Didelphids use vertical strata in different ways, suggesting the existence of a wider variety of niches than simply arboreal or terrestrial. This variety could be related to the differential ability to deal with support diameters and inclines, and might be important for the coexistence of species in local assemblages. From data obtained with the spool-and-line technique, the use of the vertical space and above-ground supports is described in four species of an assemblage of didelphid marsupials in south-east Brazil. The stratification in this and other assemblages in the Atlantic forest and in the Amazon is also compared. Animals were trapped in Serra dos Órgãos, state of Rio de Janeiro, and equipped with a spool-and-line device before release. The paths were tracked by measuring variables related to support diameter, incline, distance and height moved above ground. The diameter of supports used was positively related to body size, and the incline to the dominant direction of movement (horizontal vs vertical). The more cursorial species, Metachirus nudicaudatus, only once moved above ground in > 3200 m of paths followed. Didelphis aurita moved mostly on the ground, but was the only species that occasionally reached the canopy. Philander frenata also moved mostly on the ground, occasionally used the understorey, but never reached the canopy. The more arboreal species, Marmosops incanus, moved mostly in the understorey, but never in the canopy. This pattern of stratification is similar to that observed in other sites in the Atlantic forest and in the Amazon.

Film sequences were used to measure functional hind limb-segment proportions and joint angles at successive stages of walking strides for 22 species of quadrupedal mammals from five orders. Similar data were obtained from three trotting dogs. For each animal, nine Fourier series coefficients describing the movement of each of the hip, hock and ankle joints were obtained. Multivariate statistical analysis of these coefficients revealed that animals with similar limb-segment proportions move their joints in similar ways. However, it should be noted that animals with similar leg-segment proportions also tended to be phylogenetically related. Most of the discriminatory power was between animals of different stances (plantigrade, digitigrade or unguligrade) and between walking and trotting.

The integrity of genetically determined morphs of the same species in sympatry may be facilitated by sexual incompatibility (and thus reduced gene flow) between morphs. A test for such incompatibility was carried out between fully metamorphosed and paedomorphic forms of the North American mole salamander Ambystoma talpoideum, which differ greatly in life-history characteristics. A few significant differences were found in the content and timing of courtship between homomorphic (within-morph) and heteromorphic (between-morph) encounters during 2-h observation sessions. However, no significant differences were apparent in the incidence of spermatophore deposition (which is an index of the potential for sperm transfer), both as recorded at the end of observation sessions and as determined for pairs left to interact for 16 h overnight. Fertilized and viable eggs were laid by females of both morphs that were exposed to spermatophores from either homomorphic or heteromorphic males, but not to both. We conclude that sexual incompatibility probably plays little or no role in preventing gene flow between sympatric morphs of A. talpoideum. Gametic incompatibility may also be of little or no importance. We suggest that differences in the phenology of breeding are of greater significance in the maintenance of discrete morphs of the mole salamander in sympatry.

Moult and pre-migratory fuelling are energy-demanding processes in birds, usually showing a limited degree of temporal overlap. The barn swallow Hirundo rustica, a strictly aerial insectivorous, long-distance passerine migrant (15–20 g), accumulates conspicuous energy stores (up to 30–40% of lean body mass) before embarking on the autumn migratory flight between western European breeding areas and African sub-Saharan winter quarters. During the pre-migratory fattening period (September–October), both adult and juvenile birds replace body (contour) feathers. The seasonal overlap between moult and energy storing was studied in barn swallows in Italy. Data from 23 000 birds, measured during eight study seasons, were analysed to investigate whether the simultaneous replacement of body feathers and fuelling was associated with reduced energy stores. Among all age and sex-classes, non-moulting individuals showed a relatively greater level of energy stores compared to moulting birds. This was particularly evident during the last phase of the pre-migratory fuelling period, when birds were building up energy stores at maximum rate. The proportion of moulting birds was greater among adults as compared to juveniles, and adult males moulted faster/earlier than females. The frequency of individuals with growing feathers among the innermost primary feathers was greater among birds replacing body feathers. The presence of moulting wing feathers in adult birds only marginally affected energy stores, as compared to the replacement of body feathers. Hence, our data show a negative association between replacement of contour feathers and energy stores in a long-distance migratory bird, suggesting that a physiological trade-off between these two energy-demanding processes may occur, and that a late moult may ultimately have a negative effect on the successful termination of the migratory journey.

The spatial resources used by a population of lace monitors (Varanus varius) were examined over an active season (September–April) and an inactive season (May–August). In total, 33 monitors were observed, of which 23 monitors were radio-tracked for up to 11 months. Radio tracking provided new information on the spatial ecology of V. varius. During summer (December–February), V. varius moved often, over large (184.5 ha) overlapping home-range areas. In the intermediate seasons of spring (September–November) and autumn (March–May), monitors moved less often and used less than 39% of the summer home-range. Finally, in the cold winter season (June–August) many monitors did not move at all and most used less than 5% of their summer home-ranges. The thermal environment, and reproductive status of V. varius affected its use of space, and the importance of these factors varied seasonally. No spatial segregation was noted between monitors, with home-ranges overlapping on average for eight other radio-tracked monitors. The home-range size of V. varius was accurately predicted using published data on body mass and home-range size for the Varanidae.

In southern Norway, population fluctuations of the herbivorous bank vole Clethrionomys glareolus and the granivorous wood mouse Apodemus sylvaticus were analysed in relation to mast seeding of bilberry Vaccinium myrtillus, sessile oak Quercus petraea and Norway spruce Picea abies. Bilberries ripen in August, acorns are dispersed in September, whereas spruce seeds are usually dispersed during winter or spring. The bilberry index of both the current and previous year contributed significantly to explain the population growth indices of bank vole. The spruce seed index significantly influenced only the bank vole, whereas the acorn index significantly influenced only the wood mouse, apparently through increased winter survival. Because of the lack of significant responses to bilberry masting by granivorous wood mice, we conclude that the most likely explanation for the observed peak populations of bank voles in post-mast years of bilberry is that high seed crops have a positive influence on the chemical composition of bilberry plants, which are important as food for bank voles during winter.

Using a porthole camera the architecture of the warrens of the southern hairy-nosed wombat Lasiorhinus latifrons was examined at two sites in southern Australia. The complexity of warrens varied from simple, single-entrance warrens to a system 89 m long with 28 entrances. Logging of deep tunnel temperatures showed daily ranges of < 1 °C over periods in which surface temperatures ranged up to 24 °C, but mean tunnel temperatures varied 15.9 °C between winter and summer. Humidity gradients were maintained between the tunnel and the surface and depended on the length and depth of the tunnel. Oxygen and carbon dioxide levels were similar to those in free atmospheric air in unoccupied tunnels, but in occupied tunnels reached 16.3% and 3%, respectively. There is no specific orientation of tunnel entrances or defined mound shape. Wombat warrens ameliorate surface conditions in habitats of low humidity and high temperatures while humidity advantages promote the construction of warrens beyond the requirements for temperature modulation.

Vocalization is an important component of male reproductive behaviour in a wide range of animal taxa. In some species there is considerable intraspecific variation of call characters partitioned on a regional basis. Such ‘regional accents’ could originate from cultural or genetic evolution and have been widely studied in birds. Amphibians, however, have limited learning abilities, and where regional accents occur in this group they are primarily a consequence of genetic evolution. This raises the possibility that regional variations in anuran call characters might be informative about phylogeographic history. Microsatellite studies of the pool frog Rana lessonae have been used previously to infer patterns of post-glacial colonization in Europe, with unexpectedly complex implications for northernmost populations of this species. Therefore, regional variation in call characters of the pool frog was quantified and the pattern observed was concordant with the differentiation of a distinct northern clade as implied by the microsatellite study. We therefore conclude that regional accents in this amphibian are useful phylogeographic indicators of distribution history.

Specialization for a locomotor behaviour may affect limb bone morphology throughout ontogeny. Ontogenetic development of the limb skeletons of two mammalian species, which are behaviourally specialized for the half-bounding gait (Chinchilla lanigera and Oryctolagus cuniculus), were compared to two similarly-sized species which are not specialized for half-bounding (Rattus norvegicus and Monodelphis domestica). Limb bone lengths and anteroposterior diameters (mediolateral diameters for the radius and metacarpal) were measured from radiographs taken throughout the ontogeny of each species. Body mass was also measured repeatedly during growth. Bone measurements were regressed against body mass, as well as forelimb bone length vs serially homologous hindlimb bone length, bone length vs total limb length and bone length vs width. Similar comparisons were made among adults of each species using ratios. Although there were many significant differences among species, overall there were few consistent differences in adult scaling ratios or ontogenetic allometry slopes between specialized and generalized groups. Adult specialized half-bounders had significantly narrower tibiae and metatarsals than the gait-generalized runners. Specialized half-bounders usually had similar slopes for hindlimb length vs width ontogenetic comparisons, but the non-specialized species did not group together. However, there were two patterns that occurred among all four species: (1) hindlimb bone lengths nearly always grew faster than the serially homologous forelimb bone lengths in all species; (2) proximal elements usually increased in length proportionally faster than distal elements. In conclusion, small mammals may share strong developmental constraints that govern their relative growth rates. It is also likely that there are different selective pressures on juveniles and adults, but that these selective pressures may not be different between specialized and unspecialized runners during ontogeny.

Many simultaneously hermaphroditic land snails have sperm digesting glands and multiple sperm storage organs, which it is suggested give the sperm recipient control over the number of sperm accepted and hence fertilization. In order to increase fertilization success, the sperm donor should manipulate the recipient to accept more sperm, especially so in situations of sperm competition. In helicid snails, the love dart optionally pushed into the partner's body during courtship, has been suggested to be such a manipulative tool. We investigated the influence of the sperm donor's size, sperm volume transferred and dart pushing on the volume of allosperm stored by the recipient in virgin Arianta arbustorum. In addition, we were interested in sperm storage patterns within the spermathecae. Fifty per cent of the snails already possessed a dart and tried to use it. However, most of them missed the partner. The main tubule always contained more than 50% of the total amount of sperm stored. Otherwise sperm storage patterns were very variable. The volume of sperm stored was significantly influenced only by the number of spermathecal tubules. The significance of spermathecal morphology for sperm storage needs further exploration.

Morphological variation was investigated in hatchling squid Loligo forbesi Steenstrup 1856 reared at three constant temperatures. Twenty-seven morphometric and chromatophore characters were measured on 180 hatchlings. Hatchlings were randomly sampled from 15 egg strings, representing six egg mops and spread across two spawning seasons. Size at hatching varied inversely with temperature and was significantly reduced at 16°C (mean mantle length 2.87±0.04 se mm) compared to 8°C (3.26±0.03 se mm). Hatchlings reared at 12°C developed significantly narrower mantles than those reared at 8 or 16°C. Principal components, stepwise elimination and canonical variates analyses performed using all 27 measured characters revealed that nine characters were vital in discriminating between temperature groups. Canonical structure values associated with eight of these characters were used in the construction of a canonical equation. By measuring the same eight characters on field-sampled L. forbesi, this equation can be used to estimate mean thermal history of wild hatchlings. Field-application of the techniques developed during the present study may allow assessment of realized thermal niche in a mobile marine invertebrate.

In ungulates, females typically need to reach a critical threshold body weight in order to reproduce. Females born in ‘poor’ years may lose 1 year of reproduction, as they reach the critical body mass 1 year later. Some studies report also a lasting effect of low initial body weight into prime age, while several other studies have shown that nearly all prime-age females ovulate or are pregnant. However, the quality of the offspring (as measured by offspring body weight) is often not considered. We tested whether female ungulates with an initially low body weight (at around weaning) reach the same reproductive output as females with higher initial weights, and thus whether or not they are able to compensate for their initial low weight. Data on body weight of 123 533 lambs of domestic sheep Ovis aries from 73 299 litters that in turn derived from 32 359 different ewes were used. All ewes and lambs had been free-ranging on outlying pastures in Norway during the entire summer season. Ewes with an initially low body weight produced smaller offspring throughout their lifespan. Ewes with an initially low body weight also produced fewer lambs at first and second parturition, but lifetime number of offspring was not related to ewes' initial weight. We concluded that bigger was better: the smaller offspring of ewes with a low initial weight demonstrate a lasting cost on reproductive effort, with consequences for animal production systems and management of wild ungulates.

Aspects of the skeletal growth of the deep-sea hexactinellid sponge Euplectella oweni Herklots and Marshall, and host size and type selection by the symbiotic shrimp Spongicola japonica Kubo were investigated using field-collected material. Two phases, flexible and stiff, were observed in the framework of the sponges. In the flexible sponges, the circular, longitudinal and oblique systems of the skeletal beams that constitute the principal framework were not fused to each other, and the parietal ledges running circularly, or sometimes obliquely, on the wall were not developed. The skeletal wall was fragile in texture, readily torn by any external force. The wall was much sturdier in the stiff sponges, in which the systems of the skeletal beams were coarse, fused to each other to make the principal framework tough in texture, and pareital ledges developed so as to reinforce the sponge wall. The flexible phase is mainly seen in smaller and younger sponges, while the stiff phase was seen in the larger (or dead) ones. Almost all the solitary and young pairs of shrimps were collected from flexible sponges.

Many orb-web building spiders add conspicuous, white silk decorations termed stabilimenta onto the central portion of the webs. Stabilimenta are known to vary greatly in form and quantity from species to species, and also within a species. In the present study, stabilimentum variations in form and quantity are described, and the factors influencing stabilimentum variations in Argiope versicolor from Singapore, in both the field and the laboratory, are examined. Our results from field survey and laboratory experiments show that: (1) the form and occurrence of stabilimenta varied with developmental stage of spiders: A. versicolor juveniles (body length: < 0.6 cm) built disc-like (discoid) stabilimenta while adults spun cross-like (cruciform) stabilimenta; (2) the quantity of stabilimenta (percentage of stabilimentum area covering the web to the web area) decreased with increasing web size and spider size; (3) light intensity affected the density and percentage cover of stabilimentum on the web: A. versicolor tend to build more and denser stabilimenta in dim conditions than in bright surroundings; (4) well-fed A. versicolor adults added more stabilimenta than starved spiders. These findings suggest that A. versicolor may adjust the frequency and quantity of stabilimenta to suit multiple functions, specifying the circumstances under which to use each function (conditional stabilimentum-building strategies).

The epidermis of snakes produces two types of keratinocytes containing an alpha (soft) and a beta (hard) form of keratin. During epidermal renewal, which allows body growth, six types of epidermal layers are produced before moulting: oberhautchen, beta-, mesos, alpha-, lacunar, and clear. The precise layers in which beta-keratin, alpha-keratin and matrix proteins (loricrin and filaggrin) are produced, have been studied by light and ultrastructural immunocytochemistry. An antibody against chick scale beta-keratin recognizes also snake beta-keratin only in the oberhautchen and beta-layer. This confirms the phylogenetic relationships between avian and reptilian hard (beta) keratins. Beta-keratin rapidly disappears in mesos-cells, where little beta-keratin is present. Antibodies that recognize alpha-keratins (AE1, AE2, AE3) show that acidic keratins (AE1 positive) mainly localize in the most basal layers and basic keratins (AE3 positive) in all layers but disappear in those layers that are keratinized, especially in the beta-layer. The AE2 immunolabelling (a marker of keratinization in mammalian epidermis) is localized in the compact alpha-layer. This pattern is similar to that for loricrin and filaggrin, although in the latter the reaction is less intense and located mainly in the hinge regions among scales. Alpha-keratins and associated proteins disappear in the oberhautchen and beta-cells where beta-keratin is produced instead. This study suggests that the shedding mechanism in snakes evolved after the hard beta-keratin was compartmentalized beneath the soft alpha-keratin to create an intra-epidermal weakness region. The study also suggests that some common mechanism of alpha-keratinization is present in snakes, and the other amniotes in general.