Sex-biased parental care and sexual size dimorphism in a provisioning arthropod

The diverse selection pressures driving the evolution of sexual size dimorphism (SSD) have long been debated. While the balance between fecundity selection and sexual selection has received much attention, explanations based on sex-specific ecology have proven harder to test. In ectotherms, females are typically larger than males, and this is frequently thought to be because size constrains female fecundity more than it constrains male mating success. However, SSD could additionally reflect maternal care strategies. Under this hypothesis, females are relatively larger where reproduction requires greater maximum maternal effort – for example where mothers transport heavy provisions to nests. To test this hypothesis we focussed on digger wasps (Hymenoptera: Ammophilini), a relatively homogeneous group in which only females provision offspring. In some species, a single large prey item, up to 10 times the mother’s weight, must be carried to each burrow on foot; other species provide many small prey, each flown individually to the nest. We found more pronounced female-biased SSD in species where females carry single, heavy prey. More generally, SSD was negatively correlated with numbers of prey provided per offspring. Females provisioning multiple small items had longer wings and thoraxes, probably because smaller prey are carried in flight. Despite much theorising, few empirical studies have tested how sex-biased parental care can affect SSD. Our study reveals that such costs can be associated with the evolution of dimorphism, and this should be investigated in other clades where parental care costs differ between sexes and species

Oldest Known Eucalyptus Macrofossils Are from South America

The evolutionary history of Eucalyptus and the eucalypts, the larger clade of seven genera including Eucalyptus that today have a natural distribution almost exclusively in Australasia, is poorly documented from the fossil record. Little physical evidence exists bearing on the ancient geographical distributions or morphologies of plants within the clade. Herein, we introduce fossil material of Eucalyptus from the early Eocene (ca. 51.9 Ma) Laguna del Hunco paleoflora of Chubut Province, Argentina; specimens include multiple leaves, infructescences, and dispersed capsules, several flower buds, and a single flower. Morphological similarities that relate the fossils to extant eucalypts include leaf shape, venation, and epidermal oil glands; infructescence structure; valvate capsulate fruits; and operculate flower buds. The presence of a staminophore scar on the fruits links them to Eucalyptus, and the presence of a transverse scar on the flower buds indicates a relationship to Eucalyptus subgenus Symphyomyrtus. Phylogenetic analyses of morphological data alone and combined with aligned sequence data from a prior study including 16 extant eucalypts, one outgroup, and a terminal representing the fossils indicate that the fossils are nested within Eucalyptus. These are the only illustrated Eucalyptus fossils that are definitively Eocene in age, and the only conclusively identified extant or fossil eucalypts naturally occurring outside of Australasia and adjacent Mindanao. Thus, these fossils indicate that the evolution of the eucalypt group is not constrained to a single region. Moreover, they strengthen the taxonomic connections between the Laguna del Hunco paleoflora and extant subtropical and tropical Australasia, one of the three major ecologic-geographic elements of the Laguna del Hunco paleoflora. The age and affinities of the fossils also indicate that Eucalyptus subgenus Symphyomyrtus is older than previously supposed. Paleoecological data indicate that the Patagonian Eucalyptus dominated volcanically disturbed areas adjacent to standing rainforest surrounding an Eocene caldera lake

Thermal Variability Increases the Impact of Autumnal Warming and Drives Metabolic Depression in an Overwintering Butterfly

Increases in thermal variability elevate metabolic rate due to Jensen's inequality, and increased metabolic rate decreases the fitness of dormant ectotherms by increasing consumption of stored energy reserves. Theory predicts that ectotherms should respond to increased thermal variability by lowering the thermal sensitivity of metabolism, which will reduce the impact of the warm portion of thermal variability. We examined the thermal sensitivity of metabolic rate of overwintering Erynnis propertius (Lepidoptera: Hesperiidae) larvae from a stable or variable environment reared in the laboratory in a reciprocal common garden design, and used these data to model energy use during the winters of 1973–2010 using meteorological data to predict the energetic outcomes of metabolic compensation and phenological shifts. Larvae that experienced variable temperatures had decreased thermal sensitivity of metabolic rate, and were larger than those reared at stable temperatures, which could partially compensate for the increased energetic demands. Even with depressed thermal sensitivity, the variable environment was more energy-demanding than the stable, with the majority of this demand occurring in autumn. Autumn phenology changes thus had disproportionate influence on energy consumption in variable environments, and variable-reared larvae were most susceptible to overwinter energy drain. Therefore the energetic impacts of the timing of entry into winter dormancy will strongly influence ectotherm fitness in northern temperate environments. We conclude that thermal variability drives the expression of metabolic suppression in this species; that phenological shifts will have a greater impact on ectotherms in variable thermal environments; and that E. propertius will be more sensitive to shifts in phenology in autumn than in spring. This suggests that increases in overwinter thermal variability and/or extended, warm autumns, will negatively impact all non-feeding dormant ectotherms which lack the ability to suppress their overwinter metabolic thermal sensitivity

Insect Eggs Can Enhance Wound Response in Plants: A Study System of Tomato Solanum lycopersicum L. and Helicoverpa zea Boddie

Insect oviposition on plants frequently precedes herbivory. Accumulating evidence indicates that plants recognize insect oviposition and elicit direct or indirect defenses to reduce the pressure of future herbivory. Most of the oviposition-triggered plant defenses described thus far remove eggs or keep them away from the host plant or their desirable feeding sites. Here, we report induction of antiherbivore defense by insect oviposition which targets newly hatched larvae, not the eggs, in the system of tomato Solanum lycopersicum L., and tomato fruitworm moth Helicoverpa zea Boddie. When tomato plants were oviposited by H. zea moths, pin2, a highly inducible gene encoding protease inhibitor2, which is a representative defense protein against herbivorous arthropods, was expressed at significantly higher level at the oviposition site than surrounding tissues, and expression decreased with distance away from the site of oviposition. Moreover, more eggs resulted in higher pin2 expression in leaves, and both fertilized and unfertilized eggs induced pin2 expression. Notably, when quantified daily following deposition of eggs, pin2 expression at the oviposition site was highest just before the emergence of larvae. Furthermore, H. zea oviposition primed the wound-induced increase of pin2 transcription and a burst of jasmonic acid (JA); tomato plants previously exposed to H. zea oviposition showed significantly stronger induction of pin2 and higher production of JA upon subsequent simulated herbivory than without oviposition. Our results suggest that tomato plants recognize H. zea oviposition as a signal of impending future herbivory and induce defenses to prepare for this herbivory by newly hatched neonate larvae

Germ band retraction as a landmark in glucose metabolism during Aedes aegypti embryogenesis

<p>Abstract</p> <p>Background</p> <p>The mosquito <it>A. aegypti </it>is vector of dengue and other viruses. New methods of vector control are needed and can be achieved by a better understanding of the life cycle of this insect. Embryogenesis is a part of <it>A. aegypty </it>life cycle that is poorly understood. In insects in general and in mosquitoes in particular energetic metabolism is well studied during oogenesis, when the oocyte exhibits fast growth, accumulating carbohydrates, lipids and proteins that will meet the regulatory and metabolic needs of the developing embryo. On the other hand, events related with energetic metabolism during <it>A. aegypti </it>embryogenesis are unknown.</p> <p>Results</p> <p>Glucose metabolism was investigated throughout <it>Aedes aegypti </it>(Diptera) embryonic development. Both cellular blastoderm formation (CBf, 5 h after egg laying - HAE) and germ band retraction (GBr, 24 HAE) may be considered landmarks regarding glucose 6-phosphate (G6P) destination. We observed high levels of glucose 6-phosphate dehydrogenase (G6PDH) activity at the very beginning of embryogenesis, which nevertheless decreased up to 5 HAE. This activity is correlated with the need for nucleotide precursors generated by the pentose phosphate pathway (PPP), of which G6PDH is the key enzyme. We suggest the synchronism of egg metabolism with carbohydrate distribution based on the decreasing levels of phosphoenolpyruvate carboxykinase (PEPCK) activity and on the elevation observed in protein content up to 24 HAE. Concomitantly, increasing levels of hexokinase (HK) and pyruvate kinase (PK) activity were observed, and PEPCK reached a peak around 48 HAE. Glycogen synthase kinase (GSK3) activity was also monitored and shown to be inversely correlated with glycogen distribution during embryogenesis.</p> <p>Conclusions</p> <p>The results herein support the hypothesis that glucose metabolic fate changes according to developmental embryonic stages. Germ band retraction is a moment that was characterized as a landmark in glucose metabolism during <it>Aedes aegypti </it>embryogenesis. Furthermore, the results also suggest a role for GSK3 in glycogen balance/distribution during morphological modifications.</p

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave (GW) transient was identified in data recorded by the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors on 2015 September 14. The event, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the GW data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network circulars, giving an overview of the participating facilities, the GW sky localization coverage, the timeline, and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic (EM) signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the EM data and results of the EM follow-up campaign are being disseminated in papers by the individual teams

Localization and broadband follow-up of the gravitational-wave transient GW150914

A gravitational-wave transient was identified in data recorded by the Advanced LIGO detectors on 2015 September 14. The event candidate, initially designated G184098 and later given the name GW150914, is described in detail elsewhere. By prior arrangement, preliminary estimates of the time, significance, and sky location of the event were shared with 63 teams of observers covering radio, optical, near-infrared, X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In this Letter we describe the low-latency analysis of the gravitational wave data and present the sky localization of the first observed compact binary merger. We summarize the follow-up observations reported by 25 teams via private Gamma-ray Coordinates Network Circulars, giving an overview of the participating facilities, the gravitational wave sky localization coverage, the timeline and depth of the observations. As this event turned out to be a binary black hole merger, there is little expectation of a detectable electromagnetic signature. Nevertheless, this first broadband campaign to search for a counterpart of an Advanced LIGO source represents a milestone and highlights the broad capabilities of the transient astronomy community and the observing strategies that have been developed to pursue neutron star binary merger events. Detailed investigations of the electromagnetic data and results of the electromagnetic follow-up campaign will be disseminated in the papers of the individual teams

Inelastic buckling of tubular section beams

104 σ.Στη μηχανική με τον όρο “λυγισμό”, νοείται αστοχία λόγω απώλειας της ευστάθειας ενός φορέα που υπόκειται μόνο σε αυστηρά κεντρικό αξονικό φορτίο. Η ύπαρξη, ωστόσο, αρχικών ατελειών ή εκκεντρότητας του φορτίου, οδηγεί στην καμπτοθλιπτική καταπόνηση του μέλους. Έτσι, η κατανομή των τάσεων καθ’ ύψος της διατομής δεν είναι ομοιόμορφη, και η τάση στη δυσμενέστερη ίνα του μέλους, που είναι η ακραία θλιβόμενη της μεσαίας διατομής, μπορεί να φτάσει την τιμή της τάσης διαρροής πριν φτάσει η φόρτιση το κρίσιμο φορτίο λυγισμού, οπότε και έχουμε πλαστικό λυγισμό. Το φαινόμενο του πλαστικού λυγισμού εμφανίζεται περισσότερο σε ένα εύρος τιμών της λυγηρότητας των υποστυλωμάτων. Στη συγκεκριμένη εργασία επιλέξαμε διάφορες διατομές κλιμακωτά αυξανόμενης διαμέτρου ,τις οποίες ελέγξαμε στο φαινόμενο του πλαστικού λυγισμού, αφού θεωρήσαμε σε αυτές διάφορες τιμές αρχικών βελών, επί του ισχυρού άξονα. Για να το κάνουμε αυτό, θέσαμε κάποιες παραδοχές και εν συνεχεία προσεγγίσαμε θεωρητικά την εκδήλωση του φαινομένου. Το επόμενο βήμα είναι η σύγκριση των αποτελεσμάτων που προέκυψαν από την προσέγγισή μας, με τις αντίστοιχες κρίσιμες τιμές που προκύπτουν από τον Ευρωπαικό Κανονισμό (EC3) και η επαλήθευση των αποτελεσμάτων από πρόγραμμα Η/Υ με τη μέθοδο των πεπερασμένων στοιχείων (Abaqus). Τέλος, παρουσιάζονται διάφορες καμπύλες για τις υπό μελέτη διατομές, όπου φαίνεται η επίδραση της αλλαγής των γεωμετρικών τους στοιχείων,η ποιότητα χάλυβα,οι αρχικές ατέλειες κτλ,στην εκδήλωση του πλαστικού λυγισμού. Το φαινόμενο του πλαστικού λυγισμού, χαρακτηρίζεται από μικρές τιμές του ποσοστού της διαφοράς ανάμεσα στο κρίσιμο φορτίο (πλαστικό) και του ελαστικού φορτίου (φορτίο πρώτης διαρροής) ως προς το δεύτερο. Οι τιμές αυτές της πλαστικής “υπεραντοχής” εξαρτώνται από τη διατομή και την ποιότητα του χάλυβα, αλλά ακόμη περισσότερο από τη λυγηρότητα του κάθε υποστυλώματος. Επίσης, είδαμε ότι όσο πιο μεγάλη είναι η αρχική ατέλεια (αρχικό βέλος κάμψης), τόσο μικρότερο είναι το κρίσιμο φορτίο και τόσο πιο μεγάλη η τελική παραμόρφωση του υποστυλώματος.In mechanics, the term "buckling" means failure due to loss of stability of a member, that is subject of strictly central axial load. The presence, however, of initial imperfections or load eccecintricity leads to compressive and flexural loading of the member. Thus, the stress distribution on height of the section is not uniform., and the stress of the least favourable fiber of the member, which is the farther fiber under compression at the middle section of the member, can reach the value of the characteristic yield stress of the steel, before the load reaches the critical buckling load, so it appears the effect of inelastic buckling. This effect appears more in a value range of the slenderness of the columns.In this particular thesis we chose various sections of increasing diameter ,which we had them tested on the effect of inelastic buckling, since we considered different values of initial bending displacement, on the strong axis. To do that, we have some assumptions and then we approached theoritically the progress of the effect. The next step is the comparison of the theoritical results of our approach, with the corresponding critical values result-ing by the Eurocodes. (EC3) and the verification of the results with the use of a PC programm with finite elements analysis (Abaqus). Finally, are being presented some curves for the studied sections, where we can see the effects of the geometrical changes,steel quality,initial imperfections etc. at inelastic buckling. The effect of inelastic buckling, characterized by small values of the percentage of the difference between the critical load (inelastic) and the elastic load (first failure) divided by the second. The values of this inelastic “overstrength”, depend on the section and the quality of the steel, but even more on the slenderness of each column. We also noticed, that the bigger the initial imperfection (initial bending displacement), the less the critical load, and the bigger the final displacement of the column.Αντώνιος Χ. Ανουσάκη

Invasive weed species – a threat to sustainable agriculture

There are two main threats to biodiversity in the world. One of them is the direct inadvertent destruction of habitats by people which is done basically through inappropriate resource use or pollution the other highly serious but under estimated problem is the threat to natural and semi-natural habitats by invasion of alien organisms it is the lasting threat as compared to the first one because when exploitation stops the existing aliens do not disappear but continue to spread and consolidate. Our planet is quickly being taken over by hundreds of hardy aggressive species spread either knowingly or accidentally by human hands these are considered the second most significant threat to biodiversity after habitat destruction. These weeds are causing damages worth billions of dollars world wide and Pakistan being no exception. The countries rich repository of 6,000 of vesicular plants is highly threatened by a number of alien weeds among those some are worth mentioning such as Parthenium weed (Parthenium hysterophorus), Lantana (Lantana camara), Paper mulberry (Brossonetia papyrifera), Mesquet (Prosopis juliflora), Wild tamarind (Leucaena leucocephala), Khakiweed (Alternanthera pungens) etc. These weeds especially P. hysterophorus are highly noxious plant species and threatening the natural and agriculture ecosystem of the country. Parthenium is allergenic to both humans and animals and after invading Punjab is quickly moving towards NWFP. This is primarily because of unawareness about this plant and secondly that it is being constantly used in floral bouquets. Similarly there are many more in the list developed by IUCN in the year 2000 for Pakistan. Though it is difficult to manage these aggressive alien organisms but success stories have been documented regarding biological/chemical control and other integrated approaches. More over a careful revision of legislation regarding quarantine and enforcement of the same may prove useful to mitigate the threats of these weeds