Impact of the hen egg size on its fracture point measuring the eggshell deformation.

A recent study on geographical variation in egg size of Great Tits Parus major concluded that: (1) mean egg size tended to increase with increasing latitude; and (2) mean egg size was positively correlated with mean clutch size. Including new data on both egg and clutch size, we reanalysed the relationships between egg size, clutch size and latitude, and investigated the possible effects of habitat type, female body size and egg shape on these relationships. We found that (1) egg volume showed minimum values around 51°N, increasing both north and southwards; (2) female body size increased linearly with increasing latitude; (3) female body size was positively correlated with egg breadth, but not with egg length or egg volume; (4) the sphericity index of the eggs (breadth to length ratio) was largest at medium latitudes, and eggs were more elongated towards the north and the south; (5) the relationship between clutch size and latitude was curvilinear, with the largest clutch sizes at intermediate latitudes; (6) egg size was not correlated with clutch size when the complete latitudinal range was considered, but egg size was negatively correlated with clutch size between 40 and 51°N; and (7) egg size did not differ among habitat types. We suggest that female body size (which probably limits egg breadth), and the pressure for producing large eggs (which in turn increases the reproductive success) are the main determinants of geographical variation in egg size and shape. Populations of small‐bodied Great Tits seem to escape from the limits of their size, producing relatively elongated eggs, so that from a certain latitude southwards, egg volume does not decrease in spite of a decrease in female body size. Moreover, the negative relationship between egg and clutch size at low latitudes suggests that energetic trade‐offs may also contribute to determine egg size in the south.

Reproduction in a Northern Population of Clemmys guttata

Effect of egg size and strain and age of hens on the solids content of chicken eggs

The green anole (Anolis carolinensis) occurs throughout the southeastern United States and its distribution defines the northern limit of the range of this genus of neotropical lizards. The variation in female, egg, and hatchling sizes is quantified for eight populations of the green anole that range from south Florida to the mountains of east Tennessee. Six populations are composed of the typical red-throated (dewlap) morph of this species, one of the gray-throated morph, and one population is representative of a variant of the red-throated morph. Among populations of the red-throated morph, female, egg, and hatchling sizes all increased significantly with increasing latitude. Additionally, females in the north had disproportionately larger eggs and offspring than did females to the south. We propose that increased selection pressure for large hatchling body size associated with decreasing winter temperatures (i.e., in- creasing latitude) results in the observed latitudinal diversification in the sizes of green anole eggs, juveniles, and adults. Whereas egg size was largely independent of female body size in southern popu- lations, there was a significant positive relationship between egg and female sizes in northern populations. The relationships between egg width and pelvic aperture width, relative to female body size, were examined for lizards from three populations that varied in the degree to which egg size was related to female body size. The size of the pelvic girdle aperture appeared to constrain the egg size of northern females to a greater extent than it did in southern females. Taken together, these data suggest that egg size may be optimized by natural selection in southern populations, but not in northern populations. Optimization of egg size may not be possible for lizards in northern populations due to this apparent morphological constraint on egg size, which is consistent with predictions of the pelvic constraint model. The environ- mental, physiological, and morphological factors that may combine to limit the continued northward range expansion of this successful colonizer are discussed. The genus Anolis is an ecologically and mor- phologically diverse group of approximately 300 species and subspecies of neotropical lizards in the family Iguanidae. Most species of Anolis are arboreal, but several are either saxicolous, ter- restrial, or semi-aquatic. Maximum adult female body size may be as little as 2 g in some species to over 50 g in one Puerto Rican anole (Andrews and Rand, 1974). Whereas species of Anolis have diverged in body size and habitat preference,

Egg volumes are most often estimated using a mathematical model that incorporates length and width measurements and a species-specific shape variable. Although adequate in many respects, this technique does not account for intraspecific variation in egg shape. We developed a computer-automated technique that uses calibrated digital photographs to render precise measurements of several egg-size parameters including length, width, volume, and surface area. The system extracts egg outlines from photographs, and divides each egg into latitudinal slices that are subsequently regarded as simple geometric shapes (cylinders or cone frustra) with volumes and surface areas that can be summed to generate size parameters for the entire egg. We tested this technique using 491 eggs from Florida Scrub-Jay (Aphelocoma coerulescens) nests and compared the resulting egg volumes with volumes calculated using the preeminent method of estimating volume from linear measurements. Our method was highly accurate, and differences between the volumes from our method and the alternative method were strongly associated with variation in egg shape. Advantages of our technique include decreased handling of eggs and increased accuracy. Software resources and additional information regarding the technique are available at http://www.archbold-station.org/abs/data/birddata/Bridge-JFO-eggsize.htm. SINOPSIS. Medidas de huevos utilizando fotograf´ ia digital: poniendo a pruebas el m´ etodo

Eggs of the turtle Chrysemys picta bellii from four western Nebraska populations were incubated under laboratory conditions to compare egg size and hatchling size as measures of offspring size among populations and in the context of maternal body size. Generally, hatchling size (mass and carapace length) was linearly related to egg size (mass, width, and length) and did not vary between the two years of the study or among populations after adjusting for egg size. However, hatchling carapace length adjusted for egg width was greatest in a population with the most elongate eggs indicating that linear egg measurements may not be useful for interpopulation comparisons. The smaller range of variation, but greater variability in hatchling size relative to egg size and a narrow range of maternal body sizes (carapace length and mass), seemed to preclude a correlation between maternal body size and hatchling size within two populations. In two other populations, hatchling carapace length, egg width, and egg length increased with maternal carapace length by a common slope, although egg wet mass had a steeper slope than did hatchling wet mass. It is probable that under natural incubation conditions (e.g., warmer, drier, and more variable), hatchling mass may increase only slightly or not at all with maternal body size. My results suggest that both hatchling and egg size should be considered in turtle life history studies, particularly for models that predict delayed sexual maturation when offspring size and survival increase with maternal body size and age.

Female size constrains egg size via the influence of reproductive organ size and resource storage in the seed beetle Callosobruchus chinensis

Optimal egg size theory predicts that natural selection optimizes egg size within populations and most of the variation in reproductive output is attributable to clutch size variation driven by body size, available resources, and age. For small-bodied turtles, morphological (pelvic) constraint on egg size has been considered the main explanation when populations exhibit considerable variation in egg size, because the pelvis could be under selection for other functions besides reproduction. Kinosternids, a small-bodied and semiterrestrial lineage of turtles, show evidence for both pelvic and nonpelvic constraint on egg size. In order to test if small species show a tendency toward pelvic constraint on egg size, we examined possible pelvic constraints in 1 population of the small-bodied Kinosternon chimalhuaca from western Mexico and in 3 populations of medium- to large-bodied Kinosternon integrum from central Mexico. Gravid females were X-rayed to measure both pelvic aperture and egg width. To test for pelvic constraint on each population we compared the slopes of pelvic aperture and egg width (mean and maximum) to body size (plastron length) with analysis of covariance (ANCOVA); we also compared egg elongation with fresh egg measurements among populations using ANCOVA (with body size as covariate), and we conducted an allometric analysis in order to test for egg size optimization. We found evidence of pelvic constraint in 1 population of K. integrum, and evidence of nonpelvic constraint in the K. chimalhuaca population and in the other 2 populations of K. integrum. Our data did not support the supposed adaptive compromise and pelvic constraints on egg size in small-bodied turtles reported in other studies. Environmental factors such local pressure on egg size (stability of the environment) could explain this pelvic constraint discrepancy in kinosternids.

Egg size is a useful metric for maternal investment, offspring quality, and contaminant studies. Yet these values and the egg shape coefficients required to estimate egg size are not available for many species, including White-faced-Ibis (Plegadis chihi). We provide egg morphometrics derived from 319 White-faced Ibis eggs sampled at Bear River Migratory Bird Refuge, Great Salt Lake, Utah, from 2010 to 2012. Measured egg length (mean ± SD) was 51.20 ± 1.99 mm, egg width was 36.08 ± 1.15 mm, and whole egg mass was 34.1 ± 3.3 g. Estimated whole egg volume was 34.63 ± 3.73 cm3 and estimated egg shape coefficients were 0.507 for Kv (whole egg and egg contents), 0.547 for Kw (whole egg), and 0.524 for Kw (egg contents only). In addition, we documented expected declines in egg mass over time due to incubation (–0.22 g/d) and desiccation during storage (–0.03 g/d), that should be accounted for prior to analyses that use egg mass of freshly laid eggs.

A survey of the microbial quality based on enterobacteriaceae counts of the table eggs sold in Egyptian markets was conducted to evaluate their quality and the possibility of presence of Enterovirulent Escherichia coli strains. Six hundred random table egg samples were collected from different shops, supermarkets and homes. Each six pooled eggs constituted a composite sample. Higher log10 cfu/g of Baladi hen and Duck eggs respectively. Lower enterobacteriaceae counts in brown shell and white shell hen eggs (4.9x10, 6.3x10 log10 cfu/g) in the content and the shell of both types. Twenty (%) of white shell and brown shell, 20, 36% of baladi hen eggs; and 36, 68% of duck eggs (content and shell) were marginally exceeded the maximum permissible count of enterobacteri aceae by European Communities Standards. Escherichia coli, Enterobacter, Citrobacter, Klebsiella, Protus, Providencia and Shigella had been recovered from the content and the shell of different types of table eggs. E. coli strains isolated from different types of table eggs were serotyped into 7 different serotypes included O44, O111, O114, O125, O126, O127 and O128. Most of these isolates (37/39) were stx2 positive. Interstingly, all stx2 positive isolates were negative for stx1 and eae genes. Enterobacteriacae count limits should be added to the microbiological criteria for fresh table eggs as regulation in Egyptian standards. Hygienic measures should applied in home produced hen and duck eggs to lower bacterial load in egg shell and subsequently in egg content.

The eggs and broods of crustaceans that carry their embryos attached to their appendages or within a marsupium are examined. Larger crustaceans within an order or suborder have larger eggs than smaller crustaceans but the egg size relative to body size decreases except in 2 groups: the relative volume of the eggs of calanoid copepods and deep-living mysids is maintained at about 1.0 O/O and 0.4 % of body volume respectively across the ranges of size of the females examined. Brood volume relative to body volume tends to remain constant as body size increases and represents about 10 to 15 % of body volume. The constraints on brood volume probably devolve from the possession of a ngid exoskeleton but some variation independent of body volume is possible. Egg size and number are dependent variables. Mysids, euphausiids and decapods divide into species that produce large and those that produce small eggs. There may be a minimum viable size of egg. Consequently, small crustaceans may increase fecundity through production of successive broods whereas larger crustaceans can increase the number of eggs by decreasing egg size. The effect of increased lipid content of large eggs relahve to an increase in egg size and incubation time is discussed.

The number, size, and carbon and nitrogen contents of eggs in the pouches of a euphausiid crustacean, Nematoscelis difficilisHansen, were examined. A clear linear relationship exists between the number of eggs in the pouch and the body weight of the maternal euphausiid. The eggs are not spherical in shape, and the size of eggs is greater in larger egg masses. The carbon content of the egg masses (50.2%) is higher than that of the bodies (40.7%). The carbon: nitrogen ratio (C/N) is also higher in the egg masses than in the bodies of euphausiids. The carbon content of the eggs is equivalent to 28.4% of the body carbon, the nitrogen content to 19.2% of the body nitrogen.

A study was undertaken to predict the correlation between egg weight and egg characteristics in quail. Data was collected on 102 eggs collected from female quails at 28 weeks. Eggs were numbered, weighed and classified into six egg weight groups: below 9.0g, 9.0-9.5g, 9.6-10.0g, 10.1-10.5g, 10.6-11.0g, and above 11g group. There were 17 eggs per egg weight group. Data was collected on egg weight, shell weight, shell ratio, albumen height, albumen weight, albumen ratio, albumen index, yolk height, yolk diameter, yolk weight, yolk ratio and Haugh Unit. Data collected were analysed using the General Linear Model (GLM) procedure of the Genstat edition 11. The correlation between the various characteristics of egg were determined. The result shows that Albumen diameter, albumen length and albumen width were influenced by size of egg (<i>p</i><0.05). Albumen diameter and albumen length increases with increasing egg size. There was a positive correlation between egg length and albumen (0.448), albumen diameter (0.463), shell surface area (<i>p</i><0.01). Egg width, height, shape index, shell ratio and shell surface area were significantly (<i>p</i>>0.05) influenced by the sizes of quail eggs. The egg sizes of above 11g had the best egg length followed by 10.6g-11.0g, 10.1g-10.5g, 9.6g-10.5g, 9.0g-9.5g and below 9.0 g had the least egg length indicating a direct relationship between egg length and egg weight. The positive correlations between the internal and external egg quality traits indicated that the traits can be improved through selection.

Some freshwater turtles appear unable to produce eggs large enough to achieve the balance between size and number of eggs predicted by optimal egg size theory. We present evidence that pelvic girdle structure constrains egg size and thus offspring size in females of smaller-bodied species (Chrysemys picta and Deirochelys reticularia). The constraint is demonstrated by the correspondence of slopes of the increase of the pelvic aperture and egg width with increasing body size. This constraint appears to be relaxed in a larger-bodied species (Pseudemys scripta), in which the increase in pelvic aperture relative to body size is greater than the increase in egg width. This type of structural constraint on a reproductive trait should not occur unless there is strong selection on pelvic architecture for other functions, such as locomotion, support, and limb retraction, that prevent expansion of the pelvic aperture. Although other explanations may exist for other groups of organisms that appear to vary egg size, the large variation in egg size associated with body size in some species of turtles can be reconciled with optimal egg size theory only if a pelvic constraint model is accepted.

In layered reservoirs characterised by low matrix permeability, fracture networks control the main fluid flow paths. In limestone-marl alternations, however, the vertical fractureassociated permeability varies considerably between distinct layers. Within a succession, various sedimentological features (e.g. sedimentary layering or diagenetic bedding) lead to contrasting rock properties and thus may act as stress barriers. Stress barriers such as lithological contacts or thick marl layers can prevent the fracture propagation in layered rocks, making the prediction of potential fluid flow paths in such successions even more complicated. To improve the prediction of potential fluid flow path, it is crucial to find several layers without stress barriers, which act mechanically as a single unit (‘mechanical unit’). The aim of this doctoral study is to assess the impact of sedimentological and diagenetic features and petrophysical properties on vertical fracture propagation in limestone-marl alternations of the Jurassic Blue Lias Formation (Bristol Channel Basin, United Kingdom), in order to define different kinds of stress barriers and mechanical units. For this purpose, six sections characterised by different morphological variations (e.g. from limestone-dominated to marldominated) were comprehensively investigated combining sedimentological (e.g. field observations, thin section petrography, scanning electron microscopy, CaCO3- and Corgmeasurements), quantitative structural geological (e.g. characterisation of fracture networks) and petrophysical data (e.g. tensile and compressive strength-, rock hardness- and porositymeasurements). Concerning the quantitative structural geological approach, more than 4000 fractures were traced over several layers along a 15 m scan-line using a modified scan-line method (i.e. a combination of scan-line and window sampling). It is generally assumed that the spacing between tension fractures increases and the fracture density decreases with increasing bed thicknesses. This study revealed, however, that in the respective beds of these alternations this relationship is only limitedly applicable and can only be applied in cases of beds with laterally planar surfaces (i.e. well-bedded limestones). Even in beds with the same thickness the fracture spacing varies significantly in beds with irregular surfaces (i.e. semi-nodular limestones). That means fractures are unregularly spaced in seminodular limestones and more regularly spaced in well-bedded limestones. Furthermore, wellbedded limestones in the successions are generally characterised by higher percentages of stratabound fractures (57 %), while semi-nodular limestones show higher percentages of nonstratabound fractures (67 %). Not only is the fracture distribution in single beds crucial for the fracture propagation in layered rocks, but also stress barriers such as lithological contacts, thicknesses and heterogeneities within marl layers inhibit fracture propagation, as well. Stress barriers were identified based on vertical fracture termination at and crossing through lithological contacts and vertical fracture extension through layers (stratabound vs. nonstratabound fractures). Since not all lithological contacts prevent the fracture propagation in layered rock, the term was only used in this doctoral project for 50 % of fracture terminations at these contacts (i.e. ‘mechanical interfaces’). In addition thick marl layers (>0.20 m) bounded by mechanical interfaces and less than 50 % non-stratabound fractures are defined as ‘mechanical buffer’. Given the high heterogeneity of the Blue Lias Formation in fracture distribution also the impact of diagenesis varies significantly from section to section. For instance, three subsections in Wales were studied in detail, despite of their close vicinity and relative contemporaneous time, all three subsections reveal different sedimentological and diagenetic features on metre to micrometre scales (from early lithified over physically compacted) and are all characterised by dissimilar patterns of fracture terminating at and crossing through lithological contacts and fracture extension (e.g. percentages of nonstratabound fractures) within beds. Lithological contacts in diagenetic influenced successions are more gradual and hence are no mechanical interfaces, if additionally the contrast of CaCO3 contents between limestones and marls is low the succession can be defined as a mechanical unit which promotes the fracture propagation. The prediction of fracture network connectivity is difficult in lithological heterogeneous limestone-marl alternations such as the Blue Lias Formation with high heterogeneity in fracture distribution, different impact of diagenesis and effect of different stress barriers. This is particularly problematic for the characterisation of fracture networks and its application in outcrop analogue studies, which are commonly used to predict main fluid flow paths in such systems. The findings of this study are crucial to improve the quantification of fracture distribution and propagation in heterogeneous rock successions and, consequently, to refine definitions of mechanical units, being an important prerequisite for the prediction of fractureassociated permeability and fluid flow models.