A Miocene pygmy right whale fossil from Australia
Neobalaenines are an enigmatic group of baleen whales represented today by a single living species: the pygmy right whale, Caperea marginata, found only in the Southern Hemisphere. Molecular divergence estimates date the origin of pygmy right whales to 22–26 Ma, yet so far there are only three confirmed fossil occurrences. Here, we describe an isolated periotic from the latest Miocene of Victoria (Australia). The new fossil shows all the hallmarks of Caperea, making it the second-oldest described neobalaenine, and the oldest record of the genus. Overall, the new specimen resembles C. marginata in its external morphology and details of the cochlea, but is more archaic in it having a hypertrophied suprameatal area and a greater number of cochlear turns. The presence of Caperea in Australian waters during the Late Miocene matches the distribution of the living species, and supports a southern origin for pygmy right whales.
Marx et al. (2018) A Miocene pygmy right whale fossil from Australia. PeerJ 6:e5025 https://doi.org/10.7717/peerj.5025
Effects of equal-volume resistance training with different training frequencies in muscle size and strength in trained men
Background The objective of the present study was to compare the effects of equal-volume resistance training (RT) performed with different training frequencies on muscle size and strength in trained young men. Methods Sixteen men with at least one year of RT experience were divided into two groups, G1 and G2, that trained each muscle group once and twice a week, respectively, for 10 weeks. Elbow flexor muscle thickness (MT) was measured using a B-Mode ultrasound and concentric peak torque of elbow extensors and flexors were assessed by an isokinetic dynamometer. Results ANOVA did not reveal group by time interactions for any variable, indicating no difference between groups for the changes in MT or PT of elbow flexors and extensors. Notwithstanding, MT of elbow flexors increased significantly (3.1%, P < 0.05) only in G1. PT of elbow flexors and extensors did not increase significantly for any group. Discussion The present study suggest that there were no differences in the results promoted by equal-volume resistance training performed once or twice a week on upper body muscle strength in trained men. Only the group performing one session per week significantly increased the MT of their elbow flexors. However, with either once or twice a week training, adaptations appear largely minimal in previously trained males.
Gentil et al. (2018) Effects of equal-volume resistance training with different training frequencies in muscle size and strength in trained men. PeerJ 6:e5020 https://doi.org/10.7717/peerj.5020
Melatonin significantly influences seed germination and seedling growth of Stevia rebaudiana Bertoni
Background Melatonin (MEL) is a signaling molecule in plants that affects developmental processes during vegetative and reproductive growth. Investigations have proved that exogenously applied MEL also has the potential to improve seed germination and plant development. Methods In the present study, seeds of stevia, a species with a very low germination rate, were germinated on an agar gel (AG) containing MEL at various concentrations (5, 20, 100, and 500 µM) in light. Seeds germinated on AG without MEL were used as controls. For the first 24 or 48 h of germination, the seeds were maintained in darkness as a pre-incubation step. Some seeds were not exposed to this pre-incubation step. Results At concentrations of 20 and 5 µM, MEL significantly improved germination, but only in seeds pre-incubated in darkness for 24 h (p < 0.001). At concentrations of 100 and 500 µM, MEL had an inhibitory effect on germination, regardless of the pre-incubation time. Melatonin also affected plantlet properties. At a concentration of 20 µM, MEL increased plantlet fresh weight and leaf numbers. At a concentration of 5 µM, it promoted plantlet height. Regarding root development, the most favorable MEL concentration was 500 µM. Biochemical analysis revealed that MEL promoted higher pigment concentrations but hampered superoxide dismutase activity. On the other hand, the concentrations of sugars and phenolics, as well as the activities of catalase and peroxidase, increased at a MEL concentration of 500 µM. Discussion The results suggest that MEL can improve germination of positively photoblastic stevia seeds and that it can play a role in plantlet development. However, the effects observed in the present study depended on the quantity of MEL that was applied.
Simlat et al. (2018) Melatonin significantly influences seed germination and seedling growth of Stevia rebaudiana Bertoni. PeerJ 6:e5009 https://doi.org/10.7717/peerj.5009
Vertical stratification of plant–pollinator interactions in a temperate grassland
Visitation of plants by different pollinators depends on individual plant traits, spatial context, and other factors. A neglected aspect of small-scale variation of plant–pollinator interactions is the role of vertical position of flowers. We conducted a series of experiments to study vertical stratification of plant–pollinator interactions in a dry grassland. We observed flower visitors on cut inflorescences of Centaurea scabiosa and Inula salicina placed at different heights above ground in two types of surrounding vegetation: short and tall. Even at such a small-scale, we detected significant shift in total visitation rate of inflorescences in response to their vertical position. In short vegetation, inflorescences close to the ground were visited more frequently, while in tall vegetation, inflorescences placed higher received more visits. Moreover, we found major differences in the composition of the pollinator community on flowers at different heights. In a second experiment, we measured flower visitation rate in inflorescences of Salvia verticillata of variable height. Total flower visitation rate increased markedly with inflorescence height in this case. Data on seed set of individual plants provide evidence for a corresponding positive pollinator-mediated selection on increased inflorescence height. Overall, our results demonstrate strong vertical stratification of plant–pollinator interactions at the scale of mere decimetres. This may have important ecological as well as evolutionary implications.
Klecka et al. (2018) Vertical stratification of plant–pollinator interactions in a temperate grassland. PeerJ 6:e4998 https://doi.org/10.7717/peerj.4998
Is publication bias present in gastroenterological research? An analysis of abstracts presented at an annual congress
Background Publication bias is the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on their direction or strength of findings. In this study, we investigated if publication bias was present in gastroenterological research by evaluating abstracts at Americas Hepato-Pancreato-Biliary Congresses from 2011 to 2013. Methods We searched Google, Google Scholar, and PubMed to locate the published reports of research described in these abstracts. If a publication was not found, a second investigator searched to verify nonpublication. If abstract publication status remained undetermined, authors were contacted regarding reasons for nonpublication. For articles reaching publication, the P value, study design, time to publication, citation count, and journals in which the published report appeared were recorded. Results Our study found that of 569 abstracts presented, 297 (52.2%) reported a P value. Of these, 254 (85.5%) contained P values supporting statistical significance. The abstracts reporting a statistically significant outcome were twice as likely to reach publication than abstracts with no significant findings (OR 2.10, 95% CI [1.06–4.14]). Overall, 243 (42.7%) abstracts reached publication. The mean time to publication was 14 months and a median time of nine months. Conclusion In conclusion, we found evidence for publication bias in gastroenterological research. Abstracts with significant P values had a higher probability of reaching publication. More than half of abstracts presented from 2011 to 2013 failed to reach publication. Readers should take these findings into consideration when reviewing medical literature.
Meyer et al. (2018) Is publication bias present in gastroenterological research? An analysis of abstracts presented at an annual congress. PeerJ 6:e4995 https://doi.org/10.7717/peerj.4995
Predicted effects of landscape change, sea level rise, and habitat management on the extirpation risk of the Hawaiian common gallinule (Gallinula galeata sandvicensis) on the island of O‘ahu
We conducted a spatially explicit, stochastic, individually based population viability analysis for the Hawaiian common gallinule (Gallinula galeata sandvicensis), an endangered subspecies of waterbird endemic to fragmented coastal wetlands in Hawai‘i. This subspecies persists on two islands, with no apparent movement between them. We assessed extirpation risk for birds on O‘ahu, where the resident gallinule population is made up of several fragmented subpopulations. Data on genetic differentiation were used to delineate subpopulations and estimate dispersal rates between them. We used sensitivity analyses to gauge the impact of current uncertainty of vital rate parameters on population projections, to ascertain the relative importance of gallinule vital rates to population persistence, and to compare the efficacy of potential management strategies. We used available sea level rise projections to examine the relative vulnerability of O‘ahu’s gallinule population to habitat loss arising from this threat. Our model predicted persistence of the island’s gallinule population at 160 years (∼40 generations), but with high probabilities of extirpation for small subpopulations. Sensitivity analyses highlighted the importance of juvenile and adult mortality to population persistence in Hawaiian gallinules, justifying current predator control efforts and suggesting the need for additional research on chick and fledgling survival. Subpopulation connectivity from dispersal had little effect on the persistence of the island-wide population, but strong effects on the persistence of smaller subpopulations. Our model also predicted island-wide population persistence under predicted sea level rise scenarios, but with O‘ahu’s largest gallinule populations losing >40% of current carrying capacity.
van Rees et al. (2018) Predicted effects of landscape change, sea level rise, and habitat management on the extirpation risk of the Hawaiian common gallinule (Gallinula galeata sandvicensis) on the island of O‘ahu. PeerJ 6:e4990 https://doi.org/10.7717/peerj.4990
High prevalence of Lynx rufus gammaherpesvirus 1 in wild Vermont bobcats
Gammaherpesviruses (GHVs) are host specific DNA viruses that infect a large range of mammalian species. These viruses preferentially target host lymphocyte cell populations and infection may lead to morbidity or mortality in immunocompromised, co-infected, or non-adapted hosts. In this study, we tested for the presence of Lynx rufus gammaherpesvirus 1 (LruGHV1) in a northeastern United States population of wild bobcats (L. rufus). We estimated prevalence of infection and viral load in infected individuals using quantitative real-time PCR analysis of spleen DNA from 64 Vermont bobcats. We observed an overall prevalence of 64% using this methodology. Bobcat age was significantly positively associated with GHV infection status, and we noted a trend for higher viral loads in young animals, but prevalence and viral load were similar in male and female bobcats. A single LruGHV1 variant was identified from the sequencing of the viral glycoprotein B gene of Vermont bobcats. This gene sequence was 100% similar to that reported in Florida bobcats and slightly variant from other isolates identified in the Western USA. Our work suggests broad geographic distribution and high prevalence of LruGHV1 in bobcat populations across the United States with infection attributes that suggest horizontal transmission of the agent. Geographic differences in viral genotype may reflect historical migration and expansion events among bobcat populations.
Loisel et al. (2018) High prevalence of Lynx rufus gammaherpesvirus 1 in wild Vermont bobcats. PeerJ 6:e4982 https://doi.org/10.7717/peerj.4982
Cities may save some threatened species but not their ecological functions
Background Urbanization is one of the main causes of biodiversity loss worldwide. Wildlife responses to urbanization, however, are greatly variable and, paradoxically, some threatened species may achieve much larger populations in urban than in natural habitats. Urban conservation hotspots may therefore help some species avoid regional or even global extinctions, but not conserve their often overlooked ecological functions in the wild. We aim to draw attention to this issue using two species of globally threatened parrots occurring in the Dominican Republic: the Hispaniolan amazon (Amazona ventralis) and the Hispaniolan parakeet (Psittacara chloropterus). Methods We conducted a large-scale roadside survey in June 2017 across the country to estimate the relative abundance of parrots in natural habitats, rural habitats, and cities. We combined this with informal interviews with local people to collect information on past and current human impacts on parrot populations. We also looked for foraging parrots to assess their potential role as seed dispersers, an ecological function that has been overlooked until very recently. Results Relative abundances of both parrot species were negligible in rural areas and very low in natural habitats. They were generally between one and two orders of magnitude lower than that of congeneric species inhabiting other Neotropical ecosystems. Relative abundances were six times higher in cities than in natural habitats in the case of the Hispaniolan parakeet and three times higher in the case of the Hispaniolan amazon. People indicated hunting for a source food and to mitigate crop damage as causes of parrot population declines, and a vigorous illegal trade for parrots (131 individuals recorded, 75% of them poached very recently), mostly obtained from protected areas where the last small wild populations remain. We observed parrots foraging on 19 plant species from 11 families, dispersing the fruits of 14 species by carrying them in their beaks and consuming them in distant perching trees. They discarded undamaged mature seeds, with the potential to germinate, in 99.5% of cases (n = 306), and minimum dispersal distances ranged from 8 to 155 m (median = 37 m). Discussion The loss of ecological functions provided by some species when they disappear from natural habitats and only persist in cities may have long-term, unexpected effects on ecosystems. Our example demonstrates how two cities may soon be the last refuges for two endemic parrots if overharvesting continues, in which case their overlooked role as seed dispersers would be completely lost in nature. The functional extinction of these species could strongly affect vegetation communities in an island environment where seed-dispersal species are naturally scarce. While conservation plans must include urban populations of threatened species, greater efforts are needed to restore their populations in natural habitats to conserve ecological functions.
Luna et al. (2018) Cities may save some threatened species but not their ecological functions. PeerJ 6:e4908 https://doi.org/10.7717/peerj.4908
Ampelisca eschrichtii Krøyer, 1842 (Ampeliscidae) of the Sakhalin Shelf in the Okhotsk Sea starve in summer and feast in winter
Background Ampelisca eschrichtii Krøyer, 1842 of the Sakhalin Shelf of the Okhotsk Sea, Far Eastern Russia, comprise the highest known biomass concentration of any amphipod population in the world and are a critically important prey source for western gray whales. Growth and reproduction in this population has not been apparent in summer. However, they are not accessible for sampling in winter to test a previous default conclusion that they grow and reproduce in winter. Methods We tested the default winter growth and reproduction hypothesis by detailed comparisons of the brood and gonad development among 40 females and 14 males and brood sizes among females observed since 2002. Our test included six predictions of reproductive synchrony that would be apparent from gonad and brood morphology if active reproduction occurs in summer. Results We found high prevalences of undersized and damaged oocytes, undersized broods, a lack of females brooding fully formed juveniles, atrophied ovaries, and males with mature sperm but lacking fully developed secondary sex morphologies required for pelagic mating. All of these conditions are consistent with trophic stress and starvation. Discussion These A. eschrichtii populations therefore appear to starve in summer and to grow and reproduce in winter. The Offshore A. eschrichtii populations occur in summer below water strata bearing high phytoplankton biomasses. These populations are more likely to feed successfully in winter when storms mix phytoplankton to their depths.
Durkina et al. (2018) Ampelisca eschrichtii Krøyer, 1842 (Ampeliscidae) of the Sakhalin Shelf in the Okhotsk Sea starve in summer and feast in winter. PeerJ 6:e4841 https://doi.org/10.7717/peerj.4841
Psychological, pharmacological, and combined treatments for binge eating disorder: a systematic review and meta-analysis
Objective To systematically review the efficacy of psychological, pharmacological, and combined treatments for binge eating disorder (BED). Method Systematic search and meta-analysis. Results We found 45 unique studies with low/medium risk of bias, and moderate support for the efficacy of cognitive behavior therapy (CBT) and CBT guided self-help (with moderate quality of evidence), and modest support for interpersonal psychotherapy (IPT), selective serotonin reuptake inhibitors (SSRI), and lisdexamfetamine (with low quality of evidence) in the treatment of adults with BED in terms of cessation of or reduction in the frequency of binge eating. The results on weight loss were disappointing. Only lisdexamfetamine showed a very modest effect on weight loss (low quality of evidence). While there is limited support for the long-term effect of psychological treatments, we have currently no data to ascertain the long-term effect of drug treatments. Some undesired side effects are more common in drug treatment compared to placebo, while the side effects of psychological treatments are unknown. Direct comparisons between pharmaceutical and psychological treatments are lacking as well as data to generalize these results to adolescents. Conclusion We found moderate support for the efficacy of CBT and guided self-help for the treatment of BED. However, IPT, SSRI, and lisdexamfetamine received only modest support in terms of cessation of or reduction in the frequency of binge eating. The lack of long-term follow-ups is alarming, especially with regard to medication. Long-term follow-ups, standardized assessments including measures of quality of life, and the study of underrepresented populations should be a priority for future research.
Ghaderi et al. (2018) Psychological, pharmacological, and combined treatments for binge eating disorder: a systematic review and meta-analysis. PeerJ 6:e5113 https://doi.org/10.7717/peerj.5113