A Differential Role of Volatiles from Conspecific and Heterospecific Competitors in the Selection of Oviposition Sites by the Aphidophagous Hoverfly Sphaerophoria rueppellii

The selection of oviposition sites by syrphids and other aphidophagous insects is influenced by the presence of con- and heterospecific competitors. Chemical cues play a role in this selection process, some of them being volatile semiochemicals. Yet, little is known about the identity and specificity of chemical signals that are involved in the searching behavior of these predators. In this study, we used olfactometer bioassays to explore the olfactory responses of gravid females and larvae of the syrphid Sphaerophoria rueppellii, focussing on volatiles from conspecific immature stages, as well as odors from immature stages of the competing coccinellid Adalia bipunctata. In addition, a multiple-choice oviposition experiment was conducted to study if females respond differently when they can also sense their competitors through visual or tactile cues. Results showed that volatiles from plants and aphids did not affect the behavior of second-instars, whereas adult females strongly preferred odors from aphid colonies without competitors. Odors from conspecific immature stages had a repellent effect on S. rueppellii adult females, whereas their choices were not affected by volatiles coming from immature heterospecific A. bipunctata. The results imply that the syrphid uses odors to avoid sites that are already occupied by conspecifics. They did not avoid the odor of the heterospecific competitor, although in close vicinity they were found to avoid laying eggs on leaves that had traces of the coccinellid. Apparently adult syrphids do not rely greatly on volatile semiochemicals to detect the coccinellid, but rather use other stimuli at close range (e. g., visual or non-volatile compounds) to avoid this competitor.

Specific herbivore-induced volatiles defend plants and determine insect community composition in the field

In response to insect attack, plants release complex blends of volatile compounds. These volatiles serve as foraging cues for herbivores, predators and parasitoids, leading to plant-mediated interactions within and between trophic levels. Hence, plant volatiles may be important determinants of insect community composition. To test this, we created rice lines that are impaired in the emission of two major signals, S-linalool and (E)-β-caryophyllene. We found that inducible S-linalool attracted predators and parasitoids as well as chewing herbivores, but repelled the rice brown planthopper Nilaparvata lugens, a major pest. The constitutively produced (E)-β-caryophyllene on the other hand attracted both parasitoids and planthoppers, resulting in an increased herbivore load. Thus, silencing either signal resulted in specific insect assemblages in the field, highlighting the importance of plant volatiles in determining insect community structures. Moreover, the results imply that the manipulation of volatile emissions in crops has great potential for the control of pest populations.

The changing pace of insular life: 5000 years of microevolution in the Orkney vole (Microtus arvalis orcadensis)

Island evolution may be expected to involve fast initial morphological divergence followed by stasis. We tested this model using the dental phenotype of modern and ancient common voles (Microtus arvalis), introduced onto the Orkney archipelago (Scotland) from continental Europe some 5000 years ago. First, we investigated phenotypic divergence of Orkney and continental European populations and assessed climatic influences. Second, phenotypic differentiation among Orkney populations was tested against geography, time, and neutral genetic patterns. Finally, we examined evolutionary change along a time series for the Orkney Mainland. Molar gigantism and anterior-lobe hypertrophy evolved rapidly in Orkney voles following introduction, without any transitional forms detected. Founder events and adaptation appear to explain this initial rapid evolution. Idiosyncrasy in dental features among different island populations of Orkney voles is also likely the result of local founder events following Neolithic translocation around the archipelago. However, against our initial expectations, a second marked phenotypic shift occurred between the 4th and 12th centuries AD, associated with increased pastoral farming and introduction of competitors (mice and rats) and terrestrial predators (foxes and cats). These results indicate that human agency can generate a more complex pattern of morphological evolution than might be expected in island rodents.

The scaling of genetic diversity in a changing and fragmented world

Most species do not live in a constant environment over space or time. Their environment is often heterogeneous with a huge variability in resource availability and exposure to pathogens or predators, which may affect the local densities of the species. Moreover, the habitat might be fragmented, preventing free and isotropic migrations between local sub-populations (demes) of a species, making some demes more isolated than others. For example, during the last ice age populations of many species migrated towards refuge areas from which re-colonization originated when conditions improved. However, populations that could not move fast enough or could not adapt to the new environmental conditions faced extinctions. Populations living in these types of dynamic environments are often referred to as metapopulations and modeled as an array of subdivisions (or demes) that exchange migrants with their neighbors. Several studies have focused on the description of their demography, probability of extinction and expected patterns of diversity at different scales. Importantly, all these evolutionary processes may affect genetic diversity, which can affect the chance of populations to persist. In this chapter we provide an overview on the consequences of fragmentation, long-distance dispersal, range contractions and range shifts on genetic diversity. In addition, we describe new methods to detect and quantify underlying evolutionary processes from sampled genetic data.

Systemic root signalling in a belowground, volatile-mediated tritrophic interaction

Plants attacked by leaf herbivores release volatile organic compounds (VOCs) both locally from the wounded site and systemically from non-attacked tissues. These volatiles serve as attractants for predators and parasitoids. This phenomenon is well described for plant leaves, but systemic induction of VOCs in the roots has remained unstudied. We assessed the spatial and temporal activation of the synthesis and release of (E)-β-caryophyllene (EβC) in maize roots upon feeding by larvae of Diabrotica virgifera virgifera, as well as the importance of systemically produced EβC for the attraction of the entomopathogenic nematode Heterorhabditis megidis. The production of EβC was found to be significantly stronger at the site of attack than in non-attacked tissues. A weak, but significant, increase in transcriptional activity of the EβC synthase gene tps23 and a corresponding increase in EβC content were observed in the roots above the feeding site and in adjacent roots, demonstrating for the first time that herbivory triggers systemic production of a volatile within root systems. In belowground olfactometers, the nematodes were significantly more attracted towards local feeding sites than systemically induced roots. The possible advantages and disadvantages of systemic volatile signalling in roots are discussed.

Canopy gaps promote selective stem-cutting by small mammals of two dominant tree species in an African lowland forest: the importance of seedling chemistry

Small mammals can impede tree regeneration by injuring seedlings and saplings in several ways. One fatal way is by severing their stems, but apparently this type of predation is not well-studied in tropical rain forest. Here, we report on the incidence of 'stem-cutting' to new, wild seedlings of two locally dominant, canopy tree species monitored in 40 paired forest understorey and gap-habitat areas in Korup, Cameroon following a 2007 masting event. In gap areas, which are required for the upward growth and sapling recruitment of both species, 137 seedlings of the long-lived, light-demanding, fast-growing large tropical tree (Microberlinia bisulcata) were highly susceptible to stem-cutting (83% of deaths) - it killed 39% of all seedlings over a c. 2-y period. In stark contrast, seedlings of the more shade-tolerant, slower-growing tree species (Tetraberlinia bifoliolata) were hardly attacked (4.3%). In the understorey, however, stem-cutting was virtually absent. Across the gap areas, the incidence of stem-cutting of M. bisulcata seedlings showed significant spatial variation that could not be explained significantly by either canopy openness or Janzen-Connell type effects (proximity and basal area of conspecific adult trees). To examine physical and chemical traits that might explain the species difference to being cut, bark and wood tissues were collected from a separate sample of seedlings in gaps (i.e. not monitored for stem-cutting). These analyses suggested that, compared with T. bifoliolata, the lower stem density, higher Mg and K and fatty acid concentrations in bark, and fewer phenolic and terpene compounds in M. bisulcata seedlings made them more palatable and attractive to small-mammal predators, likely rodents. We conclude that selective stem-cutting is a potent countervailing force to the current local canopy dominance of the grove-forming M. bisulcata by limiting the recruitment and abundance of its saplings. Given the ubiquity of gaps and ground-dwelling rodents in pantropical forests, it would be surprising if this form of lethal browsing was restricted to Korup.

The Impact of Whaling on the Ocean Carbon Cycle: Why Bigger Was Better

Background: Humans have reduced the abundance of many large marine vertebrates, including whales, large fish, and sharks, to only a small percentage of their pre-exploitation levels. Industrial fishing and whaling also tended to preferentially harvest the largest species and largest individuals within a population. We consider the consequences of removing these animals on the ocean's ability to store carbon. Methodology/Principal Findings: Because body size is critical to our arguments, our analysis focuses on populations of baleen whales. Using reconstructions of pre-whaling and modern abundances, we consider the impact of whaling on the amount of carbon stored in living whales and on the amount of carbon exported to the deep sea by sinking whale carcasses. Populations of large baleen whales now store 9.1 x 10(6) tons less carbon than before whaling. Some of the lost storage has been offset by increases in smaller competitors; however, due to the relative metabolic efficiency of larger organisms, a shift toward smaller animals could decrease the total community biomass by 30% or more. Because of their large size and few predators, whales and other large marine vertebrates can efficiently export carbon from the surface waters to the deep sea. We estimate that rebuilding whale populations would remove 1.6 x 10(5) tons of carbon each year through sinking whale carcasses. Conclusions/Significance: Even though fish and whales are only a small portion of the ocean's overall biomass, fishing and whaling have altered the ocean's ability to store and sequester carbon. Although these changes are small relative to the total ocean carbon sink, rebuilding populations of fish and whales would be comparable to other carbon management schemes, including ocean iron fertilization.

Predator-Induced Plasticity in Spotted Salamanders (Ambystoma maculatum)

The ability to respond plastically to the environment has allowed amphibians to evolve adaptive responses to spatial and temporal variation in predation threat. However, animals exposed to predators may also show costs of plasticity or tradeoffs. This study examines predator-induced plasticity in larval development, behavior, and metamorphosis in the spotted salamander, Ambystoma maculatum. Salamanders were raised in two treatments: with predator cues (a fish predator, genus Lepomis, on the other side of a divided tank), or without predator cues. During the larval stage the predator treatment group experienced higher mortality rates than the no-predator treatment group. Behavioral trials revealed that predator treatment animals ate less than those not exposed, and that this feeding response was immediately inducible and had lasting effects. Animals in the predator treatment group had smaller tail areas during the mid-larval period. Feeding and body size effects may have contributed to increased mortality in the predator-treatment animals. The timing of metamorphic onset was not affected by the presence of predators, but predator-treatment salamanders had shorter snout/vent lengths at metamorphosis. The duration of metamorphosis showed a potentially adaptive plastic response to the presence of predator cues: metamorphosis was longest in the no-predator treatment group, reduced in the predator treatment group, and even further reduced for animals exposed to predator cues only during metamorphosis. Overall, we found a mix of potentially adaptive and costly plastic responses in spotted salamanders.

Longitudinal Study of Tree Swallows

Tree swallows (Tachycineta bicolor) are the most widely distributed of the Tachycineta species, extending from northern Alaska and Canada to the southern United States. They are semi-colonial, secondary cavity nesters, primarily aerial insectivores, and migratory throughout most of their range. Tree swallows are a widely used model organism for avian ecologists and environmental physiologists because their life history lends itself to longterm study. They can be readily and repeatedly trapped at nests, and losses to nest predators are low. Adults return to previous breeding sites with high fidelity, so individuals marked during or after their first reproductive season can be reliably captured in subsequent years, and return rate to the breeding area can be used as an index of survival. Swallows using nest boxes are extraordinarily resistant to the disturbance of handling, allowing repeated captures to obtain measurements, blood samples, etc., both within and between breeding seasons.

Ocean temperature measured by elephant seal-CTDs in the Southern Ocean with links to datasets

The potential effects of ocean warming on marine predators are largely unknown, though the impact on the distribution of prey in vertical space may have far reaching impacts on diving predators such as southern elephant seals. We used data from satellite-tracked southern elephant seals from Marion Island to investigate the relationship between their dive characteristics (dive depths, dive durations and time-at-depth index values) and environmental variables (temperature at depth, depth of maximum temperature below 100 m, frontal zone and bathymetry) as well as other demographic and behavioural variables (migration stage, age-class, track day and vertical diel strategy). While other variables, such as bathymetry and vertical diel strategy also influenced dive depth, our results consistently indicated a significant influence of temperature at depth on dive depths. This relationship was positive for all groups of animals, indicating that seals dived to deeper depths when foraging in warmer waters. Female seals adjusted their dive depths proportionally more than males in warmer water. Dive durations were also influenced by temperature at depth, though to a lesser extent. Results from time-at-depth indices showed that both male and female seals spent less time at targeted dive depths in warmer water, and were presumably less successful foragers when diving in warmer water. Continued warming of the Southern Ocean may result in the distribution of prey for southern elephant seals shifting either poleward and/or to increasing depths. Marion Island elephant seals are expected to adapt their ranging and diving behaviour accordingly, though such changes may result in greater physiological costs associated with foraging.

(Table 3) Stable isotope composition of sof t tissues of specimens from the Sea of Okhotsk

We discovered and investigated several cold-seep sites in four depth zones of the Sea of Okhotsk off Northeast Sakhalin: outer shelf (160-250 m), upper slope (250-450 m), intermediate slope (450-800 m), and Derugin Basin (1450-1600 m). Active seepage of free methane or methane-rich fluids was detected in each zone. However, seabed photography and sampling revealed that the number of chemoautotrophic species decreases dramatically with decreasing water depth. At greatest depths in the Derugin Basin, the seeps were inhabited by bacterial mats and bivalves of the families Vesicomyidae (Calyptogena aff. pacifica, C. rectimargo, Archivesica sp.), Solemyidae (Acharax sp.) and Thyasiridae (Conchocele bisecta). In addition, pogonophoran tubeworms of the family Sclerolinidae were found in barite edifices. At the shallowest sites, on the shelf at 160 m, the seeps lack chemoautotrophic macrofauna; their locations were indicated only by the patchy occurrence of bacterial mats. Typical seep-endemic metazoans with chemosynthetic symbionts were confined to seep sites at depths below 370 m. A comparative analysis of the structure of seep and background communities suggests that differences in predation pressure may be an important determinant of this pattern. The abundance of predators such as carnivorous brachyurans and asteroids, which can invade seeps from adjacent habitats and efficiently prey on sessile seep bivalves, decreased very pronouncedly with depth. We conclude from the obvious correlation with the conspicuous pattern in the distribution of seep assemblages that, on the shelf and at the upper slope, predator pressure may be high enough to effectively impede any successful settlement of viable populations of seep-endemic metazoans. However, there was also evidence that other depth-related factors, such as bottom-water current, sedimentary regimes, oxygen concentrations and the supply of suitable settling substrates, may additionally regulate the distribution of seep fauna in the area. As a consequence of the pronounced pattern in the distribution of seep communities, their ecological significance as food sources of surrounding background fauna increased with water depth. Isotopic analyses suggest that in the Derugin Basin seep colonists feed on chemoautotrophic seep organisms, either directly or by preying on metazoans with chemosynthetic symbionts. In contrast, seep organisms apparently do not contribute to the nutrition of the adjacent background fauna on the shelf and at the slope. In this area, elevated epifaunal abundances at seep sites were caused primarily by the availability of suitable settling substrates rather than by an enrichment of food supply.

Lists of seamounts and knolls in different formats

Seamounts and knolls are 'undersea mountains', the former rising more than 1000 m from the sea floor. These features provide important habitats for aquatic predators, demersal deep-sea fish and benthic invertebrates. However most seamounts have not been surveyed and their numbers and locations are not well known. Previous efforts to locate and quantify seamounts have used relatively coarse bathymetry grids. Here we use global bathymetric data at 30 arc-second resolution to identify seamounts and knolls. We identify 33,452 seamounts and 138,412 knolls, representing the largest global set of identified seamounts and knolls to date. We compare estimated seamount numbers, locations, and depths with validation sets of seamount data from New Zealand and Azores. This comparison indicates the method we apply finds 94% of seamounts, but may overestimate seamount numbers along ridges and in areas where faulting and seafloor spreading creates highly complex topography. The seamounts and knolls identified herein are significantly geographically biased towards areas surveyed with ship-based soundings. As only 6.5% of the ocean floor has been surveyed with soundings it is likely that new seamounts will be uncovered as surveying improves. Seamount habitats constitute approximately 4.7% of the ocean floor, whilst knolls cover 16.3%. Regional distribution of these features is examined, and we find a disproportionate number of productive knolls, with a summit depth of <1.5 km, located in the Southern Ocean. Less than 2% of seamounts are within marine protected areas and the majority of these are located within exclusive economic zones with few on the High Seas. The database of seamounts and knolls resulting from this study will be a useful resource for researchers and conservation planners.

Escape performance of temperate king scallop, Pecten maximus under ocean warming and acidification

Among bivalves, scallops are exceptional due to their capacity to escape from predators by swimming which is provided by rapid and strong claps that are produced by the phasic muscle interspersed with tonic muscle contractions. Based on the concept of oxygen and capacity-limited thermal tolerance, the following hypothesis was tested: ocean warming and acidification (OWA) would induce disturbances in aerobic metabolic scope and extracellular acid-case status and impair swimming performance in temperate scallops. Following long-term incubation under near-future OWA scenarios [20 vs. 10 °C (control) and 0.112 kPa CO2 (hypercapnia) vs. 0.040 kPa CO2 (normocapnic control)], the clapping performance and metabolic rates (MR) were measured in resting (RMR) and fatigued (maximum MR) king scallops, Pecten maximus, from Roscoff, France. Exposure to OA, either alone or combined with warming, left MR and swimming parameters such as the total number of claps and clapping forces virtually unchanged. Only the duration of the escape response was affected by OA which caused earlier exhaustion in hyper- than in normocapnic scallops at 10 °C. While maximum MR was unaffected, warm exposure increased RMR in both normocapnic and hypercapnic P. maximus resulting in similar Q 10 values of ~2.2. The increased costs of maintenance and the observation of strongly reduced haemolymph PO2 levels indicate that at 20 °C scallops have reached the upper thermal pejus range with unbalanced capacities for aerobic energy metabolism. As a consequence, warming to 20 °C decreased mean phasic force during escape performance until fatigue. The observed prolonged recovery time in warm incubated scallops might be a consequence of elevated metabolic costs at reduced oxygen availability in the warmth.

Biology community and bottom sediments in the West Bay of the Furugelm Island, Sea of Japan

An experiment was carried out on the soft bottom in the sublitoral zone of the Furugelm Island (Peter the Great Bay, Sea of Japan) to study formation of benthic communities. Boxes with defauned sediments were placed on depths of 4, 6 and 13 m and exposed during 60 days in the summer period. Half of them were covered with a net with mesh size 2 cm to prevent effect of large predators. It was found that spatial pattern of invertebrates' sinking in the bay conforms to distribution of benthic communities. Larvae of benthic invertebrates sinks in general in places inhabited by their adult species. The main factors responsible for recolonzation are: sediment type and local hydrodynamic conditions. Heart-shaped sea urchin Echinocardium cordatum is numerically dominated in the bay on depth 3-4.5 m, but its larvae sinks in the deeper area. Community structure is supported by mature specimen migration to places inhabited by species. Predators affect largely on the species.

Uso de trampas "Barber" para determinar la diversidad de coleópteros epígeos asociados al cultivo de maní (Arachis hypogaea L.). Córdoba, Argentina

El objetivo fue estudiar la diversidad de coleópteros epígeos en el cultivo de maní, su composición taxonómica y su hábito alimenticio, a fin de aportar conocimientos acerca de especies potencialmente dañinas o benéficas al cultivo. Durante las campañas agrícolas 2004/05, 2005/06 y 2006/07 se colocaron 10 trampas Barber en un lote de maní ubicado en la localidad de Olaeta (Córdoba, Argentina). Se instalaron siguiendo un diseño en "X" dentro del lote en el momento de la siembra del cultivo y se dejaron hasta la cosecha. La colecta se realizó con una frecuencia semanal y el material fue identificado y cuantificado. Se determinó la frecuencia y constancia de cada especie colectada y la riqueza de especies fue calculada a través del Índice de diversidad de Simpson. Se registraron 10 familias y dentro de ellas 19 géneros/especies: los individuos fitófagos representaron entre el 66 y el 71%; los predadores entre el 18 y el 27% y los coprófagos entre el 2 y el 16% en los tres ciclos estudiados. La mayor diversidad (0,80-0,82) se obtuvo entre mediados de diciembre y principios de enero. Las especies fitófagas que se encontraron podrían comportarse como plagas para el cultivo.