Multi-trait mimicry of ants by a parasitoid wasp

Many animals avoid attack from predators through toxicity or the emission of repellent chemicals. Defensive mimicry has evolved in many species to deceive shared predators, for instance through colouration and other morphological adaptations, but mimicry hardly ever seems to involve multi-trait similarities. Here we report on a wingless parasitoid wasp that exhibits a full spectrum of traits mimicing ants and affording protection against ground-dwelling predators (wolf spiders). In body size, morphology and movement Gelis agilis (Ichneumonidae) is highly similar to the black garden ant (Lasius niger) that shares the same habitat. When threatened, G. agilis also emits a volatile chemical that is similar to an ant-produced chemical that repels spiders. In bioassays with L. niger, G. agilis, G. areator, Cotesia glomerata and Drosophila melanogaster, ants and G. agilis were virtually immune to spider attack, in contrast the other species were not. Volatile characterisation with gas chromatography-mass spectrometry identified G. agilis emissions as 6-methyl-5-hepten-2-one, a known insect defence semiochemical that acts as an alarm pheromone in ants. We argue that multi-trait mimicry, as observed in G. agilis, might be much more common among animals than currently realized

Man and the Last Great Wilderness: Human Impact on the Deep Sea

The deep sea, the largest ecosystem on Earth and one of the least studied, harbours high biodiversity and provides a wealth of resources. Although humans have used the oceans for millennia, technological developments now allow exploitation of fisheries resources, hydrocarbons and minerals below 2000 m depth. The remoteness of the deep seafloor has promoted the disposal of residues and litter. Ocean acidification and climate change now bring a new dimension of global effects. Thus the challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem. This paper provides scientific expert judgement and a semi-quantitative analysis of past, present and future impacts of human-related activities on global deep-sea habitats within three categories: disposal, exploitation and climate change. The analysis is the result of a Census of Marine Life – SYNDEEP workshop (September 2008). A detailed review of known impacts and their effects is provided. The analysis shows how, in recent decades, the most significant anthropogenic activities that affect the deep sea have evolved from mainly disposal (past) to exploitation (present). We predict that from now and into the future, increases in atmospheric CO2 and facets and consequences of climate change will have the most impact on deep-sea habitats and their fauna. Synergies between different anthropogenic pressures and associated effects are discussed, indicating that most synergies are related to increased atmospheric CO2 and climate change effects. We identify deep-sea ecosystems we believe are at higher risk from human impacts in the near future: benthic communities on sedimentary upper slopes, cold-water corals, canyon benthic communities and seamount pelagic and benthic communities. We finalise this review with a short discussion on protection and management methods

Mating and aggregative behaviors among basal hexapods in the Early Cretaceous

Among the many challenges in paleobiology is the inference and reconstruction of behaviors that rarely, if ever, leave a physical trace on the environment that is suitable for fossilization. Of particular significance are those behaviors tied to mating and courtship, individual interactions critical for species integrity and continuance, as well as those for dispersal, permitting the taxon to expand its distribution as well as access new habitats in the face of local or long-term environmental change. In this context, two recently discovered fossils from the Early Cretaceous amber of Spain (ca. 105 mya) give a detailed view of otherwise fleeting ethologies in Collembola. These occurrences are phylogenetically spaced across the class, and from species representing the two major clades of springtailsÐSymphypleona and Entomobryomorpha. Specifically, we report unique evidence from a symphypleonan male (Pseudosminthurides stoechus SaÂnchez-GarcõÂa & Engel, 2016) with modified antennae that may have functioned as a clasping organ for securing females during mating on water's surface, and from an aggregation of entomobryomorphan individuals (Proisotoma communis Sánchez-García & Engel, 2016) purportedly representing a swarming episode on the forest floor. We demonstrate that the mating behavioral repertoire in P. stoechus, which is associated with considerable morphological adaptations, likely implied elaborate courtship and maneuvering for guarantee sperm transfer in an epineustic species. These discoveries reveal significant behaviors consistent with modern counterparts and a generalized stasis for some ancient hexapod ethologies associated with complex mating and courtship and social or pre-social aggregations, so critical to specific constancy and dispersal

The initial stage of dam-break flow

The liquid flow and the free surface shape during the initial stage of dam breaking are investigated. The method of matched asymptotic expansions is used to derive the leading-order uniform solution of the classical dam-break problem. The asymptotic analysis is performed with respect to a small parameter which characterizes the short duration of the stage under consideration. The second-order outer solution is obtained in the main flow region. This solution is not valid in a small vicinity of the intersection point between the initially vertical free surface and the horizontal rigid bottom. The dimension of this vicinity is estimated with the help of a local analysis of the outer solution close to the intersection point. Stretched local coordinates are used in this vicinity to resolve the flow singularity and to derive the leading-order inner solution, which describes the formation of the jet flow along the bottom. It is shown that the inner solution is self-similar and the corresponding boundary-value problem can be reduced to the well-known Cauchy-Poisson problem for water waves generated by a given pressure distribution along the free surface. An analysis of the inner solution reveals the complex shape of the jet head, which would be difficult to simulate numerically. The asymptotic solution obtained is expected to be helpful in the analysis of developed gravity-driven flows.Scientific and Technological Research Council of Turkey; International Centre for Theoretical Physics-Triest