bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early embryonic development of the grey short‐tailed opossum, Monodelphis domestica, in vivo and in vitro
Authors: Baggott L. M. , Moore H. D. M. 
Published: March 2009

Eggs and embryos (up to the unilaminar blastocyst stage) were collected from grey short‐tailed opossums, Monodelphis domestica, at known time intervals after mating. Some were fixed immediately for examination by light and electron microscopy while others were maintained in culture at 37 °C in 5% CO2 in Ham's F10 medium containing foetal calf serum. Cleavage to the early blastocyst stage was obtained in vitro although most embryos displayed arrested development at the eight‐cell stage. From gross morphological and ultrastructural observations a pattern of embryogenesis to the unilaminar blastocyst was constructed. Comparisons were made with the events of early development in other marsupials.SummaryOocytes were fertilized soon after ovulation and their zonae pellucidae surrounded by a mucoid layer originating from mucopolysaccharide secretion of oviductal epithelial cells. Within 24 hours zygotes passed into the uterus and shell membrane formation commenced.

The early embryonic development in vivo and in culture of the grey short‐tailed opossum, Monodelphis domestica, was investigated by light and electron microscopy. The following timetable of events was constructed:
The first cleavage at about 28 hours after ovulation (54 hours after mating) was at right angles to the equator of the zygote and was accompanied by the vesiculation of yolk mass. The resulting two blastomeres were composed of peripheral polar cytoplasm.
The second cleavage (44 hours) and third cleavage (approx. 72 hours) produced small blastomeres with no cell contact. Yolky vesicles surrounded the blastomeres.
The fourth cleavage division (approx. 96 hours) occurred in the same equatorial plane as the second resulting in two tiers of cells which subsequently flattened against the inner surface of the zona pellucida. Tight junctions formed between adjacent blastomeres.
Unilaminar blastocysts were formed about 5 days after fertilization.
Development in vitro followed a similar time course to that in vivo, however, most embryos were arrested at the 8‐cell stage.
Estimating small mammal abundance for predator studies: snap‐trapping versus sign indices
Authors: Village A. , Myhill D. 
Published: March 2009

Small mammal abundance was estimated by snaptrapping and sign indices every three months for seven years on two farmland areas in eastern England. Microtus were caught more often than Clethrionomys in both areas, and Apodemus more often in arable than mixed farmland. Clethrionomys apparently produced more signs per vole caught than did Microtus, and year‐to‐year changes in the sign index were better correlated with changes in the Clethrionomys, than the Microtus, snap‐trap index.When there were few Clethrionomys caught, between‐site variations in the sign index were best explained by variations in the Microtus snap‐trap index, but this was not so when Clethrionomys trap scores increased. Seasonal changes in the production of sign per vole meant that the sign index was a poor indicator of the extent of seasonal variation in the snap‐trap index. The sign index may give an approximate measure of spatial or annual variations in vole abundance where there is only one vole species present, but it gives misleading estimates if more than one species produces signs.
Gestation period and between‐birth intervals in Carollia perspicillata (Phyllostomatidae, Chiroptera)
Authors: Laska Matthias 
Published: March 2009

Several aspects of reproduction were investigated in a captive colony of Carollia perspicillata.The gestation period of four females was found to be 125, 121, 108 and 105 days, respectively.Twenty‐eight to 32 days post‐partum sexual receptivity seemed to occur in females, as only during this period copulations resulted in pregnancy.The statistical median of the distribution of between‐birth intervals (B.B.I.) fell into the class of 121–130 days and the shortest B.B.I, was 120 days.Young bats gave birth for the first time at the age of 381±25 days (mean±S.D.; N = 6), the youngest female being 350 days when she gave birth. Thus female leaf‐nosed bats seem to reach sexual maturity at approximately nine months of age.The synchronization of sexual activity with seasons that was typical under field conditions was maintained during the first year of captivity, but faded within four years.The data presented suggest that the females of this colony may exceed the expected pattern of two births per year and at least three females gave birth to eight young within 36 months.Increase in population density seemed to cause infanticide and a reduction of the number of individuals housed together led to a marked increase in rearing success.
Ultrastructure of Holothuria polii encapsulating body
Authors: Cancicatti C. , Quaglia A. 
Published: March 2009

The coelomic cavity of freshly collected Holothuria polii specimens contains a variable number of brown pigmented and unpigmented encapsulating structures. They are composed of nodules with entrapped parasites and an internodular mass which comprises a number of nodules. Both brown and unpigmented bodies occur in different size classes depending upon the number of nodules accumulated in a complete body. The unpigmented bodies probably represent an early unmelanized stage of the brown ones.The nodule was ultrastructurally constituted by foreign bodies surrounded by a fibrous, electron‐dense, non‐cellular layer, probably melanin, followed by a layer of elongated and extremely flattened amoebocytes. Nodules were assembled in an internodular mass formed by amoebocytes type I, II and III spherule cells. As for the amoebocytes constituting the nodule, those present in the spaces between nodules did not develop junctional complexes. It is conceivable that the intricate network established among the cell processes could represent the mechanical force maintaining the whole structure.As suggested by our results, two functional amoebocyte populations seem to be responsible for the organization of the scavenger body: 1. encapsulating amoebocytes, characteristically non phagocytosing, elongated cells; and 2, phagocytosing amoebocytes. The former organize the nodules, the latter constitute the internodular mass of several nodules.Most probably, the double scavenger activity justifies the considerable complexity of the H. polii encapsulating structure compared to other invertebrates.Spherule cells participate only in constituting the internodular mass.
Activity patterns of termite‐eating land planarians Microplana termitophaga (Platyhelminthes: Tricladida)
Authors: Cumming Meg S. 
Published: March 2009

The land planarian Microplana termitophaga is one of three invertebrate predators feeding at the open chimneys of the mound of the termite Odontotermes transvaalensis in Harare. This paper records over 4000 field observations of the mound and reports on the planarians over three rainy seasons from 1990 to 1993. Microplana termitophaga is crepuscular with a large early morning and a smaller evening activity peak. Rainfall appears to be of over‐riding importance; activity is confined to the rainy season, occurring once the cumulative rainfall reaches 150‐250 mm and being suspended during longish dry spells. Activity is also favoured by ambient relative humidity above 70%, light intensity below 50,000 lux (but not total darkness) and ambient temperature between 13 and 23d̀C. Planarians on sun‐exposed, but not on shaded, mounds disappeared after a drought. Dispersal occurs during prolonged wet weather. Microplana termitophaga occurs with two predatory spider species and a commensal phorid fly and they all utilize the same termites. These four species exhibit temporal separation, probably related to their specific micro‐climatic needs.
Habitat relations within lowland grassland rodent communities in Taiwan
Authors: Adler Gregory H. 
Published: March 2009

Patterns of habitat use by murid rodents were examined in lowland grasslands in Taiwan. Fifteen grassland sites were live‐trapped in 1990, and 16 microhabitat variables were measured at each of 539 trap stations in the sampling sites. Mus caroli, Apodemus agrarius, Rattus losea, and Bandicota indica were captured regularly during the sampling. Rattus norvegicus and Nivivenrer coxingi were captured infrequently. The analysis focused on the four common species. Mus caroli, R. losea, and B. indica have been considered to be commensals of humans and to be largely dependent upon agricultural crops. However, these species were captured in natural habitats, often far from agricultural areas. M. caroli and R. Iosea were by far the most abundant species.Vertical stratification of the habitat did not increase the number of species or overall rodent abundance. Rather, sites with well‐developed grass cover and little vertical development of vegetation above the grass layer had the highest overall densities of rodents.Use of habitat was very similar among the four common species and was concentrated in areas with dense grass cover. Overlap in habitat use was particularly extensive in the core areas of greatest occupancy. Relative population abundances (number of individuals captured per trap station) of the four species were related weakly to the microhabitat variables. These variables were better predictors of capture probabilities of M. caroli and R. losea at individual trap stations, as revealed by multiple logistic regression. Abundances and capture probabilities did not appear to be affected by the presence or abundance of other species.It is suggested that body size differences may facilitate coexistence of these four species of ecologically similar murids. Beginning with the smallest species (M. caroli), body masses of each subsequent species in the series differ by at least a factor of two. These grassland communities may be somewhat resistant to invasion by more similar‐sized species of murids.
The diet of the diadem leaf‐nosed bat Hipposideros diadema: confirmation of a morphologically‐based prediction of carnivory
Authors: Pavey C. R. , Burwell C. J. 
Published: March 2009

The diet of Hipposideros diadema was investigated over three seasons at two sites on Cape York Peninsula, Australia using faecal analysis (at both sites) and prey remains identification (at one site). The possibility that this species feeds on terrestrial vertebrates, a behaviour here referred to as carnivory, was suggested by the similarity of three of its morphological features with those of eight of the 10 species of bats known to exhibit carnivory.The study confirmed that H. diadema is at least occasionally carnivorous. Bird feathers were found in faeces at both sites; however, their occurrence was limited to a collection of faecal pellets from the early dry season at Iron Range and a single pellet from the wet season at Chillagoe. The birds taken could not be identified to family or species. Coleoptera, Lepidoptera and various orthopteroid orders were the main insect taxa in faecal pellets. The frequency of these taxa in the diet varied significantly among the three seasons at both sites. Analysis of prey remains indicated that large, hard‐bodied insects, mainly cerambycid and scarabaeid beetles and acridid grasshoppers, particularly the locust Gastrimargus musicus, were taken frequently. The mean length of intact beetle elytra collected below roosts was 18.0 mm. No vertebrate material was found in prey remains. Hipposideros diadema is similar to several other bats which exhibit carnivory in preying infrequently on vertebrates. The term ‘partial carnivore’ or ‘occasional carnivore’ is suggested for these species.
Paedomorphosis and skull structure in Malagasy chamaeleons (Reptilia: Chamaeleoninae)
Authors: Rieppel Olivier , Crumly Charles 
Published: March 2009

The phylogenetic analysis of skull characteristics, along with data derived from lung and hemipenial morphology, does not support monophyly of the predominantly terrestrial chamaeleons, Brookesiinae (Brookesia plus Rhampholeon), as sister‐taxon of a monophyletic clade of arboreal chamaeleons, the Chamaeleoninae. Instead, the phylogenetic interrelationships of chamaeleonine lizards are (Brookesia (“Rhampholeon” (Bradypodion, Chamaeleo)). The monophyly of the genus Rhampholeon is not demonstrated. The arboreal chamaeleons form a monophyletic group comprising two genera, Bradypodion and Chamaeleo. Bradypodion may be placed as sister‐group of the genus Chamaeleo, but its phyletic position and monophyly cannot at present be corroborated.This study documents that there is a high degree of intraspecific variability in skull characters which may be due to paedomorphic reduction in the skull, especially of small species. Characters affected by a variable degree of ossification include the separation of a prefrontal fontanelle, the contact of the squamosal with the parietal, the size and position of the fenestra vestibuli, the degree of ossification in the basicranial rim of the fenestra, the extent of ossification of the pterygoid wing, and the shape of the skull roof as indicated by the bones forming the dorsal margin of the orbit. The closure of the lateral aperture of the occipital recess might indicate that miniaturization, and concomitant paedomorphosis, may have played a role in the initial phases of chamaeleonine phylogeny.
Sexual dimorphism in the canines and skulls of carnivores: effects of size, phylogency, and behavioural ecology
Authors: Gittleman J. L. , Valkenburgh B. Van 
Published: March 2009

Sexual dimorphism in craniodental features is investigated in a sample of 45 carnivore species in relation to allometry, phylogeny, and behavioural ecology. Dimorphism is more pronounced in both upper and lower canine size and strength than in carnassial size, skull dimensions and biomechanical features, but all dimorphism indices covary. As with most morphological characters, differences in canine sexual dimorphism are significantly related to phylogeny, estimated from either taxonomic rankings or a limited matrix of molecular distances; in particular, mustelids, felids and procyonids are more dimorphic than other carnivore families. Thus, because of problems related to species dependence in comparative data, remaining analyses are based on phylogenetically transformed values using a spatial autoregressive method.In contrast to other mammals, sexual dimorphism in carnivore canines is not correlated with differences in body weight, skull length or basicranial axis length. Nor is it correlated with categorical variables of activity pattern, habitat, or diet. In our Carnivore sample, canine dimorphism is related only to breeding system: uni‐male, group‐living (harem) species have significantly greater canine dimorphism than multi‐male, multi‐female groups and monogamous pair‐bonding species. By contrast, dimorphism in carnassial size is related to dietary differences, specifically greater dimorphism in meat‐eating species, and not breeding patterns. Dimorphism in estimates of jaw muscle size suggest functional demands from both diet and breeding type. It is concluded that, befitting patterns of heterodont dentition, sexual selection influences variation in canine dimorphism while feeding ecology is related to carnassial dimorphism.
Repertoires of social behaviour in captive and free‐ranging grey kangaroos, Macropus giganteus and Macropus fuliginosus (Marsupialia: Macropodidae)
Authors: Coulson Graeme 
Published: March 2009

The eastern grey kangaroo, Macropus giganteus, and the western grey kangaroo, M. fuliginosus, are sibling species. The behaviour of 48 eastern grey kangaroos and 15 western grey kangaroos was observed for 249 h at Melbourne Zoo. Up to 31 eastern grey kangaroos and 38 western grey kangaroos were observed for 305 h where they occurred syntopically in the Grampians National Park.In total, 46 social acts were identified in four social contexts between conspecifics. All but one of the acts were performed by both species in captivity, whereas fewer were seen performed by either species in the field. Five general acts were performed by all age/sex classes, and 10 acts occurred in mother‐young contexts. High‐intensity agonistic acts and all sexual acts were performed exclusively by adult males. In captivity, western grey males performed a truncated range of sexual acts directed at eastern grey females, but no interspecific sexual acts were performed by males of either species in the field, supporting the distinctiveness of the two species. The close evolutionary relationship between the two species was confirmed by high degree of concordance between their behavioural repertories, which differed only in the structure of the isolation call given by large pouch young.
Differential growth patterns between successive litters of the eusocial Damaraland mole‐rat, Cryptomys damarensis, from Namibia
Authors: Bennett N. C. , Navarro R. 
Published: March 2009

Differential mean rates of growth were calculated for successive litters of mole‐rats born to genetically unrelated pairs of C. damarensis. The Logistic equation provided the closest fit to the growth data.Both intra‐ and inter‐colonial variation in mean maximum growth rate between successive litters incorporated into the natal colonies were determined.The mean asymptote (A), growth rate constant (K) and inflection time (I) were modelled for the first five litters of pups born to pairs of mole‐rats. Inter‐colonial analysis of recruitment to colonies revealed litters 1, 2, and 5 to grow faster than litters 3 and 4. Litters 1 and 2 had significantly higher asymptotes and inflection times than litters 3, 4, and 5 (P < 0.001). All litters were assimilated into their natal colonies. There were no significant differences between males and females for the asymptote, growth rate constant, or inflection time (P < 0.05).Intra‐colonial variation of litters 1 to 4 born to a single colony revealed comparable results to that obtained for inter‐colonial comparisons. Multiple comparisons showed litters 1 and 2 to have a significantly higher absolute growth rate than litters 3 and 4. The lowest rate of growth being for litter 4.The patterns of mean differential growth are discussed in the light of the social organization of the colony. It is postulated that growth rates in litters 1, 2, and 3 are more rigid since they constitute the main functional unit of colony organization. Litters 4 and 5 show a greater plasticity in growth; it is speculated that these colony members become incorporated into the various worker and defender groupings which are characteristic of C. damarensis colonies.
Age, sex, and condition as predictors of moult and the efficacy of a novel fur‐clip technique for individual marking of the European badger (Meles meles)
Authors: Stewart P. D , Macdonald D. W. 
Published: March 2009

The European badger (Meles meles) moults once a year. In our study site in lowland England, pelage replacement of the guard hairs and a protracted period of fur growth (follicular anagen) occur between May and early November, with a peak in July. The precise timing of the moult depends on the age and condition of the badger. Yearling badgers undergo moult significantly earlier than adults. Adult females that have lactated, moult significantly later than other classes of adult, delaying the moult until autumn which corresponds to an annual period of food abundance. Lactation was significantly associated with poor condition in these badgers. It was not possible to determine whether delayed moult was due to poor condition per se, or due to some other physiological consequence of lactation, e.g. hormonal changes. We hypothesize that delay of moult in laclating/poor condition individuals has the adaptive consequence of delaying the metabolic costs of pelage replacement from a time of energy deficit until a time of relative plenty.These findings are of practical importance to a novel solution to the problem of individually marking badgers during observational studies. The technique involves clipping the dark band near the tips of the badger's guard hairs to reveal the white under‐fur and produce patterning of the coat. The highly contrasting marks were well suited to visual identification during observations under low light and infra‐red illumination, and they allowed a large number of individuals (over 80 in our study) to be distinctively marked. The mark persists until the badger undergoes its single annual moult, or until three months of the active phase of fur growth have passed. Clip marks on adults made in late August had the greatest longevity, with 80% still visible after nine months. Though clipping had no significant effect on body condition in our study site, it should be cautiously applied with individuals in poor condition or in cold climates.
Coastal residence periods and reproductive timing in southern right whales, Eubalaena australis
Authors: Burnell S. R. , Bryden M. M. 
Published: March 2009

The duration and timing of coastal residence of individually identified southern right whales at a principal aggregation area on the southern Australian coast differed markedly between females with calves and unaccompanied whales. The mean residence period of females that calved within the aggregation area was 70.9 days, with mean residence mid‐points of 20 August in 1993 and 22 August in 1994. In contrast, unaccompanied adults remained resident for an average of only 20.4 days with mean residence mid‐points of 27 July and 11 August in 1993 and 1994, respectively. Whales have been sighted at this aggregation area from mid May to late October (approx. 160 days), although the effective calving season (95‐100% of calves born) lasted only 88 days in 1993 and 96 days in 1994. The mean birth date based on first sighting with neonatal calf, and corrected for sightability bias, was 15 July in 1993 and 17 July in 1994, with 100% of calves born before 31 August 1993 and 23 September 1994.The time between birth and dispersal from the aggregation area, at or just prior to the commencement of the southward migration, was highly variable. Calves bom before the mean calving date averaged 80 days within the aggregation area, twice as long as those born after the mean (40 days). The large number of calves estimated to be less than 14 days old at first sighting, combined with the sighting of 26 pregnant females prior to parturition, suggests the majority of births occurred within, or very near to, the aggregation area.