The sugar composition of fruits in the diet of spider monkeys (Ateles geoffroyi) in tropical humid forest in Costa Rica

Spider monkeys (Ateles geoffroyi) detect sucrose at a threshold lower than any primate yet tested and prefer sucrose to glucose or fructose in laboratory tests. This preferential selection of sucrose led to the hypothesis that such acute discrimination is related to a diet of sucrose-rich fruits. Furthermore, it has been suggested that fruit sugars may be related to distinct guilds of vertebrate seed-dispersers. The objectives of this study were: (1) to test if spider monkeys select sucrose-rich fruits both within and among plant species and (2) to test the hypothesis that sugar concentration is related to bird, bat or monkey seed-dispersal syndromes. Data were collected from one troop of spider monkeys in south-western Costa Rica. Interspecific comparison of ingested fruits shows that spider monkeys consumed species with significantly higher concentrations of glucose and fructose than sucrose. Similarly, at the intraspecific level, food-fruits had significantly more fructose and glucose than non-food fruits, but no difference was found for sucrose. The three different sugar types were not correlated with the importance of the species in the diet based on the amount of time they spent consuming each species. Although sucrose concentrations were significantly higher in primate-dispersed species compared with those dispersed by other vertebrates, soluble carbohydrates in primate-dispersed fruits were principally composed of glucose and fructose. Neither fructose nor glucose concentrations showed significant differences across the three categories of seed dispersal.published_or_final_versio

Relationship between Spatial Working Memory Performance and Diet Specialization in Two Sympatric Nectar Bats

Behavioural ecologists increasingly recognise spatial memory as one the most influential cognitive traits involved in evolutionary processes. In particular, spatial working memory (SWM), i.e. the ability of animals to store temporarily useful information for current foraging tasks, determines the foraging efficiency of individuals. As a consequence, SWM also has the potential to influence competitive abilities and to affect patterns of sympatric occurrence among closely related species. The present study aims at comparing the efficiency of SWM between generalist (Glossophaga soricina) and specialist (Leptonycteris yerbabuenae) nectarivorous bats at flowering patches. The two species differ in diet – the generalist diet including seasonally fruits and insects with nectar and pollen while the specialist diet is dominated by nectar and pollen yearlong – and in some morphological traits – the specialist being heavier and with proportionally longer rostrum than the generalist. These bats are found sympatrically within part of their range in the Neotropics. We habituated captive individuals to feed on artificial flower patches and we used infrared video recordings to monitor their ability to remember and avoid the spatial location of flowers they emptied in previous visits in the course of 15-min foraging sequences. Experiments revealed that both species rely on SWM as their foraging success attained significantly greater values than random expectations. However, the nectar specialist L. yerbabuenae was significantly more efficient at extracting nectar (+28% in foraging success), and sustained longer foraging bouts (+27% in length of efficient foraging sequences) than the generalist G. soricina. These contrasting SWM performances are discussed in relation to diet specialization and other life history traits

Markedly Divergent Tree Assemblage Responses to Tropical Forest Loss and Fragmentation across a Strong Seasonality Gradient

We examine the effects of forest fragmentation on the structure and composition of tree assemblages within three seasonal and aseasonal forest types of southern Brazil, including evergreen, Araucaria, and deciduous forests. We sampled three southernmost Atlantic Forest landscapes, including the largest continuous forest protected areas within each forest type. Tree assemblages in each forest type were sampled within 10 plots of 0.1 ha in both continuous forests and 10 adjacent forest fragments. All trees within each plot were assigned to trait categories describing their regeneration strategy, vertical stratification, seed-dispersal mode, seed size, and wood density. We detected differences among both forest types and landscape contexts in terms of overall tree species richness, and the density and species richness of different functional groups in terms of regeneration strategy, seed dispersal mode and woody density. Overall, evergreen forest fragments exhibited the largest deviations from continuous forest plots in assemblage structure. Evergreen, Araucaria and deciduous forests diverge in the functional composition of tree floras, particularly in relation to regeneration strategy and stress tolerance. By supporting a more diversified light-demanding and stress-tolerant flora with reduced richness and abundance of shade-tolerant, old-growth species, both deciduous and Araucaria forest tree assemblages are more intrinsically resilient to contemporary human-disturbances, including fragmentation-induced edge effects, in terms of species erosion and functional shifts. We suggest that these intrinsic differences in the direction and magnitude of responses to changes in landscape structure between forest types should guide a wide range of conservation strategies in restoring fragmented tropical forest landscapes worldwide

Performance Analysis of Orthogonal Pairs Designed for an Expanded Eukaryotic Genetic Code

Background: The suppression of amber stop codons with non-canonical amino acids (ncAAs) is used for the site-specific introduction of many unusual functions into proteins. Specific orthogonal aminoacyl-tRNA synthetase (o-aaRS)/amber suppressor tRNA CUA pairs (o-pairs) for the incorporation of ncAAs in S. cerevisiae were previously selected from an E. coli tyrosyl-tRNA synthetase/tRNACUA mutant library. Incorporation fidelity relies on the specificity of the o-aaRSs for their ncAAs and the ability to effectively discriminate against their natural substrate Tyr or any other canonical amino acid. Methodology/Principal Findings: We used o-pairs previously developed for ncAAs carrying reactive alkyne-, azido-, or photocrosslinker side chains to suppress an amber mutant of human superoxide dismutase 1 in S. cerevisiae. We found worse incorporation efficiencies of the alkyne- and the photocrosslinker ncAAs than reported earlier. In our hands, amber suppression with the ncAA containing the azido group did not occur at all. In addition to the incorporation experiments in S. cerevisiae, we analyzed the catalytic properties of the o-aaRSs in vitro. Surprisingly, all o-aaRSs showed much higher preference for their natural substrate Tyr than for any of the tested ncAAs. While it is unclear why efficiently recognized Tyr is not inserted at amber codons, we speculate that metabolically inert ncAAs accumulate in the cell, and for this reason they are incorporated despite being weak substrates for the o-aaRSs. Conclusions/Significance: O-pairs have been developed for a whole plethora of ncAAs. However, a systematic and detaile

Embedding cultural competence in faculty : a mixed-methods evaluation of an applied Indigenous proficiency workshop

One of the most pressing issues in Australian society is the gap between Indigenous and non-Indigenous health and life expectancies (Marmot, 2017). Australia agreed with the World Health Organisation’s 2008 Closing the Gap in a Generation report (WHO, 2008), spending approximately 5.6% of government expenditure towards ameliorating this gap (Gardiner-Garden & Simon-Davies, 2012), yet there have been only minimal positive outcomes (Alford, 2015; Gannon, 2018). In applied terms, this means Indigenous people are still dying younger (Anderson et al., 2016), scoring higher on psychological distress (Markwick, Ansari, Sullivan, & McNeil, 2015) and suffering poorer indices on all chronic diseases (e.g. Walsh & Kangaharan, 2016; Thompson, Talley, & Kong, 2017). The level of complexity involved in addressing these “wicked” or seemingly “impossible to solve” health problems is made worse by the lack of any pan-national strategic planning and/or intervention evaluation (Lokuge et al., 2017), even though there has been a plethora of programs and projects designed to improve Indigenous health (see for example, AGPC, 2016). Leaders in health and educational institutions must consider why there is a lack of progress in closing the gap in Indigenous health and life expectancies. Addressing the inequities in Indigenous health requires a determinant of health approach (Mitrou et al., 2014), as 39% of the gap in health outcomes can be explained by social determinates (AIHW, 2017; Markwick, Ansari, Sullivan, Parsons, & McNeil, 2014). The social determinant considered to most reliably predict Indigenous poor health is racism (Kelaher, Ferdinand, & Paradies, 2014; Paradies, 2006; Paradies & Cunningham, 2009; Paradies et al., 2015; Paradies, Truong, & Priest, 2014)

Local and Landscape Factors Determining Occurrence of Phyllostomid Bats in Tropical Secondary Forests

Neotropical forests are being increasingly replaced by a mosaic of patches of different successional stages, agricultural fields and pasture lands. Consequently, the identification of factors shaping the performance of taxa in anthropogenic landscapes is gaining importance, especially for taxa playing critical roles in ecosystem functioning. As phyllostomid bats provide important ecological services through seed dispersal, pollination and control of animal populations, in this study we assessed the relationships between phyllostomid occurrence and the variation in local and landscape level habitat attributes caused by disturbance. We mist-netted phyllostomids in 12 sites representing 4 successional stages of a tropical dry forest (initial, early, intermediate and late). We also quantitatively characterized the habitat attributes at the local (vegetation structure complexity) and the landscape level (forest cover, area and diversity of patches). Two focal scales were considered for landscape characterization: 500 and 1000 m. During 142 sampling nights, we captured 606 individuals representing 15 species and 4 broad guilds. Variation in phyllostomid assemblages, ensembles and populations was associated with variation in local and landscape habitat attributes, and this association was scale-dependent. Specifically, we found a marked guild-specific response, where the abundance of nectarivores tended to be negatively associated with the mean area of dry forest patches, while the abundance of frugivores was positively associated with the percentage of riparian forest. These results are explained by the prevalence of chiropterophilic species in the dry forest and of chiropterochorous species in the riparian forest. Our results indicate that different vegetation classes, as well as a multi-spatial scale approach must be considered for evaluating bat response to variation in landscape attributes. Moreover, for the long-term conservation of phyllostomids in anthropogenic landscapes, we must realize that the management of the habitat at the landscape level is as important as the conservation of particular forest fragments

The Spread of Fecally Transmitted Parasites in Socially-Structured Populations

Mammals are infected by a wide array of gastrointestinal parasites, including parasites that also infect humans and domesticated animals. Many of these parasites are acquired through contact with infectious stages present in soil, feces or vegetation, suggesting that ranging behavior will have a major impact on their spread. We developed an individual-based spatial simulation model to investigate how range use intensity, home range overlap, and defecation rate impact the spread of fecally transmitted parasites in a population composed of social groups (i.e., a socially structured population). We also investigated the effects of epidemiological parameters involving host and parasite mortality rates, transmissibility, disease–related mortality, and group size. The model was spatially explicit and involved the spillover of a gastrointestinal parasite from a reservoir population along the edge of a simulated reserve, which was designed to mimic the introduction pathogens into protected areas. Animals ranged randomly within a “core” area, with biased movement toward the range center when outside the core. We systematically varied model parameters using a Latin hypercube sampling design. Analyses of simulation output revealed a strong positive association between range use intensity and the prevalence of infection. Moreover, the effects of range use intensity were similar in magnitude to effects of group size, mortality rates, and the per-contact probability of transmission. Defecation rate covaried positively with gastrointestinal parasite prevalence. Greater home range overlap had no positive effects on prevalence, with a smaller core resulting in less range overlap yet more intensive use of the home range and higher prevalence. Collectively, our results reveal that parasites with fecal-oral transmission spread effectively in socially structured populations. Future application should focus on parameterizing the model with empirically derived ranging behavior for different species or populations and data on transmission characteristics of different infectious organisms

A simulation study comparing supertree and combined analysis methods using SMIDGen

<p>Abstract</p> <p>Background</p> <p>Supertree methods comprise one approach to reconstructing large molecular phylogenies given multi-marker datasets: trees are estimated on each marker and then combined into a tree (the "supertree") on the entire set of taxa. Supertrees can be constructed using various algorithmic techniques, with the most common being matrix representation with parsimony (MRP). When the data allow, the competing approach is a combined analysis (also known as a "supermatrix" or "total evidence" approach) whereby the different sequence data matrices for each of the different subsets of taxa are concatenated into a single supermatrix, and a tree is estimated on that supermatrix.</p> <p>Results</p> <p>In this paper, we describe an extensive simulation study we performed comparing two supertree methods, MRP and weighted MRP, to combined analysis methods on large model trees. A key contribution of this study is our novel simulation methodology (Super-Method Input Data Generator, or <it>SMIDGen</it>) that better reflects biological processes and the practices of systematists than earlier simulations. We show that combined analysis based upon maximum likelihood outperforms MRP and weighted MRP, giving especially big improvements when the largest subtree does not contain most of the taxa.</p> <p>Conclusions</p> <p>This study demonstrates that MRP and weighted MRP produce distinctly less accurate trees than combined analyses for a given base method (maximum parsimony or maximum likelihood). Since there are situations in which combined analyses are not feasible, there is a clear need for better supertree methods. The source tree and combined datasets used in this study can be used to test other supertree and combined analysis methods.</p

Newtype single-layer magnetic semiconductor in transition-metal dichalcogenides VX 2 (X = S, Se and Te)

We present a newtype 2-dimensional (2D) magnetic semiconductor based on transition-metal dichalcogenides VX2 (X = S, Se and Te) via first-principles calculations. The obtained indirect band gaps of monolayer VS2, VSe2, and VTe2 given from the generalized gradient approximation (GGA) are respectively 0.05, 0.22, and 0.20 eV, all with integer magnetic moments of 1.0 μB. The GGA plus on-site Coulomb interaction U (GGA + U) enhances the exchange splittings and raises the energy gap up to 0.38~0.65 eV. By adopting the GW approximation, we obtain converged G0W0 gaps of 1.3, 1.2, and 0.7 eV for VS2, VSe2, and VTe2 monolayers, respectively. They agree very well with our calculated HSE gaps of 1.1, 1.2, and 0.6 eV, respectively. The gap sizes as well as the metal-insulator transitions are tunable by applying the in-plane strain and/or changing the number of stacking layers. The Monte Carlo simulations illustrate very high Curie-temperatures of 292, 472, and 553 K for VS2, VSe2, and VTe2 monolayers, respectively. They are nearly or well beyond the room temperature. Combining the semiconducting energy gap, the 100% spin polarized valence and conduction bands, the room temperature TC, and the in-plane magnetic anisotropy together in a single layer VX2, this newtype 2D magnetic semiconductor shows great potential in future spintronics

Effects of Trophic Skewing of Species Richness on Ecosystem Functioning in a Diverse Marine Community

Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions