bluuebunny/crossref_metadata_2025 huggingface dataset:
Dominance and fertility among female primates
Authors: Harcourt A. H.
Published: March 2009

Under some circumstances dominant females in social groups of primates start to breed significantly earlier in life than do subordinate ones, produce significantly more offspring per year, and mate significantly earlier in the breeding season, if there is one. Thus, competition appears to influence fertility. Observations that dominant individuals sometimes feed on better quality foods, expend less energy or time in obtaining food, or are interrupted less often when feeding, indicate that the effects of competition on fertility could be working through nutrition. In addition, subordinate animals usually suffer more threats and have to avoid others more frequently than do dominants, which may result in ‘stress’ causing lowering of fertility. Whilst ‘stress’ might explain the total suppression of reproduction in subordinate female tamarins in the wild, a correlation between ‘stress’ and fertility has yet to be conclusively demonstrated in wild Old World primates. Evidence that competitive ability might influence a female's rate or timing of copulation is sparse, and nobody has shown that subordinate females mate so infrequently that their fertility is compromised. The situation in which dominant animals are especially likely to produce more offspring than subordinates is seen when resources are so clumped that the dominants can exert their greater competitive ability with sufficient frequency to obtain preferential access to the resources and maybe to influence levels of ‘stress’. The effects of belonging to a large group seem to be very similar to those of being a subordinate, and might operate through the same mechanisms of nutrition and ‘stress’. If so, analysis of the relationship between competitive ability and fertility could be confounded. Whatever the social correlates of variance in fertility, most stages of reproduction appear to be influenced by nutrition and ‘stress’. Finally, in the wild, where mortality rates are often high, a female's reproductive success might be determined more by characteristics that promote survival of offspring than by those that favour production of them.
Resources and reproductive success in women with an example from the Kipsigis of Kenya
Authors: Mulder Monique Borgerhoff
Published: March 2009

Contrary to findings in studies of many mammalian species, the relationship between resources and reproductive success of women is highly variable across societies. This has led some social scientists to suggest that evolutionary biological models are inappropriate to the study of human social behaviour. This paper proposes that variability in the relationship between resources and reproductive success arises from an inadequate specification of the nature and availability of resources critical to reproduction and a failure to understand the mechanisms whereby resources confer reproductive differentials in different environments. Data are presented from the Kipsigis of Kenya showing how land ownership affects female reproductive success; reasons why the effects of landholding are changing over time are examined.
Spatial distribution and time budget of radio‐tagged grey herons, Ardea cinerea, during the breeding season
Authors: van Vessem Janine , Draulans D.
Published: March 2009

Spatial distribution of foraging grey herons during the breeding season seemed to be determined by a trade‐off between costs and benefits of area sampling versus site fidelity. Breeding birds with little experience of the area spent more time exploring than birds with more experience in the early stages of reproduction. Non‐breeding herons and first‐year breeders showed little site fidelity. Time budgets appeared to be affected mainly by daily changes in food availability and, for breeding birds, by demands of the brood.
Seasonal and regional variations in the feeding habits of the harbour seal, Phoca vitulina, in the Skagerrak and the Kattegat
Authors: Härkönen Tero
Published: March 2009

Studies of the feeding of harbour seals have been carried out at the Tjärnö Marine Biological Laboratory since 1977. The studies are based on fish otoliths found in faeces at seal haulouts. The present paper compares feeding habitats at two different localities. Three families of fish, gadoids, pleuronectids and clupeoids were predominant in the seals' diet at a rocky shore habitat. Pleuronectids made up 75% of the diet at a sandy shore habitat. Temporal variations in feeding habits are also examined. The results indicate that harbour seals are opportunists in their choice of prey species, but some locally abundant species do not appear in their diet.
Scale epidermis of Natrix piscator during its sloughing cycle‐structural organization and protein histochemistry (Reptilia: Colubridae)
Authors: Mittal Ajay Kumar , Singh Jai Prakash Narain
Published: March 2009

The structure and histochemistry of proteinaceous constituents in cellular components of various layers of the epidermis of the chequered water snake, Natrix piscator, throughout the sloughing cycle have been described.

Histologically, six consecutive stages are recognized during one complete sloughing cycle. In Stage I, immediately following sloughing, the epidermis consists of an inner stratum germinativum, one or two layers of undifferentiated epidermal cells and the new outer epidermal generation represented by the Oberhautchen, β‐layer, mesos layer and an α‐layer which continues to differentiate and mature throughout Stage 1 and is observed even in Stage 2. The presence of several layers of undifferentiated epidermal cells over the stratum germinativum, a characteristic feature of Stage 2, results from the temporary slowing of their differentiation into the cells of various epidermal layers. Stage 3 includes differentiated lacunar tissue and the clear layer of the outer epidermal generation, and the presumptive Oberhautchen and β‐layer of the inner epidermal generation. In addition to marked cytological and histochemical changes in the lacunar tissue and the maturation of various keratinized layers. Stages 4 and 5 include the presumptive mesos and α‐layers, respectively. Stage 6 is characterized by total disintegration of the lacunar tissue and maturation of various keratinized layers, except the presumptive α‐layer, of the inner epidermal generation, which is still incomplete. The degeneration of the lacunar tissue is discussed in relation to the cessation of the supply of nutrients and other body fluids from underlying epidermal cells.

Histochemically, the Oberhautchen resembles the mesos and α‐layers in being strongly positive for ‐SH and ‐NH2 groups, bound calcium and basic proteins. However, it shows more similarity with the α‐layer in its moderate reaction for tyrosine and tryptophan, which is more intense in the mesos layer; and shows more similarity with the mesos layer with its very strong reactions for ‐SS groups, unlike the α‐layer which remains unstained.

The functional value of tyrosine‐ and tryptophan‐rich proteins in the keratinized layers of the epidermis is not immediately apparent.

In addition to the high content of‐SS groups, providing durability and mechanical strength, and protein‐bound calcium, adding hardness, the vertical striations in the Oberhautchen of the scales probably reinforce the epidermal superficial layer to guard against wear and tear by abrasion.
Ontogeny, life history and sex ratio evolution in Ensliniella kostylevi (Acari: Winterschmidtiidae)
Authors: Klompen J. S. H. , Lukoschus F. S. , O'Connor B. M.
Published: March 2009

The nest‐inhabiting ontogenetic stages of the mite Ensliniella kostylevi Zakhvatkin, 1941, an associate of the eumenine vespid Allodynerus rossii (Lepeletier, 1841), are described, with a redescription of the phoretic deutonymph. Observations on the life history of E. kostylevi show the presence of male dimorphism and a very high degree of correlation in developmental timing of the mites and their hosts. This life history is compared to that of related species, with an emphasis on the variously biased sex ratios observed among the oviparously produced adults. The extent of this bias is hypothesized to be directly related to the number of founders in each wasp cell, a number which, in turn, is largely determined by morphological and behavioural characteristics of the hosts.
Sex ratio in the spider Pityohyphantes phrygianus affected by winter severity
Authors: Gunnarsson Bengt
Published: March 2009

The sex ratio of subadult Pityohyphantes phrygianus was recorded before and after five winters in a natural population in coniferous forest in south‐west Sweden. In autumn, the proportion of males was on average 33–8% (range 28–7–40–1) and the proportion of females was 66–2% (59–9–71–3). In each of the winters 1981 82, 1982–83, 1984–5, the proportion of males decreased significantly. The proportion of males decreased more the lower the February mean temperature. Field experiments showed that low ambient temperature in winter caused high mortality among spiders. Experimental data also suggest that males are more vulnerable to low winter temperatures than are females. Indirect evidence indicates that neither predation pressure nor starvation alone are likely to cause the observed changes in sex ratio in the three winters. However, the combined effect of sex differences in predation by birds and cold‐induced mortality may explain why males disappear faster than females in certain winters.
Fracture toughness of horns and a reinterpretation of the horning behaviour of bovids
Authors: Kitchener Andrew
Published: March 2009

The keratinous horns of bovids are used in intraspecific combat to gain access to females in oestrus. Horn sheath keratin is a composite material consisting of stiff protein fibres and a pliant protein matrix. Unlike antlers, horns are permanent structures which are likely to accumulate damage during fighting. Therefore, horn sheath keratin should be resistant to fracture (tough) and insensitive to surface defects (scratches and cracks) which may weaken horns by acting as stress concentrators.

The effect of water on the toughness and notch‐sensitivity of horn sheath keratin was investigated in three‐point bending and tensile tests. Several measures of toughness were made on dry (0% water content), fresh (20%) and wet (40%) horn keratin, including total work of fracture, Gurney & Hunt work of fracture, critical strain energy release rate and critical stress intensity factor.

The mean total work of fracture of fresh horn is about 40 kJ/m2 which is relatively much greater than most biological and synthetic materials. Most of the work of fracture is due to plastic yielding of the matrix (50–75%); the rest is due to crack‐tip specific fracture mechanisms such as fibre pull‐out and Cook Gordon crack‐stopping. Dehydration reduces the total work of fracture of horn keratin by preventing the yielding of the matrix.

The strength of fresh and wet horn is insensitive to notches, but dry horn is very notch‐sensitive. Therefore, bovids must avoid dehydration of their horns due to the desiccating effect of the environment. The ‘horning’ behaviour of bovids may be a maintenance activity which ensures that the horn sheath is adequately hydrated to remain tough and notch‐insensitive.
Group size and association patterns of the common eland (Tragelaphus oryx)
Authors: Hillman Jesse C.
Published: March 2009

This paper presents data on aspects of the social organization of the eland antelope in the wild in Kenya, based on long‐term observations of eland groups and of individual known animals. Group size varied from solitary animals to groups of several hundred. The largest groups always contained calves and juveniles, while small groups comprised adult animals only. Groups were largest in wet seasons in open grassland, and smallest in dry seasons in forest. Associations between individual eland were brief in duration, and group membership was in a constant state of flux. These findings are related to current knowledge of the social organization of antelope, and of the tribe Tragelaphini.
Quantitative estimation of pancreatic polypeptide (PP) cells of islet tissue of pancreas in Australian mammals
Authors: Edwin Nalini
Published: March 2009

Pancreases from three male and three female echidnas (Tachyglossus aculeatus), possums (Trichosurus vulpecula), grey kangaroos (Macropus fuliginosus), spinifex hopping mice (Notomys alexis) and water rats (Hydromys chrysogaster) were studied using a point‐intercept method and Weibel graticule (Weibel, Kistler & Scherle, 1966) on sections stained by an immunoperoxidase method for pancreatic polypeptide (PP). PP cells were assessed in the head, neck, body and tail regions. There was a greater percentage proportion of PP cells in the head than in the other regions of echidna, possum and water rat. PP cells were not identified in grey kangaroo and spinifex hopping mouse, although control sections were positive.

These results show some agreement with a previously proposed hypothesis (Bonner‐Weir & Weir, 1979) concerning the distribution of cell types in the mammalian endocrine pancreas.
Maternal behaviour and early behavioural ontogeny of grey seals (Halichoerus grypus) on the Isle of May, UK
Authors: Kovacs Kit M.
Published: March 2009

Female grey seals allocated more resources to individual sons than to individual daughters. Mothers of male pups spent significantly larger proportions of their time defending and feeding their young than did mothers of female pups. The amount of time females spent ashore and the proportion of time spent in various behavioural states was influenced by the habitat of the birth site and the age of the pup.

Grey seal neonates spent the majority of their time prone and immobile, perhaps to allow maximum energy retention (maximum mass gain) and to facilitate mothers relocating their pups. The proportion of time pups spent in the various behavioural states was influenced by the whelping habitat. Pups became increasingly active with age. Males were significantly more aggressive than females and, at one site they performed nosing behaviour with their mothers significantly more often than did female neonates.
Variations in the post‐natal growth of pipistrelle bats (Pipistrellus pipistrellus)
Authors: Boyd I. L. , Myhill D. G.
Published: March 2009

Adult female pipistrelle bats were captured from two colonies in eastern England before the time of parturition. Bats from each colony were fed freely in the laboratory. Growth models were used to estimate growth rate and asymptotic size for each neonate. The proportion of bats giving birth was greatest in those from Colony 1 (P< 0·03). The logistic growth model gave a better description of juvenile growth than either the Gompertz or the von Bertalanffy models. Bats from Colony 1 had slower growth rates than bats from Colony 2 (P<0·005). Gravid females from Colony 2 were heavier on the day after birth than those from Colony 1 (P< 0·005). Bats from Colony 1 gave birth earlier than those from Colony 2 (P<0·001) but weaned their young later than Colony 2 (P< 0·001). Males were born earlier than females in the sample from Colony 1 (P< 0·001). Growth of males and females was similar. These results show that post‐natal growth rates of pipistrelles are highly variable and can approach the growth rate of birds. Growth rates of young bats are probably also affected by environmental conditions experienced by mothers during gestation.
Effects of sex ratio on male behaviour and reproductive success in a field population of threespine sticklebacks (Gasterosteus aculeatus) (Pisces: Gasterosteidae)
Authors: Ward G. , FitzGerald G. J.
Published: March 2009

Biased sex ratios of breeding threespine sticklebacks (Gasterosteus aculeatus L.) occur naturally in tide‐pools of a Quibec saltmarsh. We experimentally manipulated sex ratios in certain pools to evaluate the effects on male behaviour and reproductive success (RS). Sticklebacks were stocked at male: female ratios of 1: I, 1: 2 and 2: 1 and observed for a 23‐day inter‐tidal period. In male‐biased pools, only half of the males built nests, compared to nearly 100% in unbiased and female‐biased pools. Males in male‐biased pools also were less likely to rebuild after losing a nest, visited their nests less often, were more likely to abandon or destroy their nests, had lower RS (measured as the proportion of males hatching fry), but hatched fry sooner, than males in other pools. In female‐biased pools, males built nests sooner, lost more nests due to nest‐raiding by females, spent more time in aggression (proportion of time spent fighting and threatening), spent more time attacking female conspecifics than male conspecifics or heterospecifics, and courted more frequently, than males in other pools. Habituation to conspecific males, but not to females, occurred in all pools. These findings are discussed with respect to sexual selection theory.
Renal form and function in relation to the ecology of bats (Chiroptera)from Malawi, Central Africa
Authors: Happold D. C. D. , Happold M.
Published: March 2009

The ratio of the medulla to the cortex (M/C ratio) was determined for three species of Megachiroptera, and the ratio of the inner medulla to the cortex (IM/C ratio) was determined for 28 species of insect‐eating Microchiroptera from diverse savanna and montane habitats within Malawi. Although all these species occur in the southern savanna biotic zone of Africa, each varies in its ability to exploit the African rainforest, arid and desert biotic zones. The kidneys of the Megachiroptera were very different to those of the insect‐eating Microchiroptera, and these differences were related to the need of fruit‐bats to excrete the surplus water associated with their diet. The urine concentrating capacity of each species of Microchiroptera was predicted from the IM/C ratio. Family characteristics were examined, and the urine concentrating capacities of the Malawian bats were compared with bats from elsewhere, and with some rodents. The insect‐ eating Microchiroptera exemplified a very diverse range of IM/C ratios. The IM/C ratio of each species was compared with its drinking behaviour in captivity, diet, foraging strategy, flight, aspect ratio, domicile, roosting behaviour and habitat. It was hypothesized that the ability of insect‐eating Microchiroptera to conserve urinary water would be an advantage to species: (a) living in xeric habitats; (b) adapted for sustained high‐speed flight; (c) roosting in hot dry domiciles; (d) roosting in solitude; and (e) living at high altitudes where seasonal low temperatures induce torpidity. These hypotheses were tested, and it was concluded that, while the ability to conserve urinary water may have been an advantage in most of these situations, it was not essential.
On the morphology of spermatozoa of tuco‐tucos, Ctenomys (Rodentia: Ctenomyidae): New data and its implications for the evolution of the genus
Authors: Vitullo A. D. , Roldan E. R. S. , Merani Maria Susana
Published: March 2009

Sperm morphology was studied in 10 species of the caviomorph rodent Ctenomys. Ctenomys argentinus, C. conoueri, C. dorbigny and C.perrensis had symmetric spermatozoa with paddle‐like heads. Ctenomys australis, C. mendocinus, C. porteousi, C. rionegrensis and Ctenomys sp., on the other hand, had spermatozoa with paddle‐like heads but with the tail inserted at one side of the central axis and a nuclear caudal extension originating from the base of the head at the opposite side of the insertion of the tail and running parallel to the flagellum; these spermatozoa are referred to as simple‐asymmetric. In C. yolandae, a complex‐asymmetric morphological type not previously described for the genus was found. This type is characterized by the presence of two nuclear caudal extensions. Symmetric spermatozoa (total length = 52 pm) were shorter than asymmetric (both simple and complex) ones (total length = 87 pm). In spite of these differences, the relative size of heads, midpieces and tails were maintained in the three groups, representing 12%, I I YO and 88% of the average total length, respectively. Within each group of species bearing the same sperm type, a low interspecific variability both in morphological patterns and dimensions of sperm cells was observed. This low interspecific variability associated with the north to south geographical distribution of species having, respectively, symmetric and asymmetric spermatozoa, suggests that these characters appeared at an early stage in evolution of the group, and probably played an important role in the first steps of speciation by promoting reproductive isolation.
Population size and growth rate, sex ratio and behaviour in the ant isopod, Platyarthrus hoffmannseggi
Authors: Williams T. , Franks N. R.
Published: March 2009

Female‐biased sex ratios are often associated with small, isolated populations. These conditions are exhibited in populations of Platyarthrus hoflmannseggi (Brandt, 1833), a small, blind woodlouse which lives almost solely in ant nests. This study was undertaken to determine how sex ratio varies with population size in P. hoffmunnseggi and how both of these factors affect population growth rate. To accomplish this, a total of 2155 of these isopods were collected from 20 nests of the ant LusiusJaour (Fabricius, 1781). The majority of the isopod populations were female‐biased. The behaviour and survivorship of the isopods in their own and foreign antcolonies were compared and suggest that the free movement of P. hoffmannseggi individuals among ant colonies may be extremely limited. These studies also show how isopods are nutritionally linked to their hosts. Measurement of the woodlice revealed two distinct size/age classes in each population and allowed the change in sex ratio from one generation to the next to be estimated. Female‐biased populations produce in future generations relatively more females and fewer males than populations of a similar size with a sex ratio of unity. There was no correlation between the degree of female bias and the rate of population growth. These findings are reviewed in the light of recent theoretical sex ratio models and the possible control of the isopods sex allocation by unusual chromosomal mechanisms and intracellular parasites.
Influences of status and recent breeding experience on the moult strategy of the yellow‐nosed albatross Diomedea chlororhynchos
Authors: Furness R. W.
Published: March 2009

The primary moult of individually colour‐ringed, adult yellow‐nosed albatrosses at nests on Gough Island was examined in 1983 and related to the status of each bird and its breeding history in the previous year. Adults renew only about half of their primaries each winter and suspend moult while breeding. Birds that bred successfully renewed fewer primaries than did unsuccessful birds or nonbreeders. There were no differences in primary moult between the sexes or in relation to size. Yellow‐nosed albatrosses show complex wave moult as an adaptation to slow renewal of flight feathers. The energy, nutrient or time requirements for feather renewal may conflict with breeding annually so that there is a trade‐off between the extent of moult desirable to maintain flight efficiency and the benefits of breeding in successive seasons.
Food habits of the sympatric insectivorous bats Rhinolophus rouxi and Hipposideros lankadiva from Sri Lanka
Authors: Eckrich M. , Neuweiler G.
Published: March 2009

The diets of Rhinolophus rouxi and Hipposideros lankadiva were studied during October 1984 in Sri Lanka, by analysing the faeces collected from individuals. As a comparison, insects were collected with a light trap at different sites in the study area.

Rhinolophus rouxi showed no specialization for any particular insect prey. The diet composition in this species shows a good correspondence to the composition in dry weight of insects collected by light traps. Dipterans were under‐represented in the faeces compared to the numbers trapped. This suggests that R. rouxi forages unselectively on prey larger than the generally very small dipterans. After the first monsoon showers, the remains of beetles, especially scarabaeids, and termites were more common in the faeces of R. rouxi. Bats caught at hourly intervals during one night showed an increase in the proportion of moths consumed.

In contrast, H. lankadiva was found to feed mainly on beetles, particularly scarabaeids, together with large, slow‐flying insects such as bugs or nuptial ants. The proportion of beetles (79%‐100%) in the faeces of this species was about three times higher than their representation in the insect collections. This suggests that H. lankudiuu forages selectively.
A scanning and transmission electron microscopic study of the lung of a caecilian Boulengerula taitanus
Authors: Maina J. N. , Maloiy G. M. O.
Published: March 2009

The lung of an apodan amphibian Bouiengerula taitanus has been investigated by scanning and transmission electron microscopy. This caecilian has only a single, long tubular lung that tapers towards the caudal end of the body. The lung has a central air duct which radially opens into a single stratum of alveoli lined by well developed septa that attach to two diametrically opposite trabeculae. The trabeculae carry the pulmonary artery and vein. The septa have blood capillaries on both surfaces and supportive and contractile elements like collagen, smooth muscle, elastic tissue and fibrocytes. The alveolar surface has only a single population of pneumocytes that combine the morphological features of the mammalian type 1 and 2 cells, i.e. they contain the osmiophilic, lamellated bodies and are squamous in form. Through subepithelial cytoplasmic invaginations, the pneumocytes, together with their basement lamina, were observed to be firmly attached to the septa1 tissue elements, presumably to avoid mechanical detachment during the rapid respiratory movements. The compartmentation of the whole lung in this species is viewed as a means of increasing the surface area available for gas exchange which, coupled with other already established cardiovascular adaptations in this species, may be of significance in its fossorial mode of life, an environment that is usually hypoxic and hypercarbic.
Further studies on the evolution of land and freshwater nemerteans: generic relationships among the paramonostiliferous taxa
Authors: MOORE JANET , GIBSON RAY
Published: March 2009

Morphological characteristics of the terrestrial (Acteonemertes, Antiponemertes, Argonemertes, Katechonemertes, Leptonemertes) and freshwater (Campbellonemertes, Potamonemertes) paramonostiliferous nemerteans, all of which are at present unplaced at the family level, are compared and contrasted with those of the marine genera Plectonemertes (Plectonemertidae), Cratene‐mertes, Korolkevilschia and Nippormemertes (Cratenemertidae). It is concluded that whilst Acteonemertes, Antiponemertes, Argonemertes, Campbellonemertes and Potamonemertes can with certainty be placed in the family Plectonemertidae, the unspecialized and geographically isolated genera Katechonemertes and Leptonemertes, although lacking positive grounds for their exclusion, are only questionably included in this taxon. The possible evolutionary relationships of the plectonemertid genera are discussed and a diagnosis of the family is provided.
Multiple group principal component analysis and population differentiation
Authors: THORPE R. S.
Published: March 2009

This paper explores the requirements and advantages of multiple group principal component analysis (MGPCA) when it is used to investigate population differentiation. A distinction is drawn between equality of orientation of the within‐group axes and equality of variance along these axes. Several examples of the use of MGPCA are discussed and it is shown that MGPCA per se does not require equality of variance along the axes although it may be a requirement of some of the techniques subsequently used to analyse the component scores. MGPCA is simple and direct, being based on the mathematically well defined eigenvector analysis of a symmetric positive definite (pooled within‐group covariance) matrix and it can be thought of as a step in the computation of canonical variate analysis (CVA). It can be used with CVA (which is the most popular method of biometrically assessing population affinities) to assess the contribution of within‐group components to among‐group discrimination. It is also one of a range of appropriate techniques that can be used to define (and delete if required) within‐group growth effects and is particularly suitable when CVA is being used to assess the population affinities. When used in this way it has the advantage of being more influenced by the groups with the greatest growth range.
An application of common principal component analysis to cranial morphometry of Microtus californicus and M. ochrogaster (Mammalia, Rodentia): further remarks
Authors: AlROLDI J.‐P. , FLURY B. K.
Published: March 2009

We welcome Dr Thorpe's interesting discussion (Thorpe, 1988), and we would like to take this opportunity to clarify some points.

Both MGPCA (multiple group principal component analysis) and CPCA (common principal component analysis) serve essentially the same purpose, namely estimation of principal components simultaneously in several groups, based on the assumption of equality of principal component directions across groups, while eigenvalues may differ between groups. However, CPCA has the distinct advantage that this assumption can actually be tested, using the (CPC) statistic. In analyses involving more than two variables, it is usually difficult to decide, without a formal test, whether or not the assumption of common directions of principal components is reasonable.

There is also a conceptual difficulty with MGPCA. In statistical terms, both methods assume that:

(a) a certain set of parameters (namely those determining the eigenvectors) are common to all groups

(b) there are sets of parameters (namely p eigenvalues per group) which are specific to each group.

CPCA sets up a model that reflects this structure and estimates the parameters accordingly. MGPCA, on the other hand, ignores part (b), at least temporarily, by pooling the variance‐covariance matrices and extracting eigenvectors from the single pooled matrix. This may lead to reasonable results, but there is no guarantee that it will indeed do so. The reader may find a more familiar analog in the fitting of regression lines when data are in groups. If it is assumed that all regression lines are parallel, one should set up an appropriate model based on a single slope parameter common to all groups, and groupwise intercepts. One should then estimate the parameters of this model, and not simply apply a technique which is appropriate in the one‐group case only.
Growth, development and parental investment in the spotted hyaena, Crocuta crocuta
Authors: JAARSVELD A. S. VAN , SKINNER J. D. , LINDEQUE M.
Published: March 2009

Growth in the spotted hyaena (Crocuta crocuta) was investigated using material obtained from the Southern African subregion. A mathematical approximation for post‐natal growth of this species was best achieved by a Gompertz equation. An analysis of actual growth in this species revealed that the self‐accelerating and self‐retarding phases last for up to three years and 10 years, respectively. The exponentially declining growth rate of linear post‐natal growth indices suggest that the Huggett & Widdas foetal age estimation procedure may have limited value in this species. Furthermore, some observed limitations of the von Bertalanffy equation for describing post‐natal growth in this species are pointed out. The life‐history strategy of this reported precocial carnivore is examined in terms of its development and reproductive characteristics.
Ultrastructural data on the scales of the dipnoan Protoptems annectens (Sarcopterygii, Osteichthyes)
Authors: ZYLBERBERG L.
Published: March 2009

The structure and the mineralization of the scales of the living dipnoan (lungfish) Protoptems annectens have been investigated by transmission electron microscopy (TEM). The thin and imbricated scales are composed of two layers: the squamulae and the basal plate. At the outer surface, the squamulae form isolated plates superficially ornamented with spines and concretions and made up of acellular bone. After demineralization, the squamulae show a heterogeneous organic matrix composed of thin randomly oriented collagen fibrils forming a loose network within which the concretions appear as electronlucent circular areas. Abundant and aggregated concretions are located within the spines. The crystallites are oriented by the collagen fibrils except in the concretions. Anchoring bundles composed of parallel collagen fibrils arise from the squamulae and connect the scales to the overlying dermis.

The basal plate, the most developed part of the scale, is made up of isopedine. Its main component consists of thick, closely packed collagen fibrils organized in a ‘double twisted plywood‐like structure’. Fibroblasts are present in the basal plate. Mineralization occurs only in few plies located beneath the squamulae. Mandl's corpuscles are found in front of the mineralization front. The mineral deposit is oriented by the collagen fibrils.

The scales of Protoptems annectens differ from the typical elasmoid scales of the teleosts by the peculiar structure of the squamulae, nevertheless they show enough structural characteristics to support the hypothesis that they can be considered as scales of the elasmoid grade, which have retained some plesiomorphic characteristics.
Food and feeding ecology of Wilson's storm petrel Oceanites oceanicus at South Georgia
Authors: CROXALL J. P. , HILL H. J. , LIDSTONE‐SCOTT R. , O'CONNELL M. J. , PRINCE P. A.
Published: March 2009

At South Georgia, the diet of Wilson's storm petrel was studied using the regurgitates of adults arriving to feed chicks. Feeding frequency and meal size were estimated by weighing chicks twice daily, or in some cases every 3 h during daytime. Crustaceans contributed 98% of the total number of individual items and 68% of the total weight consumed; fish, 1% of the number of items and 28% of the weight. The most abundant crustacean was the amphipod Themisto gaudichaudii, which accounted for 90% of the total number but only 44% of the total weight of crustaceans eaten. Most (79%) of the Themisto were juveniles. Euphausiids were much less numerous in the diet (5% by number) but were the main group by weight (55%); most (52%) were Antarctic krill, with juveniles and sub‐adults (25–50 mm long) predominating. Mysids, copepods and barnacle larvae were also present. Fish were all myctophids (lanternfish), Protomyctophum normani and P. bolini being identified; specimens were 50–85 mm long and weighed 1–4 g. Meal sizes averaged 6‐5‐7‐5 g (14–22% adult body mass); about 75% of chicks were fed each day (mainly at night), about 10% probably receiving meals from both parents. A review of storm petrel diets emphasizes the importance of fish to Oceanodroma species and of crustaceans to Oceanites, Garrodia and Pelagodroma. Euphausiids and amphipods (chiefly Themisto and Hyperia) are the main crustacean prey and range from 5–50 mm and 0‐005‐0‐7 g. Myctophids are the main fish prey and range from 20–100 mm and 1–5 g. Meal size ranges from 15–25% adult body mass and chicks are fed on 50–85% of days. This low delivery rate is mainly responsible for the disproportionately slow growth and long fledging period of storm petrel chicks.
Auditory communication in the cane rat (Thryonomys swinderianus)
Authors: Cox J. M. , MARINIER S. L. , ALEXANDER A. J.
Published: March 2009

The auditory communication of the Old World hystricomorph rodent, the cane rat (Thryonomys swinderianus, Temminck), was studied in two captive groups of animals. Sounds fell into five categories of vocalizations, named the quirr, squeak, wheet, growl and boom, and two percussive sounds, the hind‐foot stamp and the tooth‐chatter. The quirr, squeak and wheet vocalizations were the most variable in structure and were graded both within and between categories. The growl and boom were more uniform and discrete in structure. The sound repertoire of the cane rat ranged in frequency from the boom with low frequencies of 40–100 Hz and high frequencies of 250–1500 Hz to the wheet with low frequencies of 200–3750 Hz to high frequencies of 600–9000 Hz. Quirrs were the most common calls and occurred in a variety of situations linked to bringing about group cohesion. The squeak was most often given by female adults or young animals and appeared to indicate fear and submission on the part of the sender, functioning to decrease the chance of attack. Young cane rats from a few days to a few weeks old used the wheet as a longdistance contact‐seeking call. The growl was given most often by dominant adults as an indication of aggression and threat. Booms often occurred together with hind‐foot stamping as an alarm signal. Tooth‐chatter was most often a consequence of feeding and, though communication is not thought to be its primary function, it may help to synchronize eating activities in a group of animals. Occasionally, tooth‐chattering was given by young cane rats after bouts of play and by the male after bouts of courtship but the function of this sound is unknown. Three aspects of cane rat sound communication imply a gregarious social structure: the large sound repertoire, the high degree of variability in the sounds and the occurrence of a warning call. Cane rats are mainly nocturnal and live in dense habitats. These conditions of poor visibility account for the use of a close‐contact call with physical characteristics that make it easy to locate the caller, but only at close range, and a warning call that is well adapted to carry for long distances through thick grass and reed habitats.
Semen cryopreservation and artificial insemination in budgerigars (Melopsittacus undulatus)
Authors: SAMOUR J. H. , MARKHAM J. A. , MOORE H. D. M. , WATSON P. F.
Published: March 2009

Semen samples were obtained from budgerigars. Undiluted samples were used directly for artificial insemination (AI) while other samples were diluted with a modified glycerolated BWW and Lake's freezing medium and subjected to two different cryopreservation protocols. Micro‐dialysis was used post‐thawing to remove the glycerol present in the medium. The assessment of glycerol concentration during micro‐dialysis was carried out by means of an ultraviolet spectrophotometry method. Functional assessment of spermatozoal fertilizing capacity post‐thawing included the measurement of spermatozoal swimming speed and AI.
Maternal care in house mice (Mus musculus): II. The energy cost of lactation as a function of litter size
Authors: KOUNIG BARBARA , RIESTER J. , MARKL H.
Published: March 2009

In mammals, lactation performance may influence future reproduction of a mother and her young. We measured the quantity and quality of milk produced by female house mice (Mus musculus) during a period of 28 days after birth of a litter. We aimed to analyse how females cope with the energy demands of different sized litters as a tradeoff between current and future reproduction. Litter sizes examined were small (six young), intermediate (7.3 0–7), and large (12 young).

Females met the energy demand of a growing litter both by increasing the amount of milk given to the young and by improving the quality (through an increase in total solid and fat concentrations) to a peak during days 9–16. At the onset of weaning (day 17), milk production decreased and young shifted to solid food. The main energy source in the milk of house mice was fat, which provided more than 80% of the energy to the suckling young. Average lipid concentrations were 20%, and peak values of 33% were reached during days 13–16. Protein concentrations were 6–8% and carbohydrate (lactose) concentrations 3–4%.

With larger litters, females increased both the amount of milk and the absolute amount of major nutrients (lipids, proteins, lactose). However, regulation was imperfect. When litter size was doubled from six to 12, amount of milk produced rose by 44%, and energy content only rose by 30%. The reduction in milk supply for individual young in larger litters was reflected in slower growth and lower weaning weight.

The efficiency of conversion of milk energy into biomass of young was highest for intermediate litters (51%; for small litters, 43%; for large ones, 36%). During days 5–16, a single pup in an intermediate litter needed less energy for metabolism and growth than pups in the other litter sizes examined.

Although individual young of small litters have a relatively high weaning weight‐which might improve their future reproduction‐females gain higher reproductive success by dividing the energy available per litter between the largest number of young they can raise to a weaning weight of on average 9 g.

For the time‐lifen reproductive success of a female house mouse‐at least for the strain used in this study‐an intermediate litter size of seven seems to be best because of a favourable ratio of energy cost of lactation to number and size of young produced.
Investigations of photoperiodically induced fattening in migratory blackheaded bunting (Emberiza melanocephala)(Ayes)
Authors: KUMAR VINOD
Published: March 2009

The body fattening and weight gain preceding vernal migration in birds is timed by a set of environmental factors of which daylength is predominant. However, the mechanism(s) by which these events is determined is poorly understood. Previous investigations on a photoperiodic migratory species, the blackheaded bunting (Emberiza melanocephala), indicate the involvement of a light‐sensitive circadian rhythm during initiation of fat deposition and body weight gain. This communication presents data from another set of experiments aimed to characterize further the mechanism(s) of fat deposition in the same species.

Groups of photosensitive, unstimulated and stimulated birds were subjected to transfer and superimposition experiments for 30 days. While the former set included shifting of long‐day (LD) birds to DD, SD (short days), DD/LD and SD/LD, in the latter a 90‐minute bright light was superimposed at two different times of the day during the dim‐green lighted phase 15L:9D of varying intensity. Birds were weighed at the beginning and at the end of experiments. Those in transfer cycles were also weighed at 10‐day intervals. The results suggest that the premigratory body fattening and weight gain in blackheaded buntings is light dependent and timed by environmental daylength in accordance with the photosensitive endogenous circadian rhythm (ECR). They also show that the photoperiodic responses in birds in general are mediated by circadian rhythm(s).
Shell morphometry in barnacles: quantification of shape and shape change in Balanus
Authors: SPIVEY HENRY R.
Published: March 2009

Geometric design in the barnacle genus Balanus has been studied in relation to variation in adult shell form, that includes differences among species, and size‐related changes in shape. The genus comprises 40 Recent species, and as a group these display a more or less constant morphology over an extraordinary size range (10 to 200 mm in basal length).

Linear and volumetric measurements were collected from 232 adult individuals of 14 species representing the variation in size, shell form and shell design thought to occur in the genus. Specimens were chosen to represent the size ranges of the species. Only isolated individuals growing on planar surfaces were used; shells were complete, undamaged and undistorted.

Shell form differs among taxa, and no two species scale alike; intraspecific variation for five ratio variables shows strong allometry over the adult size range of each species. As size increases, there is a trend for the basis and orifice to maintain their shapes or to become slightly more elliptical, and for shells to become more conical and proportionately taller.

Throughout their size ranges, species can be described by these geometries: paraboloid (6 species), frustum of an ellipsoidal cone (5 species), frustum of a cone (2 species) and a cone (1 species). Shell geometry is not a function of species size, but there does appear to be a correlation between shell geometry and shell volume. Species with relatively small shell volumes are described by a frustum of an ellipsoidal cone, or by a cone, while those with a relatively large shell volume are described by a paraboloid, or by the frustum of a cone.
Assessment of body condition in live birds; measurements of protein and fat reserves in the mute swan, Cygnus olor
Authors: SEARS JANE
Published: March 2009

Condition in animals is often measured in relation to various demands, such as reproduction, migration and cold weather. Usually, indices of protein and fat reserves have to be measured on dead animals. Measurements on live animals enable variations in the condition of individuals to be monitored over time, and can be related to their life histories.

In birds, the size of the breast muscle is the most commonly used measure of protein reserves. A technique for measuring breast muscle thickness was developed, using ultrasound, and was tested on mute swans. The measurements were accurate and highly repeatable. Breast muscle thickness was positively related to the lean dry weight of the breast muscle, and is likely to be a good indicator of total protein reserves.

A system of fat scoring by colour was developed to assess the size of the subcutaneous fat layer. Although the method relies on subjective judgements, the results were highly correlated with the percentage of fat in the subcutaneous layer, and with other measures of fat reserves.

Measurements were made on live, non‐breeding swans to monitor seasonal variations in reserves. The seasonal pattern of fat reserves was similar to the normal cycle of weight changes; high in winter and low in summer. There was no change in relation to the moult. No distinct seasonal variation in muscle thickness was found.

There is an unusual pattern of change in the relative size of reserves during emaciation in swans. Muscle reserves appear to be depleted to a greater extent than fat reserves. This is possibly due to the effects of lead poisoning, causing protein necrosis and preventing muscle regeneration.
Colony size and structure, activity patterns and foraging behaviour of a colony of the social mole‐rat Cryptomys damarensis (Bathyergidae)
Authors: LOVEGROVE B. G.
Published: March 2009

A complete colony of 20 Cryptomys damarensis was trapped in the Kalahari Gemsbok National Park, South Africa. The colony consisted of 15 males and five females and formed three distinct size classes, two of which were presumed to represent worker (smallest mole‐rats) and soldier (largest males) castes. Body masses ranged from 86–197 g, with the dominant male being the largest mole‐rat. The activity patterns of five animals in the colony were monitored by radiotelemetry. Activity patterns were not influenced by diel fluctuations in burrow temperature and photoperiod. It was suggested that the chance of hyperthemia influenced activity, such that in order to maximize the daily distance burrowed (foraging efficiency), the mole‐rats had to engage in frequent (5.58 times. day‐1), but short (c. 60 min) foraging bouts.