Interclutch Variation in Egg Mass among Starlings Sturnus vulgaris Reflects Female Condition

1993 ◽  
Vol 24 (4) ◽  
pp. 311 ◽  
Author(s):  
Henrik G. Smith ◽  
Ulf Ottosson ◽  
Thomas Ohlsson
Keyword(s):  
Sturnus Vulgaris ◽  
Egg Mass ◽  
Female Condition

scholarly journals Sources of Egg-Size Variation in House Wrens (Troglodytes Aedon): Ontogenetic and Environmental Components

The Auk ◽  
2002 ◽  
Vol 119 (3) ◽  
pp. 800-807 ◽  
Author(s):  
John D. Styrsky ◽  
Robert C. Dobbs ◽  
Charles F. Thompson
Keyword(s):  
Egg Size ◽  
Size Variation ◽  
Egg Mass ◽  
Female Size ◽  
Ontogenetic Variation ◽  
Troglodytes Aedon ◽  
House Wrens ◽  
Female Condition ◽  
Evolutionary Response ◽  
Central Illinois

Abstract Evolutionary theory predicts that heritability of fitness-related traits should be low. Egg size in birds is a fitness-related trait, but exhibits high heritability. One possible explanation for the apparent failure of natural selection to exhaust variability is that variation in egg size is mediated by female condition. In this study, we estimated repeatability of egg size within and between successive clutches in a wild, double-brooded population of House Wrens (Troglodytes aedon) in central Illinois, and examined the relationship of egg size with female size and condition. Repeatability of egg volume and mass in individual birds was high within years and between successive years (>0.77), suggesting a substantial heritable component to variation in egg size. However, egg mass was also significantly correlated with female condition. We suggest that the high repeatability values largely reflect permanent but nongenetic (ontogenetic) variation in egg size among females, which is reflected in the positive correlation of egg size with female condition. If variation in egg size is attributable to a combination of nonheritable, ontogenetic variation and variation due to current environmental conditions among females, then selection may not produce an evolutionary response in egg size.

Effects of exogenous 17(β)-estradiol on the reproductive physiology and reproductive performance of european starlings (Sturnus vulgaris)

1999 ◽  
Vol 202 (19) ◽  
pp. 2679-2685 ◽  
Author(s):  
J.K. Christians ◽  
T.D. Williams
Keyword(s):  
Reproductive Performance ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Sturnus Vulgaris ◽  
Reproductive Physiology ◽  
Egg Mass ◽  
Very Low Density Lipoprotein ◽  
Estradiol Treatment ◽  
European Starlings ◽  
Egg Formation

Egg mass shows large intraspecific variation in birds and yet the mechanisms underlying this variation remain unknown. We hypothesized that estradiol would play a central role in determining egg mass, since this hormone stimulates the production of yolk precursors (vitellogenin and very-low density lipoprotein, VLDL) by the liver, and of albumen by the oviduct. We gave European starlings (Sturnus vulgaris) silastic implants containing estradiol prior to egg formation, which we predicted would increase egg mass. As expected, exogenous estradiol stimulated a marked (49 %) increase in plasma vitellogenin levels at the beginning of laying. At clutch completion, plasma VLDL levels and oviduct mass were also elevated in estradiol-treated females compared with controls. However, estradiol had no effect on fresh egg mass or clutch size. Estradiol treatment actually decreased the mass of yolk protein and lipid, perhaps by decreasing the rate of uptake of yolk precursors at the ovary. The failure of estradiol to increase egg mass indicates that this phenotype may be regulated at higher levels of organization (e.g. negative feedback, uptake of yolk precursors) than those studied in this experiment. Despite elevating yolk precursor levels, treatment with estradiol had no effect on the mass of the liver or endogenous stores of protein and lipid at clutch completion.

ANATOMICAL AND HISTOLOGICAL STUDY OF CEREBRAL IN STURNUS VULGARIS

2013 ◽  
Vol 12 (2) ◽  
pp. 221-227 ◽  
Author(s):  
A Ali ◽  
Sawsan A ◽  
Faleha. H aziz ◽  
Nathum .A.Shehan ◽  
Samira .A.Dhage
Keyword(s):  
Histological Study ◽  
Sturnus Vulgaris

Probiotics in the diets of laying quails

2020 ◽  
pp. 60-66
Author(s):  
O. Merzlyakova ◽  
V. Rogachyev ◽  
V. Chegodaev
Keyword(s):  
Bacillus Subtilis ◽  
Bacillus Licheniformis ◽  
Egg Production ◽  
Positive Impact ◽  
Hematological Parameters ◽  
Economic Effect ◽  
Egg Laying ◽  
Control Group ◽  
Egg Mass ◽  
The Cost

The efficiency of introducing probiotics based on strains of Bacillus subtilis, Bacillus licheniformis and their consortium in the amount of 150 g/t of feed into the diets of laying quails has been studied. The experiment lasting 182 days has been carried out on four groups of quails with 30 heads in each. The quails have been housed in the broiler battery in compliance with the required microclimate conditions. Quails of all groups have been received the main diet (compound feed) developed taking into account their age and physiological characteristics. The quails of the 1st, 2nd and 3rd experimental groups in addition to the main diet received probiotics (150 g/t compound feed) based on strains Bacillus subtilis, Bacillus licheniformis and their consortium, respectively. It has been found that feeding the laying quails of the consortium of strains Bacillus subtilis and Bacillus licheniformis had the most significant positive impact on their productive performance, it allowed to increase egg production by 7,81 %, egg laying intensity by 5,0 %, egg mass yield by 9,77 %, while reducing feed expenditures for 10 eggs by 13,35 %. The yield of hatching eggs has been increased by 7,03 %, hatchability of chickens from laid and fertilized eggs by 8,33 and 8,35 %, brooding waste decreased by 21,74 %. Hematological parameters of quails during the whole experiment were within the physiological norm. The economic effect calculated on the basis of data on the cost of compound feed, probiotics and the cost of sold eggs of quail laying was 14,56 % in the 3rd experimental group (in relation to the control group).

scholarly journals First evidence for a latitudinal body mass effect in extant Crocodylia and the relationships of their reproductive characters

2020 ◽  
Vol 129 (4) ◽  
pp. 875-887
Author(s):  
Rebecca J Lakin ◽  
Paul M Barrett ◽  
Colin Stevenson ◽  
Robert J Thomas ◽  
Matthew A Wills
Keyword(s):  
Clutch Size ◽  
Body Mass ◽  
Linear Models ◽  
Incubation Temperature ◽  
Mass Effect ◽  
Distribution Patterns ◽  
Egg Mass ◽  
Phylogenetically Independent Contrasts ◽  
Extant Species ◽  
Female Body Mass

Abstract Relationships between distribution patterns and body size have been documented in many endothermic taxa. However, the evidence for these trends in ectotherms generally is equivocal, and there have been no studies of effects in crocodylians specifically. Here, we examine the relationship between latitudinal distribution and body mass in 20 extant species of crocodylians, as well as the relationships between seven important reproductive variables. Using phylogenetically independent contrasts to inform generalized linear models, we provide the first evidence of a latitudinal effect on adult female body mass in crocodylians. In addition, we explore the relationships between reproductive variables including egg mass, hatchling mass and clutch size. We report no correlation between egg mass and clutch size, upholding previously reported within-species trends. We also find no evidence of a correlation between measures of latitudinal range and incubation temperature, contrasting with the trends found in turtles.

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