A 16-year study of wild, unprovisioned sifaka Propithecus verreauxi verreauxi at Beza Mahafaly in south-west Madagascar provides estimates of age-specific fertility, mortality, and dispersal in a population of 426 marked animals, and longitudinal records of individual life histories. Sifaka females give birth for the first time later and live longer, for their size, than mammals in other orders; they also give birth later and continue reproducing longer, for their size, than other primates. Theory postulates that these features, commonly referred to as bet-hedging, evolve in unpredictable environments in association with widely varying infant survival and a trade-off between reproductive effort and adult survival. The climate of south-west Madagascar is highly unpredictable compared to almost all other regions in the tropics with similar average rainfall, and we argue that sifaka females are bet-hedgers par excellence. Male sifaka, in contrast, become reproductively active at an earlier age than females, and are less likely to have long lives than females. The atypical direction of this asymmetry between males and females reflects a ‘slowing down’ of female life histories rather than a ‘speeding up’ of male life histories. Two other unusual features of sifaka biology and behaviour may be linked to the unpredictability of Madagascar's climate: intense local competition between females, and a sex ratio at birth strongly biased in favour of males in most years. In drought years, reproductive females must cope with suddenly intensified resource constraints. This, in turn, may strongly limit the number of ‘breeding slots’ available over the long-term for females.

Temporal distribution and composition of ichthyoplankton and their relationships with some environmental variables of Leopoldo's Inlet (Ressaco do Leopoldo) on the upper Paraná River floodplain, southern Brazil, were analysed. Samples were taken from February 1991 to February 1992, and 3480 larvae were collected. The highest density of larvae was observed in November 1991 (36.79 larvae/10 m3) at night (night/day ratio 7: 1). Species composition showed a predominance of Characiformes (80%). There was a high density (4.28 larvae/10 m3) of Bryconamericus stramineus throughout almost the whole study period. The majority of the species were more frequently collected at night. Pearson's correlation indicated a relationship between larval density, temperature, and pluviometric index. Leopoldo's Inlet, whose ichthyofauna is mainly composed of grazing and resident species, shows favourable conditions for fish reproduction and development.

Non-reproductive female Damaraland mole-rats Cryptomys damarensis that were caught before a period of good rainfall (during which 90% of the average annual fell) (Group 1), exhibited a significantly lower pituitary sensitivity to gonadotrophin-releasing hormone compared to non-reproductive females (Group 2) caught in the same area, close to the end of the wet period. Group 2 were also significantly heavier than Group 1. Pituitary sensitivity was not significantly correlated to body mass within either group of females, nor within groups of reproductive males and non-reproductive males from a laboratory held colony. This suggests that rainfall may have resulted in the simultaneous, but unrelated, increase in pituitary sensitivity and body mass. Larger size and reduced sexual inhibition assist dispersal and the probability of successful independent reproduction, during periods when environmental constraints on dispersal are relaxed. These findings support the hypothesis that low rainfall may be an important constraint on dispersal and an important factor promoting the evolution of reproductive inhibition, and consequently eusociality, in this species.

Successful capture of prey often depends, in part, on the magnitude, duration and speed of feeding behaviours. Animal size and experience are potentially important to these aspects of behaviour, but the effects of scale on the muscular dynamics of and capture by aquatic vertebrates remain relatively unknown. This study examines scale effects on prey capture kinematics in the nurse shark Ginglymostoma cirratum, an inertial suction feeder. Morphometric analyses were performed on the heads and feeding apparati of 12 specimens between 71 and 244 cm total length (TL). These data indicated isometric growth of the feeding apparatus. The kinematics of prey capture in another 12 specimens (33 to 268 cm TL) were recorded with high speed video (200 fps). Across the size range, maximal angular excursions remained constant whereas the maxima of linear excursions increased isometrically. However, various phases of the prey capture sequence apparently did not increase in duration. Regressions of the components of prey capture timing generally had slopes between 0 and 0.5, supporting a model of muscular scaling initially proposed for largemouth bass. This model implies that increases in the duration of prey capture are the result of physiological constraints on muscular contraction. There is also a pattern of scaling across several taxa of aquatic vertebrates consistent with a second model of musculoskeletal scaling, although it does not necessarily apply within each taxon.

The morphology of the mouthparts and proventriculus of the wood-boring isopod Sphaeroma terebrans has been described, with particular reference to its possible filter-feeding abilities. Scanning electron microscopy revealed that while the mandibles might be designed to scrape pieces of wood from the cavity wall during boring, the rest of the mouthparts are better suited for microphagous feeding. Video observations of the mouthparts demonstrated the ability of S. terebrans to filter out particulate material from the water column, by means of the filtering setae on the first three pairs of pereiopods. The morphology of the gut was found to be largely similar to that of terrestrial herbivorous isopods; primary and secondary filter apparatuses were present, but the masticatory apparatus present in terrestrial herbivores was missing. The morphology of both the gut and mouthparts provides additional support for the assumption that wood is an unlikely food source for S. terebrans.

The purpose of this study was to evaluate the impact of moonlight on the swarming activity of bats at an abandoned mine in southern Sweden. The mine serves as a hibernaculum for six species of insectivorous bats. Swarming activity at one of the mine entrances was measured on 12 nights between 1 August and 8 September 2000, by electronically counting the number of bats passing through an opening (about 30×40 cm) leading to a mine tunnel. The number of bat passes outside the mine was also counted, using a bat detector. Most bats were males, as confirmed by mist-netting outside the mine. Low frequency vocalizations, indicating territorial interactions, were heard frequently. The number of bats entering the mine was closely correlated with the number of bats flying outside, and neither was affected by moonlight. We conclude that the insectivorous bats at high latitudes may not have been exposed to significant nocturnal predator pressure, leading to the evolution of lunar phobia, as have many tropical bats.

Changes in hepatopancreas mass in nymphs, male and female Scorpio maurus fuscus (Scorpiones, Scorpionidae) from northern Israel, were followed through the year, and its percentage water content calculated. The hepatopancreas mass was positively correlated with body mass in males, females and nymphs, and changed significantly with season. In nymphs it ranged between 0.1549 g and 0.5351 g, in males between 0.1631 g and 0.3431 g, and in females between 0.2240 g and 0.6669 g. The hepatopancreas mass of males differed significantly from that of females during summer and autumn, and from nymphs during summer and winter. The hepatopancreas mass of nymphs differed significantly from that of females during autumn, winter and spring. In females, the hepatopancreas mass increased from autumn to spring. During that time, the embryonic diverticula (Ed) containing the embryos increase in number and size during embryogenesis. The depletion of the hepatopancreas mass is positively correlated with the Ed during the latter part of the gestation period before parturition. The percentage water content of the hepatopancreas ranged between 47.8% and 68.4%, and varied seasonally as well as between the genders. It is suggested that these changes in both hepatopancreas mass and water content are related to physiological events such as growing and moulting in nymphs, feeding and mating activities in males and the oogenetic cycle in females.

Based on a computer-assisted method and regression analysis several structural parameters of the hair cuticle pattern of primary hairs of 94 mammalian species from seven orders were evaluated and compared between the different groups studied. Relevant relationships could only be demonstrated for directly scale-dependent parameters (scale area, scale perimeter, ratio of scale width to height). However, the species-specific shape and size of hair cuticle scales in mammals may be of certain value for biological interpretations of hair coat structure and function. This seems to be especially true for the Canidae and the Felidae, and even more for small mammals (insectivores, chiropterans, small rodents). In the latter group relationships between scale-dependent parameters and hair coat density indicate a homogeneity of hair coat structure which reflects effective insulation qualities.

A new species of the oligochaete family Parvidrilidae Erséus, 1999 is described from several subterranean waterbodies of southern Europe. A comparison with the type species suggests that the so called ‘genital body’ and ‘copulatory organ’ of the latter can be interpreted as the atrium and spermathecae, respectively. A critical analysis of the most important diagnostic features known is made to increase understanding of the real position of the Parvidrilidae in a natural system within the Oligochaeta. The parvidrilids seem to be closely related to the Phreodrilidae. Waiting for the results of molecular and ultrastructural analyses, and considering the dorsal crotchets ‘buried’ in the body wall as an autapomorphy for the phreodrilids, the rank of family for the parvidrilids is maintained on the basis of the three following autapomorphies: the location of the setae in a marked posterior position within the segments; the lateral development of the clitellum, with large clitellar cells in relation to the body diameter; the singular glandular pouches present in the mid-dorsal line of the mesosomial segments.

The physical and morphological characteristics of red-fronted gazelles Gazella rufifrons kanuri Gray 1846 were determined in Waza National Park between September 1989 and December 1993 by describing body colour code and coloration, measuring body weight, body length, ear length, head length, horn length, hip height, shoulder height, tail length, and counting orbital glands from 141 carcasses. Mean body weight of red-fronted gazelles ranged from 7.8 kg for the young to 29.7 kg for the adult, while shoulder height varied from 38.7 cm in the young to 68.7 cm in the adult. Irrespective of age and sex, the shoulder height was lower than hip height by a fixed ratio of c. 1.04. Regardless of age and sex, orbital glands, though deeper in the adults, numbered nine with the highest concentration of four in the inter-digital fossae. The relationship between body weight and body length and horn length were significantly (P < 0.05, r = 0.8) positively correlated. The spatial appearance of horns, when viewed from the muzzle direction, is the most obvious physical and morphological characteristic for age and sex differenation of red-fronted gazelles in the field.

Current life-history paradigms predict that an organism's total reproductive output is determined by its intrinsic level of ‘reproductive effort’ (RE), interacting with local resource availability. In turn, RE is driven by ‘costs of reproduction’. Within the total allocation, selective forces on offspring size ultimately determine both the number and size of offspring (because of a trade-off between these two traits). Although patterns of life-history variation are broadly consistent with this scenario, the evidence is weak: it is generally difficult to measure ‘costs’ or selective forces on offspring size. To test this paradigm, we need a study organism which differs in these respects from related taxa, so that we can unequivocally generate predictions about life-history traits. A remarkable island population of Asian pit-vipers Gloydius shedaoensis was studied for which (unlike mainland conspecifics) ‘costs of reproduction’ are low, food availability is high, and there is intense selection for large offspring size. Maternal body sizes and condition, and offspring numbers and sizes were quantified for 79 litters over 2 years. As predicted, the snakes display high reproductive output per female (relative to maternal body mass, litter mass is about twice as high as in related taxa), large offspring size (about three times the mass of related taxa) and a strong trade-off between offspring size and litter size. Reproductive output was only weakly correlated with maternal body size, and output was adjusted mostly by manipulating litter size rather than offspring size. Reproductive output varied between years, but maternal body condition after parturition did not. Measures of reproductive output (such as the mass or energy content of the litter) bear little relationship to ‘costs of reproduction’ in this system.

Morphological variation was studied in the crania of seven species of kangaroos and wallabies (Macropus). How function and phylogeny interact to influence cranial form amongst adults of diverse species was considered. Thirty-six, three-dimensional landmarks were acquired on each of 65 adult Macropus specimens from Western Australia. The different species occupy a wide range of habitats and latitudes and there are well-known differences in diet among the species. Size and shape variability was examined using the methods of geometric morphometrics. Aspects of inter-specific variation explained by principal components were visualized and examined for correlations with size, latitude, and diet. The first principal component correlates strongly with inter-specific differences in latitude and it primarily contrasts species on the basis of the relative length of the snout anterior to the molar teeth, this being greater in species that live in cooler climates. Species scores on the second principal component correlate strongly with centroid size such that smaller crania have more flexed muzzles. Principal component three separates the short grass-eating, red kangaroo M. rufus, from all other species (most of which eat tough herbage from trees and shrubs). This principal component represents differences in the masticatory apparatus. Variation on the fourth principal component also seems to be functionally interpretable in terms of further differences in the masticatory apparatus of M. agilis. The relationship between phylogeny and cranial form was investigated by comparing a phenogram based on the shape distances between taxa with a consensus phylogeny drawn from the literature on Macropus genetics, ecology and morphology. The phenogram shows considerable similarity to current taxonomic views, but, our results also indicate differences that are related to function. Thus, this study serves to unravel the interaction of functional and phylogenetic influences on cranial form amongst Macropus species and raises further issues relating to ontogeny and phylogeny.

Aspects of the ecology of populations of the western pond turtle Clemmys marmorata were investigated in the Mojave River of the central Mojave Desert, California, U.S.A. One population occupied man-made ponds and the other occurred in natural ponds in the flood plain of the Mojave River. Both habitats are severely degraded as a result of ground water depletion from human activities along the river and one is infested with the exotic shrub saltcedar Tamarix ramosissima. Mean female carapace length (CL) was significantly greater (14.4 cm) than that of males (13.7 cm). Live juveniles were not detected during the period of study. Shelled eggs were visible in X-radiographs from 26 May to 14 July. Mean clutch size was 4.46 and ranged from 3 to 6 eggs. Clutch size did not vary between 1998 and 1999 but was significantly correlated with CL for both years combined, increasing at the rate of 0.548 eggs/cm CL. Gravid female CL ranged from 13.3–16.0 cm. Some females nested in both years. Mean X-ray egg width (21.8 mm) was not significantly correlated with CL or clutch size. X-ray egg width differed more among clutches than within, whether including CL as a co-variate or not. Nesting migrations occurred from 6 June to 8 July with minimum round trip distances ranging from 17.5–585 m with a mean of 195 m. Mean estimated time of departure as measured at the drift fence was 18:13. Most females returned to the ponds in the early morning. Nesting migrations required females to be out of the water for estimated periods of 0.83 to 86 h. The destination of nesting females was typically fluvial sand bars in the channel of the dry riverbed. Overall, the ecology of C. marmorata in the Mojave River is very similar to that reported for populations in less severe habitats along the west coast of the United States. Notable exceptions include long nesting migrations to sandbars in the dry river channel, a possible result of human modifications to the environment, and an apparent lack of terrestrial overwintering behaviour in Mojave River populations. The general similarity of desert and coastal populations is possibly a reflection of their recent geographic separation. Overall, populations in the Mojave River exhibit few obvious adaptations to living in the desert and are considered to be tenuous relicts of the Pleistocene. The small size and tenuous status of these populations suggests that immediate conservation action is needed, including establishment of satellite populations as a hedge against extirpation.

Winter attendance patterns of lactating Steller sea lions Eumetopias jubatus and their offspring were recorded during the late stages of nursing when the young were expected to move from milk to independent foraging. Trip duration and nursing visits to shore by 24 mothers with pups (7–9 months old) and six mothers with yearlings (19–21 months old) were noted during 600 h of observations (from 22 January to 1 April 1996) at a non-breeding haulout site in south-eastern Alaska. Pups and yearlings tended to stay on or near the haulout while their mothers were away and showed no signs of weaning during winter. Their average trips to sea were 43% shorter in duration than those of lactating females, suggesting that pups and yearlings make independent trips away from the haulout while their mothers forage. The winter attendance cycle of lactating females (consisting of one trip to sea and one visit on land) averaged about 3 days, with the mothers of pups spending an average of 15 h of this time onshore with their offspring. The winter attendance cycle of pups and yearlings averaged just over 2 days, with the immature sea lions spending an average of 22 h on shore. Foraging trips by mothers of yearlings were significantly longer than those by mothers of pups. However, there was no significant difference in the foraging times of mothers of male and female pups. Lactating females spent more time at sea during winter than during summer. The probability of sighting an individual on the winter haulout during daylight hours was 15% for lactating females and 40% for immature animals.