bluuebunny/crossref_metadata_2025 huggingface dataset:
Reproduction and productivity of white‐lipped and collared peccaries in the Peruvian Amazon
Authors: Gottdenker Nicole , Bodmer Richard E.
Published: February 2006

White‐lipped peccaries (Tayassu pecari) and collared peccaries (Tayassu tajacu) are common ungulates of Amazonia that are integral to the ecosystem and are important sources of meat for local people. Information on the reproduction and productivity of peccaries is essential for implementing management practices that conserve peccary populations over short and long time‐scales. This paper examines the reproductive biology of white‐lipped and collared peccaries in the northeastern Peruvian Amazon in and around the Tamshiyacu‐Tahuayo Community Reserve. Skulls and reproductive tracts of white‐lipped and collared peccary were examined from hunted samples collected by local people, as part of a participatory wildlife management programme. In this Amazonian site both white‐lipped and collared peccaries were in follicular and luteal stages year round. Similarly, conceptions, births and pregnancies were aseasonal for both species. Of white‐lipped peccary females, 32.4% were pregnant (n= 219 adult females examined) compared with 46% of collared peccary females (n= 89 adult females examined). Overall, gross productivity was 0.53 foetuses/adult female for white‐lipped peccaries and 0.89 foetuses/adult female for collared peccaries. Gross fecundity (number of female young produced/number of adult females) was 0.26 for white‐lipped peccaries and 0.37 for collared peccaries. The estimated parturition–conception interval was 250 days (192–331 at the 90% confidence interval) for white‐lipped peccaries and 129 days (80–205 at the 90% confidence interval) for collared peccaries. This study shows that reproductive productivity of white‐lipped peccary is lower than collared peccary in the northeastern Peruvian Amazon. This difference in reproductive productivity has implications for management strategies, and suggests that white‐lipped peccaries are more susceptible to the effects of hunting than collared peccaries.
The effect of social interactions on tadpole activity and growth in the British anuran amphibians (Bufo bufo, B. calamita, and Rana temporaria)
Authors: Griffiths R. A. , Foster J. P.
Published: February 2006

Tadpoles of different species of frogs and toads display different tendencies to aggregate. We investigated some of the costs and benefits of aggregating in three British species by examining their behavioural responses to the presence of conspecifics, and by monitoring the performance of tadpoles under different levels of social interaction with other individuals. The common toad (Bufo bufo), an aggregating species, displayed higher levels of activity than the natterjack toad (B. calamita) and common frog (Rana temporaria), two species that form aggregations less frequently. Moreover, out of the three species, only B. bufo increased activity in the presence of conspecifics. In all three species, increased interaction between individuals resulted in increased variation in size. However, average growth rate was affected only in B. bufo, which grew faster when raised in isolation and not interacting with other individuals. Under certain conditions intraspecific competition therefore seems to be more important than social facilitation, but may lead to average size at metamorphosis being larger within the population. The consequences of intraspecific competition within aggregations may therefore be different for individuals and populations.
Behavioural response of wild rodents to the calls of an owl: a comparative study
Authors: Hendrie Colin A. , Weiss Scott M. , Eilam David
Published: February 2006

Effective anti‐predator defence mechanisms depend on efficient recognition of possible predators. However, nocturnal aerial predators, such as owls, present very few stimuli to enable their detection by potential prey. The most prominent of these are their territorial calls which are believed to provide sufficient stimuli to activate anti‐predator defence mechanisms in species heavily predated upon by owls. To test this hypothesis, the behaviour of voles (Microtus socialis), dormice (Eliomys melanurus), jerboas (Jaculus jaculus), and spiny mice (Acomys cahirinus) was analysed during and following exposure to playback of tape recorded calls of the tawny owl (Strix aluco). In response, voles crouched, and retreated to a small burrow present in the test arena; dormice also reduced the distances they travelled in the arena, and spent an increased amount of time around the burrow; jerboas crouched and froze during the playback of the owl call but not thereafter; spiny mice, however, displayed enigmatic behaviour in apparently ignoring the owl calls. The results, which demonstrate an induction of defensive behaviours to recorded owl calls, support the results of others who have examined the effects of exposing wild rodents to live owls.
Predation risk as an influence on group size in cercopithecoid primates: implications for social structure
Authors: Hill R. A. , Lee P. C.
Published: February 2006

Predation pressure has long been proposed as a determinant of mammalian social systems. Group size and composition were compared for 121 populations of cercopithecoid primates, from 39 species of 13 genera, living under low, moderate or high predation risk. In confirmation of previous studies, predation risk was found to have a major effect on group size, with populations under high predation pressure living in significantly larger groups than those at lower risk. However, there were differences in social structure between the predation risk categories. Unimale groups were smaller, had fewer females than multimale groups and were infrequently found under conditions of high predation risk. Predation risk had marked effects on the composition of multimale groups. Under conditions of high predation risk there was a disproportionate increase in the number of adult males over that predicted by the number of females present or by group size. At low predation risk there were fewer males than predicted on the basis of female group size. Together, these results suggest that male strategies to monopolize females depend both on the females' grouping patterns and on the needs of both sexes to maximize group size under high predation pressure.
Habitat selection by Dall's sheep (Ovis dalli): maternal trade‐offs
Authors: Rachlow Janet L. , Bowyer R. Terry
Published: February 2006

Habitat selection by female Dall's sheep (Ovis dalli dalli) during lambing was studied in interior Alaska, U.S.A., in 1988 and 1989. Selection of habitat changed with the chronology of lambing. During the pre‐lambing period, maternal females selected sites with forage and avoided snow‐covered areas. During peak lambing, food and steep slopes continued to be selected. Distance to escape terrain was a critical component of habitat selection by females throughout lambing. Maternal bands that ventured farther from escape terrain were in larger groups. Abundance of forage also increased in areas that were farther from this terrain.

Habitat selection by females also differed between years. In 1989, a late spring storm resulted in deep snow and delayed phenology of plants; forage was of lower quality, and the growing season was much shorter in 1989 than in 1988. Births of lambs also occurred later and less synchronously in the second year. Females selected terrain characteristics that were related to avoiding predators in 1988 when forage was more plentiful, but selected sites with forage in 1989 when food was less abundant.

Group size of maternal bands was larger in 1988 than in 1989, and females foraged most efficiently during 1988. Large groups may not have occurred in 1989 because lambs were born asynchronously, preventing cohesive movements of maternal bands with lambs of differing ages.

Both the chronology of lambing and a variable environment affected habitat selection by females. Maternal females made trade‐offs between the requirements for forage to meet the high energetic costs of lactation and the risk of predation.
Diet of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae)
Authors: Chiarello Adriano G.
Published: February 2006

The diet of maned sloths was studied throughout 14 months in an Atlantic forest reserve of south‐eastern Brazil. Three adult sloths were observed for a total of 680 h and located monthly by radio‐telemetry. Data were collected on diet, recording the actual time the sloths spent eating plant species. Overall, the diet was composed of 99% leaves, with young leaves (68%) preferred to mature ones (7%) throughout the year. A higher proportion of tree leaves (83%) than liana leaves (16%) were included in the diet. When analysed together, the diet of the three animals included a total of 21 plant species (16 tree and 5 liana), but each individual made up its diet with an even smaller number of species (7–12) and with a particular subset of the local flora. This is a very small portion of the total number of tree and liana species available to the sloths; furthermore, the top species consumed were present at very low population densities in the forest. Thus, B. torquatus, like other congeneric species studied elsewhere in the Neotropics, is a strictly arboreal folivore with a highly selective diet, probably resulting from evolving physiological adaptations to cope with a smaller range of plant secondary compounds. This is possible for the species of this genus through a combination of low basal rates of metabolism, which enable the sloths to survive on an energy‐poor diet, and a very long passage time of digesta, which, in turn, aids the digestion of a fibre‐rich diet while possibly contributing to the degradation of secondary compounds.
The reproductive potential and strategy of Scorpio maurus fuscus (Scorpiones: Scorpionidae): anatomical clues in the ovariuterus
Authors: Warburg M. R. , Elias Rivka
Published: February 2006

The reproductive potential of scorpions is difficult to assess since several stages of their life histories cannot be clarified under natural conditions. The female's age when she first reproduces, the frequency of parturitions, litter size, and longevity cannot be known with accuracy. A new approach to such questions is suggested, whereby clues in the female's ovariuterus can be used to shed some light on previous and forthcoming litter sizes.

The ovariuterus of a female scorpion is unique among invertebrates in that past and forthcoming parturitions can be traced in its structure. Degenerated post‐partum diverticulae and the scars remaining after these have been completely resorbed indicate past parturitions, whereas young rudimentary diverticulae provide an estimate for future generations.

It is estimated that Scorpio maurus fuscus (Scorpionidae), matures in its second year, and first reproduces when 3 years old. Ovariuterus structure shows that it can have at least four and perhaps up to eight litters. If parturition takes place every year this would imply that a female scorpion can reach a minimum age of 6 years or perhaps up to 10 years. Evidence based on population analysis of females indicates that it is unlikely that all females reproduce in consecutive years; more probably they reproduce every other year. Thus, longevity may reach 9 years and perhaps as much as 17 years.
A new family of cyclopoid copepods (Fratiidae) symbiotic in the ascidian (Clavelina dellavallei) from Cádiz, Spain
Authors: Ho Ju‐shey , Conradi Mercedes , López‐González Pablo J.
Published: February 2006

Fratia gaditana, n. gen., n. sp., is described based on the specimens obtained from the atrium of the ascidian, Clavelina dellavallei (Zirpolo), collected at Tarifa Island in Cádiz, Spain. The new species belongs to a new family of Cyclopoida. Cladistic analysis revealed that phylogenetically it is closer to the Ascidicolidae than to the two other ascidicolous families, Archinotodelphyidae and Notodelphyidae.
The dynamics of growth in naked mole‐rats: the effects of litter order and changes in social structure
Authors: O'Riain M. J. , Jarvis J. U. M.
Published: February 2006

In this study factors that influence the plasticity in growth and adult body mass in the naked mole‐rat (Heterocephalus glaber) are explored. Growth functions (Gompertz transformation) revealed that naked mole‐rat pups have the slowest mean maximum growth rate (0.207 g.day−1) of all the Bathyergidae. Growth functions varied significantly between litters and there was an inverse trend between asymptotic body mass and litter order. Similarly, the magnitude of the growth response following the death of the breeding male or older siblings was greater for older litter members. There was a significant correlation between body mass and age at all stages of the colony's history although this relationship weakened with time. It is suggested that dominance interactions between old and young mole‐rats within the colony are important factors influencing the growth and reproductive potential of all colony members. Changes in body mass were linked to the behaviour of the individual within the colony providing a mechanism for the apparent match between large body size and colony defence and small body size and work frequency. Despite low genetic variation within colonies there is considerable variation in the size of colony members suggesting that plasticity in growth is the product of different ontogenetic histories of colony members that may serve as the basis for variation in size amongst adults.
Reproduction in the male Cape fur seal Arctocephalus pusillus pusillus: age at puberty and annual cycle of the testis
Authors: Stewardson C. L. , Bester M. N. , Oosthuizen W. H.
Published: February 2006

Seasonal changes in the reproductive anatomy and histology of the male Cape fur seal Arctocephalus pusillus pusillus were examined. Studies were based on 99 specimens collected between Algoa Bay on the south‐east coast of South Africa, and Cape Frio, Namibia, during 1974 to 1990. Reproductive organs are briefly described. The presence of sperm in the seminiferous and epididymal tubules indicates that males attain puberty between 3 and 4 years of age. Quantitative measurements of testis weight, testis volume, and the diameter of the seminiferous and epididymal tubules were analysed on a monthly basis and spermatogenesis documented. Although some males may remain in breeding condition until March, the absence of spermatozoa in the epididymis during February to June, when mean testis mass and mean tubule diameter reached a minimum, clearly showed reproductive quiescence following the rut. Four stages of spermatogenesis were observed: (1) inactive (February/March–June); (2) early spermatogenesis (July); (3) late spermatogenesis (July/August–December/January); and (4) epithelial regression (February–June). Individual variation between males, possibly differences in social status and body condition, may influence the duration of spermatogenesis, hence the overlap in duration between epithelial regression and inactivity. It appears that photoperiod may act as an obligatory proximate factor initiating spermatogenesis 3–4 months before the relatively short breeding season from November to December.
Short‐ and long‐term resistance to desiccation in a minute litter‐dwelling land snail Lauria cylindracea (Pulmonata: Pupillidae)
Authors: Arad Zeev , Goldenberg Shoshana , Heller Joseph
Published: February 2006

This study examines the water economy and resistance to desiccation in a minute (5 mg snail mass; 3 mm shell height) litter‐dwelling land snail Lauria cylindracea (Pupillidae). As expected from its small size and from its moist habitat, L. cylindracea exposed to normothermic desiccation lost water at the highest rate revealed so far in our studies of resistance to desiccation in some 30 Israeli species and populations of land snails—22.7% of the whole snail mass within 5 days. This high water loss was selectively contributed by the extra‐pallial (free) compartment while soft body water content was closely maintained, without catabolism of body tissue as a source of metabolic water. Surprisingly, however, samples of L. cylindracea survived long periods (2–4 months) of aestivation when left undisturbed in the laboratory, sustaining a mass loss of 25–40%. This long‐term aestivation revealed a different pattern of water compartmentalization, as the snails also lost water from the soft body tissue. Samples of these snails were rehydrated for 48 h and then exposed to an identical desiccation regime as the original, field‐collected snails. Most of the water taken up during rehydration was lost within the first 24 h of desiccation, after which the rate of water loss dropped sharply. We conclude that short‐term water regulatory responses to experimental desiccation differ from long‐term responses to aestivation. We suggest that during long‐term aestivation, a new set‐point of water economy is established, in association with a metabolic depression, and that an extended period of contact with moisture is needed to change this set‐point.
Tooth breakage and diet: a comparison of bats and carnivorans
Authors: Fenton M. B. , Waterman J. M. , Roth J. D. , Lopez E. , Fienberg S. E.
Published: February 2006

Species of carnivorans that eat bone are believed to break teeth more often than those eating mainly meat. Two predictions that arise from this hypothesis are that bats, which do not eat bone, will have a lower incidence of broken teeth than carnivorans and that smaller carnivorans, which often feed heavily on arthropods and other insects, will exhibit less tooth damage than larger carnivorans. We found no difference between bats and carnivorans in the proportion of skulls with broken or missing teeth in a sample including 10 species of carnivorans from ermines to bears, and 13 species of bats including some that eat insects, fruit, nectar and pollen, and blood. When the sample is expanded to include larger carnivorans studied by Van Valkenburgh (1988), there is a significant difference in the incidence of tooth breakage, indicating that the selection of species in the sample affects the results. Tooth breakage was strongly influenced by body size in carnivorans but not in bats. This evidence suggests that factors other than diet influence tooth breakage in mammals. We propose that lifespan, which increases with body size in carnivorans but not in bats, is a better predictor of tooth breakage than diet.
Morphology of the otoliths of Barbus sclateri (Pisces: Cyprinidae)
Authors: Escot Carmelo , Granado‐Lorencio Carlos
Published: February 2006

This is the first description of the otoliths (sagitta, asteriscus, and lapillus) of the European barbel (Barbus sclateri, Pisces: Cyprinidae), as well as the location, the procedure for extracting them and preparing them for age and growth studies. The otoliths were observed by light and scanning electron microscopy. With this last technique each otolith had a variable external crystalline morphology which may be related to different growth rates of the crystals. When seen through reflected light, the lapillus and the asteriscus showed opaque and translucent radial bands, and those in the lapillus were more clearly defined than in the other otolith.
Allozyme homozygosity and phally polymorphism in the land snail Zonitoides nitidus (Gastropoda, Pulmonata)
Authors: Jordaens K. , Backeljau T. , Ondina P. , Reise H. , Verhagen R.
Published: February 2006

Genetic variation in the pulmonate land snail Zonitoides nitidus was examined by means of allozyme electrophoresis in 17 European populations. We observed no heterozygotes, indicating that Z. nitidus consists of several homozygous multilocus genotypes (strains) probably produced by self‐fertilization. Nine strains were detected. Strains appeared not to be equally distributed over the regions considered. One strain was strongly differentiated from the others, which is suggestive of a taxonomic differentiation. Anatomically, two major phally types were distinguished: euphallics, with well‐developed male reproductive organs, and hemiphallics, with weakly developed male reproductive organs. Both phally types were found together in natural populations, but euphally ratios were very low (0–19%; overall mean = 7.79%) and differed between geographical regions (Belgium, Germany, and Sweden). In some populations, hemiphallic individuals were smaller compared to euphallic individuals although the difference is small and its biological significance remains to be established. We found no clear relation between phally type and allozyme data.
A systemic secondary vessel system is present in the teleost fish Tandanus tandanus and absent in the elasmobranchs Carcharhinus melanopterus and Rhinobatos typus and in the dipnoan Neoceratodus forsteri
Authors: Chopin Lisa K. , Amey Andrew P. , Bennett Michael B.
Published: February 2006

A system of secondary vessels emerging from the primary vessels as numerous coiled capillaries has been described in numerous teleost and holost fishes. The systemic secondary vessels of the teleost Tandanus tandanus are typical of this system and are described in this study. The existence of a secondary vessel system has been postulated in the elasmobranch group. No secondary vessel origins, as seen in the teleosts, are present in the elasmobranchs Rhinobatos typus and Carcharhinus melanopterus. Vessels with a similar distribution to secondary arteries are observed but these are venous rather than arterial in nature and do not connect with the primary arteries. Like the secondary veins in teleosts, the cutaneous veins in R. typus contain blood with a low haematocrit. There is no morphological evidence for a secondary vessel system in the dipnoan Neoceratodus forsteri.
Functional morphology of the gizzard of the domestic goose: design of an artificial gizzard
Authors: Moore S. J. , Lill C. A. , Sanson G. D.
Published: February 2006

An artificial gizzard was developed to investigate the functional basis of the asymmetry of the gizzard muscles of herbivorous birds, such as the domestic goose (Anser anser). Two types of gizzard muscle morphology were modelled: asymmetric muscles that generated a translational movement; and symmetric muscles that generated a compressional movement. The extent of breakdown of grass in the artificial gizzard was estimated by measuring nitrogen loss from blades of wheat (Triticum aestivum). The effect of grit and its interaction with the two types of gizzard muscle movement were also explored. In the artificial gizzard, translational movements caused more damage to grass than compressional movements and the damaging effect of grit was greatest when there was a translational movement. This type of movement was found to be particularly important as it prepares plant material for subsequent processing by stripping the matrix cells from the fibre bundles. Without such preparation, the breakdown of grass is limited.
Use of an artificial gizzard to investigate the effect of grit on the breakdown of grass
Authors: Moore S. J.
Published: February 2006

How geese break down food in their gizzards was investigated using an artificial gizzard that was loaded with grass (blades of wheat Triticum aestivum) and different quantities of four types of grit; large and small quartzite particles and large and small glass beads. Measuring nitrogen loss from the grass indicated the extent of damage to the grass. It was found that grass breakdown in the gizzard was most effective when it contained a small quantity of quartzite particles. In contrast, glass beads in the gizzard often resulted in less damage to grass than if they were absent. This suggests that there is a trade‐off between the damaging effect of grit on grass and the damaging translational movement of the gizzard lumen walls generated as the gizzard contracts. The damaging force produced by the gizzard is distributed across the gizzard contents. Thus with an increase in grit quantity in the gizzard, the force experienced by each grass particle will be reduced, resulting in reduced breakdown.
Food resource partitioning of a community of snakes in a swamp rainforest of south‐eastern Nigeria
Authors: Luiselli Luca , Akani Godfrey C. , Capizzi Dario
Published: February 2006

The food resource partitioning in a community of snakes from a moist rainforest of south‐eastern Nigeria (Eket, Akwa‐Ibom State) is studied in the present paper. The community consisted of 24 different species, belonging to different families and ecological guilds: some species were terrestrial, some were semi‐aquatic, and others were arboreal. Six species were primarily mammal‐eating, two were bird‐eating, four were lizard‐eating, three were frog‐eating, one species fed on both mammals and birds, and one species fed on both fish and frogs. A UPGMA tree diagram showed that three clusters of snakes are formed on the basis of their diet composition: a cluster formed by the two large arboreal species (Dendroaspis jamesoni and Boiga blandingi), another formed by the group of the terrestrial mammal‐eating Calabaria reinhardti, Bitis gabonica, and Bitis nasicornis, and the third cluster formed by the lizard‐eating Psammophis phillipsi, Thelotornis kirtlandii, and Gastropyxis smaragdina. The relationships between these and the other taxa remain unclear. In terms of both frequency of occurrence of the various prey types and biomass contribution of each prey type, the semi‐aquatic snakes showed the narrowest niche breadth values and the terrestrial snakes showed the widest niche breadth values. The overlap values were not significantly correlated with the rank of phylogenetic distance. The mean overlap values calculated between species belonging to a same guild were significantly higher than those calculated between species belonging to different guilds, but the mean overlap values between species belonging to a same guild did not differ significantly among guilds. Prey size and predator size (total length) were positively correlated. There was no statistically significant difference between snake guilds as far as mean prey size is concerned, but the various species within each guild differed significantly in terms of mean prey size.
Comparison between the ecology of the new European frog Rana pyrenaica and that of four Pyrenean amphibians
Authors: Serra‐Cobo Jordi , Lacroix Gérard , White Sue
Published: February 2006

The objectives of the present study are to provide information about the habitat, behaviour, and reproduction of the new European frog species Rana pyrenaica, endemic in the central and western Pyrenees, and to compare the breeding characteristics of R. pyrenaica with those of four amphibians present in the same geographical area (Rana temporaria, Alytes obstetricans, Euproctus asper, and Triturus helveticus). Unlike R. temporaria, A. obstetricans, and T. helveticus, which are typically found in standing waters and are rather ubiquitous species, R. pyrenaica is a stenothermic, rheophilous species. Small torrents with cold, well‐oxygenated waters constitute its typical habitat. This species – which seems much more aquatic than R. temporaria– has been most often found in sympatry with the endemic urodele E. asper. Unlike R. temporaria, the females of R. pyrenaica lay small clutches of large eggs.
Movement of bottlenose dolphins around the south‐west coast of Britain
Authors: Wood C. J.
Published: February 2006

After an absence of two decades a group of bottlenose dolphins, Tursiops truncatus, became resident in the coastal waters of Cornwall, U.K. in 1991. Using a combination of field techniques and information from the general public, the movements of this group were monitored. The dolphins demonstrated a seasonal residency pattern, spending the winter in southern Cornwall and moving further north‐eastward during spring and summer. Residency was flexible with a number of individual dolphins using the region intermittently. The dolphins occupied a linear range of coast of 650 km. Within this range they repeatedly made long‐distance journeys. Mean swimming speed was documented at 7.9 km·h−1, with the dolphins travelling the coast at a mean of 3.6 km·h−1. The longest journey recorded covered 1076 km and took 20 days. In one confirmed case the dolphins left the south‐west of England and were resighted in Wales. Such wide ranging movements have important implications for the conservation of bottlenose dolphins in U.K. waters.
Evolutionary implications of developmental and functional integration in bat wings
Authors: Adams Rick A.
Published: February 2006

This paper addresses how the wing membrane and skeletal system in bats are developmentally and functionally integrated during morphogenesis in the little brown bat (Myotis lucifugus). A truss network is used to quantify changes in the size and shape of the wing membrane during morphogenesis. Growth of the forearm and of third and fifth digits of the manus are also quantified. Principal component analysis indicates that changes in size of the wing (PC‐1) contribute 78% of growth variation, whereas shape changes (PC‐2, PC‐3) contribute only about 18% of growth variation. ANOVA run on component scores shows significant differences in size (PC‐1) of the wing between juveniles and sub‐adults, whereas no significant difference in shape (PC‐2 and 3) of the wing occurs during morphogenesis. In addition, growth compensation is shown to occur among sequentially developing skeletal elements comprising the hand wing. Coefficients of variation were significantly higher for phalangeal lengths than for total wing length and width. Compensation scores generated by summing residual scores produced by bivariate plots of wing bone elements show variable levels of compensation among individuals. However, a plot of scores against wing length shows compensation to occur throughout morphogenesis as scores are not correlated with wing size (r= 0.089). Apparently, selection has favoured a developmental system within which wing shape is conserved while simultaneous plasticity in the hand skeleton helps maintain functional integrity during rapid morphogenesis.
The social structure and dominance hierarchy of the highveld mole‐rat Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)
Authors: Moolman M. , Bennett N. C. , Schoeman A. S.
Published: February 2006

The highveld mole‐rat Cryptomys hottentotus pretoriae occurs in the summer rainfall region of the highveld of South Africa. It lives in colonies of up to 10 individuals, in which reproduction is limited to one to two of the largest males and the largest female in the colony. Of three field captured colonies, the mean colony size was 10 ± 0 animals with a mean biomass of 900 ± 147 g. The study colony had a sex ratio of 1.5:1 in favour of males.

The social hierarchy of the highveld mole‐rat is non‐linear and has a value of 0.3 calculated from Landau's linearity index. Dominance was negatively correlated with capture order.

Histological examination of the gonads of reproductively active and sexually quiescent members of both sexes of two colonies provides further support of there being a single reproductive male and female responsible for procreation in the colony.

The non‐reproductives of both sexes appear to be important in burrow maintenance activity and in foraging for geophytes upon which the mole‐rats feed. The non‐reproductive members of the colony cannot be subdivided into different worker groups based on body mass. The available evidence suggests that the highveld mole‐rat is a transiently social species, at one extreme of a sociality continuum in the genus Cryptomys. The position of this subspecies in respect to the sociality continuum is discussed.
Costs of reproduction and the evolution of sexual dimorphism in a ‘flying lizard’Draco melanopogon (Agamidae)
Authors: Shine Richard , Keogh Scott , Doughty Paul , Giragossyan Hamlet
Published: February 2006

Life‐history models suggest that ‘costs of reproduction’ can influence the evolution of sexual dimorphism, but empirical data on this effect are scarce. We tested the idea using ‘flying lizards’ (Asian agamids of the genus Draco), because the evolution of ‘flight’ (gliding) is likely to have increased the degree to which pregnancy affects maternal locomotor ability (and hence, we infer, has increased the ‘costs of reproduction’). As predicted, Draco display patterns of sexual dimorphism that are different from those seen in most other lizards. The ‘wings’ (gliding membranes) of female D. melanopogon are significantly larger than those of males of the same body size, a dimorphism that we attribute to natural selection on the ability to glide while encumbered with eggs. Comparisons with non‐flying lizards suggest that the same selective pressure has also reversed pre‐existing patterns of sexual dimorphism in body size and body proportions (relative head size, relative tail length). Measurements of wing‐loading, centre of balance and gliding distances of preserved specimens support the hypothesis that a larger body, relatively larger head, and longer tail may improve a female's aerial mobility when she is gravid. Thus, selection for locomotor ability in egg‐burdened females (reduction in ‘costs of reproduction’) may have been responsible for a reversal of sexually‐selected traits in this lineage.
Phylogenetic relationships of the Pomacanthidae (Pisces: Teleostei) inferred from allozyme variation
Authors: Chung K. C. , Woo N. Y. S.
Published: February 2006

Phylogenetic relationships of 31 pomacanthid species representing all genera were investigated by horizontal starch gel electrophoresis. Nei's genetic distances (D) were calculated and dendrograms constructed from allozyme variation in 23 loci. The average D value was 0.03 between conspecific colour variants, 0.40 between congeneric subgenera, and 1.27 between confamilial genera. From the dendrograms the following were revealed: (1) the generic status of Apolemichthys arcuatus and Holacanthus venustus, as well as the generic and subgeneric status of Centropyge multifasciata were confirmed; (2) the subgeneric status of Xiphypops was confirmed; (3) Pygoplites diacanthus was found to be closely related to members of the subgenus Pomacanthus; (4) Pomacanthus zonipectus was found to be biochemically distinct from its con‐subgeners; (5) the genera Pomacanthus and Holacanthus are more closely related than currently thought; (6) the Genicanthus species might warrant a subfamily of their own.
Reconstruction of the predatory behaviour of the extinct marsupial thylacine (Thylacinus cynocephalus)
Authors: Jones Menna E. , Stoddart D. Michael
Published: February 2006

The European colonists of Tasmania named the thylacine Thylacinus cynocephalus a ‘marsupial wolf’ or the ‘Tasmanian tiger’ or ‘hyena’, in reference to its resemblance to large canids and the bold stripes on its rump. The largest marsupial carnivore in historic times, it was persecuted for alleged sheep killing and became extinct before its ecology was documented. We have reconstructed the likely prey size and the hunting and killing methods of the thylacine by comparing canine tooth strength and limb bone length ratios with those of extant marsupial and placental carnivores. The thylacine was probably a pounce–pursuit predator of fairly open habitats, which killed medium‐sized prey (1–5 kg) that were small relative to its body size (15–30 kg), with a crushing, penetrating bite. The trophic niche of the thylacine was similar to that of smaller canids such as the coyote Canis latrans (rather than the wolf C. lupus), but ecomorphological convergence of the thylacine with canids was superficial. Phylogenetic constraint has resulted in unique patterns of tooth eruption, molar tooth and jaw geometry, calcaneum architecture, and perhaps FMT/running speed relationships in the Dasyuroidea.
Impacts of invasions by alien species
Authors: Rainbow Philip
Published: February 2006

Are British animals and plants being threatened by the invasion of alien species? This was the question addressed at a Scientific Meeting of the Zoological Society of London on 10 March 1998 in three talks exploring the potential impacts of invading Chinese mitten crabs in the Thames catchment (Paul Clark and Philip Rainbow, The Natural History Museum), introduced foreign crayfish (David Holdich, University of Nottingham) and alien terrestrial flatworms (Hugh Jones, University of Manchester).
Factors affecting movements and home ranges in the jay (Garrulus glandarius)
Authors: Rolando Antonio
Published: February 2006

The winter home ranges, movements and density of the jay Garrulus glandarius in the Maremma Natural Park (Tuscany, Italy) are presented, and compared with those already known for the other seasons. The movements of jays were studied for short periods over 6 years by radiotelemetric techniques (26 home ranges), direct observations of movements from vantage points, and transect counts. Summer and autumn ranges were much larger than spring and winter ones. Incremental area plots and auto‐overlap analyses showed that, on average, spring ranges increased in area with time without shifting, whereas winter ranges were rather stable. In both periods, however, some birds moved as floaters since the degree of range auto‐overlap decreased significantly with time. In winter and spring, range sizes of jays inhabiting different habitats were significantly different, being larger in sites with higher habitat heterogeneity. The structure of home ranges was variable in all seasons; birds showed jointed and disjointed ranges, with one or more activity centres, in all the possible combinations. In every season the average degree of range overlap between jays caught at the same site was rather high and overall actual overlap, when non‐tagged birds were also considered, was even higher. No territorial behaviour was ever observed. During summer jays moved into the pinewood for the greater part of the day to collect cicadas, Cicada orni, and returned to the maquis in the evening. During autumn birds regularly moved within the maquis or from the maquis to the pinewood to cache oak (Quercus ilex) acorns. No regular long movements between habitats were observed during spring and winter. Direct observations and analyses of pellets suggested that food was abundant and highly diversified throughout the year. Thus, seasonal movements and home ranges were flexible and mainly controlled by food availability and its distribution in space and time.
Limited intra‐specific variation in male grey seal (Halichoerus grypus) dominance relationships in relation to variation in male mating success and female availability
Authors: Twiss S. D. , Anderson S. S. , Monaghan P.
Published: February 2006

Inter‐male aggressive encounters were examined at three grey seal breeding colonies that differed in topography, adult dispersion patterns and operational sex ratios; North Rona and the Monach Isles (Scotland), and Sable Island (Nova Scotia). At North Rona, known males were observed over three successive breeding seasons, with a total of 275 males being individually identified. A single season's observations at both the Monach Isles and Sable Island provided data on 53 and 80 individual males respectively. Cardinal dominance ranks were computed for 68, 92 and 112 males on North Rona in each season respectively, 37 males on the Monach Isles and 68 males on Sable Island. All sites showed close approximation to dominance hierarchies when considering only interactions resulting in a clear outcome (wins), with less than 10% of interactions resulting in reversals. Measures of variance in male mating success showed no significant differences between colonies. These results show the existence of male dominance hierarchies in colonies from both east and west Atlantic populations and at breeding sites with widely differing habitat structure, seal dispersion patterns and levels of inter‐male competition, suggesting limited plasticity in the form of grey seal mating systems and limited variation in the degree of polygyny attained at these sites.
A second species of legless scuttle fly (Diptera: Phoridae) associated with ants (Hymenoptera: Formicidae)
Authors: Disney R. H. L. , Weissflog A. , Maschwitz U.
Published: February 2006

Vestigipoda maschwitzi Disney sp. nov. is described from females and larvae collected from a colony of Aenictus gracilis in Malaysia. It is the second species in this remarkable genus, the type species being associated with a different species of Aenictus in Malaysia.
Cellular diversity in the epidermis of Raja clavata (Chondrichthyes)
Authors: Whitear M. , Moate R.
Published: February 2006

The epidermal layer of the skin of the cartilaginous fish Raja clavata taken from a suitable place on the ventral side of the head was examined by light and electron microscopy. Cells of the basal layer divide and differentiate as epithelial cells of the mid‐epidermis, characterized by numerous electron‐dense, membrane‐bound vesicles; their content is assumed to be mucus. Cells at the superficial layer of the epidermis lose these vesicles but have a palisade of mucous vesicles below the apical membrane. A modified glycocalyx coats the outer leaflet of the apical membrane.

In addition to epithelial cells, there are epidermal cells differentiated as two kinds of mucous goblet cells, sacciform cells similar to those found in teleost fish epidermis, holocrine cells with some resemblance to the club cells of teleosts but differing in their cytology, and chemosensory cells similar to those found in the oral epithelium of Raja. Merkel cells were not found. Cells that might be interpreted as ionocytes were seen but their nature was not confirmed. The epidermis is penetrated by numerous nerve fibres; swellings contain mitochondria and glycogen granules. The nerve fibres also contain 50–70 nm vesicles with an indistinct core. Cells intrusive to the epidermis include melanocytes, lymphocytes, macrophages, and several types of granular leucocyte. The cytology of the various epidermal elements is generally similar to that known in teleost fishes.
Does food competition from red fox (Vulpes vulpes) influence the breeding density of goshawk (Accipiter gentilis)? Evidence from a natural experiment
Authors: Selås Vidar
Published: February 2006

The impact of food competition from the red fox Vulpes vulpes on the breeding density of the goshawk Accipiter gentilis was studied in a 650 km2 area in southern Norway by investigating the density of goshawks and their grouse prey before, during, and after a period when the red fox population was low because of an epizootic of sarcoptic mange Sarcoptes scabiei. The number of goshawk pairs per 100 km2 was approximately nine/year in the 1950s, three/year in 1972–75 and in 1980–85, and four/year in 1988–91. In each of these periods, nesting territories of goshawks were regularly spaced. There was a positive correlation between the breeding density of goshawk and the population size of grouse. Both grouse numbers and goshawk breeding density increased at the same time that fox populations declined in the 1980s, while the re‐establishment of the fox population in the 1990s was associated with decreases in grouse and goshawk numbers. During the partial absence of red foxes, there was a continuously high grouse population. It is concluded that the red fox may influence the goshawk breeding density negatively by limiting the numbers of grouse.
A 32‐year demography of yellow‐bellied marmots (Marmota flaviventris)
Authors: Schwartz Orlando A. , Armitage Kenneth B. , Van Vuren Dirk
Published: February 2006

Yellow‐bellied marmots Marmota flaviventris in the East River Valley of Colorado were live‐trapped and individually marked annually from 1962 through 1993. These pooled data were used to produce a demography and life table for these years. Females had significantly better survivorship than males beyond the first‐year age class, and the sex ratio became progressively female biased. The major mortality factors of predation and unsuccessful hibernation acted evenly on all age classes as shown by the constant rates of survivorship. The rate of senescence indicated that the probability of mortality did not increase with age. Females produced litters from ages 2 to 10 years. Mean litter size was 4.1 and did not differ among age classes. The female generation length of 4.49 years was 2.4 times the life expectancy and the median survivorship. The net reproductive rate (Ro) was 0.67, yet the population did not continually decline; adjustments to these data increased Ro to 0.85. Reproductive values (Vx) were approximately equal across the reproductive age classes. The polygynous mating system is both cause and effect of the demography. Marmot population size is affected by weather factors that influence reproduction and survival, by predation, and by movement into and out of the study area.
Reproductive biology of the neotropical harvestman (Goniosoma longipes) (Arachnida, Opiliones: Gonyleptidae): mating and oviposition behaviour, brood mortality, and parental care
Authors: Machado Glauco , Oliveira Paulo S.
Published: February 2006

Goniosoma longipesis a neotropical cavernicolous harvestman that exhibits parental care. Reproductive activity inG. longipesis more intense during the wet season. Mating lasts up to 3 min, and the whole oviposition process may take over 5 h. During oviposition the female may be reinseminated once or twice by the mating male. Females oviposit 60–210 eggs on the cave wall and guard egg batches for nearly 2 months, until the 1st‐instar nymphs disperse. Four main factors can affect egg survival inG. longipes: dehydration, fungal attack, cannibalism, and interspecific predation. Frequency of fungal attack on egg batches was greater in the wet season and more intense near the river inside the study cave. Although egg‐guarding by females failed to prevent fungal attack on eggs inG. longipes, the choice of a suitable oviposition site by the gravid female can reduce fungal attack within the cave habitat of this species. Guarding females successfully repel conspecific egg predators, but unguarded eggs are frequently consumed by adult and juvenileG. longipes, as well as cave cricketsStrinatiasp. Field experiments in which females were removed from egg batches demonstrated that egg‐guarding by the mother has an anti‐predator role inG. longipes, with a significant positive effect on egg survival. MaleG. longipesactively patrol their egg‐guarding mates, and take over brood care for up to 2 weeks if the latter are experimentally removed. The degree to which male assistance can play a relevant role in parental care is still unclear for this species. Damage to the brood is regarded as a major force favouring the evolution of parental care in harvestman species. This field study provides the first experimental demonstration that egg‐guarding by females affords protection against egg predation in a harvestman species.
The effect of tooth shape on the breakdown of insects
Authors: Evans A. R. , Sanson G. D.
Published: February 2006

This study investigates the effect of tooth sharpness on the force and energy necessary for a tooth to divide foods of differing physical properties. The material properties of foods are likely to affect the shape that is best to divide them. In order to test the effect of sharpness on a tooth's proficiency in dividing insect prey, experiments involving penetrating and driving through insect prey of differing physical properties were carried out using specially designed punches that varied in tip‐ and cusp‐sharpness. A refinement of tooth measurements which are relevant to their effectiveness in penetrating and driving through food is expounded. ‘Tip‐sharpness’ is defined as the radius of curvature at the tip of a cusp. ‘Cusp‐sharpness’ is defined as the volume or surface area of the tooth per unit distance from the tip of a cusp. The experiments show that tooth shape is important in the force and energy needed for teeth to penetrate and drive through insects. Also, the scale of teeth is important – teeth of the same shape but different size vary in their effectiveness to divide foods.