compared (despite problems with these materials) with Tréhougol’naya. In the eastern limits of Central Europe, layer VI in Korolevo I is the only stratified assemblage that may be compared with Tréhougol’naya. All these Lower Paleolithic occupations yielded the Pre-Mousterian small tool industries with some pebble tools, but without Acheulean bifaces and Levallois technique. These data suggest that Eastern Europe lies outside the distribution range of the Acheulean techno-complex demarcated with the “Movius Line”. In the Southern Caucasus, the Dmanissi hominine and lithic records document the fact that the earliest small-brained humans – probably later H. habilis-rudolfensis or earlier H. ergaster-erectus hominids bearing Pre-Oldowan technology – initially left Africa and appeared in Western Asia as early as 1.8 Ma ago. However, in the Southern Caucasus, the available chronological data indicate that the Acheulean complex has a later temporal appearance here compared to the Upper Acheulean or Acheulo-Yabrudian in Western Asia. Two main Upper Acheulean industrial variants currently can be recognized in the Southern Caucasus. The first, called the Kudarian by the author (from the caves of Kudaro I, Kudaro III, and Azyk), is characterized by lithics made from mostly siliceous rocks, rare Acheulean bifaces, and non-Levallois flaking technique. The second variant is characterized by lithics made from volcanic rocks, numerous Acheulean bifaces, and often more laminar or Levallois debitage. It can be suggested that there are independent origins for these Southern Caucasus Upper Acheulean industrial variants. Possible roots of the Acheulean assemblages of Kudarian variant might be in the local earlier Lower Paleolithic small tool assemblages with some pebble tools but without Acheulean bifaces. The other Caucasus variant of the Upper Acheulean appears to be related to the Levantine Upper Acheulean.     

Flowering phenology of <Emphasis Type="Italic">Ulex europaeus</Emphasis>: ecological consequences of variation within and among populations

Reproductive phenology of gorse (Ulex europaeus L., Genisteae, Fabaceae) is unusual in that the onset and duration of flowering vary greatly among individuals within populations: some plants initiate flowering in autumn or winter and continue flowering through spring, others initiate flowering in early spring. To understand the origin of this diversity and its ecological consequences, we investigated flowering phenology of randomly sampled individuals from five different natural populations in Brittany (France). Reproductive success was evaluated for individuals with contrasting flowering patterns, from 16 natural populations. Flower production, pod production, seed production and seed predation were estimated. Plants initiating flowering in spring produced larger numbers of flowers and pods over a shorter period than plants flowering from winter to spring, which produced few flowers and pods at a time but over a longer period. Pod production of long-flowering plants did not differ significantly between winter and spring, but their pods were more intensively attacked by seed predators in spring than in winter. We discuss our results in relation to biotic and abiotic parameters. We postulate that long-flowering can be interpreted as a bet-hedging strategy, spreading the risk of pod failure (rotting or freezing) in winter and of seed predation in spring.     

Life history of the harlequin ladybird, <Emphasis Type="Italic">Harmonia axyridis</Emphasis>: a global meta-analysis

The harlequin ladybird, Harmonia axyridis, is an important natural enemy of aphids throughout the world, but is now also considered an invasive alien species. We performed a meta-analysis of published life history data to address the question whether invading populations in Europe and North America have life history parameters that differ from native populations in Asia, explaining the beetle’s invasion success in new territories. In this meta-analysis, we accounted for important covariables that are often reported in published studies such as temperature, food source (aphids or eggs of Ephestia kuehniella), strain (laboratory or field populations) and photoperiod. Temperature was a key factor having consistent large effects on development rate, survival and reproductive characteristics of H. axyridis. Food source, strain, and photoperiod had effects on some, but not all characteristics, and their overall effect across characteristics was minor. Individuals of invasive populations had a shorter pre-oviposition period and higher fecundity at low temperatures than those of native populations, and a greater longevity across all temperatures. No differences in survival were found between native and invasive populations, while differences in development rate were not consistent, with opposing results obtained according to the way development rate was measured in trials reported in the literature. Results of this meta-analysis support the hypothesis that the life history of the beetle has changed during its invasion into North America and Europe. Invasive populations had a shorter pre-oviposition period and higher fecundity at low temperatures, as well as a greater longevity across all temperatures than native populations. These differences may partially explain the invasive success of H. axyridis.     

Données paléobiologiques et paléobiogéographiques sur quelques Strophochonetinae du Dévonien d'Espagne et du Massif Armoricain

The lack of hinge spines on the left side of the ventral valve in Chonetacea is demonstrated here for the first time. This morphological peculiarity has a special bearing on the evolutionary trends of the Strophochonetinae. The existence of several species of Chonetacea, both in the Armorican Massif, the Cantabrian Mountains, and Aragon, is a new fact which confirms very close relations between these three areas during Lower Devonian times.     

Rapid evolutionary responses in a translocated population of intertidal snail (<Emphasis Type="Italic">Bembicium vittatum</Emphasis>) utilise variation from different source populations

The artificial movement of individuals between populations (translocation) can be an effective way to increase genetic diversity within populations, but few studies have undertaken long term genetic monitoring to determine if variation introduced by translocation is maintained over many generations or whether it can be used to adapt to local conditions. Here, we report on the changes in morphological and molecular variation over a 12-year period in a population of an intertidal littorine snail (Bembicium vittatum) that was created by mixing individuals from three geographically disjunct populations. These source populations differ genetically in shell shape and in allele frequency at several allozyme loci. We found that the translocated population had higher allozyme diversity than any of the source populations and that this pattern was maintained over multiple generations. Variation in shell shape also increased, but this declined over time as shells became taller. Some allozyme loci also showed significant changes in frequency over time. These changes were not consistently towards the genetic makeup of a single source population, and in the case of shell shape, were towards a phenotype that was most suited to the local environment. Our results suggest that genetic variation introduced into a population by translocation can be rapidly incorporated and used to adapt to local conditions without domination by a single source population’s genome. However, more studies are needed before generalisations on the benefits of mixing individuals from disjunct populations can be made.     

The recent spread of <Emphasis Type="Italic">Artemia parthenogenetica</Emphasis> in Western Australia

In Western Australia, populations of Artemia parthenogenetica in coastal salt lakes at Rottnest Island and Lake Hayward, and in salterns at Port Hedland and Shark Bay, are widely accepted to have been introduced by humans. Further, within the past 10 years, populations of A. parthenogenetica have been found in inland playa salt lakes in the wheatbelt of south-west Western Australia, where none had been recorded in previous salt lake studies. Here we hypothesise that birds act as transport vectors for Artemia cysts both within Australia and between the Asian and Australian continents. Allozyme analysis was used to identify clonal types (multi-locus genotypes), clonal frequencies, genotypic diversities and genotypic identity of six populations (three coastal, three inland). Overall, the inland populations displayed almost identical genotypic structure to the coastal population from Lake Hayward, indicating that Lake Hayward could be the major source for dispersal and colonisation of inland populations. Results support the hypothesis of dispersal inland by nomadic bird species. Furthermore, evidence suggests that the inland and Lake Hayward populations may be an example of a metapopulation. The greater variety of genotypes present in the Rottnest population indicates that this population has received a large number of small immigrations, or that it received one large introduction. The former may indicate a long period of suitable salinities, providing a greater time-span over which migration and succession of clonal types could occur in comparison to other populations. While we cannot rule out the possibility of human introduction of A. parthenogenetica to Rottnest, the hypothesis of cyst dispersal along the Austral-Asian flyway remains possible. Guest Editor: John M. Melack Saline Waters and their Biota     

Perturbateurs endocriniens et écosystèmes

Hormonal imbalances, sexual changes and unusual behaviours are observed in wildlife. Some chemicals are implicated as endocrine disruptors (EDCs). Their dispersal into ecosphere allows them to reach biotopes isolated of emission sources and they accumulate in organisms and they cause alterations in biological functions (reprotoxicity, immunotoxicity, etc.). Beyond the individual, the community equilibrium is endangered with a potential impact on biodiversity. The organohalogen substances are historically concerned. Despite the prohibition of organochlorine pesticides and PCBs, they persist in aquatic and terrestrial habitats. But the “emerging substances” are also dangerous. Numerous examples of endocrine disruption in animal communities are described. The imposex in female of marine gastropods related to tributyltin (TBT) is one of the earliest known events. The feminization of fish in the estuary of the Seine, the hermaphroditism of some amphibians and the strange behaviour of birds, are famous facts. The cumulative effects are of concern to wild populations. These are mix of pollutants or the concomitancy of other global changes, the decline of polar bears or seals from the Baltic Sea proves it. In conclusion, endocrine disruption jeopardizes all natural biological systems and contributes in loss of biological diversity by reducing the number of sensitive species and making them vulnerable, considering the global extinction risk.     

Genetic Typing of <Emphasis Type="Italic">Corallium rubrum</Emphasis>

Corallium rubrum taxonomy is based on morphologic criteria; little is known about its genome. We set up a rapid, easy method based on amplified fragment length polymorphism to characterize the genetic patterns of C. rubrum in an attempt to understand better the evolutionary relations between species from diverse geographic areas and to help define migration patterns. Applying this procedure to C. rubrum specimens from Spain and Italy, we identified 6 AFLP amplification fragments common to the 4 coral populations studied and 4 fragments that differentiated between these populations. Using this characterization we were able to plot a genetic identity card of this commercially harvested species, which is also a marker of pollution.     

ADAPTATION TO DESICCATION FAILS TO GENERATE PRE‐ AND POSTMATING ISOLATION IN REPLICATE DROSOPHILA MELANOGASTER LABORATORY POPULATIONS

Many laboratory speciation experiments have raised allopatric populations in different environments to determine whether reproductive isolation evolves as a byproduct of adaptation (a form of ecological speciation). Few, however, have addressed the evolution of both pre‐ and postmating isolation or investigated the conditions affecting the process. We present results of an evolution experiment in which 12 lines of Drosophila melanogaster were derived from a common population and then independently evolved for more than 57 generations under alternative selection treatments. Six “desiccation” populations had access to food and water removed during a period of their adult lives generating strong desiccation selection, and six “starvation” populations had access to food but not water removed for the same period, generating a mild starvation stress. Substantial divergence of cuticular hydrocarbons occurred between the desiccation and starvation populations, key traits that have been implicated in sexual isolation in Drosophila. Despite this divergence, there was no detectable premating isolation between desiccation and starvation populations and postmating isolation was asymmetrical: the fitness of F1 hybrids was reduced in the desiccation but not the starvation environment. This asymmetry was likely caused by the absence of divergent selection: adaptation to desiccation appears to have come at no cost to performance in the starvation environment. Novel environments are thought to promote the evolution of reproductive isolation. Understanding the conditions that favor or hamper this remains a key challenge for speciation research.