scholarly journals A Comparative Analysis of the Diets of a Genus of Freshwater Turtles across Africa

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 165
Author(s):  
Luca Luiselli ◽  
Gift Simon Demaya ◽  
John Sebit Benansio ◽  
Fabio Petrozzi ◽  
Godfrey C. Akani ◽  
...  
Keyword(s):  
Body Size ◽  
Vegetation Cover ◽  
Diet Composition ◽  
Linear Models ◽  
Dietary Diversity ◽  
Original Data ◽  
Animal Origin ◽  
Freshwater Turtles ◽  
Adult Age ◽  
Positive Effects

Pelusios (Testudines: Pleurodira) is an Afrotropical endemic genus of freshwater turtles that have adapted to a variety of habitats, with savannahs and forests being their two main habitat types. Although considered generally carnivorous, these turtles have rarely been subjected to detailed field surveys for determining their quantitative diet. In this paper, by using both the literature and original data, we analyze the diet of several Pelusios populations: three P. adansonii populations from South Sudan, one P. nanus from Zambia, seven P. castaneus from Nigeria, Benin and Togo, and four P. niger from Nigeria. All species were omnivorous but with a clear preponderance of the prey items being of animal origin (e.g., amphibians, fish, arthropods and annelids). Saturation curves revealed that the diet composition of all the surveyed populations was adequately assessed, and the diversity profiles indicated that all the populations were relatively similar in terms of overall dietary diversity. General Linear Models (GLM) showed a negative effect of vegetation cover on Anura adult consumption by turtles, and showed that the frequencies of Anura tadpoles, fish, reptiles and birds on Pelusios diets increased with the increase in vegetation cover. The GLM model also showed positive effects of individual body size on algae, Bivalvia, reptiles, birds and small mammal consumption by turtles, and underlined that the predation on Arachnida decreased with the increase in turtle body size. In all species, there were no significant intersexual dietary differences, whereas there were substantial ontogenetic dietary changes in three out of four species. Small-sized individuals of P. castaneus, P. niger and P. adansonii tended to feed mainly upon insects, with the adults also taking many fish and adult frogs, and in the case of P. niger, also birds and small mammals. Conversely, in P. nanus, the diet composition did not vary substantially from the juvenile to the adult age. All species appeared substantially generalist in terms of their diet composition, although the effects of season (wet versus dry) were not adequately assessed by our study.

Age-class influences on feeding choices of free-ranging wild boars (Sus scrofa)

1989 ◽  
Vol 67 (11) ◽  
pp. 2792-2796 ◽  
Author(s):  
Maryse Dardaillon
Keyword(s):  
Diet Composition ◽  
Dietary Diversity ◽  
Age Classes ◽  
Wild Boars ◽  
Adult Age ◽  
Plant Parts ◽  
Age Class ◽  
The Mean ◽  
Feeding Choices ◽  
Free Ranging

Diet composition and diversity were compared between juvenile, yearling, and adult wild boars living in the Camargue region (southern France). Despite close similarity, feeding choices differed in various respects. First, the mean stomach content included a greater proportion of animal matter in subadults (juveniles and yearlings combined) than in adults. Secondly, yearlings and adults ate larger proportions of rice, and larger quantities by weight of underground plant parts, than juveniles. These differences were attributed to differing nutritional requirements according to age-class. On the other hand, greater diversity of feeding choices was found in juveniles than within the yearling and adult age-classes. It is argued that early experience of a broad dietary diversity is an advantage for coping with fluctuations in food availability such as those encountered in the Camargue.

scholarly journals Competition-free gaps are essential for the germination and recruitment of alpine species along an elevation gradient in the European Alps

Alpine Botany ◽  
2021 ◽  
Author(s):  
Vera Margreiter ◽  
Janette Walde ◽  
Brigitta Erschbamer
Keyword(s):  
Vegetation Cover ◽  
Seedling Recruitment ◽  
Environmental Control ◽  
Elevation Gradient ◽  
European Alps ◽  
Plant Interactions ◽  
Experimental Conditions ◽  
Positive Effects ◽  
Seed Sowing ◽  
Plant Plant

AbstractSeed germination and seedling recruitment are key processes in the life cycle of plants. They enable populations to grow, migrate, or persist. Both processes are under environmental control and influenced by site conditions and plant–plant interactions. Here, we present the results of a seed-sowing experiment performed along an elevation gradient (2000–2900 m a.s.l.) in the European eastern Alps. We monitored the germination of seeds and seedling recruitment for 2 years. Three effects were investigated: effects of sites and home sites (seed origin), effects of gaps, and plant–plant interactions. Seeds of eight species originating from two home sites were transplanted to four sites (home site and ± in elevation). Seed sowing was performed in experimentally created gaps. These gap types (‘gap + roots’, ‘neighbor + roots’, and ‘no-comp’) provided different plant–plant interactions and competition intensities. We observed decreasing germination with increasing elevation, independent of the species home sites. Competition-released gaps favored recruitment, pointing out the important role of belowground competition and soil components in recruitment. In gaps with one neighboring species, neutral plant–plant interactions occurred (with one exception). However, considering the relative vegetation cover of each experimental site, high vegetation cover resulted in positive effects on recruitment at higher sites and neutral effects at lower sites. All tested species showed intraspecific variability when responding to the experimental conditions. We discuss our findings considering novel site and climatic conditions.

Return to apprenticeships: a comparison between existing apprentices and newly recruited apprentices

2021 ◽  
Author(s):  
Stefan Speckesser ◽  
Lei Xu
Keyword(s):  
Labour Market ◽  
Market Entry ◽  
Minimum Duration ◽  
Adult Age ◽  
Occupational Roles ◽  
Apprenticeship Training ◽  
Positive Effects ◽  
Younger Age ◽  
New Entrants ◽  
Labour Market Entry

Abstract In England, half of all apprentices are now of adult age. Most of them—and many of younger age, too—worked with their training firm for some time before starting their apprenticeship. In this article, we estimate the benefit of apprenticeship completion making the distinction between groups of newly recruited and existing staff. To deal with sources of endogeneity resulting from apprenticeship completion, we exploit an exogenous change in minimum duration of training affecting apprenticeship completion. Our findings show much higher benefits for new compared with existing staff. Also, increasing apprenticeship training only creates positive effects for new entrants, but not for existing workers. Therefore, policy should aim to refocus apprenticeships to be a mechanism of labour market entry combined with education to provide access to and acquire competences required for actual occupational roles, but not as a generic mechanism to train existing staff.

scholarly journals Diet composition and feeding habits of the eyespot skate, Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae), off Uruguay and northern Argentina

2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Santiago A. Barbini ◽  
Luis O. Lucifora
Keyword(s):  
Body Size ◽  
Diet Composition ◽  
Prey Size ◽  
Prey Availability ◽  
Feeding Habits ◽  
Warm Season ◽  
Cold Season ◽  
The North ◽  
Multiple Hypothesis ◽  
Modelling Approach

ABSTRACT The eyespot skate, Atlantoraja cyclophora, is an endemic species from the southwestern Atlantic, occurring from Rio de Janeiro, Brazil, to northern Patagonia, Argentina. The feeding habits of this species, from off Uruguay and north Argentina, were evaluated using a multiple hypothesis modelling approach. In general, the diet was composed mainly of decapod crustaceans, followed by teleost fishes. Molluscs, mysidaceans, amphipods, isopods, lancelets and elasmobranchs were consumed in lower proportion. The consumption of shrimps drecreased with increasing body size of A. cyclophora. On the other hand, the consumption of teleosts increased with body size. Mature individuals preyed more heavily on crabs than immature individuals. Teleosts were consumed more in the south region (34º - 38ºS) and crabs in the north region (38º - 41ºS). Shrimps were eaten more in the warm season than in the cold season. Prey size increased with increasing body size of A. cyclophora , but large individuals also consumed small teleosts and crabs. Atlantoraja cyclophora has demersal-benthic feeding habits, shifts its diet with increasing body size and in response to seasonal and regional changes in prey availability and distribution.

scholarly journals Density and body size of the larval stages of the invasive golden mussel (Limnoperna fortunei) in two neotropical rivers

2012 ◽  
Vol 23 (3) ◽  
pp. 282-292 ◽  
Author(s):  
Vivianne Eilers ◽  
Márcia Divina de Oliveira ◽  
Kennedy Francis Roche
Keyword(s):  
Body Size ◽  
Larval Stage ◽  
Larval Density ◽  
Limnoperna Fortunei ◽  
Larval Size ◽  
Larval Stages ◽  
Positive Effects ◽  
Paraguay River ◽  
Body Sizes ◽  
Golden Mussel

AIM: The present study involved an analysis of the monthly variations in the population densities and body sizes of the different stages of planktonic larvae of the invasive golden mussel (Limnoperna fortunei), in the rivers Paraguay and Miranda; METHODS: The study was carried out between February 2004 and January 2005. Monthly collection of the plankton samples was accompanied by physical, chemical and biological analyses of the water; RESULTS: The Miranda River presented higher values of calcium, pH, alkalinity, conductivity and total phosphorous. Larval density varied from 0-24 individuals.L-1 in the Paraguay River, with a peak in March of 2004, while in the Miranda River, densities varied between 0-9 individuals.L-1 with a peak in February of 2004. No larvae were encountered during the coldest months, May and June. No significant correlations were found between environmental variables and larval density in either river. Only the valved larval stages were recorded. The "D" and veliger forms were most abundant; umbonate larvae were rare in the Miranda River samples. Mean body sizes of "D", veliger and umbonate larval stages were, respectively, 111, 135 and 152 µm, in the Paraguay River, and 112, 134 and 154 µm in the Miranda River. Principal Components Analysis indicated positive relationships between "D" larval stage size and the ratio between inorganic and organic suspended solids, while negative relationships were found between larval size and calcium and chlorophyll-<img border=0 width=7 height=8 src="/img/revistas/alb/2012nahead/ALB_AOP_230307car01.jpg">; CONCLUSIONS: The larvae were recorded in the plankton during most of the year, with the exception of the two colder months. Neither densities nor larval stage body sizes were significantly different between the two rivers. Possible positive effects of food and calcium concentrations on body size were not recorded. This species may be adapted to grow in environments with elevated sediment concentrations.

The Rhetorical Psychology of Trumpism: Threat, Absolutism, and the Absolutist Threat

The Forum ◽  
2017 ◽  
Vol 15 (2) ◽  
pp. 313-332 ◽  
Author(s):  
Morgan Marietta ◽  
Tyler Farley ◽  
Tyler Cote ◽  
Paul Murphy
Keyword(s):  
Original Data ◽  
Perceived Threat ◽  
Economic Decline ◽  
Personal Safety ◽  
Group Status ◽  
Strategy Analysis ◽  
Rhetorical Strategy ◽  
Electoral Success ◽  
Positive Effects ◽  
Positive Character

Abstract Conventional wisdom suggests that Donald Trump’s rhetoric – aggressive, insulting, often offensive – would be counterproductive to electoral success. We argue that Trump’s surprising victories in both the primary and general campaigns were partly due to the positive effects of his appeals grounded in the intersection of threat and absolutism. The content of Trump’s rhetoric focused on threats to personal safety (terrorism), personal status (economic decline), and group status (immigration). The style of Trump’s rhetoric was absolutist, emphasizing non-negotiable boundaries and moral outrage at their violation. Previous research has shown perceived threat to motivate political participation and absolutist rhetoric to bolster impressions of positive character traits. Trump employed these two rhetorical psychologies simultaneously, melding threat and absolutism into the absolutist threat as an effective rhetorical strategy. Analysis of Trump’s debate language and Twitter rhetoric, as well as original data from political elites at the Republican National Convention and ordinary voters at rallies in New Hampshire confirm the unconventional efficacy of Trump’s rhetorical approach.

scholarly journals Vegetation Cover Drives Arthropod Communities in Mediterranean/Subtropical Green Roof Habitats

2018 ◽  
Vol 10 (11) ◽  
pp. 4209 ◽  
Author(s):  
Ibrahim Salman ◽  
Leon Blaustein
Keyword(s):  
Vegetation Cover ◽  
Urban Areas ◽  
Green Roof ◽  
Structural Complexity ◽  
Green Roofs ◽  
Life Forms ◽  
Suitable Habitat ◽  
Positive Effects ◽  
Habitat Template ◽  
Arthropod Abundance

Worldwide, urban areas are expanding both in size and number, which results in a decline in habitats suitable for urban flora and fauna. The construction of urban green features, such as green roofs, may provide suitable habitat patches for many species in urban areas. On green roofs, two approaches have been used to select plants—i.e., matching similar habitat to green roofs (habitat template approach) or identifying plants with suitable traits (plant trait approach). While both approaches may result in suitable habitats for arthropods, how arthropods respond to different combinations of plants is an open question. The aim of this study was to investigate how the structural complexity of different plant forms can affect the abundance and richness of arthropods on green roofs. The experimental design crossed the presence and absence of annuals with three Sedum sediforme (Jacq.) Pau (common name: stonecrops) treatments—i.e., uniformly disrupted Sedum, clumped disrupted Sedum, and no Sedum. We hypothesized that an increased structural diversity due to the coexistence of different life forms of plants on roofs is positively related to the abundance and richness of arthropods. We found that arthropod abundance and richness were positively associated with the percent of vegetation cover and negatively associated with substrate temperature. Neither arthropod abundance nor richness was influenced by the relative moisture of substrate. We also found that arthropod abundance and richness varied by green roof setups (treatments) and by seasonality. Arthropod abundance on green roofs was the highest in treatments with annuals only, while species richness was slightly similar between treatments containing annuals but varied between sampling periods. This study suggests that adding annuals to traditional Sedum roofs has positive effects on arthropods. This finding can support the development of biodiverse cities because most extensive green roofs are inaccessible to the public and can provide undisturbed habitat for several plant and arthropod species.

scholarly journals Foraging behaviour and performance of steers from two local breeds (Asturian Valley and Asturian Mountain) grazing in Cantabrian (N Spain) summer pastures

2019 ◽  
Vol 17 (1) ◽  
pp. e0601
Author(s):  
Alicia Román-Trufero ◽  
Antonio Martínez ◽  
Luis M. M. Ferreira ◽  
Valentín García-Prieto ◽  
Rocío Rosa-García ◽  
...  
Keyword(s):  
Body Weight ◽  
Body Size ◽  
Diet Composition ◽  
Foraging Behaviour ◽  
Meat Production ◽  
Market Demand ◽  
Nutrient Requirements ◽  
Northern Spain ◽  
Sward Height ◽  
And Performance

Steer meat production in northern Spain is deficient to attend market demand. This research aimed to compare the foraging behaviour and production of yearling steers from two local breeds differing in body weight (BW), Asturian Valley (AV, 372 kg) and Asturian Mountain (AM, 307 kg), grazing in summer pastures consisting of 70% grassland and 30% heathland. Bodyweight gains from a total of 42 steers were recorded during four grazing seasons (from June to October). In two years, in July and September, plant community selection and diet composition were estimated by direct observation and using faecal markers, respectively. Grazing time increased from July to September (488 vs. 557 min/day; p<0.001) as sward height in the grassland decreased. Although AV steers grazed proportionally for longer on herbaceous pastures than AM steers (81.3 vs. 73.3%; p<0.05), no differences between breeds were found in diet composition. AM steers showed greater mean daily BW gains than AV steers (252 vs. 133 g/day; p<0.01). From June to August, steers from both breeds gained BW (487 vs. 360 g/day for AM and AV, respectively; p<0.01), but thereafter BW gains decreased (120 vs. –12 g/day for AM and AV, respectively; p<0.05), because of reduced availability of grassland herbage. Yearling steers from AM breed seem to be better suited to mountain conditions than those from AV breed, probably because of their smaller body size and lower total nutrient requirements for maintenance.

scholarly journals Evaluation of the Contribution of Cassava Staple to the Recommended Dietary Allowance of Selected Nutrients Among the under Five Children in Mtwara Rural District, Tanzania

2019 ◽  
Vol 7 (1) ◽  
pp. 190-201
Author(s):  
DIANA NICODEMAS ◽  
LEONARD WILLIAM TUNGARAZA FWEJA ◽  
HAPPY STEVEN MAGOHA
Keyword(s):  
Dietary Diversity ◽  
Rural District ◽  
Recommended Dietary Allowance ◽  
Animal Origin ◽  
Consumption Pattern ◽  
Mineral Contents ◽  
Dietary Recall ◽  
Under Five ◽  
Under Five Children ◽  
Dietary Allowance

This study aimed at evaluating the contribution of cassava recipe in meeting Recommended Dietary Allowance (RDA) of the under five children for the selected nutrients (protein, fat, iron and zinc) in Mtwara rural district. This was achieved by identifying the common cassava recipes and the consumption pattern by using a 24h dietary recall and Food Frequency Questionnaire (FFQ). Proximate composition, mineral contents and anti-nutrients (cyanide and phytate contents) were also determined. The rate of consumption of a child was computed based on food portion and consumption frequency in a day. The sufficiency of nutrient of cassava recipes was determined on the basis of the quantity of food eaten per day. Computed nutrient intake was evaluated against the RDA of respective nutrient for respective age category. The findings indicate that the contribution of cassava to the RDAs of the respective nutrients were 19.4% for iron, 21% for zinc, 0.527% for fat and 4.26% for protein among the under five children which is extremely low. The anti-nutrient (phytate) content was far above the tolerable level of 25 mg/100g but cyanide was within the acceptable level. The computed Individual Dietary Diversity Score (IDDS) of 2.5 was similarly far below the target IDDS of 5. This implies an extremely poor dietary diversity indicative of very low consumption of food varieties including those of animal origin. It is thus important to develop strategies which encourage and make easy for dietary diversification among community members in order to complement cassava based recipes with readily available foods rich in macro and micronutrients. The strategy should also consider dietary practices such as control of intake of inhibitors e.g. of iron absorption and increase intake of enhancers of absorption in a given meal. These strategies can also include cassava recipe supplementation and fortification.

A macro-level analysis of language learning and migration

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Silke Uebelmesser ◽  
Ann-Marie Sommerfeld ◽  
Severin Weingarten
Keyword(s):  
Language Learning ◽  
Fixed Effects ◽  
Distance Measures ◽  
Macro Level ◽  
Free Access ◽  
The European Union ◽  
Adult Age ◽  
Positive Effects ◽  
Skilled Immigration ◽  
And Migration

Abstract This article investigates the macro-level drivers of adult-age language learning with a focus on migration based on a new dataset on German language learning in 77 countries (including Germany) for 1992–2006. Fixed-effects regressions show that language learning abroad is strongly associated with immigration from countries of the European Union and the Schengen Area whose citizens enjoy free access to Germany, while language learning in Germany is strongly associated with immigration from countries with restricted access. The different degrees of uncertainty about access to Germany seem to be of importance for preparatory language learning. To shed light on country heterogeneities, we substitute the location fixed effects with a vector of country characteristics, which include several distance measures among others, and we estimate a random-effects model. Last, we provide some tentative arguments in favour of a causal interpretation. The main results related to the role of uncertainty are mostly unaffected. The Skilled Immigration Act from 2020 removes part of this uncertainty with potential positive effects on preparatory language learning and economic and social integration.

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