A series of laboratory experiments were conducted to determine if adult wolf spiders Gladicosa pulchra were capable of acting as predators of juvenile spotted salamanders Ambystoma maculatum. Spiders preyed upon salamanders in two of 20 trials and attacked salamanders in five trials. As attacks did not always kill salamanders, multiple attacks per trial were possible. A total of 11 attacks was observed: two complete attacks, and nine incomplete attacks. Attacks were considered complete if the spider inserted its chelicerae into the salamander and incomplete if the spider did not. In response to complete attacks, the salamander would flip onto its back. Salamanders occasionally responded to incomplete attacks by continuously raising and lowering their heads. To our knowledge, this behaviour is undescribed in this group of salamanders. An additional experiment investigated the influence of increased levels of salamander movement on this interaction. In this experiment, spiders preyed upon salamanders in one of eight trials and attacked salamanders in six trials (28 total attacks: four complete attacks, 24 incomplete attacks). The results of this study indicate that wolf spiders can prey upon juvenile spotted salamanders, and that the ecological relationship between wolf spiders and amphibians may be quite complex.

The osmoregulatory function of common spiny mice Acomys cahirinus living on opposite slopes of the lower Nahal Oren (‘Evolution Canyon’) on mount Carmel, Israel, was investigated by increasing the salinity of the water source whilst maintaining a high-protein diet. The southern-facing slope (SFS) of this canyon differs from the northern-facing slope (NFS) as it receives considerably more solar radiation and consequently forms a more xeric, sparsely vegetated habitat. During the summer, mice living on the two opposite slopes significantly differed in their urine osmolality, which also increased significantly as dietary salinity increased. Offspring of wild-captured mice, born in captivity, and examined during the winter, continued to show a difference in osmoregulatory function depending on the slope of origin. However, they differed from wild-captured mice, as they did not respond to the increase in dietary salinity by increasing the concentration of their urine, but rather by increasing the volume of urine produced. This study shows that A. cahirinus occupying different microhabitats may exhibit differences in their ability to concentrate urine and thus in their ability to withstand xeric conditions. We suggest that they may also differ genetically, as offspring from the NFS and SFS retain physiological differences, but further studies will be needed to confirm this hypothesis.

Alternative mating tactics are found in many species, and may have important implications for population genetics and speciation. The existence of such alternative mating tactics is well-documented in the three-spined stickleback Gasterosteus aculeatus, and sneaking and egg-stealing may occur in a significant proportion of matings under natural conditions. Sneaking can impose high costs on territorial males, both in terms of reduced reproductive output and caring for unrelated offspring. We ask whether territorial males adjust their behaviour in response to the risk of sneaking. In a field study of three-spined sticklebacks on the Isle of Arran, Scotland, territorial males were presented with glass bottles containing either a male, a female or neither, to address whether territorial males were more aggressive to other males in the presence of a female, and whether territorial males courted females less in the presence of another male. Behavioural observations showed that territorial males did not behave more aggressively towards rival males in the presence of a female, but did reduce their rate of courtship towards females in the presence of rival males. We conclude that territorial males adopt behavioural strategies that may reduce their risk of reproductive parasitism.

Communication sounds or ‘social calls’ of 16 European bat species (Chiroptera, Vespertilionidae) were recorded at a range of roost and foraging sites. A comparative analysis of more than 5400 individual calls for general structures and for inter- as well as intraspecific variability resulted in 50 types of calls, which differed by their specific structure and by the calling species. These types could be grouped into four different general types of calls, according to the kind and complexity of their structure, independent of the calling species. Distinct types of calls seem to have similar functions in different bat species. One general type may be used predominantly in female–infant interactions as an isolation or direction call, which serves as mutual recognition. This type of social call was also used in ‘tandem flights’ of pairs of bats, which might increase individual knowledge of roost sites and foraging success. A second type was used in mate attraction, and a further one in an aggressive context. The fourth one was used by hindered or distressed bats. The group of ‘aggressive’ calls is least variable, but the complex mating calls and isolation calls are very diverse. Species-specific sound structures were identified, which allowed a computational species distinction. The measured inter-individual variability of social calls should be significant for their functions in individual recognition. So, beyond common features concerning the frequency structure of bat social calls, interspecific differences, as well as the intraspecific variability of details of sonagraphic parameters, should elucidate the specific functions of the calls.

The social structure and social interactions of the nocturnal slow loris Nycticebus coucang are described from locational as well as observational data on wild animals. Data were collected during 600 h of nocturnal radio-tracking and 400h spent radio-locating sleeping slow lorises during the day. Data are also presented on morphometrics, injuries and ectoparasites, and dispersal. The slow loris is generally described as solitary, but although close-range encounters were rare, animals were observed to form stable social units (‘spatial groups’) characterized by home-range overlap and friendly interactions among members and non-overlap between units. Four spatial groups were observed, each consisting of a single adult female, a single adult male and a varying number of younger individuals. Group composition, together with relatively small testis volume and natal dispersal occurring in both sexes, hints towards a monogamous mating system. One extended family group was formed by the delayed dispersal of a primary pair's offspring. We did not find another often quoted correlate of monogamy – a weak sexual size dimorphism. Friendly interactions among members of a spatial group included allogrooming, following, alternate click-calls, and sleeping in contact. Yet, members did not engage in any co-operative behaviour of the types usually thought to be responsible for group formation in gregarious mammals. One important factor contributing to the sharing of space between slow lorises is probably that chances of successful dispersal are low. However, subtle benefits arising from the presence of conspecifics (allogrooming, transfer of information on food resources) may also be crucial for the formation or maintenance of slow loris spatial groups.

The pattern of correlations between geographic–environmental variables and geometric shape descriptors for the skull and mandible of Thrichomys apereoides was studied by recently developed combinations of geometry and multivariate statistical techniques. Environmental variables were obtained for each locality: altitude, mean temperature, rainfall, human population density, and vegetation type. The three views of the skull (dorsal, lateral and ventral) and the mandible were significantly associated with a latitudinal environmental gradient along the diagonal of open areas (caatinga and cerrado) throughout the range sampled. The populations from xeric environments presented relatively larger coronoid processes, larger jugals and wider snouts (related to the activity of jaw closing muscles). A correlation of patterns of shape variation from data sets of different skull views showed that lateral skull shape is the most informative view. Further studies are necessary to separate completely the contribution of genetic and environmental components to skull and mandible shape divergence among populations of T. apereoides.

Hyphydrus ovatus beetles inhabit lakes, ponds and slow running streams. In central Europe the larvae develop at water temperatures of >10°C from May to July. All three instars live on or close to plants. The first instar prefers the upper areas of plants. Its prey are insect larvae and small stages of planktonic crustaceans. The second instar chooses deeper areas and catches larger prey, whereas the third instar prefers the root zone and feeds mainly on tubificids and chironomids that are caught in the detritus of the bottom layer. The elongated nasale of Hyphydrus ovatus is equipped with different sensilla. Despite the rather different shape of their outer parts, their ultrastructure indicates that they all have a mechanoreceptive function. Chaetiform sensilla are especially numerous and are especially long near the tip. Plate-like mechanosensilla are positioned in a half circle at the ventral edge of the rostral tip. The assumed function of these sensilla is the location of prey. As in other Hydroporinae, the axis connecting the dorsal and ventral points of articulation of the mandibles is sloped laterally. Thereby, the closing mandibles move upwards and press the prey against the underside of the nasale, which – like the upper jaw in vertebrates – serves as the counterpart of the mandibles. On its ventral side, the nasale is equipped with various cuticular teeth that serve to hold the prey when it is pressed against them by the mandibles.

The burrowing habits of thalassinidean shrimps presuppose their high susceptibility to the deleterious effects of gill fouling by particulate debris and epibionts. The structures and strategies used to prevent gill fouling were examined in Nihonotrypaea japonica and Upogebia major by morphological inference and aquarium observations. The gill complement of both species consists of 10 arthrobranchs, with flattened filaments of the phylloid trichobranch type. Nihonotrypaea japonica and U. major lack passive gill-cleaning setal systems in the branchial chamber, but were found to actively groom gills by inserting and brushing the gill filaments with a pad of dense setae on the distal segments of their fifth pereiopods (P5 brush). Grooming setae of the P5 brush in N. japonica are of serrate and plumose types, whereas they are serrate and pappose in U. major. Serrate setae with distally curved spiniform denticules were morphologically similar in both species. Phylogenetic mapping of the gill-cleaning mechanisms suggests that gill-cleaning characters are homoplasic and systematically conservative among the families of the Thalassinidea.

Three locomotor modes were examined (sprinting, jumping and climbing) in eight species of skinks: seven Niveoscincus spp. and Pseudemoia entrecasteauxii. These species formed four distinct ecological types: ground-dwelling, arboreal, heath/rock dwelling, and saxicolous. Significant behavioural preferences for particular escape modes in the field were found, which reflected the performance capabilities at an animal in the laboratory. This study used both non-phylogenetic and evolutionary based analyses to demonstrate that species occupying different microhabitats and using different escape tactics exhibit corresponding differences in performance abilities. Four Niveoscincus species are specialized in performance abilities and behavioural responses (N. greeni, N. ocellatus, N. pretiosus, N. orocryptus) by excelling in some performance abilities but having behavioural restrictions at attemping other locomotor modes. Only N. microlepidotus and N. orocryptus used escape tactics opportunistically; these species possess a suite of behavioural responses that may reflect the wide range of microhabitats they occupy. Ground-dwelling species N. metallicus, N. coventryi and Pseudemoia entrecasteauxii performed poorly at all performance abilities and seemed to have biomechanical limitations, rather than behavioural restrictions, on locomotor mode. Thus, when making interspecific comparisons, the behaviour of an animal needs to be considered before appropriate performance measures are selected. Phylogenetic analyses demonstrate that escape tactics and performance abilities have co-evolved in Niveoscincus, with an evolutionary trend towards behavioural and locomotor specialization.

The relationships between haematozoan parasites, cell-mediated immune response, territory features and colour morph were investigated in tawny owls Strix aluco, in the Park of Monza in Milan, northern Italy. Rufous and grey birds were found to differ significantly in their blood parasite loads, particularly during the breeding season, when rufous birds hosted more parasites than grey birds. The increase in parasitaemia of rufous owl was not, however, owing to the breeding status of sampled individuals. Although body condition was similar between the two colour morphs, immune response was higher in grey than in rufous owls for the same level of parasites. Moreover, parasites seemed to influence breeding of rufous birds negatively, because only individuals with no or few parasites reproduced. Both these results suggested a higher susceptibility to parasites of rufous owls. Nevertheless, a habitat effect existed because parasite loads increased significantly with woodland extent and tree-density within owl territories, and rufous birds defended more wooded territories than grey ones. Thus, the differential parasitaemia between colour morphs in tawny owls may be the result of both a differential exposure to flying vectors depending on habitat selection and a differential colour-based susceptibility of individuals.

The most familiar examples of erectile tissue are the genitalia of mammals, notably the penis and clitoris. Among the soft-bodied invertebrates, erectile tissue is virtually unknown, even in sex organs. Here we report that the ligula, the copulatory organ that is a modification of an arm tip of male octopuses, is erectile in Octopus bimaculoides. The normally minute ligula was observed during an unsuccessful mating attempt to be engorged. Histological sections of the ligula reveal striking structural convergences with mammalian erectile tissue: large, well-vascularized internal cavities subdivided by networks of collagen fibres and enclosed by an array of collagen fibres. This internal structure differs markedly from the dense, three-dimensional array of muscles and connective tissues seen in the other octopodid ligulae examined. Erectile tissue may represent an evolutionary compromise between opposing selective forces. Small ligulae may be advantageous because O. bimaculoides hunts in daylight and the white-faced ligula may be conspicuous to predators. Large ligulae, however, may be advantageous if the intense sexual selection thought to occur among octopodids selects for large ligulae, which can transfer larger spermatophores that carry more sperm. An erectile ligula may minimize the impact of these opposing selective forces.

5th International Symposium on Tropical Biology: African Biodiversity – Molecules, Organisms, Ecosystems 2–6 May 2004