Costs of large communal clutches for male and female Greater Rheas Rhea americana

The breeding system of the Greater Rhea Rhea americana is almost unique among birds as it combines harem polygyny and sequential polyandry, with communal egg-laying and uniparental male care. In this species, large communal clutches (more than 30 eggs) are rare and have a lower hatching success than smaller clutches. Here we analyse the proximate causes of hatching failures and the costs of large communal clutches (and therefore the costs of extensive polygyny) for males and females. We evaluated if length of the nesting period, egg viability, egg losses during incubation and male parental activity at the nest were affected by clutch size. We also evaluated if chicks hatched from large clutches have a lower survival during the first 2 months after hatching. Large clutches had longer nesting period and lower hatching success, mainly as a result of bacterial contamination of the eggs and increased hatching asynchrony. In addition, large clutches tended to lose more eggs as a result of accidental breakage or predation. Male activity at the nest and chick survival were not related to clutch size. Low hatching success, nest predation risk and energetic costs associated with large clutches penalize females that join large harems and males that accept additional eggs into the nest.     

Phospholipid hydration studied by deuteron magnetic resonace spectroscopy

Deuteron magnetic resonance spectra were obtained from ²H₂O in mixtures with egg lecithin, egg phosphatidylethanolamine, and ox brain sodium phosphatidylserine. The acid form of phosphatidylserine does not hydrate. Details of the different hydration “shells” were obtained by studying the spectral splittings as a function of ²H₂O concentration. Several different types of water are present, including bulk water (exchanging only slowly with water associated with the lipid), “trapped” water (not present with phosphatidylethanolamine), and up to three types of bound water. The spectral splittings characteristic of each water environment yielded information about the water binding energies and degrees of anisotropy of motion of the phospholipid polar groups; lecithin polar groups have least motional restriction and sodium phosphatidylserine most, while phosphatidylethanolamine binds water most tightly.Spectra of some lecithin and phosphatidylserine dispersions varied with time, due to a slow reorganization of randomly oriented multilamellar regions into longer, more ordered systems, with a length of about 1 μm. At ?20°C the timescales of the change were of the order of a week and a month for lecithin and phosphatidylserine respectively.Complex changes in the spectra were observed as the temperature was raised; these are interpreted in terms of changes in the motions of the phospholipid molecules.     

4种平胸鸟类腰荐部骨骼的比较

对鹤鸵(Casuarius casuarius)、鸸鹋(Dromaius novaehollandiae)、美洲鸵鸟(Rhea americana)和鸵鸟(Struthio camelus)的腰荐部骨骼进行了对比。鸸鹋与鹤鸵在愈合荐骨的数目与构成、腰带的结构方面最为相似,均为开放式骨盆。美洲鸵鸟和鸵鸟均为非开放式骨盆,前者的坐骨大部愈合,后者的耻骨后角左右愈合。与突胸鸟类对比发现:平胸类的愈合荐骨相对较长,髂骨后翼狭窄、几乎垂直伸向下方;突胸鸟类的髂骨后翼宽阔、水平侧向伸展并微微向背方拱起。反映了平胸类结构的原始性。     

Sexual,Seasonal and Group Size Differences in the Allocation of Time between Vigilance and Feeding in the Greater Rhea,Rhea americana

We studied the effect of sex and group size on the proportion of time a greater rhea, Rhea americana, allocates to vigilance and feeding during the breeding and the non-breeding seasons. We analysed 175 records of focal animals that were feeding alone or in groups of 2 to 26 birds. In both seasons, males spent more time in vigilance and less time in feeding than females. Both sexes spent more time in vigilance and less time in feeding during the breeding season. Sexual and seasonal differences in vigilance were the result of different mechanisms. Males had shorter feeding bouts than females but there were no sexual differences in the length of the vigilance bouts. On the contrary, seasonal differences were the result of males and females having longer vigilance bouts during the breeding season but there were no seasonal differences in the length of the feeding bouts. During the non-breeding season, individual vigilance was higher in rheas foraging alone than in groups. In this case, solitary birds had longer vigilance and shorter feeding bouts than birds foraging in groups. We discuss the possible effect of intragroup competition and food availability on the allocation of time between feeding and vigilance in this species.     

Magellanic Penguin eggshell pores: does number matter?

Most penguin species lay two eggs 3–4 days apart that hatch 1–2 days apart. Hypotheses to explain the shorter incubation period for the second egg include differences in porosity of the eggshells. Eggs with more or larger pores and/or thinner shells have higher gas exchange rates and faster embryonic development. We used eggshells from hatchling Magellanic Penguins Spheniscus magellanicus to test whether eggshell thickness and pore density affect incubation period. We expected: (i) second eggs to have thinner shells and/or more pores than first eggs; (ii) eggs to have thinner shells and/or more pores if they were laid by older females, later in the season, or in burrow nests (more humid than open nests under bushes). We found no support for these hypotheses. Egg pores and shell thickness were not related to incubation period. Eggs from the same clutch were similar in eggshell thickness and pore density. Female age, laying date and nest type were poor predictors of eggshell thickness and pore density. Egg pores, we conclude, have little explanatory power for differences in incubation time of eggs in Magellanic Penguins, and suggest that synchronous onset of incubation matters.     

A computer simulation study of the hydrated proton in a synthetic proton channel

Classical molecular dynamics simulations using the multistate empirical valence bond model for aqueous proton transport were performed to characterize the hydration structure of an excess proton inside a leucine-serine synthetic ion channel, LS2. For such a nonuniform pore size ion channel, it is found that the Zundel ion (H(5)O(2)(+)) solvation structure is generally more stable in narrow channel regions than in wider channel regions, which is in agreement with a recent study on idealized hydrophobic proton channels. However, considerable diversity in the relative stability of the Zundel to Eigen cation (H(9)O(4)(+)) was observed. Three of the five wide channel regions, one located at the channel's center and the other two located near the channel mouths, are found to show extraordinary preference for the Eigen solvation structure. This implies that proton hopping is inhibited in these regions and therefore suggests that these regions may behave as barriers in the proton conducting pathway inside the channel. The proton solvation is also greatly influenced by the local molecular environment of the protein. In particular, the polar side chains of the Ser residues, which are intimately involved in the solvation structure, can greatly influence proton solvation. However, no preference of the influence by the various Ser side chains was found; they can either promote or prevent the formation of certain solvation structures.     

The burrow ofDasypus hybridus (Cingulata: Dasypodidae)

Dasypus hybridus (Desmarest, 1804) inhabits open fields in southern South America. Burrows ofD. hybridus were cylindrical with a conical end. They had an entrance and a single tunnel without branches. Three locations of the burrows in the terrain were detected: in banks of dried waterways, near rocks, and in open field. The orientation of 29 burrow mouths was not random and, although they did not point to any cardinal point, in particular there was a strong tendency to avoid the south quadrant. In a sample area of 90 × 140 m, burrow mouths were arranged in a random spatial pattern with a density of 25.4 burrows per ha. Great variation in burrow length was found (118.8 ± 105.69 cm, CV = 89.0%). Tunnels may be used as refuges and/or for thermoregulation. The orientation of burrow mouths can also be related to thermoregulation as tunnels are covered from dominant winds, and, for many hours every day, the temperature at the mouths can be influenced by insolation. The possible existence of shelter-burrows and resting-burrows is discussed.     

Morphology of the egg shell and the developing embryo of the Red Palm Weevil,Rhynchophorus ferrugineus (Oliver)

The harvested eggs of Rhynchophorus ferrugineus are ovo-cylindrical shaped, averaged 1.09 mm in length and 0.43 mm in width, with ratio of L\W 4.42. The chorionic layer of electron dense material is seen covering the exochorion structure of the eggs. The egg main body chorion exhibits a polygonal pattern and architecture surface of the egg is supported by a system of irregular interconnecting grooves. The micropylar apparatus of the eggs of the Red Palm Weevil, R. ferrugineus is described in the present study for the first time. Two micropylar openings are found closed to the center of the posterior wide pole of the egg. Each micropylar opening presents a single small orifice and its surrounding chorion is porous and densely set with tiny projections allowing the spermatozoa to penetrate the egg. Respiratory aeropyles are distributed on the borders of reticulations in the area chorionic surface of egg capsule. The hatching region is detected on the anterior part at the opposite side of the egg. Changes in the appearance and shape of R. ferrugineus eggs as well as the incidence of embryonic development are observed.     

A study of low pH-induced refolding of Env of avian sarcoma and leukosis virus into a six-helix bundle

The fusion protein of avian sarcoma and leukosis virus is likely to fold into a six-helix bundle as part of its final configuration. A peptide, R99, inhibits fusion, probably by binding into the grooves of the triple-stranded coiled coil that becomes the central core of the six-helix bundle. The stages at which the envelope protein (Env) of avian sarcoma and leukosis virus subgroup A folds into a bundle during low pH-induced fusion were determined. Effector cells expressing Env were bound to target cells expressing the cognate receptor Tva, and intermediates of fusion were created. R99 was added and the extent of fusion inhibition was used to distinguish between a prebundle state with exposed grooves and a state in which the grooves were no longer exposed. The native conformation of Env was not sensitive to R99. But adding a soluble form of Tva to effector cells conferred sensitivity. Acidic pH applied at low temperature created an intermediate state of local hemifusion. Surprisingly, R99 caused these locally hemifused membranes to separate. This indicates that the grooves of Env were still exposed, that prebundle configurations of Env stabilized hemifused states, and that binding of R99 altered the conformation of Env. In the presence of an inhibitory lipid that blocks fusion before hemifusion, applying low pH at 37 degrees C created an intermediate in which R99 was without effect. This suggests that the six-helix bundle can form before hemifusion and that subsequent conformational changes, such as formation of the trimeric hairpin, are responsible for pore formation and/or growth.     

Activity‐induced dental modification in holocene siberian hunter‐fisher‐gatherers

The use of teeth as tools provides clues to past subsistence patterns and cultural practices. Five Holocene period hunter‐fisher‐gatherer mortuary sites from the south‐western region of Lake Baikal, Siberia, Russian Federation, are observed for activity‐induced dental modification (AIDM) to further characterize their adaptive regimes. Grooves on the occlusal surfaces of teeth are observed in 25 out of 123 individuals (20.3%) and were most likely produced during the processing of fibers from plants and animals, for making items such as nets and cordage. Regional variation in the frequency of individuals with occlusal grooves is found in riverine versus lakeshore sites. This variation suggests that production of material culture items differed, perhaps in relation to different fishing practices. There is also variation in the distribution of grooves by sex: grooves are found predominately in females, except at the Late Neolithic‐Bronze Age river site of Ust'‐Ida I where grooves are found exclusively in males. Occlusal grooves were cast using polyvinylsiloxane and maxillary canine impressions were examined by scanning electron microscopy (SEM) to determine striation patterns. Variation in striae orientation suggests that a variety of activities, and/or different manufacturing techniques, were involved in groove production. Overall, the variability in occlusal groove frequency, sex and regional distribution, and microscopic striae patterns, points to the multiplicity of activities and ways in which people used their mouths and teeth in cultural activities. Am J Phys Anthropol 143:266–278, 2010. © 2010 Wiley‐Liss, Inc.     

A single camera roentgen stereophotogrammetry method for static displacement analysis

A new method to quantify motion or deformation of bony structures has been developed, since quantification is often difficult due to overlaying tissue, and the currently used roentgen stereophotogrammetry method requires significant investment. In our method, a single stationary roentgen source is used, as opposed to the usual two, which, in combination with a fixed radiogram cassette holder, forms a camera with constant interior orientation. By rotating the experimental object, it is possible to achieve a sufficient angle between the various viewing directions, enabling photogrammetric calculations. The photogrammetric procedure was performed on digitised radiograms and involved template matching to increase accuracy. Co-ordinates of spherical markers in the head of a bird (Rhea americana), were calculated with an accuracy of 0.12mm. When these co-ordinates were used in a deformation analysis, relocations of about 0.5mm could be accurately determined.     

Physical features of grass leaves influence the placement of eggs within the plant by the Hessian fly

Hessian fly eggs are more likely to be found on adaxial rather than abaxial surfaces of wheat leaves. These leaf surfaces differ in their physical features: the adaxial side of the leaf has parallel grooves and ridges while the abaxial side is relatively smooth. We used leaf models to investigate the relationship between Hessian fly egglaying and these physical features. When both sides of a green paper leaf model were treated with a wheat leaf extract, but only one side of the model was scored with parallel grooves, the grooved side received more eggs than the smooth side. As the number of grooves per surface increased from 0 to 10, eggs per model increased. When grooves and the wheat leaf extract were tested together and separately, the grooves significantly increased egg numbers in the presence, but not the absence, of wheat extract. In contrast, wheat extract increased egg numbers both in the absence and presence of grooves. Molding techniques were used to recreate the physical features of the adaxial and abaxial leaf surfaces of five grasses. For four of the grass genotypes (a triticale, two common wheats, and a durum wheat), patterns of egglaying on real leaves and molded models were similar, i.e., adaxial leaf surfaces and adaxial molded models were preferred over abaxial leaf surfaces and abaxial models. On the fifth grass, oat, preferences for the adaxial side of real leaves and for adaxial models were not as obvious. We conclude that the adult female Hessian fly obtains information about the leaf surface through her tactile and/or kinesthetic senses and uses this information when making egglaying decisions.     

Effects of electromagnetic fields on the reproductive success of American kestrels

Reduced reproductive success of birds nesting near power lines has been documented but never directly attributed to electromagnetic fields (EMFs). Laboratory studies have identified EMF effects on embryonic development, but reproductive success of wild birds is dependent on additional factors, including fertility, egg size, hatching, and fledging success. We tested whether EMFs affect reproductive success of birds. Captive American kestrels (Falco sparverius) were bred for one season per year for 2 yr under either controlled or EMF conditions. EMF exposure was equivalent to that experienced by wild reproducing kestrels and was weakly associated with reduced egg laying in 1 yr only. In both years fertility was higher, but hatching success was lower in EMF pairs than control pairs. Fledging success was higher in EMF pairs than control pairs in 1995 only. Egg composition and embryonic development were examined in 1 yr only, but hatchlings were measured in both years. EMF eggs were larger, with more yolk, albumen, and water, but had thinner egg shells than control eggs. Late-term EMF embryos were larger and longer than control embryos, although hatchlings were similar in body mass and size. EMF exposure affected reproductive success of kestrels, increasing fertility, egg size, embryonic development, and fledging success but reducing hatching success.     

Three new species of Huffmanela Moravec, 1987 (Nematoda: Trichosomoididae) from the gills of marine fish off New Caledonia

Three new species of Huffmanela, here described from eggs only, are reported from the gills of marine fish caught off Nouméa, New Caledonia. Eggs of Huffmanela branchialis n. sp., from Nemipterus furcosus (Nemipteridae), are 45-52 (mean 48) microm in length and 23-30 (mean 25) microm in width, with thin shells. Each egg is enclosed in a thin membrane forming a spindle-shaped envelope 53-85 (mean 63) microm in length. Eggs of H. filamentosa n. sp., from Gymnocranius grandoculis (Lethrinidae), are 48-53 (mean 50) microm in length and 25-30 (mean 27) microm in width, with thin shells. Each egg bears a few long (150 microm), thin filaments. Eggs of these two new species were compared to those of H. paronai Moravec & Garibaldi, 2000, which are redescribed. Eggs of H. ossicola n. sp. were found within the branchial arch bone of Bodianus loxozonus (Labridae) and also filled the spinal chord bone and other bones. This is the first species of Huffmanela reported from bone tissue. Eggs are large, 72-88 (mean 79) microm in length and 32-40 (mean 36) microm in width, with a very thick shell. Each egg is covered with numerous filaments enclosed in a thin envelope. Fresh eggs were unembryonated, but embryos were visible after incubation in seawater. The three new species can be distinguished from other species of Huffmanela by size and the nature of the egg covering. Egg morphology of and their location in the host suggest different life-cycles: those of the first two species (small eggs, thin shells, egg covering possibly favouring flotation) are released from the gill mucosa with the turnover of living tissues and immediately continue their life-cycle, but eggs of H. ossicola (large eggs, thick shell) are only available for the continuation of the life-cycle after the host's death.     

Preferential predatory peeling: Ammonoid vs. nautiloid shells from the Upper Carboniferous of Texas,USA

Narrow groove-like excavations on ammonoid and coiled nautiloid shells are rare in Upper Carboniferous units from Texas, USA. The morphological characteristics of the excavation grooves typically are confined to the ventral and ventrolateral parts of the outer whorl of the shell, are narrower than the length, and have irregular edges where small segments or chips of shells have been removed. Analysis of these features reveals a statistically significant preferential occurrence on ammonoids (1.195% of ca. 3515 specimens) as compared to coiled nautiloids (0.506% of ca. 2965 specimens). The ammonoids typically have longer excavations that penetrate the phragmocone more frequently than those observed in the coiled nautiloids. The groove-like excavations were probably formed by the removal and peeling of shell material by one or more predatory or scavenging arthropods to obtain organic material (tissue and membranes) within the ammonoid and nautiloid body chambers and phragmocones. The excavations probably occurred when the cephalopod was alive (i.e., the cause of death) or shortly after the cephalopod's death. There is no evidence that the excavations are related to sheltering by the excavating organism.     

Neuronal input contributes to sequence of Aplysia egg laying behaviors

Egg laying in Aplysia is controlled by the bag cell neuroendocrine system, which releases multiple peptides during a long-lasting electrical discharge. Following the discharge, a fixed sequence of head and neck movements is performed in which two phases can be distinguished: an appetitive or preparatory phase, in which the substrate is prepared, and a consummatory phase, when the egg string is deposited. During egg laying, feeding responses are suppressed. In this study, Aplysia fasciata was used. When the movement of the egg string through the genital groove was prevented by ligation, lesions of the nerve innervating the genital pore completely abolished the consummatory egg-laying behaviors. This shows that a nervous connection between the genital pore area and the central nervous system is important for the consummatory egg-laying behaviors.We found that suppression of feeding responses to seaweed occurred only during the consummatory phase of egg laying in controls, but animals with ligated genital grooves continued to show normal responses to food. It is hypothesized that a neuronal feedback, possibly together with the bag cell peptides, is critical for the temporal organization of egg-laying behavior in Aplysia.Abbreviations CNS central nervous system - ELH egg laying hormone     

Morphological variation among populations of Lecocarpus (Asteraceae) on the Galápagos Islands

Representative samples were collected from almost all known populations of the endemic Galapagos genus Lecocarpus. Multivariate statistical methods were applied to morphological characters to investigate differentiation among species and populations. In discriminant analysis no misclassifications were made among species. Populations of L. darwinii and L. lecocarpoides were better discriminated than populations of L. pinnatifidus . Principal Component Analysis (PCA) separated species well although intermediate populations occur between L. darwinii and L. lecocarpoides . Clear patterns of within-species differentiation were seen among populations of L. darwinii and L. lecocarpoides , but not among populations of L. pinnatifidus .
Populations of L. lecocarpoides at present grow on separate islands. All populations of L. darwinii are found on San Cristóbal, but this island might have been separated into more islands in the past. Lecocarpus pinnatifidus has probably always been growing on only one island. This suggests that the sea is the major barrier to dispersal of the three species. We find it likely that the degree of reproductive isolation caused by the sea is crucial to the differentiation among populations, and that genetic drift rather than adaptation has been responsible. The analyses cast new light on the identity of classic collections made by Darwin in 1835 and Stewart in 1906. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 523–544.     

Characterization of shell gland lipids from chickens (Gallus domesticus) producing strong or weak egg shells

1. The reduction in egg shell strength in hens at the end of the first reproductive cycle was not associated with abnormal uterine or body fat accumulation. 2. The phosphatidylcholine concentration was greater in the shell glands of hens producing strong egg shells compared to that of producing weak egg shells. 3. Differences were not detected in the total lipid or cholesterol concentrations or the fatty acid profiles of phosphatidylcholine or phosphatidylethanolamine fractions. 4. Following an induced molt, the fatty acid profile of the total lipid fraction of the shell gland was altered with a decrease in stearic acid and an increase in oleic acid. 5. The results demonstrate that alterations in egg shell strength are mainly associated with changes in shell gland phospholipid polar head group composition and not with changes in phospholipid fatty acid profile or cholesterol concentration.     

Calcite and aragonite in the egg shell of Chelonia mydas L.

The structure of the calcified layer of egg shells from farm-reared and wild turtles has been examined using scanning electron microscopy and infrared analysis. Farm-reared egg shells contained discrete morphologically distinct regions of blocks of calcite and spherulites of aragonite. In contrast, the egg shells from feral populations consisted only of the spherulites. Differences in the impurity contents of the calcite and aragonite structures have been observed. SEM revealed a thin cuticular membrane.