scholarly journals Chick Growth Variability and Parental Provisioning in the Magnificent Frigatebird

The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 612-622
Author(s):  
Emilio Tobón ◽  
José Luis Osorno
Keyword(s):  
Food Availability ◽  
Life Histories ◽  
Food Sources ◽  
Feeding Rates ◽  
Chick Growth ◽  
Growth And Survival ◽  
Growth Variability ◽  
Socially Monogamous ◽  
Breeding Seasons ◽  
The Relationship

Abstract In two contrasting breeding seasons, we investigated the effects of provisioning on chick growth and survival of the Magnificent Frigatebird (Fregata magnificens), a socially monogamous, dimorphic seabird that rears a single chick for more than a year, shows specialized feeding techniques, and depends on unpredictable food sources. We hypothesized that chicks of this seabird would increase their chances of survival by varying their growth in relation to food availability. We estimated the amount of food ingested by a chick using electronic scales placed at the nest and recorded feeding rates, growth rate, fledging size, and fledging age. Body mass and bill and ulna lengths were also measured. Not surprisingly, provisioning and growth were higher in the year with apparently higher food availability; however, developmental variables did not show the same pattern. This work shows a clear relationship between provisioning and growth and that growth variability occurs in this species. Understanding the relationship between provisioning and growth provides insight into life histories and elucidates the influence of variation in provisioning on fitness.

scholarly journals Extra-pair young in house wren broods are more likely to be male than female

2009 ◽  
Vol 276 (1665) ◽  
pp. 2285-2289 ◽  
Author(s):  
L. Scott Johnson ◽  
Charles F. Thompson ◽  
Scott K. Sakaluk ◽  
Markus Neuhäuser ◽  
Bonnie G.P. Johnson ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Sex Allocation ◽  
House Wren ◽  
Cavity Nesting ◽  
Socially Monogamous ◽  
Pair Mating ◽  
Sex Allocation Theory ◽  
Breeding Seasons ◽  
Extra Pair Mating ◽  
The Relationship

Sex-allocation theory predicts that females should preferentially produce offspring of the sex with greater fitness potential. In socially monogamous animal species, extra-pair mating often increases the variance in fitness of sons relative to daughters. Thus, in situations where offspring sired by a female's extra-pair mate(s) will typically have greater fitness potential than offspring sired by the within-pair mate, sex-allocation theory predicts that females will bias the sex of offspring sired by extra-pair mates towards male. We examined the relationship between offspring sex and paternity over six breeding seasons in an Illinois population of the house wren ( Troglodytes aedon ), a cavity-nesting songbird. Out of the 2345 nestlings that had both sex and paternity assigned, 350 (15%) were sired by extra-pair males. The sex ratio of extra-pair offspring, 0.534, was significantly greater than the sex ratio of within-pair offspring, 0.492, representing an increase of 8.5 per cent in the proportion of sons produced. To our knowledge, this is the first confirmed report of female birds increasing their production of sons in association with extra-pair fertilization. Our results are consistent with the oft-mentioned hypothesis that females engage in extra-pair mating to increase offspring quality.

scholarly journals An exploration of the relationship between recruitment communication and foraging in stingless bees

2021 ◽  
Author(s):  
Robbie I’Anson Price ◽  
Francisca Segers ◽  
Amelia Berger ◽  
Fabio S Nascimento ◽  
Christoph Grüter
Keyword(s):  
Stingless Bees ◽  
Sugar Content ◽  
Social Information ◽  
Food Resources ◽  
Food Sources ◽  
Foraging Strategies ◽  
High Quality ◽  
Recruitment Communication ◽  
Eusocial Bees ◽  
The Relationship

Abstract Social information is widely used in the animal kingdom and can be highly adaptive. In social insects, foragers can use social information to find food, avoid danger or choose a new nest site. Copying others allows individuals to obtain information without having to sample the environment. When foragers communicate information they will often only advertise high quality food sources, thereby filtering out less adaptive information. Stingless bees, a large pantropical group of highly eusocial bees, face intense inter- and intra-specific competition for limited resources, yet display disparate foraging strategies. Within the same environment there are species that communicate the location of food resources to nest-mates and species that do not. Our current understanding of why some species communicate foraging sites while others do not is limited. Studying freely foraging colonies of several co-existing stingless bee species in Brazil, we investigated if recruitment to specific food locations is linked to (1) the sugar content of forage, (2) the duration of foraging trips and (3) the variation in activity of a colony from one day to another and the variation in activity in a species over a day. We found that, contrary to our expectations, species with recruitment communication did not return with higher quality forage than species that do not recruit nestmates. Furthermore, foragers from recruiting species did not have shorter foraging trip durations than those from weakly-recruiting species. Given the intense inter- and intraspecific competition for resources in these environments, it may be that recruiting species favour food resources that can be monopolised by the colony rather than food sources that offer high-quality rewards.

Storie di violenza in infanzia e adolescenza e prostituzione in etŕ adulta: quali legami?

2009 ◽  
pp. 93-112
Author(s):  
Emanuela Confalonieri ◽  
Cristina Giuliani ◽  
Alessandra Bongiana ◽  
Paola Pavesi
Keyword(s):  
Childhood Maltreatment ◽  
Life Histories ◽  
Descriptive Analysis ◽  
Sexual Exploitation ◽  
Sexual Revictimization ◽  
East Europe ◽  
The Social ◽  
Forced Prostitution ◽  
The One ◽  
The Relationship

- The present study, related to the one published some years ago (Confalonieri et al., 2004), is an investigation on forced prostitution and the related violence's types in immigrant women involved in streetwalking prostitution. Using the social records available by the Ufficio Stranieri (Comune di Milano), the purpose is to identify the presence of 1) childhood maltreatments or violence before the entry in sex exploitation market and 2) subsequent adult sexual revictimization from partners, pimps and clients. Data were analysed using phenomenological descriptive analysis. The relationship between childhood maltreatment and abuse and subsequent involvement in sex work is discussed comparing data and life histories of immigrant prostitutes coming from Nigeria and East Europe. The role played by social and contexual variables in sexual exploitation story are also considered.Key words: immigration, violence, prostitution, infancy, adulthood.Parole chiave: immigrazione, violenza, prostituzione, infanzia, etŕ adulta.

scholarly journals Student Column: The Relationship between Local Food Sources and Open Space to Body Mass Index in Urban Children

2011 ◽  
Vol 126 (6) ◽  
pp. 890-900 ◽  
Author(s):  
James J. Burns ◽  
Sarah Goff ◽  
Greg Karamian ◽  
Coleen Walsh ◽  
Lela Hobby ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Open Space ◽  
Local Food ◽  
Urban Children ◽  
Food Sources ◽  
The Relationship

scholarly journals Protein utilization, growth and survival in essential-fatty-acid-deficient rats

1996 ◽  
Vol 75 (2) ◽  
pp. 237-248 ◽  
Author(s):  
Christiani Jeyakumar Henry ◽  
Amal Ghusain-Choueiri ◽  
Philip R. Payne
Keyword(s):  
Growth Rate ◽  
Dietary Protein ◽  
Essential Fatty Acids ◽  
Coconut Oil ◽  
Deficient Diet ◽  
Protein Utilization ◽  
Growth And Survival ◽  
Retarded Growth ◽  
Pregnancy And Lactation ◽  
The Relationship

AbstractThe relationship between essential fatty acids (EFA) deficiency and the utilization of dietary protein, growth rate and survival of offspring was investigated in rats during development and reproduction. EFA deficiency was induced by feeding a 200 g casein/kg-based diet containing 70 g hydrogenated coconut oil (HCO)/lkg as the only source of fat. The conversion efficiency of dietary protein was assessed as net protein utilization (NPU), using a 10 d comparative carcass technique. Consumption of the deficient diet during the 10 d assay period induced biochemical changes characteristic of mild EFA deficiency in humans (triene:tetraene 0·27 (SD 0·04) compared with 0·026 (SD 0·004) for wn-deficient controls), but there were no significant changes in growth rate or protein utilization. These variables were also unchanged when the deficient diet was fed for an additional 7 d before the assay, although triene: tetraene increased to 0.8 (SD 0·02). Feeding the deficient diet for 63 d before assay produced severe EFA deficiency (triene:tetraene 1.4 (SD 0·3) v. 0·036 (SD 0·005) for controls), a fall in growth rate (25% during assay period), and NPU (31.5 (SD 0·63) v. 39.0 (SD 0·93) for controls). These severely-EFA-deficient animals had a 30% higher fasting-resting rate of energy metabolism than that of age-matched controls. However, there was no change in the rate of endogenous N loss. Voluntary energy consumption was increased in animals fed on deficient diets, either with 200 g protein/kg, or protein free. The reduced efficiency of protein utilization could be entirely accounted for by the restricted amount of energy available for growth and protein deposition. Consumption of an EFA-deficient diet during pregnancy and lactation resulted in high mortality (11% survival rate at weaning compared with 79% for controls) and retarded growth in the preweaning offspring. It is concluded that animals are particularly sensitive to EFA deficiency during reproduction and pre- and post-natal stages of development. However, after weaning only severe EFA deficiency retarded growth, primarily through changes in energy balance.

scholarly journals Modeling the Impact of Inflation Uncertainty on Food Sector Growth

2020 ◽  
Author(s):  
Mohammad Reza Eslami ◽  
Ali Akbar Baghestany
Keyword(s):  
Economic Growth ◽  
Policy Decision ◽  
Macroeconomic Policies ◽  
Inflation Uncertainty ◽  
Causality Test ◽  
Agricultural Growth ◽  
Growth Variability ◽  
Augmented Dickey Fuller ◽  
The Impact ◽  
The Relationship

Background: One of the most fundamental objectives of the macroeconomic policies is to realize the relationship between economic growth and inflation. According to some monetary policy advisors, inflation reflects erosion in consumer’s purchasing power. Inflation as an important economic variable, affect the economic growth and its impact on economic growth has been proposed in various theories. Agriculture plays an important role in providing the food security in Iran. Methods: A Bivariate GARCH model was employed to investigate the relationship between inflation uncertainty and agricultural growth. Results: The Augmented Dickey Fuller and Phillips Perron tests indicated all variables were stationary. Estimated models were utilized to generate the conditional variances of inflation and agriculture growth as proxies of inflation and growth variability. During the entire period 1990-2012, Bivariate Granger Causality test indicated that inflation uncertainty was the cause of growth in agriculture. This finding was in line with the hypothesis presented by (Logue and Sweeney, 1981). Conclusion: Due to the causality relation of inflation uncertainty and growth in agriculture, macro policy decision-makers are recommended to consider the price policies for improving agricultural production.

scholarly journals An ecological study of Electra posidoniae Gautier, 1954 (Cheilostomata, Anasca), a bryozoan epiphyte found solely on the seagrass Posidonia oceanica (L.) Delile, 1813

2020 ◽  
Vol 144 (1) ◽  
Author(s):  
Gilles Lepoint ◽  
Olivier Mouchette ◽  
Corine Pelaprat ◽  
Sylvie Gobert
Keyword(s):  
Water Column ◽  
Posidonia Oceanica ◽  
Early Spring ◽  
Food Sources ◽  
Seagrass Ecosystem ◽  
Life Traits ◽  
Colonization Dynamics ◽  
Marine Angiosperms ◽  
The Relationship ◽  
Quantitative Importance

The bryozoan Electra posidoniae Gautier is found solely on the leaves of the Neptune grass Posidonia oceanica (L.) Delile, dominating the leaf epifauna of this seagrass. Epiphytes of marine angiosperms (or seagrasses) often play an important role in ecosystem functioning, for example as food web suppliers. As dysfunction of the epiphytic component is often implied in human-induced seagrass decline, it is important to understand the dynamics and life traits of this community in pristine areas. This study involved the monthly assessment of colonization dynamics, biomass seasonality, and diet composition through measurements of stable isotopes, in E. posidoniae at a depth of 10 m in the Revellata Bay (Corsica, Mediterranean Sea). Ancestrulae (i.e. colony founders) appeared towards the end of winter and were very selective in their settlement position along the leaves of P. oceanica. A maximum of 100,000 colonies per square meter was recorded. Colonies of E. posidoniae dominated the epiphytic community biomass in early spring, but were overtaken by epiphytic algae in June. Food shortage could be involved in this reduction in dominance. Although stable isotope ratios of C, N and S showed that this suspension feeder mainly relies on the water column for its food, other food sources such as re-suspended epiphytic diatoms could be important in late spring (i.e. after the phytoplanktonic bloom). Additionally, a contribution of seagrass phytodetritus to the diet of this species cannot be excluded. The species was almost absent in winter, raising the question of its recruitment in spring. This study confirms the quantitative importance of this species in the seagrass meadow and explores its role in the relationship between the water column and this seagrass ecosystem.

Feeding ecology of free-living nematodes.

2021 ◽  
pp. 185-215
Author(s):  
Nabil Majdi ◽  
Tom Moens ◽  
Walter Traunspurger
Keyword(s):  
Feeding Ecology ◽  
Trophic Interactions ◽  
Feeding Habits ◽  
Food Sources ◽  
Environmental Constraints ◽  
Feeding Rates ◽  
Feeding Selectivity ◽  
Free Living ◽  
Aquatic Nematodes ◽  
Food Recognition

Abstract This chapter provides overview of the feeding habits and food sources of aquatic nematodes. The environmental constraints on feeding, food recognition, and feeding selectivity are also addressed, together with the complex, indirect trophic interactions between nematodes and their microbial prey. To raise awareness of the inherent methodological and/or interpretational problems in studies of nematode feeding ecology, the chapter ends with a brief look at the methods that have been adapted to quantify feeding rates in nematodes.

Inferring prior distributions of recruitment compensation metrics from life-history parameters and allometries

2020 ◽  
Vol 77 (2) ◽  
pp. 295-313 ◽  
Author(s):  
Joseph Munyandorero
Keyword(s):  
Life Histories ◽  
Growth Parameters ◽  
Meta Analysis ◽  
The United States ◽  
Prior Distributions ◽  
Compensation Ratio ◽  
Species Specific ◽  
Meta Analyses ◽  
The Relationship ◽  
Spawning Biomass

The recruitment compensation metrics, the stock–recruit steepness (h) and compensation ratio (κ), are difficult to estimate, yet they are integral components of contemporary fishery models. To aid in the estimation of κ and h, a hybrid method to construct their prior distributions for a species is developed. The method is hybrid because it integrates (i) a meta-analysis of the relationship between maximum rates of recruit production (α) and asymptotic lengths obtained across fish species of different life histories and (ii) species-specific unfished spawning biomass per recruit (Φ0). This method is applied to five finfish species found off the East Coast of the United States. Uncertainty is introduced by sampling growth parameters, α, and natural mortality and — through Monte Carlo simulations — propagated into Φ0, κ, and h for the Beverton–Holt and Ricker stock–recruit relationships. Descriptive statistics and parameters from probability density functions of the simulated distributions of κ and h are generated. The method developed requires fewer inputs than the reproductive ecology method while likewise allowing the development of species-specific statistics for κ and h. These statistics, rather than their counterparts generated from classical meta-analyses, are better suited for use in fishery models.

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