Interindividual patterns of resource use in three subtropical Atlantic Forest frogs

Studies with disparate taxa suggest that generalist populations are composed of relatively specialist individuals that use a narrow part of a population's resource pool. Models based on optimum diet theory (ODT) can be used to predict different patterns of variation in resource use among individuals. In this work, we investigated the diet and measured the degree of individual specialization of three anuran species, Hypsiboas leptolineatus, Pseudis cardosoi and Scinax granulatus, from the Atlantic Forest of southern Brazil. The study is based on gut content obtained using a stomach‐flushing technique. Additionally, we tested for a correlation between the individuals’ diet and morphological variation. Furthermore, we applied methods based on network theory to investigate patterns of resource use among individuals of each species. All three study species showed generalized diets and significant values of individual specialization. However, we did not find any correlation between diet and morphology, indicating that diet variation is not a consequence of morphological trade‐offs. The individual‐resource networks of H. leptolineatus and S. granulatus showed a nested pattern. This result indicates the presence of individuals with more diverse diets than others, and the diets of the more specialist individuals are a predictable subset of the diets of the more generalist ones. The individual‐resource network of P. cardosoi did not show a distinct pattern, diverging from what was predicted by optimal diet theory‐based models. Although nested or modular patterns are commonly found in individual‐resource networks, our results indicate that they are not ubiquitous and that random patterns can also be found.     

Ablating both Fabp1 and Scp2/Scpx (TKO) induces hepatic phospholipid and cholesterol accumulation in high fat-fed mice

Although singly ablating Fabp1 or Scp2/Scpx genes may exacerbate the impact of high fat diet (HFD) on whole body phenotype and non-alcoholic fatty liver disease (NAFLD), concomitant upregulation of the non-ablated gene, preference for ad libitum fed HFD, and sex differences complicate interpretation. Therefore, these issues were addressed in male and female mice ablated in both genes (Fabp1/Scp2/Scpx null or TKO) and pair-fed HFD. Wild-type (WT) males gained more body weight as fat tissue mass (FTM) and exhibited higher hepatic lipid accumulation than WT females. The greater hepatic lipid accumulation in WT males was associated with higher hepatic expression of enzymes in glyceride synthesis, higher hepatic bile acids, and upregulation of transporters involved in hepatic reuptake of serum bile acids. While TKO had little effect on whole body phenotype and hepatic bile acid accumulation in either sex, TKO increased hepatic accumulation of lipids in both, specifically phospholipid and cholesteryl esters in males and females and free cholesterol in females. TKO-induced increases in glycerides were attributed not only to complete loss of FABP1, SCP2 and SCPx, but also in part to sex-dependent upregulation of hepatic lipogenic enzymes. These data with WT and TKO mice pair-fed HFD indicate that: i) Sex significantly impacted the ability of HFD to increase body weight, induce hepatic lipid accumulation and increase hepatic bile acids; and ii) TKO exacerbated the HFD ability to induce hepatic lipid accumulation, regardless of sex, but did not significantly alter whole body phenotype in either sex.     

Does the diurnal pattern of enteric methane emissions from dairy cows change over time?

Diet manipulation and genetic selection are two important mitigation strategies for reducing enteric methane (CH₄) emissions from ruminant livestock. The aim of this study was to assess whether the diurnal pattern of CH₄ emissions from individual dairy cows changes over time when cows are fed on diets varying in forage composition. Emissions of CH₄ from 36 cows were measured during milking in an automatic (robotic) milking station in three consecutive feeding periods, for a total of 84 days. In Periods 1 and 2, the 36 cows were fed a high-forage partial mixed ration (PMR) containing 75% forage, with either a high grass silage or high maize silage content. In Period 3, cows were fed a commercial PMR containing 69% forage. Cows were offered PMR ad libitum plus concentrates during milking and CH₄ emitted by individual cows was sampled during 8662 milkings. A linear mixed model was used to assess differences among cows, feeding periods and time of day. Considerable variation was observed among cows in daily mean and diurnal patterns of CH₄ emissions. On average, cows produced less CH₄ when fed on the commercial PMR in feeding Period 3 than when the same cows were fed on high-forage diets in feeding Periods 1 and 2. The average diurnal pattern for CH₄ emissions did not significantly change between feeding periods and as lactation progressed. Emissions of CH₄ were positively associated with dry matter (DM) intake and forage DM intake. It is concluded that if the management of feed allocation remains constant then the diurnal pattern of CH₄ emissions from dairy cows will not necessarily alter over time. A change in diet composition may bring about an increase or decrease in absolute emissions over a 24-h period without significantly changing the diurnal pattern unless management of feed allocation changes. These findings are important for CH₄ monitoring techniques that involve taking measurements over short periods within a day rather than complete 24-h observations.     

Variation in the magnitude of morphological and dietary differences between individuals among populations of small benthic Arctic charr in relation to ecological factors

The early stages of intraspecific diversity are important for the evolution of diversification and speciation. Early stages of diversification can be seen in individual specialization, where individuals consume only a portion of the diet of the population as a whole, and how such specialization is related to phenotypic diversity within populations. Here, we study the strength of the relationship between morphological and dietary distances among individuals in eighteen populations of Icelandic small benthic charr. We furthermore studied if the strength of the relationship could be related to variation in local ecological factors these populations inhabit. In all the populations studied, there was a clear relationship between morphological and dietary distances, indicating that fish that had similar morphology were at the same time‐consuming similar food items. Our findings show a systematic variation in the relationship between morphology and diet at early stages of diversification in a highly specialized small benthic charr morph. The results show the importance of fine scale comparisons within populations and furthermore the value that systematic comparisons among populations under parallel evolution can contribute toward our increased understanding of evolutionary and ecological processes.     

Meta‐barcoding insights into the spatial and temporal dietary patterns of the threatened Asian Great Bustard (Otis tarda dybowskii) with potential implications for diverging migratory strategies

Food resources are often not sufficient to satisfy the nutritional and energetic requirements during winter conditions at high latitudes. Dietary analysis is a prerequisite to fully understanding the feeding ecology of a species and the nature of trophic interactions. Previous dietary studies of Asian Great Bustard (Otis tarda dybowskii) relied on behavioral observations, resulting in categorization of diet limited to broad taxonomic groupings. Here, we applied a high‐throughput sequencing meta‐barcoding approach to quantify the diet of resident and migratory Asian Great Bustard in three wintering sites during early winter and late winter. We detected 57 unique plant taxa in the bustard diet, among which 15 species were confirmed by a local plant database we generated. Both agricultural and natural foods were detected, indicating a relatively broad dietary niche. Spatiotemporal dietary changes were discovered, revealing diet differences among wintering sites and a general shift toward lower plant diversity later in winter. For the nonmigratory population, we detected a significantly more diverse array of plant species in their diet. We hypothesize that dietary variation between resident and migratory populations could be involved in the recent transition to partial migration in this species, although climate change can not be excluded. Collectively, these results support protecting unharvested grain fields and naturally unplowed lands to help conserve and promote population growth of Asian Great Bustard.     

Intelligent Touchscreen Joystick for Controlling Electric Wheelchair

Background

The objective of this research was to design, implement, use and evaluate a human-machine touch interface for driving an electric wheelchair. This new interface allows control of the electric wheelchair with touch screen smartphone technologies (android, IOS or Windows phone). In addition, an intelligent calibration algorithm, based on the neural network (NN), is implemented in this interface to overcome manoeuvring problems, namely the inability to move correctly in one or more directions.

Pattern and process in the evolution of insect-plant associations: Yponomeuta as an example

Phylogenetic studies are increasing our understanding of the evolution of associations between phytophagous insects and their host plants. Sequential evolution, i.e. the shift of insect herbivores onto pre-existing plant species, appears to be much more common than coevolution, where reciprocal selection between interacting insects and plants is thought to induce chemical diversification and resistance in plants and food specialization in insects.Extreme host specificity is common in phytophagous insects and future studies are likely to reveal even more specialization. Hypotheses that assume that food specialists have selective advantages over generalists do not seem to provide a general explanation for the ubiquity of specialist insect herbivores. Specialists are probably committed to remain so, because they have little evolutionary opportunity to reverse the process due to genetically determined constraints on the evolution of their physiology or nervous system. The same constraints might result in phylogenetic conservatism, i.e. the frequent association of related insect herbivores with related plants. Current phylogenetic evidence, however, indicates that there is no intrinsic direction to the evolution of specialization.Historical aspects of insect-host plant associations will be illustrated with the small ermine moth genus Yponomeuta. Small ermine moths show an ancestral host association with the family Celastraceae. The genus seems to be committed to specialization per se rather than to a particular group of plants. Whatever host shift they have made in their evolutionary past (onto Rosaceae, Crassulaceae, and Salicaceae), they remain monophagous. The oligophagous Y. padellus is the only exception. This species might comprise a mosaic of genetically divergent host-associated populations.     

Lake flies and the deep-water demersal fish community of Lake Malawi

Larvae and pupae of Chaoborus edulis may be the most important food resource of some deep-water demersal fish species in southern Lake Malawi. C. edulis feed on crustacean zooplankton, which in turn feed on phytoplankton. Hence, demersal fish production is supported directly by planktonic primary production, rather than through a detrital food chain.     

Diet and predators of Tenagomysis tasmaniae Fenton, Anisomysis mixta australis (Zimmer) and Paramesopodopsis rufa Fenton from south-eastern Tasmania (Crustacea:Mysidacea)

The diets of three mysid species Tenagomysis tasmaniae Fenton, Anisomysis mixta australis (Zimmer) and Paramesopodopsis rufa Fenton were investigated together with a number of potential fish predators by gut contents and stable isotope analysis. Gut content analysis of the three mysis species revealed that all have an omnivorous diet, although the stomachs of P. rufa contained a greater percentage of crustacean remains, whereas the stomach contents of T. tasmaniae were largely composed of fragments of macroalgae. The stomach contents of A. mixta australis were composed mainly of fine particulate matter. Diel feeding rhythms were examined from mysids collected during a 24-hour sampling session in October. P. rufa appeared to be primarily a day-time feeder while T. tasmaniae fed more intensively at night. The results for A. mixta australis were inconclusive. Gut contents analysis of fish collected at the study site revealed predation on mysids by Arripis trutta (juveniles), Aldrichetta forsteri, Vincentia conspersa and Pseudolabrus fucicola. The mysid species most frequently eaten was Tenagomysis australis Fenton. The mysid species most frequently eaten was Tenagomysis australis Fenton.     

Zinc deficiency and the desaturation of linoleic acid in rats force-fed fat-free diets

Recent studies with rats force-fed zinc-deficient diets containing various types of fat failed to demonstrate a role of zinc in desaturation of linoleic acid. The present study was conducted to investigate the effect of zinc deficiency on desaturation of linoleic acid in rats that were initially force-fed fat-free diets to stimulate activity of desaturases. Therefore, rats were fed zinc-adequate and zinc-deficient fat-free diets for 6 d. After that period, the groups were divided and half of the rats continued feeding the fat-free diet for another 3.5 d whereas the other half was switched to a fat diet by supplementing the fat-free diet with 5% safflower oil. In order to assess desaturation of linoleic acid, fatty acid compositions of liver phosphatidylcholine, ethanolamine, and-serine were considered, particularly levels of individual (n-6) polyunsaturated fatty acids (PUFA). Levels of total and individual (n-6) PUFA were similar in zinc-adequate and zinc-deficient rats fed the fat-free diet throughout the experiment. Addition of 5% safflower oil increased levels of total and individual (n-6) PUFA in both zinc-adequate and zinc-deficient rats. However, total (n-6) PUFA in all types of phospholipids were higher in zinc-adequate rats than in zinc-deficient rats. Additionally, in zinc-deficient rats there were changes of (n-6) PUFA levels typical for impaired Δ5 and Δ6 desaturation: linoleic acid and dihomo-γ-linolenic acid were elevated; arachidonic acid, docosatetraenoic acid, and docosapentaenoic were lowered by zinc deficiency. Therefore, the study shows that zinc deficiency impairs desaturation of linoleic acid in rats force-fed fat-free diets and therefore supports results from former convential zinc deficiency experiments suggesting a role of zinc for desaturation of linoleic acid.