scholarly journals Diving beetle offspring oviposited in amphibian spawn prey on the tadpoles upon hatching

2019 ◽  
Author(s):  
John Gould ◽  
Jose W. Valdez ◽  
Simon Clulow ◽  
John Clulow
Keyword(s):  
Prey Species ◽  
Food Sources ◽  
Adaptive Behaviour ◽  
Food Chains ◽  
Free Swimming ◽  
First Case ◽  
Diving Beetles ◽  
Freshwater Habitats ◽  
Fitness Benefits ◽  
Sufficient Food

AbstractIn highly ephemeral freshwater habitats, predatory vertebrates are typically unable to become established, leaving an open niche often filled by macroinvertebrate predators. However, these predators are faced with the challenge of finding sufficient food sources as the rapid rate of desiccation prevents the establishment of extended food chains and limits the number of prey species present. It could therefore be advantageous for adults to oviposit their offspring in the presence of future prey within sites of extreme ephemerality. We report the first case of adult diving beetles ovipositing their eggs within spawn of the sandpaper frog, Lechriodus fletcheri. This behaviour was found among several pools used by L. fletcheri for reproduction. Beetle eggs oviposited in frog spawn were found to hatch within 24 hours of the surrounding L. fletcheri eggs, with the larvae becoming voracious consumers of the hatched tadpoles. Although it has yet to be established experimentally whether this is an adaptive behaviour, the laying of eggs among potential future tadpole prey in this instance should confer significant fitness benefits for the offspring upon hatching, ensuring that they are provided an immediate source of food at the start of their development and potentially throughout. This oviposition behaviour may be common among diving beetles and could form a significant predatory threat for amphibians with a free-swimming larval stage in ephemeral freshwater habitats.

Selenium bioaccumulation and biomagnification in Lake Wallace, New South Wales, Australia

2008 ◽  
Vol 59 (12) ◽  
pp. 1048 ◽  
Author(s):  
J. F. Jasonsmith ◽  
W. Maher ◽  
A.C. Roach ◽  
F. Krikowa
Keyword(s):  
Rainbow Trout ◽  
New South ◽  
Benthic Algae ◽  
Food Sources ◽  
Food Chains ◽  
Fish Liver ◽  
Epiphytic Algae ◽  
South Wales ◽  
Cooling Reservoir ◽  
Fish Spawning

Selenium concentrations were measured in water, sediments and organisms inhabiting a freshwater coal power station cooling reservoir. Se concentrations found were: water, 1.9 ± 2 μg L–1; sediment, 7 ± 1 μg g–1; phytoplankton, 3.4 μg g–1; zooplankton, 5.3 μg g–1; epiphytic algae, 1.3 ± 0.2 μg g–1; benthic algae, 8 ± 2 μg g–1; macrophyte leaves, 2.7–2.8 μg g–1; macrophyte roots, 0.5–6.5 μg g–1; detritus, 10 μg g–1; Oligochaeta, 11 μg g–1; Corbiculidae, 1.1 μg g–1; Insects, 3.7–8.3 μg g–1; Gastropoda, 3.2 μg g–1; Crustacea, 3.1–6 μg g–1; whole fish, 2.2–13 μg g–1; and fish liver, 134–314 μg g–1. Bioconcentration factors were similar to those found in aquatic ecosystems with comparable Se concentrations in the water column. A food web was constructed with four main food chains (phytoplankton, epiphytic algae, benthic algae and sediment/detrital), with fish fed from multiple pathways. Biomagnification only occurs along food chains for flathead gudgeons and rainbow trout. Se concentrations in food sources were above the 3 μg g–1 dietary Se level considered to induce teratogenesis in fish spawning. Flathead gudgeons were found to be suffering teratogenesis and rainbow trout showed no evidence of teratogenesis.

Overwintering Biology, Food Supplementation and Parasitism of Eggs of Homalodisca Coagulata (Say) (Homoptera: Cicadellidae) by Gonatocerus Ashmeadi Girault and Gonatocerus Morrilli (Howard) (Hymenoptera: Mymaridae)

2004 ◽  
Vol 39 (2) ◽  
pp. 214-222 ◽  
Author(s):  
Rolando López ◽  
Russell F. Mizell ◽  
Peter C. Andersen ◽  
Brent V. Brodbeck
Keyword(s):  
Early Spring ◽  
Food Sources ◽  
Food Supplementation ◽  
Late Winter ◽  
Egg Masses ◽  
First Case ◽  
Parasitism Rates ◽  
Homalodisca Coagulata ◽  
Petri Dishes ◽  
Gonatocerus Ashmeadi

The efficiency of parasitism of Gonatocerus ashmeadi Girault and G. morrilli (Howard) (Hymenoptera: Myramidae) on glassy-winged sharpshooter, Homalodisca coagulata (Say) (Homoptera: Cicadellidae), eggs of varying age was documented. Excised leaves with H. coagulata eggs of age 1 to 9 d were presented to mated female parasitoids in Petri dishes as well as on intact foliage. Parasitism rates for both species were high with 3 females in Petri dishes parasitizing virtually all eggs in 3 egg masses, and 8 mated females finding and parasitizing almost all eggs from 5 egg masses in small shrubs of Ilex opaca cv cornuta. For both species, parasitism efficiency exceeded 95% within 24 h. Parasitism rates declined for older eggs (8 and 9 d) on excised leaves. Because this did not occur on live plant material, hardening of excised foliage likely contributed to lower rates of parasitism. No cases of superparasitism were observed: Overwintering of the parasitoids was examined by monitoring the fate of eggs of H. coagulata deposited in November. We documented the first case of H. coagulata overwintering as eggs under North Florida conditions. In addition, both G. ashmeadi and G. morrilli were able to overwinter as undeveloped larvae within parasitized eggs under similar conditions. Overwintering parasitoids took approximately 85 d for emergence, which slightly exceeded the minimum predicted for emergence by existing degree day models. Feeding experiments conducted with G. ashmeadi and G. morrilli as food sources are limited during winter/spring; however, our results confirmed that honeydew from Dialeurodes citri (Ashmead) (available in North Florida in late winter/early spring) significantly increased the longevity of both parasitoid species when compared to honey and water.

scholarly journals Reservoir characterisation using artificial bee colony optimisation

2012 ◽  
Vol 52 (1) ◽  
pp. 115
Author(s):  
Mohammad Sayyafzadeh ◽  
Manouchehr Haghighi ◽  
Keivan Bolouri ◽  
Elaheh Arjomand
Keyword(s):  
Honey Bees ◽  
History Matching ◽  
Artificial Bee Colony ◽  
Food Sources ◽  
Accurate Estimation ◽  
Reservoir Performance ◽  
Bee Colony ◽  
First Case ◽  
Fitness Value ◽  
Optimisation Methods

To obtain an accurate estimation of reservoir performance, the reservoir should be properly characterised. One of the main stages of reservoir characterisation is the calibration of rock property distributions with flow performance observation, which is known as history matching. The history matching procedure consists of three distinct steps: parameterisation, regularisation and optimisation. In this study, a Bayesian framework and a pilot-point approach for regularisation and parameterisation are used. The major focus of this paper is optimisation, which plays a crucial role in the reliability and quality of history matching. Several optimisation methods have been studied for history matching, including genetic algorithm (GA), ant colony, particle swarm (PS), Gauss-Newton, Levenberg-Marquardt and Limited-memory, Broyden-Fletcher-Goldfarb-Shanno. One of the most recent optimisation algorithms used in different fields is artificial bee colony (ABC). In this study, the application of ABC in history matching is investigated for the first time. ABC is derived from the intelligent foraging behaviour of honey bees. A colony of honey bees is comprised of employed bees, onlookers and scouts. Employed bees look for food sources based on their knowledge, onlookers make decisions for foraging using employed bees’ observations, and scouts search for food randomly. To investigate the application of ABC in history matching, its results for two different synthetic cases are compared with the outcomes of three different optimisation methods: real-valued GA, simulated annealing (SA), and pre-conditioned steepest descent. In the first case, history matching using ABC afforded a better result than GA and SA. ABC reached a lower fitness value in a reasonable number of evaluations, which indicates the performance and execution-time capability of the method. ABC did not appear as efficient as PSD in the first case. In the second case, SA and PDS did not perform acceptably. GA achieved a better result in comparison to SA and PSD, but its results were not as superior as ABC’s. ABC is not concerned with the shape of the landscape; that is, whether it is smooth or rugged. Since there is no precise information about the landscape shape of the history matching function, it can be concluded that by using ABC, there is a high chance of providing high-quality history matching and reservoir characterisation.

scholarly journals Predaceous diving beetles (Coleoptera : Dytiscidae) may affect the success of amphibian conservation efforts

2018 ◽  
Vol 66 (6) ◽  
pp. 352 ◽  
Author(s):  
Jose W. Valdez
Keyword(s):  
Captive Breeding ◽  
Amphibian Conservation ◽  
Predatory Behaviour ◽  
Feeding Method ◽  
Invertebrate Predators ◽  
Diving Beetles ◽  
Freshwater Habitats ◽  
Natural Predation ◽  
Conservation Plans

The role of invertebrate predation in shaping vertebrate communities is often overlooked. This is evident with predaceous diving beetles (Coleoptera: Dytiscidae), which are often the top predator in many aquatic freshwater habitats. During weekly monitoring of a reintroduction for an endangered frog, a group of a dozen adult diving beetles were encountered attacking and quickly dismembering and consuming a tadpole. A single adult diving beetle was also discovered burrowing its head inside and consuming a tadpole approximately 3–4 times its size by seemingly piercing its prey to suck out its liquefied remains. This is in contrast with the well known behaviour of adult dytiscids, which involves tearing prey into small pieces with their chewing mouthparts. Although dytiscids are known to occasionally consume vertebrates such as tadpoles, adults are typically considered scavengers, and this communal predatory behaviour and feeding method have not previously been documented. Moreover, over 80% of the tadpoles in the monitored site were found in ponds with no beetles and despite representing only a quarter of all ponds, half of the tadpoles across the landscape were in ponds free of diving beetles, demonstrating a possible influence of diving beetles on tadpoles. These observations may have implications for amphibian conservation since management efforts are not typically concerned with naturally occurring ubiquitous threats such as those from small invertebrate predators, as it has rarely been observed in nature. Although amphibian conservation plans expect some losses from natural predation, diving beetles may affect conservation efforts such as captive breeding and reintroductions with populations where every individual is critical to success.

scholarly journals Simultaneous expression of UV and violet SWS1 opsins expands the visual palette in a group of freshwater snakes

2021 ◽  
Author(s):  
Einat Hauzman ◽  
Michele E.R. Pierotti ◽  
Nihar Bhattacharyya ◽  
Juliana H. Tashiro ◽  
Carola A.M. Yovanovich ◽  
...  
Keyword(s):  
Purifying Selection ◽  
Spectral Shift ◽  
Site Directed Mutagenesis ◽  
Single Amino Acid ◽  
First Case ◽  
Upper Visual Field ◽  
Freshwater Habitats ◽  
Terrestrial Environments ◽  
Cone Opsins

AbstractSnakes are known to express a rod visual opsin and two cone opsins, only (SWS1, LWS), a reduced palette resulting from their supposedly fossorial origins. Dipsadid snakes in the genus Helicops are highly visual predators that successfully invaded freshwater habitats from ancestral terrestrial-only habitats. Here we report the first case of multiple SWS1 visual pigments in a vertebrate, simultaneously expressed in different photoreceptors and conferring both UV and violet sensitivity to Helicops snakes. Molecular analysis and in vitro expression confirmed the presence of two functional SWS1 opsins, likely the result of recent gene duplication. Evolutionary analyses indicate that each sws1 variant has undergone different evolutionary paths, with strong purifying selection acting on the UV-sensitive copy and dN/dS ∼1 on the violet-sensitive copy. Site-directed mutagenesis points to the functional role of a single amino acid substitution, Phe86Val, in the large spectral shift between UV and violet opsins. In addition, higher densities of photoreceptors and SWS1 cones in the ventral retina suggest improved acuity in the upper visual field possibly correlated with visually-guided behaviors. The expanded visual opsin repertoire and specialized retinal architecture are likely to improve photon uptake in underwater and terrestrial environments, and provide the neural substrate for a gain in chromatic discrimination, potentially conferring unique color vision in the UV-violet range. Our findings highlight the innovative solutions undertaken by a highly specialized lineage to tackle the challenges imposed by the invasion of novel photic environments and the extraordinary diversity of evolutionary trajectories taken by visual opsin-based perception in vertebrates.

scholarly journals Spatiotemporal pattern formation in a prey-predator model with generalist predator

2021 ◽  
Author(s):  
Kalyan Manna ◽  
Malay Banerjee
Keyword(s):  
Prey Species ◽  
Landau Equation ◽  
Traveling Wave Solutions ◽  
Turing Instability ◽  
Prey Consumption ◽  
Food Sources ◽  
Spatiotemporal Pattern ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Density Level

Generalist predators exploit multiple food sources and it is economical for them to reduce predation pressure on a particular prey species when their density level becomes comparatively less. As a result, a prey-predator system tends to become more stable in the presence of a generalist predator. In this article, we investigate the roles of both the diffusion and nonlocal prey consumption in shaping the population distributions for interacting generalist predator and its focal prey species. In this regard, we first derive the conditions associated with Turing instability through linear analysis. Then, we perform a weakly nonlinear analysis and derive a cubic Stuart-Landau equation governing amplitude of the resulting patterns near Turing bifurcation boundary. Further, we present a wide variety of numerical simulations to corroborate our analytical findings as well as to illustrate some other complex spatiotemporal dynamics. Interestingly, our study reveals the existence of traveling wave solutions connecting two spatially homogeneous coexistence steady states in Turing domain under the influence of temporal bistability phenomenon. Also, our investigation shows that nonlocal prey consumption acts as a stabilizing force for the system dynamics.

scholarly journals Predaceous Diving Beetles (Coleoptera: Dytiscidae) May Affect the Success of Amphibian Conservation Efforts

2019 ◽  
Author(s):  
Jose Valdez
Keyword(s):  
Captive Breeding ◽  
Predatory Behavior ◽  
Amphibian Conservation ◽  
Feeding Method ◽  
Invertebrate Predators ◽  
Diving Beetles ◽  
Freshwater Habitats ◽  
Natural Predation ◽  
Compensatory Habitat ◽  
Conservation Plans

The role of invertebrate predation in shaping vertebrate communities is often underestimated or overlooked, which has resulted in the lack of their recognition in conservation planning. This is evident with predaceous diving beetles (Coleoptera: Dytiscidae) which are often the top predator in many aquatic freshwater habitats. During weekly monitoring of a compensatory habitat reintroduction for an endangered frog species, a group of a dozen adult diving beetles were encountered attacking and quickly dismembering and consuming a tadpole. A single adult diving beetle was also discovered burrowing its head deep inside and consuming a tadpole approximately three to four times its size. Although Dytiscidae are known to occasionally consume vertebrates such as tadpoles, adults are typically considered scavengers, and this communal predatory behavior and feeding method have not been previously documented. Besides these interesting novel behaviors, these observations may have implications for amphibian conservation since management efforts are not typically concerned with naturally occurring ubiquitous threats such as those from small invertebrate predators, as it is rarely been observed in nature. However, this may be perhaps due to their ability to consume prey rapidly, especially if predating in groups. Although amphibian conservation plans expect some losses from natural predation, diving beetles may affect conservation efforts such as captive breeding and reintroductions with populations already on the threshold of extinction and where every individual critical to success.

Hemoglobin crystals of the red blood cells in the human renal cortex: electron microscopic observations of the renal lithiasis

1978 ◽  
Vol 36 (2) ◽  
pp. 480-481
Author(s):  
Kosuke Ueda ◽  
Hiroto Washida ◽  
Nakazo Watari
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Renal Cortex ◽  
Uranyl Acetate ◽  
Osmic Acid ◽  
Renal Lithiasis ◽  
Electron Microscopic ◽  
Hemoglobin C ◽  
First Case ◽  
Ultrathin Sections

IntroductionHemoglobin crystals in the red blood cells were electronmicroscopically reported by Fawcett in the cat myocardium. In the human, Lessin revealed crystal-containing cells in the periphral blood of hemoglobin C disease patients. We found the hemoglobin crystals and its agglutination in the erythrocytes in the renal cortex of the human renal lithiasis, and these patients had no hematological abnormalities or other diseases out of the renal lithiasis. Hemoglobin crystals in the human erythrocytes were confirmed to be the first case in the kidney.Material and MethodsTen cases of the human renal biopsies were performed on the operations of the seven pyelolithotomies and three ureterolithotomies. The each specimens were primarily fixed in cacodylate buffered 3. 0% glutaraldehyde and post fixed in osmic acid, dehydrated in graded concentrations of ethanol, and then embedded in Epon 812. Ultrathin sections, cut on LKB microtome, were doubly stained with uranyl acetate and lead citrate.

Electron-diffraction studies in synthetic polymer materials

1983 ◽  
Vol 41 ◽  
pp. 362-365
Author(s):  
D.T. Grubb
Keyword(s):  
Electron Diffraction ◽  
Synthetic Polymer ◽  
Polymer Materials ◽  
Crystallographic Structure ◽  
High Dose ◽  
Electron Dose ◽  
Dose Rates ◽  
First Case ◽  
Diffraction Patterns ◽  
The Many

Diffraction studies in polymeric and other beam sensitive materials may bring to mind the many experiments where diffracted intensity has been used as a measure of the electron dose required to destroy fine structure in the TEM. But this paper is concerned with a range of cases where the diffraction pattern itself contains the important information.In the first case, electron diffraction from paraffins, degraded polyethylene and polyethylene single crystals, all the samples are highly ordered, and their crystallographic structure is well known. The diffraction patterns fade on irradiation and may also change considerably in a-spacing, increasing the unit cell volume on irradiation. The effect is large and continuous far C94H190 paraffin and for PE, while for shorter chains to C 28H58 the change is less, levelling off at high dose, Fig.l. It is also found that the change in a-spacing increases at higher dose rates and at higher irradiation temperatures.

Small-Angle Electron Scattering (SAES) of Polymers

1985 ◽  
Vol 43 ◽  
pp. 78-79
Author(s):  
Ralph Oralor ◽  
Pamela Lloyd ◽  
Satish Kumar ◽  
W. W. Adams
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Angular Resolution ◽  
Structural Features ◽  
Objective Lens ◽  
High Angular Resolution ◽  
Push Button ◽  
First Case ◽  
Diffraction Mode ◽  
Very High

Small angle electron scattering (SAES) has been used to study structural features of up to several thousand angstroms in polymers, as well as in metals. SAES may be done either in (a) long camera mode by switching off the objective lens current or in (b) selected area diffraction mode. In the first case very high camera lengths (up to 7Ø meters on JEOL 1Ø ØCX) and high angular resolution can be obtained, while in the second case smaller camera lengths (approximately up to 3.6 meters on JEOL 1Ø ØCX) and lower angular resolution is obtainable. We conducted our SAES studies on JEOL 1ØØCX which can be switched to either mode with a push button as a standard feature.

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