Haematocrit values of breeding Red-billed queleas Quelea quelea (Aves: Ploceidae) in relation to body condition and thymus activity

In a Red-billed quelea colony in north-eastern Nigeria that was later abandoned as a result of the poor nutritional condition of the adults, laying females showed low haematocrit values compared with normal pre-breeding haematocrit levels but nestbuilding males did not. In females the low haematocrits were correlated with extremely low levels of reserve lipid and labile protein but males in equally poor condition did not have such low haematocrits. This difference must result in some way from the additional nutritional burden for females of mobilizing sufficient protein to form eggs. Earlier observations of massive red blood cell production in the thymus of queleas during incubation suggest that low haematocrits, indicating anaemia, may be a normal occurrence in queleas during breeding, and were not peculiar to this abnormal abandoned colony.     

The migrations of the Red-billed Quelea Quelea quelea and their relation to crop damage

Recent studies on the migrations of the Red-billed Quelea Quelea quelea have shown that while the species is capable of long-distance movements of hundreds of kilometres, the actual migrations probably more often consist of shorter distances with a flexible timing. This flexibility allows adjustments to be made to the rainfall distribution in a particular year. New information comes from studies on the breeding distribution, on the plumage and moult of local populations, and from attempts to apply new techniques such as mass-marking with fluorescent particles. Breeding has been shown to be both more widespread and more frequent than previously recognized, while local populations can prolong breeding in one place if rainfall continues. Local populations have been identified that are apparently distinct, with limited intermixing with other populations, and some data suggest that intermixing may be reduced by flock or group cohesion. The flexibility of the migrations means that predictions of major influxes of quelea into agricultural areas have proved difficult to make, especially in regions where the rainfall patterns are complex and variable, such as East Africa.     

Evidence of itinerant breeding of the Red-billed Quelea Quelea quelea in the Ethiopian Rift Valley

This paper provides evidence for itinerant breeding by Red-billed Quelea Quelea quelea in the Ethiopian Rift Valley. Queleas were mass-marked with aerially applied fluorescent particles in two separate nesting areas in southwestern Ethiopia during June 1981. Marked adults from both areas were recovered from nesting colonies in the Awash River Valley during August and September, up to 100 days post-spray and between 500 and 700 km to the north of the spray sites. In the Awash colonies, the presence of marked adults in breeding plumage with interrupted primary wing-moult, together with two age classes of juveniles, suggests that this was the second nesting. The progress of both the post-breeding and post-juvenal primary moults was consistent with an earlier breeding in May and June. The timing of the arrival and departure of birds from these nesting areas also supported the occurrence of double breeding by the same birds. Furthermore, the composition of black facial mask types of adult males was more similar between samples from the southern Ethiopian Rift and Awash Valley than between samples from either of these areas and samples from outside the Rift, providing additional evidence that the same population of birds bred in these two areas of the Rift Valley. Nesting colonies in both areas were scattered in time and space. Colonies in the Awash were distributed for more than 300 km and were established over a two-month period, which coincided with local differences in the timing of the seeding in grasses. This wide distribution probably increases nesting success in such areas of locally variable rainfall. This contrasts with a stategy of mass migration, where concentrated breeding occurs where and when suitable conditions are first encountered. Knowledge of the location and timing of previously successful nesting areas may increase the success of itinerant breeding, as Queleas seem to use the same areas in successive years if conditions are favourable. Recoveries of marked birds in the Awash were segregated according to both spray site and sex, suggesting some degree of group cohesion by sex from the first to the second nesting. We speculate that post-nesting group cohesion of adults may provide a means to maintain the integrity of collective group information on seasonal movements. Group cohesion may be facilitated by the high degree of nesting synchrony within colonies.     

Morphological changes in the thymus of young and adult red-billed queleas Quelea quelea (aves).

In a wild population of red-billed queleas Quelea quelea L. (Ploceidae: weaver-birds) sampled throughout the year in East Africa, the thymus was found to enlarge in young birds shortly after hatching, remain enlarged during the juvenile stage, and regress towards the end of the postjuvenile moult. In adults, recrudescence occurred in many individuals during the prenuptial and postnuptial moults, and also in most if not all individuals, of both sexes, for a brief period during a breeding session. Thymus enlargement in both young and adults has been found to be accompanied by marked erythropoietic activity within the gland, and it is suggested that this activity is related to an increased demand for erythrocytes which may occur during moult and breeding.     

Flexibility in the timing of post-nuptial moult among Red-billed Queleas Quelea quelea in Botswana in relation to the timing of breeding

The timing of primary moult of adult Red-billed Queleas Quelea quelea, captured as they were completing an unusually late breeding attempt at Francistown, northern Botswana, in June 2004, was compared with the timing of moult of birds breeding earlier in the season in north-west Botswana during two earlier years, 1971 and 1972. Differences between years in the dates when local colonies finished breeding (mid-March to late June) and between two localities in the same year (mid-March and late May) were matched by corresponding differences in the estimated dates of moult onset, ranging from mid-April to mid-June. Flexibility in the timing of moult among Red-billed Queleas in southern Africa evidently enables birds to take advantage of unusually late breeding opportunities by delaying moult onset and overlapping moult and breeding at the end of the nesting cycle. Such flexibility may also include moult interruption to permit late breeding, although its incidence in southern Africa is apparently low.     

Histological changes associated with enlargement and regression of the thymus glands of the red-billed quelea Quelea quelea L. (Ploceidae: weaver-birds).

Thymic lobes form over 200 red-billed queleas, Quelea quelea L., were examined histologically. Samples were taken from embryos about to hatch, juveniles and adults. The lobes varied in size from very small to very enlarged (1- greater than 5 mm long). The constituent cell types are described in detail and the occurrence of these cells in different sized lobes is discussed. A cycle of events is proposed which accounts for the observations presented here. It is suggested that the large numbers of erythroid cells found in the cortex of some individuals were developing in situ. The significance of erythropoiesis within the thymus is discussed.     

EMMA-4 analysis of iron in cells of the thymic cortex of a weaver-bird (Quelea quelea).

Combined morphological and analytical studies with the EMMA-4 analytical electron microscope have enabled very early erythroid cells to be identified within the cortex of enlarging thymic lobes of Quelea quelea. These early erythroid cells have pale cytoplasm (sometimes with ferritin-like crystals present), slightly pachychromatic nuclei and have fewer cell organelles (mitochondria) than lymphocytes. Counts for iron were approximately 70% lower than counts from mature erythrocytes found free in the cortex. Iron was also recorded from some epithelial reticular cells and pyknotic nuclei; no iron was recorded from small lymphocytes (thymocytes) in the cortex. The presence of very early erythroid cells is a further indication that erythropoiesis occurs in situ in the avian thymus.     

A possible physiological basis for ocular dominance

An experiment is undertaken to investigate the relationship between "sighting" and motor dominance. A review of recent work on the neurophysiology of vision is carried out and an attempt to explain ocular dominance using this is made.     

A possible physiological basis for the dud-stud phenomenon

Intact male rats were tested on two successive weekly tests with females to determine their level of sexual activity. Nuclear estrogen receptor content was measured in specific brain regions of individual sexually responsive and sexually nonresponsive males. Sexually nonresponsive male rats had significantly reduced nuclear estrogen receptor levels in the preoptic area compared to sexually responsive males. Sexually active males did not differ from inactive males in nuclear estrogen receptors in the medialbasal hypothalamus.     

A physiological basis for control of a prosthetic hand

Recent surveys from upper limb amputees indicate the sentiment that prosthetic hands do not function in a life-like manner and are not intuitively controlled. Thus, two methods of control for a prosthetic hand are presented. A proportional derivative (PD) force controller is compared to a novel biomimetic application of sliding mode control. The biomimetic sliding mode (BSM) controller was designed to map human muscle signals into prosthesis motor command signals in a physiologically expected manner.The BSM and PD controllers were evaluated analytically and subjectively by one amputee and nine nonamputee test subjects. The posture of the hands of the nonamputee test subjects were measured with a CyberGlove and used to determine if the position of the prosthesis (when driven by both controllers) was highly correlated to the posture of the human hands. Force tracking experiments were also performed by all test subjects with both controllers to evaluate the ability to control the applied force. Finally, a dual object lifting task was performed by all test subjects to determine if the mapping of electromyogram (EMG) signals with the BSM controller resulted in physiologically expected motions. A nonparametric Mann–Whitney U-test was performed on the subjective evaluations to determine the statistical significance of the evaluations.The BSM controller was shown to replicate the posture of the human hand much more accurately than the PD force controller. The BSM controller also enabled better average force tracking results and higher success rates with the dual object lifting experiment while the same task was nearly impossible to perform with the PD controller. Finally, the BSM controller was subjectively rated to be more similar to control in comparison to the human hand with respect to position and force.     

Factors affecting mate desertion by males in free-ranging convict cichlids (Cichlasoma nigrofasciatum)

Convict cichlid fish have biparental care for a period of about6 weeks lasting from egg laying until the young (fry) have grownto about 10 mm. However, the young can sometimes survive withcare from only one parent, and desertion of the mate and offspringby males has been observed. I tested a theoretical model modifiedfrom Lazarus (1990) which predicted that mate and offspringdesertion by male convict cichlids should be promoted by lowpredation pressure on fry, high remating opportunities for males,increasing age of fry, and decreasing number of fry. Males deserted7.8% of 334 broods studied during two breeding seasons in CostaRican streams. As predicted, males deserted their broods mostfrequently at sites with the highest brood survivorship (lowestbrood predation pressure), when fry were close to independenceand when brood size was smaller than average. Sex ratios andinterspawning intervals did not indicate any relationship betweenmate desertion and opportunities for remating for males. Thereuse of spawning caves may favor fidelity to the mate and brood,and defending the young from predators at the same time as defendingthe cave from conspecifics may favor biparental care in thisspecies.     

Variation in mating system among birds: ecological basis revealed by hierarchical comparative analysis of mate desertion

Since most bird species are socially monogamous, variation among species in social mating systems is determined largely by variation in the frequency of mate desertion. Mate desertion is expected to occur when the benefits, in terms of additional reproductive opportunities, outweigh the costs, in terms of reduced reproductive success from the present brood. However, despite much research, the relative importance of costs and benefits in explaining mating system variation is not well understood. Here, we investigate this problem using a comparative method. We analyse changes in the frequency of mate desertion at different phylogenetic levels. Differences between orders and families in the frequency of desertion are negatively associated with changes in the potential costs of desertion, but are not associated with changes in the potential benefits of desertion. Conversely, differences among genera and species in the frequency of desertion are positively associated with increases in the potential benefits of desertion, but not with changes in the potential costs of desertion. Hence, we suggest that mate desertion in birds originates through a combination of evolutionary predisposition and ecological facilitation. In particular, ancient changes in life-history strategy determine the costs of desertion and predispose certain lineages to polygamy, while contemporary changes in the distribution of resources determine the benefits of desertion and thereby the likelihood that polygamy will be viable within these lineages. Thus, monogamy can arise via two very different evolutionary pathways. Groups such as albatrosses (Procellariidae) are constrained to social monogamy by the high cost to desertion, irrespective of the potential benefits. However, in groups such as the accentors (Prunellidae), which are predisposed to desertion, monogamy occurs only when the benefits of desertion are very limited. These conclusions emphasise the additional power which a hierarchical approach contributes to the modern comparative method.     

Investigating microbial (micro)colony heterogeneity by vibrational spectroscopy

Fourier transform infrared and Raman microspectroscopy are currently being developed as new methods for the rapid identification of clinically relevant microorganisms. These methods involve measuring spectra from microcolonies which have been cultured for as little as 6 h, followed by the nonsubjective identification of microorganisms through the use of multivariate statistical analyses. To examine the biological heterogeneity of microorganism growth which is reflected in the spectra, measurements were acquired from various positions within (micro)colonies cultured for 6, 12, and 24 h. The studies reveal that there is little spectral variance in 6-h microcolonies. In contrast, the 12- and 24-h cultures exhibited a significant amount of heterogeneity. Hierarchical cluster analysis of the spectra from the various positions and depths reveals the presence of different layers in the colonies. Further analysis indicates that spectra acquired from the surface of the colonies exhibit higher levels of glycogen than do the deeper layers of the colony. Additionally, the spectra from the deeper layers present with higher RNA levels than the surface layers. Therefore, the 6-h colonies with their limited heterogeneity are more suitable for inclusion in a spectral database to be used for classification purposes. These results also demonstrate that vibrational spectroscopic techniques can be useful tools for studying the nature of colony development and biofilm formation.     

A breeding colony of cotton-top tamarins (Saguinus oedipus)

A breeding colony of cotton-top tamarins is described where 91% of the breeding females are from the first and second laboratory-born generations, and whose infants have a one year survival rate of 62%. Mortality is greatest in the first week of life, and mortality rate is greater for a female's first litter than for subsequent litters. Females without early experience in caring for other infants have a higher infant mortality rate than females with such experience. No seasonal birth patterns have been observed. Large complex cages with food, water and runways located in the upper half of the cage, high protein diets and reduced handling of animals are suggested as additional variables affecting breeding success.     

Chlamydomonas (Chlorophyceae) colony PCR

The ease and effectiveness of colony polymerase chain reaction (PCR) has allowed rapid amplification of DNA fragments and screening of large number of colonies of interest including transformants and mutants with genetic manipulations. Here, we evaluated colony PCR in Chlamydomonas. Individual colonies were treated with 10 mM ethylenediaminetetraacetic acid (EDTA) or Chelex-100 and the resulting clear cell lysate was used for PCR reaction. Either genomic DNA or plasmid DNA incorporated into the genome was equally amplified. We found that the Chelex method is superior to EDTA method in certain cases. This colony PCR technique will bypass the tedious process of isolating genomic DNA for PCR reaction and will make it possible for rapid amplification of genomic DNA fragments as well as rapid large-scale screening of transformants.     

A colony of the hornetVespa philippinensis (Hymenoptera: Vespidae)

Summary The composition of a single colony ofVespa philippinensis Saussure from Leyte island, Philippines is described. Workers and gynes can be distinguished by size. There appear also to be two size modes of males, much less distinct. In each sex, head-width is isometric with forewing-length. The colony contained 700 adults.Dissection of 58% of the gynes showed none with developed ovaries, suggesting that the colony had a single queen or was queenless. In a smaller sample of workers, 6% without wing-wear and none with wing-wear had developed ovaries. Fat-body was more developed in gynes than workers.No gyne or male showed wear to the ends of the forewings, while 44% of workers shwed at least some wear, independently size. Workers returning to the nest had significantly greater wing-wear but showed the same size distribution. The division of labor within the worker caste is probably age-based.The colony included 838 immatures beyond the fourth larval instar, with a fresh biomass of 1,2 and dry biomas of 0.3 kg. About 1,480 new adults had been produced in the nest. Unlike in temperate and subtropicalVespa, cells were not reutilized to produce a second cycle of brood.The colony's production schedule of workers and sexuals did not fit thebang-bang model.

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Beschreibung einer Kolonie der Hornisse Vespa philippinensis (Hymenoptera: Vespidae)

Zusammenfassung Die Zusammensetzung einer Kolonie vonVespa philippinensis von der Insel Leyte, Philippinen, wird beschrieben. Arbeiterinnen und Königinnen können durch die Köpergröße unterschieden werden. Auch bei den Männchen gibt es zwei Größenklassen, die jedoch weniger deutlich unterschieden sind. Bei beiden Geschlechtern ist die Kopfbreite positiv mit der Vorderflügellänge korreliert. Die Kolonie bestand aus 700 adulten Tieren.Bei der Präparation von 58% der Königinnen wurden keine entwickelten Ovarien gefunden; das könnte darauf hindeuten, daß die Kolonie nur eine eilegende Königin hatte oder weisellos war. 6% der Arbeiterinnen ohne Flügelabnutzung hatte entwickelte Ovarien, aber keine Arbeiterin mit abgenutzten Flügeln. Bei den Königinnen war der Fettkörper bedeutend stärker entwickelt als bei den Arbeiterinnen.Weder Königinnen noch Männchen zeigten Abnutzungserscheinungen an den Enden der Vorderflügel, während bei 44% der Arbeiterinnen zumindest eine geringe Beschädigung der Flügel festzustellen war; dieses konnte nicht zu der Größe der Arbeiterinnen in Beziehung gesetzt werden. Arbeiterinnen, die zum Nest zurückkehrten, zeigten die gleiche Größenverteilung wie die übrigen Arbeiterinnen, hatten aber signifikant stärker abgenutzte Flügel. Daher ist die Arbeitsteilung wahrscheinlich altersabhängig.Das Nest enthielt 838 präimaginale Individuen nach dem 4. Larvenstadium mit einem Gesamtfrischgewicht von 1,2 kg und einem Trockengewicht von 0,3 kg. Ungefähr 1480 Imagines wurden aufgezogen. Im Gegensatz zuVespa-Arten in gemäßigten und subtropischen Klimazonen wurden die Zellen nicht noch einmal zur Brutaufzucht benutzt.Die Aufzucht von Arbeiterinnen und Geschlechtstieren in dieser Kolonie stimmt nicht mit dem bang-bang-Modell überein.