Niche Occupation Research Articles

How structured yeast multicellular communities live, age and die?

Yeasts, like other microorganisms, create numerous types of multicellular communities, which differ in their complexity, cell differentiation and in the occupation of different niches. Some of the communities, such as colonies and some types of biofilms, develop by division and subsequent differentiation of cells growing on semisolid or solid surfaces to which they are attached or which they can penetrate. Aggregation of individual cells is important for formation of other community types, such as multicellular flocs, which sediment to the bottom or float to the surface of liquid cultures forming flor biofilms, organized at the border between liquid and air under specific circumstances. These examples together with the existence of more obscure communities, such as stalks, demonstrate that multicellularity is widespread in yeast. Despite this fact, identification of mechanisms and regulations involved in complex multicellular behavior still remains one of the challenges of microbiology. Here, we briefly discuss metabolic differences between particular yeast communities as well as the presence and functions of various differentiated cells and provide examples of the ability of these cells to develop different ways to cope with stress during community development and aging.

Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary.

Pterosaurs were the first vertebrates to evolve powered flight and the largest animals to ever take wing. The pterosaurs persisted for over 150 million years before disappearing at the end of the Cretaceous, but the patterns of and processes driving their extinction remain unclear. Only a single family, Azhdarchidae, is definitively known from the late Maastrichtian, suggesting a gradual decline in diversity in the Late Cretaceous, with the Cretaceous–Paleogene (K-Pg) extinction eliminating a few late-surviving species. However, this apparent pattern may simply reflect poor sampling of fossils. Here, we describe a diverse pterosaur assemblage from the late Maastrichtian of Morocco that includes not only Azhdarchidae but the youngest known Pteranodontidae and Nyctosauridae. With 3 families and at least 7 species present, the assemblage represents the most diverse known Late Cretaceous pterosaur assemblage and dramatically increases the diversity of Maastrichtian pterosaurs. At least 3 families—Pteranodontidae, Nyctosauridae, and Azhdarchidae—persisted into the late Maastrichtian. Late Maastrichtian pterosaurs show increased niche occupation relative to earlier, Santonian-Campanian faunas and successfully outcompeted birds at large sizes. These patterns suggest an abrupt mass extinction of pterosaurs at the K-Pg boundary.

Dental topography and the diet of Homo naledi

Though late Middle Pleistocene in age, Homo naledi is characterized by a mosaic of Australopithecus-like (e.g., curved fingers, small brains) and Homo-like (e.g., elongated lower limbs) traits, which may suggest it occupied a unique ecological niche. Ecological reconstructions inform on niche occupation, and are particularly successful when using dental material. Tooth shape (via dental topography) and size were quantified for four groups of South African Plio-Pleistocene hominins (specimens of Australopithecus africanus, Paranthropus robustus, H. naledi, and Homo sp.) on relatively unworn M2s to investigate possible ecological differentiation in H. naledi relative to taxa with similar known geographical ranges. H. naledi has smaller, but higher-crowned and more wear resistant teeth than Australopithecus and Paranthropus. These results are found in both lightly and moderately worn teeth. There are no differences in tooth sharpness or complexity. Combined with the high level of dental chipping in H. naledi, this suggests that, relative to Australopithecus and Paranthropus, H. naledi consumed foods with similar fracture mechanics properties but more abrasive particles (e.g., dust, grit), which could be due to a dietary and/or environmental shift(s). The same factors that differentiate H. naledi from Australopithecus and Paranthropus may also differentiate it from Homo sp., which geologically predates it, in the same way. Compared to the great apes, all hominins have sharper teeth, indicating they consumed foods requiring higher shear forces during mastication. Despite some anatomical similarities, H. naledi likely occupied a distinct ecological niche from the South African hominins that predate it.

Syngenesis as a synonym for development process of biogeocenoses: their organization and self-organization

Syngenesis is leading and determining factor in development of biogeocenoses (Sukachev, 1942) as a phenomenon means its movement over time, and as a process describes its incremental changes toward more or less stable state. Syngenesis is a process of simultaneous formation and development of biogeocenose by living things of all kingdoms of life. We consider the process as: 1) forming, creating (stocking of free land or aquatic areas); 2) a continuous process having indefinite duration, that characterizes constant mobility of composition, structure, and linkages of biogeocenosis; 3) reorganizing process which shows fractures and changes in biogeocenosis structure; 4) recovering, that reflects restoration of general and local disturbances in biogeocenosis, that is as discrete stage-phase processes. Syngenesis is multifactorial grouping process defined by penetration and interaction, cohabitation of living organisms. It is directly related to chaos at various levels and stages of biogeocenosis state and it characterized by different-scale patterns. Statics or kinetics of syngenesis are evidenced in all its forms. Statics reflects certain fixed time points or slowing of movement, and the delay between stages; kinetics should be considered as a process of biogeocenosis motion over time. All syngeneses are subordinated to zonal type of biogeocenosis reproduction and development towards achieving a more or less steady state. All these processes fit together in «organization» category. The organization defines: development of state of being organized; systematic, that is, it embodies the integration and interaction of system-forming factors reflecting development of parts, subsystems, components, elements forming a system sustainability. It is: 1) a constant attribute property of all dynamic systems; 2) a multi-step process for development of any system with a certain level of parallelism on multi-directional and subordinates to general direction of the partial phenomena and processes; 3) completeness, simplification, expansion of composition, structure, and linkages; 4) characteristics of changes in total stereostructure of organism community, above-ground and underground layering, occupation of vertical and horizontal spatial niches. The organization determines reorganization of the network interaction system: 1) reconstruction of nature of influences; 2) changes in their power, intensity, concentrations, ranges, and 3) variability in space and time relations, accordingly to biogeocenosis demands. The organization is characterized by follow: 1. Features: 1) discreteness; 2) inequivalence of stages; 3) inequality; 4) different duration; 5) acceleration or deceleration on the background of biogeocenosis demands; 6) slowing as it approaches more or less stable state. 2. Properties: 1) importance; 2) mobility; 3) biogeocenotical conditionality; 4) continuity; 5) equifinality. 3. Functions:1) formation the state of being organized; 2) establishment of structure; 3) development of biogeocenosis; 4) self-development. Self-organization is one of the characteristic properties of the organization; it is pronounced in biogeocenosis as realization of hidden resources and capabilities by the following phenomena: 1) occurrence of necessary elements qualitatively and quantitatively different in their composition at a certain point of development; 2) elimination of their excessive amounts; 3) preservation of forms adaptive to environment; 4) numerous transitions into latent status for certain elements; their migration (removal) outside of the grouping; 5) modifications: a) taxonomic and ecomorphic spectra; b) changes in polymorphy and size of population; c) total stereostructure of community and its above-ground, subterranean layering; d) occupation of vertical and horizontal spatial niches; e) patchiness and composition; 6) reorganization of the whole network system relationships on the impact. In general, it should be noted that concept on group development and organization is one of broad and insufficiently differentiated in biogeocenology. Self-organization is an objective process of self-moving of biogeocenosis over time. It is subject to the same common factors regardless of their orientation to stable or unstable condition in the group. The same factors, phenomena and processes can be both system-forming and system-destroying: interaction of organisms, competition, adaptive response, composition replenishment and depletion, structure complication and simplification, changing in ratios of functional groups.

What do insects, anurans, birds, and mammals have to say about soundscape indices in a tropical savanna

The application of acoustic indices is incipient and still needs validation before it can reliably characterize soundscapes and monitor rapidly disappearing hot-spot areas as the Brazilian tropical savanna (Cerrado). Here we investigate which of six acoustic indices better correlate with the 24 h zoophony richness of insects, anurans, birds, and mammals. We sampled one minute every 30 minutes for seven days on three sites in Serra da Canastra National Park (Minas Gerais state, Brazil) and extracted the sonotype richness and six indices based on recordings with a bandwidth of up to 48 kHz. The Acoustic Diversity, Evenness, Entropy, and Normalized Difference Soundscape indices followed the temporal trends of the sonotype richness of insects and anurans. The Acoustic Complexity (ACI) and Bioacoustic (BIO) indices did not correlated with sonotype richness. ACI and BIO were influenced by sonic abundance and geophony. We emphasize the need to include insects and anurans on soundscape and acoustic ecology analyses and to avoid bias on avian fauna alone. We also suggest that future studies explore measures of sonic abundance and acoustic niche occupation of sonotypes to complement measures of zoophony richness and better understand what each faunal group is telling us about indices.

Sexes and species as rival units of niche saturation during community assembly

AbstractAimCommunity assembly is traditionally assumed to result from speciation and colonization mediated by available niche space. This paradigm is expanded by the theory that niche space can also be saturated by intersexual adaptive divergence (ecological sexual dimorphism) when interspecific competition is relaxed. This theory (here termed ‘niche‐packing equivalence’) predicts that the evolution of ecological sexual dimorphism constrains the ecological opportunity that would otherwise lead to ecological speciation or colonization, and that saturation of niches by different species constrains divergent selection for divergence between the sexes. Therefore, sexes and species are equivalent, yet antagonistic units of niche occupation. We present the most comprehensive test of the niche‐packing equivalence theory at ecological time‐scales (assemblage level) to date.LocationSouth AmericaMajor taxa studiedLiolaemuslizards.MethodsWe identified 23Liolaemusassemblages varying in species richness and sexual size dimorphism (SSD), distributed across a wide environmental range. We used mixed effects models, permutation tests and Markov Chain Monte Carlo (MCMC) regressions to quantify the relationship between SSD and species richness. We then partitioned the body size niche dimension between the sexes and amongst species, and tested for non‐overlapping body size distributions. We regressed SSD and species richness of each assemblage against environmental predictors, using multi‐model inference and structural equation modelling.ResultsSexual dimorphism declines with increasing species richness, and a strong signal of tension between the two remains following phylogenetic control. This pattern is accompanied by evidence of constraints on body‐size partitioning amongst species and between the sexes: the two units of niche saturation tend not to overlap. However, across assemblages, species richness and SSD correlate with different environmental variables, suggesting that their tension is context‐specific.Main conclusionsOur evidence supports the prediction that sexual dimorphism and species richness are alternative outcomes of adaptive radiation. However, this antagonism is mediated by a suite of environmental predictors that influence dimorphism and species richness differentially.

Food consumption in ground beetles is limited under hypoxic conditions in response to ad libitum feeding, but not restricted feeding

Habitats on land with low oxygen availability provide unique niches inhabited by numerous species. The occupation of such hypoxic niches by animals is hypothesized to come at a cost linked to the limitations of aerobic metabolism and thus energy budget but may also provide benefits through physical protection from predators and parasitoids or reduced competition for food. We investigated the effects of hypoxic conditions on standard metabolic rate (SMR) and specific dynamic action (SDA) in male Carabus nemoralis. SMR and SDA were determined under three manipulated oxygen availabilities: 7, 14 and 21% O2 and two feeding regimes: limited or ad libitum food consumption. In both hypoxic conditions, C. nemoralis was able to maintain SMR at levels similar to those in normoxia. When the meal size was limited, SDA duration did not differ among the oxygen availability conditions, but SDA was smaller under hypoxic conditions than at normoxic levels. The relative cost of digestion was significantly higher in normoxia than in hypoxia, but it did not affect net energy intake. In contrast, when offered a large meal to simulate ad libitum food conditions, beetles reduced their food consumption and net energy gain by 30% under hypoxia. Oxygen availability may influence the consumed prey size: the hypoxic condition did not limit net energy gain when the beetles fed on a small meal but did when they fed on a large meal. The results indicate that meal size is an important variable in determining differences in physiological costs and whole animal energy budgets at different concentrations of environmental oxygen levels.

Ecological niche and occupation by gray fox (Urocyon cinereoargenteus) at Las Barajitas Canyon, Sonora

Hutchinson defines ecological niche considering the relevance of the environment in the n-dimensional space, according to the patterns of species presence in it. For Peterson and collaborators, these patterns set the basis for niche modeling, since they directly affect the proportion of sites occupied by species. To determine the ecological variables that would favor the conservation of biodiversity at the landscape level, the ecological niche and site occupation by the gray fox ( Urocyon cinereoargenteus ) were simulated using photo-trapping monitoring at Las Barajitas Canyon, Sonora, Mexico. The potential habitat of the fox was modeled with the program MaxEnt, and the occupation (ψ) and probability of detection (p) were estimated with the program MARK. Vegetation was sampled using the quadrants and Braun-Blanquet methods to estimate importance values for the main plants for inclusion in the presence-absence models, as well as to know the state of the vegetation, using the species accumulation function. The sampling effort over one-year was 124 days/night-trap, obtaining 575 photographs of the gray fox. The analysis of the activity pattern revealed that the gray fox is a nocturnal-twilight species. The evaluation of the vegetation sampled evidenced the dominance of the Ruellia-Jatropha-Bursera association. The plant species accumulation function showed a positive linear relationship (r² = 0.97). In accordance with the information criteria (AICc), positive correlations were found between the sympatric species cacomixtle and coyote, and seasonality (i.e. spring and autumn), resulting in ψ = 38.5 % and p = 7.7 %. The spatial dynamics of plant communities and the relationships between animal species observed in this study indicate that, Las Barajitas Canyon is a suitable environment for the gray fox, since the Area Under the Curve (AUC) obtained was close to 1 (0.873).

Origin and Differentiation Trajectories of Fibroblastic Reticular Cells in the Splenic White Pulp

The splenic white pulp is underpinned by poorly characterized stromal cells that demarcate distinct immune cell microenvironments. Here, definition of the embryonic origin and tracing of the differentiation trajectories of fibroblastic reticular cells (FRCs) was enabled by the establishment of FRC-specific fate-mapping in mice. We found that all reticular cell subsets descend from pluripotent progenitors that emerge at embryonic day 19.5 from Sca-1 periarterial progenitors. Commitment of FRC progenitors was concluded during the first week of postnatal life through occupation of niches along developing central arterioles. Single cell transcriptomic analysis facilitated deconvolution of FRC differentiation trajectories and indicated that perivascular reticular cells function both as adult lymphoid organizer cells and mural cell progenitors. Finally, the lymphotoxin-β receptor-independent sustenance of postnatal progenitor stemness unveiled that systemic immune surveillance in the splenic white pulp is governed through subset specification of reticular cells from a pluripotent periarterial progenitor cell.

Black Immigration, Occupational Niches, and Earnings Disparities Between U.S.-Born and Foreign-Born Blacks in the United States

Using data from the 2000 U.S. census and the 2010 to 2014 waves of the American Community Survey, we examine the importance of occupational niches in explaining earnings disparities between U.S.-born blacks and black immigrants in the United States. Our results show that, relative to U.S.-born blacks, most black immigrant subgroups have similar or greater representation in occupational niches. Employment in a niche occupation has a small but positive association with earnings, and the returns to niche employment are greater for black immigrants, particularly black immigrant women. Niche employment does not, however, explain earnings disparities between U.S.-born and immigrant blacks.

Hiperparasitism on mycotoxigenic fungus Aspergillusochraceus G. Wilh. By Cladosporiumcladosporioides (Fresen) de Vries

Biocontrol agents (BCAs) for the control of fungal diseases and pests has been the focus in the development of, thus, the agrochemical industry has refocused priorities on integrated control to include the use of BCAs in research and programmes for disease and pest control. The mechanism of action has often included direct antagonism between the BCA and fungal pathogen, competitive exclusion of the pathogen by niche occupation, production of secondary metabolites, hyperparasitism, and the production of volatile organic compounds (VOCs). It is considered as a characteristic of antagonist, to present more than one mechanism, because in this way, their chances of success are increased. The present study, objectived to evaluate, in vitro, competition between the fungus considered a bioprotective agent of the coffee quality Cladosporiumcladosporioides (Fresen) de Vries and the potentially toxigenic fungus Aspergillus ochraceus G. Wilh. Competition between isolates of C. cladosporioides and A. ochraceus was evaluated in vitro conditions by adding conidia aliquotas in Petri dishes containing PDA (potato, dextrose, agar) culture medium.The antagonist relationship between isolates was observed in Olympus SZX7TR-ILA trinocular stereoscopic microscope coupled to a camera and in scanning electron microscopy ZEISS®. The fungus C. cladosporioides (Fresen) de Vries, showed its antagonism on potencialmycotoxigenic fungus A. ochraceus by of antibiosis and hyperparasitism mechanisms.

Carnivoran resource and habitat use in the context of a Late Miocene faunal turnover episode

AbstractWe investigate resource and habitat use by apex predators through stable isotope analysis at two Spanish Late Miocene localities: Los Valles de Fuentidueña (~9.6 Ma, LVF) and Cerro de los Batallones (~9.1 Ma, BAT). The temporal window represented by LVF and BAT was crucial in the shaping of the current Iberian mammalian structure because it corresponds to the initial stages of a faunal turnover episode and regional environmental change at ~9.5–8.5 Ma (Vallesian–Turolian transition), associated with an increase in the seasonality of precipitation. Herbivore and carnivore δ13C and δ18O values do not point to significant changes in either the vegetation cover (a woodland to mesic C3 grassland) or the hydrological regime during the time lapse represented between LVF and BAT. This suggests that the environmental shift recorded around the Vallesian–Turolian boundary may have occurred later in time, since LVF and BAT ages are synchronic with the onset of the turnover event. From the standpoint of predator–prey evaluation by means of stable isotope analysis, statistical post hoc tests, mixing model output, and the assessment of niche occupation by LVF and BAT carnivores point to high levels of interspecific competition among large active carnivores, albeit some genera, such as the amphicyonid Magericyon and specially the hyaenid Lycyaena, seemed to avoid competition by taking prey from a more open habitat. Despite the drop in diversity and change in faunal components observed between the LVF and BAT assemblages, a high degree of resource and habitat competition is evident from stable isotope data.

Implications of a specialized diet for the foraging behavior of the Honduran white bat, Ectophylla alba (Chiroptera: Phyllostomidae)

Specialist species are defined by their restricted range of tolerated environmental conditions and required resources. For example, in the New World leaf-nosed bats (Phyllostomidae), specialization in diet has been linked to morphological and behavioral innovations (i.e., skull form, foraging behaviors) that facilitate the occupation of new ecological niches by these animals. Here, we use the Honduran white bat, Ectophylla alba, as a model to test the behavioral responses of the species to a narrow diet: one based on figs of Ficus colubrinae (Moraceae). Through the use of radiotelemetry, we demonstrate that the foraging behavior of these bats is highly dependent on their main food resource. In response, behavioral adaptations have evolved to optimize the bats' foraging strategies and—at a broad level—the performance and survival of the species in their habitat. Conservation decisions should consider the tight linkage that exists among some species and their habitat characteristics or food resources (as demonstrated herein), in order to protect highly susceptible and unique species that could potentially go extinct with the disturbance or removal of specific features of their ecological interactions.

Antarctic harpacticoids exploit different trophic niches: a summer snapshot using fatty acid trophic markers (Potter Cove, King George Island)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 568:59-71 (2017) - DOI: https://doi.org/10.3354/meps12047 Antarctic harpacticoids exploit different trophic niches: a summer snapshot using fatty acid trophic markers (Potter Cove, King George Island) Eva Werbrouck1,*, Ann Vanreusel1, Dolores Deregibus2, Dirk Van Gansbeke1, Marleen De Troch1 1Marine Biology, Krijgslaan 281/S8, Ghent University, Gent 9000, Belgium 2Departamento de Biología Costera, Instituto Antártico Argentino, San Martín (CP 1650), Buenos Aires, Argentina *Corresponding author: eva.werbrouck@ugent.be ABSTRACT: Unraveling food webs is a first step toward understanding of ecosystem functioning and a requirement to forecast climate-induced ecosystem responses. In this study, the organisms under examination were benthic copepods (order Harpacticoida) inhabiting a fjord-like environment on the southern coastline of King George Island at the northwestern tip of the Antarctic Peninsula, one of the most rapidly warming regions on Earth. Despite increased understanding of Antarctic food web structures, little is known about the feeding ecology of benthic copepods in these systems. A fatty acid trophic marker strategy was used to unravel the diet composition of Antarctic harpacticoid copepod species or assemblages collected from distinct habitats in summer. Their diverse storage fatty acid composition revealed the occupation of different trophic niches associated with their specific lifestyles, i.e. endobenthic or epiphytic with (Alteutha spp.) or without (Harpacticus sp.) frequent water column excursions. Moreover, the prevalence of biosynthesized ω7 long-chain monounsaturated fatty acids in Harpacticus sp. and ω9 fatty acids in Alteutha spp. further suggested adaptations to particular habitats in polar ecosystems, as different dietary precursors—16:1ω7 (microphytobenthos, epiphytic diatoms) or 18:1ω9 (flagellates)—fuel these elongation pathways. KEY WORDS: Copepods · Diet · Storage lipids · Epiphytic · Polar Full text in pdf format Supplementary material PreviousNextCite this article as: Werbrouck E, Vanreusel A, Deregibus D, Van Gansbeke D, De Troch M (2017) Antarctic harpacticoids exploit different trophic niches: a summer snapshot using fatty acid trophic markers (Potter Cove, King George Island). Mar Ecol Prog Ser 568:59-71. https://doi.org/10.3354/meps12047 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 568. Online publication date: March 24, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Exploring the genomic diversity of black yeasts and relatives (Chaetothyriales, Ascomycota).

The order Chaetothyriales (Pezizomycotina, Ascomycetes) harbours obligatorily melanised fungi and includes numerous etiologic agents of chromoblastomycosis, phaeohyphomycosis and other diseases of vertebrate hosts. Diseases range from mild cutaneous to fatal cerebral or disseminated infections and affect humans and cold-blooded animals globally. In addition, Chaetothyriales comprise species with aquatic, rock-inhabiting, ant-associated, and mycoparasitic life-styles, as well as species that tolerate toxic compounds, suggesting a high degree of versatile extremotolerance. To understand their biology and divergent niche occupation, we sequenced and annotated a set of 23 genomes of main the human opportunists within the Chaetothyriales as well as related environmental species. Our analyses included fungi with diverse life-styles, namely opportunistic pathogens and closely related saprobes, to identify genomic adaptations related to pathogenesis. Furthermore, ecological preferences of Chaetothyriales were analysed, in conjuncture with the order-level phylogeny based on conserved ribosomal genes. General characteristics, phylogenomic relationships, transposable elements, sex-related genes, protein family evolution, genes related to protein degradation (MEROPS), carbohydrate-active enzymes (CAZymes), melanin synthesis and secondary metabolism were investigated and compared between species. Genome assemblies varied from 25.81 Mb (Capronia coronata) to 43.03 Mb (Cladophialophora immunda). The bantiana-clade contained the highest number of predicted genes (12 817 on average) as well as larger genomes. We found a low content of mobile elements, with DNA transposons from Tc1/Mariner superfamily being the most abundant across analysed species. Additionally, we identified a reduction of carbohydrate degrading enzymes, specifically many of the Glycosyl Hydrolase (GH) class, while most of the Pectin Lyase (PL) genes were lost in etiological agents of chromoblastomycosis and phaeohyphomycosis. An expansion was found in protein degrading peptidase enzyme families S12 (serine-type D-Ala-D-Ala carboxypeptidases) and M38 (isoaspartyl dipeptidases). Based on genomic information, a wide range of abilities of melanin biosynthesis was revealed; genes related to metabolically distinct DHN, DOPA and pyomelanin pathways were identified. The MAT (MAting Type) locus and other sex-related genes were recognized in all 23 black fungi. Members of the asexual genera Fonsecaea and Cladophialophora appear to be heterothallic with a single copy of either MAT-1-1 or MAT-1-2 in each individual. All Capronia species are homothallic as both MAT1-1 and MAT1-2 genes were found in each single genome. The genomic synteny of the MAT-locus flanking genes (SLA2-APN2-COX13) is not conserved in black fungi as is commonly observed in Eurotiomycetes, indicating a unique genomic context for MAT in those species. The heterokaryon (het) genes expansion associated with the low selective pressure at the MAT-locus suggests that a parasexual cycle may play an important role in generating diversity among those fungi.

Genome sequencing and transcriptome assembly of the parasitoid wasp Megaphragma amalphitanum (Hymenoptera: Trichogrammatidae)

Miniaturization of organisms is one of the most interesting evolutionary phenomena. This is a very common process and is widely represented in multicellular organisms: invertebrates (nemertean, nematodes, brachiopods, mollusks, arachnids, and insects), and vertebrates (fishes, amphibians, birds, and even mammals). Miniaturization leads to a significant reduction in the body size and simplification of some systems and organs without loss of species viability. Typically, this complex evolutionary modification is associated with occupation of the new ecological niches by the species. Reduction can affect not only the overall size of the organism but also the size of its cells as well as promote changes in the genome and the structure of specific genes. Parasitoid wasp Megaphragma amalphitanum (Hymenoptera: Trichogrammatidae) is considered one of the smallest insects described to date. Therefore, it represents an attractive object for the studies of genetic aspects of body size reduction during evolution. Whole genome sequencing of M. amalphitanum and subsequent genome annotation and transcriptome assembly allow us to define the changes in the genetic material during organism miniaturization in relation to the larger Hymenoptera species. Our preliminary analysis revealed that genome size of M. amalphitanum is 346 Mb and transcriptome size is 27.5 Mb.

Endophytic Bacillus cereus Effectively Controls Meloidogyne incognita on Tomato Plants Through Rapid Rhizosphere Occupation and Repellent Action.

Root-knot nematodes (Meloidogyne spp.), which cause severe global agricultural losses, can establish a special niche in the root vascular cylinder of crops, making them difficult to control. Endophytic bacteria have great potential as biocontrol organisms against Meloidogyne incognita. Three endophytic bacteria were isolated from plant tissues and showed high nematicidal activity against M. incognita second-stage juveniles (J2) in vitro. The gyrB gene sequence amplification results indicated that the three isolates were Bacillus cereus BCM2, B. cereus SZ5, and B. altitudinis CCM7. The isolates colonized tomato roots rapidly and stably during the colonization dynamic experiment. Three pot experiments were designed to determine the potential of three endophytic bacterial isolates on control of root-knot nematodes. The results showed that the preinoculated B. cereus BCM2 experiment significantly reduced gall and egg mass indexes. The inhibition ratio of gall and egg mass was up to 81.2 and 75.6% on tomato roots and significantly enhanced shoot length and fresh weight. The other two experiments with inoculated endophytic bacteria and M. incognita at the same time or after morbidity had lower inhibition ratios compared with the preinoculated endophytic bacteria experiment. The confocal laser-scanning microscopy method was used to further study the possible mechanism of endophytic bacteria in the biocontrol process. The results showed the localization pattern of the endophytic bacteria B. cereus BCM2-(str')-pBCgfp-1 in tomato root tissues. Root tissue colonized by endophytic bacteria repelled M. incognita J2 infection compared with the untreated control in a repellence experiment. We isolated an endophytic B. cereus strain that stably colonized tomato and controlled M. incognita effectively. This strain has potential for plant growth promotion, successful ecological niche occupation, and M. incognita J2 repellent action induction. It plays an important role in endophytic bacteria against root-knot nematodes.

Molecular diversity patterns among various phytoplankton size-fractions in West Greenland in late summer

Arctic regions have experienced pronounced biological and biophysical transformations as a result of global change processes over the last several decades. Current hypotheses propose an elevated impact of those environmental changes on the biodiversity, community composition and metabolic processes of species. The effects on ecosystem function and services, particularly when invasive or toxigenic harmful species become dominant, can be expressed over a wide range of temporal and spatial scales in plankton communities. Our study focused on the comparison of molecular biodiversity of three size-fractions (micro-, nano-, picoplankton) in the coastal pelagic zone of West Greenland and their association with environmental parameters. Molecular diversity was assessed via parallel amplicon sequencing the 28S rRNA hypervariable D1/D2 region. We showed that biodiversity distribution within the area of Uummannaq Fjord, Vaigat Strait and Disko Bay differed markedly within and among size-fractions. In general, we observed a higher diversity within the picoplankton size fraction compared to the nano- and microplankton. In multidimensional scaling analysis, community composition of all three size fractions correlated with cell size, silicate and phosphate, chlorophyll a (chl a) and dinophysistoxin (DTX). Individually, each size fraction community composition also correlated with other different environmental parameters, i.e. temperature and nitrate. We observed a more homogeneous community of the picoplankton across all stations compared to the larger size classes, despite different prevailing environmental conditions of the sampling areas. This suggests that habitat niche occupation for larger-celled species may lead to higher functional trait plasticity expressed as an enhanced range of phenotypes, whereas smaller organisms may compensate for lower potential plasticity with higher diversity. The presence of recently identified toxigenic harmful algal bloom (HAB) species (such as Alexandrium fundyense and A. ostenfeldii) in the area points out the potential risk for this vulnerable ecosystem in a changing world.

Microbial interactions: ecology in a molecular perspective.

The microorganism–microorganism or microorganism–host interactions are the key strategy to colonize and establish in a variety of different environments. These interactions involve all ecological aspects, including physiochemical changes, metabolite exchange, metabolite conversion, signaling, chemotaxis and genetic exchange resulting in genotype selection. In addition, the establishment in the environment depends on the species diversity, since high functional redundancy in the microbial community increases the competitive ability of the community, decreasing the possibility of an invader to establish in this environment. Therefore, these associations are the result of a co-evolution process that leads to the adaptation and specialization, allowing the occupation of different niches, by reducing biotic and abiotic stress or exchanging growth factors and signaling. Microbial interactions occur by the transference of molecular and genetic information, and many mechanisms can be involved in this exchange, such as secondary metabolites, siderophores, quorum sensing system, biofilm formation, and cellular transduction signaling, among others. The ultimate unit of interaction is the gene expression of each organism in response to an environmental (biotic or abiotic) stimulus, which is responsible for the production of molecules involved in these interactions. Therefore, in the present review, we focused on some molecular mechanisms involved in the microbial interaction, not only in microbial–host interaction, which has been exploited by other reviews, but also in the molecular strategy used by different microorganisms in the environment that can modulate the establishment and structuration of the microbial community.

Niche divergence facilitated by fine-scale ecological partitioning in a recent cichlid fish adaptive radiation.

Ecomorphological differentiation is a key feature of adaptive radiations, with a general trend for specialization and niche expansion following divergence. Ecological opportunity afforded by invasion of a new habitat is thought to act as an ecological release, facilitating divergence, and speciation. Here, we investigate trophic adaptive morphology and ecology of an endemic clade of oreochromine cichlid fishes (Alcolapia) that radiated along a herbivorous trophic axis following colonization of an isolated lacustrine environment, and demonstrate phenotype‐environment correlation. Ecological and morphological divergence of the Alcolapia species flock are examined in a phylogenomic context, to infer ecological niche occupation within the radiation. Species divergence is observed in both ecology and morphology, supporting the importance of ecological speciation within the radiation. Comparison with an outgroup taxon reveals large‐scale ecomorphological divergence but shallow genomic differentiation within the Alcolapia adaptive radiation. Ancestral morphological reconstruction suggests lake colonization by a generalist oreochromine phenotype that diverged in Lake Natron to varied herbivorous morphologies akin to specialist herbivores in Lakes Tanganyika and Malawi.