The dentary, a component of the transient marginal dentition found in the mandible of juveniles of the living Australian lungfish Neoceratodus forsteri, is a tooth plate exactly comparable to the tooth plates with radiating ridges that make up the marginal dentitions of Devonian dipnoans like Andreyevichthys, Orlovichthys and Ichnomylax. In N. forsteri, the dentary consists of two ridges, set almost in line with each other, and growing by the addition of cusps, of increasing sizes, to the extremity of each ridge. It is therefore equivalent to two ridges of a more normal tooth plate with radiating ridges. Despite its appearance, as a long row of sharp cusps ankylosed to a slender bone, and its position, embedded in soft tissue above the anterolabial margin of Meckel's cartilage, it is a tooth plate and is not comparable to the marginal dentitions of other vertebrates. Structure and development of the transient marginal dentition of this lungfish is another indication that dipnoans may not be the sister group of tetrapods.

This study represents the first systematic investigation of long-term anhydrobiotic survival in tardigrades, rotifers and nematodes inhabiting mosses and lichens. Sixty-three different samples from public and private collections, kept dry for 9–138 years, were examined. Rotifers of the genus Mniobia and the eutardigrade Ramazzottius oberhaeuseri (hatched from eggs) were found alive from one of the samples (9 years old). These observations represent the longest record for rotifers in the anhydrobiotic state. For tardigrades, our results confirm previous reports on the upper limit of anhydrobiotic survival under atmospheric oxygen conditions. This study suggests the possibility that tardigrade eggs are able to withstand longer periods in anhydrobiosis than animals. Some problems related to the evaluation of long-term anhydrobiotic survival, such as contamination and chemical treatments of samples, are reported. The possible role of the microenvironment in which the anhydrobiotic animals are kept is discussed.

Animal diets crucially affect fitness, yet many aspects of their ultimate determinants are unknown. The distribution and extent of herbivory in lizards, its evolutionary history, and ecological factors that may favour it are discussed. Most lizards are exclusively or primarily carnivorous, yet many species eat some plants and a few are almost exclusively herbivorous. Based on a literature survey of diets of over 450 lizard species, the distribution and degree of omnivory and herbivory are described. Some plants occur in the diets of slightly over half of lizard species, and plants formed 10% or more of the dietary volume of 12.1% of species, and 90% or more of the diet of 0.8% of species. The greatest percentage of omnivorous species (> 10% plant diet), over 30% in each, and highest mean percentage plant matter in the diet are in Iguanidae, Corytophanidae, Gerrhosauridae, Agamidae, Xantusiidae, and Tropiduridae. Numerous other omnivores occur in Lacertidae and Scincidae and fewer in several additional families. Herbivorous lizards (> 90% plant volume) tend to be folivorous and to possess adaptations for processing leaves, including specialized dentition for cutting or reducing leaves, elongated intestines, colic valves that slow passage of food, and intestinal flora that digest cellulose. Omnivorous lizards lacking such specializations may eat some leaves, but consume much more fruit, flowers, and seeds, plant parts that are easy to digest, likely to be very abundant seasonally, and may be highly nutritious. Some lizards eat nectar and pollen; even sap is eaten by at least one gecko. Ontogenetic increase in plant consumption and decrease in prey consumption is known, but its generality has been controversial. Such ontogeny has been demonstrated in three iguanid species, a skink, a lacertid, two tropidurids, a phrynosomatid, and two corytophanids, but it does not occur in some other species. The importance of specific foods may vary with age. Omnivory and/or herbivory have originated in many lizard families, with at least nine origins in Iguania and 23 in Scleroglossa. Origins have been rare in Gekkonoidea and Anguimorpha and common in Scincomorpha, especially in Lacertidae and Scincidae. Losses of omnivory have been much less frequent than gains. Only a few origins can account for all the herbivory in lizards. Concentrated changes tests show that there is a significant association in Lacertidae, Lacertiformes, Lacertoidea, Scincidae, and Scleroglossa between insularity and omnivory. Insular lizards may broaden their diets to compensate for limited availability of prey. Addition of other factors that reduce availability of prey, i.e. extreme aridity and cave-dwelling, to insularity, strengthened the relationship to omnivory in Lacertidae and Lacertoidea. We were unable to demonstrate a role of aridity independent of insularity, but present anecdotal evidence suggests that it may promote evolution of plant consumption. Large body size in lizards has long been associated with herbivory, and more recently, with omnivory in lacertid lizards. Using a conventional regression approach in which each species is considered to supply an independent data point, this relationship was confirmed for all lizards. Although larger species have diets with more plants, plant consumption accounts for only 9% of the variation in body length, which is not surprising given that other factors such as predation, competition, and sexual selection affect body size. The frequency of transitions body size associated with transitions to omnivory or carnivory was also examined. In Iguania, Scleroglossa, and all lizards, transitions supporting the hypothesis that omnivory favours increase in body size were significantly more frequent than non-supporting transitions. This suggests that substantial plant consumption favours evolution of larger size, probably because of the energetic considerations first presented by Pough (1973). Because actively foraging lizards move widely through the habitat to locate prey and tongue-flick to locate prey by chemical cues, we hypothesized that they may be more likely to evolve omnivory than ambush foragers, which wait motionless for prey and do not tongue-flick to locate or identify prey. The basis of this prediction is that the wider seaching of active foragers predisposes them to contact with a greater variety and quantity of plants and that chemosensory tongue-flicking used by omnivores to identify plant food might be easier to evolve in active foragers that already use pre-chemical discrimination. The prediction is supported by a significantly greater per species frequency of origins of omnivory by active foragers than by ambushers. A scenario for the progressive evolution of omnivory and herbivory from ancestrally carnivorous lizards is discussed.

Because sensory capacities and responsiveness must correspond to adaptively important environmental cues, they may require evolutionary modification to match shifts in the adaptive milieu. Many lizards identify prey by tongue-flicking, especially actively foraging species of Scleroglossa, the speciose lizard taxon that includes snakes. Correspondence between diet and chemosensory responsiveness, although known in two genera of colubrid snakes, has not been established in lizards because most species are generalist predators. Omnivory and herbivory are uncommon among scleroglossans, but have evolved frequently enough to permit tests of the hypothesis that shifts to plant consumption have been accompanied by acquisition of responsiveness to plant food chemicals. Based on literature surveys I traced the evolution of scleroglossan lizard diet and food chemical discrimination. Three tests taking phylogenetic relationships into account (concentrated changes tests, Pagel's tests, and a modification of Ridley's test) showed that correlated evolution has occurred, with strong responses to plant chemicals having evolved convergently in at least five taxa that underwent shifts from insectivory to omnivory or herbivory. In all four origins of omnivory and herbivory in taxa derived from ancestral active foragers, lizards retained prey chemical discrimination. In the single origin of omnivory in an ancestrally ambush foraging taxon, both plant and prey chemical discrimination evolved de novo. These findings show that one aspect of chemosensory identification of food has been evolutionarily adjusted to diet in a major group of vertebrates.

Diploid and tetraploid populations of the leptodactylid frog Odontophrynus americanus were studied in the Cordoba province (central Argentine) to evaluate whether they represent a cryptic species pair rather than forms of the same species as they are considered at present. We examined three independent character complexes (external morphology, advertisement calls, allozymes) and quantified the character-specific state of differentiation between diploids and tetraploids in comparison to that of the congeneric and widely sympatric O. occidentalis. Multivariate analysis of 15 morphometric characters indicated a remarkable degree of differention between both forms, but did not permit an unequivocal identification of individuals (rate of erroneous classification: 25%), whereas all O. occidentalis were classified correctly. In contrast, the temporal structure of the advertisement call permitted a distinction of diploids, tetraploids and O. occidentalis even based on a single call. The latter differed from the other by producing a call consisting of several pulse trains. The pulse rate of the O. americanus call, which consists of a single pulse train, was significantly lower in tetraploids than in diploids. The allozyme pattern and the corresponding allele frequencies indicated a close relationship among the three Odontophrynus taxa, but genetic distances obtained suggested a differentiation of gene pools at the level of species. Considering the degree of differentiation demonstrated in this study, the ploidy and the different geographical distribution, we conclude that diploids and tetraploids represent two species, similar to its North American counterpart Hyla chrysoscelis/H. versicolor. As the name O. americanus refers to tetraploids collected near Buenos Aires (Argentina), we describe the diploids as the new species Odontophrynus cordobae sp. nov.

The alarm vocalizations of the whistling rats Parotomys brantsii and P. littledalei were investigated at the Goegap Nature Reserve in the Northern Cape, South Africa, where they occur sympatrically. Parotomys brantsii's call is a single note vocalization, characterized by an upward frequency sweep and high frequency plateau with a dominant frequency of 10.0 ± 0.3 kHz and duration of 164 ± 11 ms. The alarm whistle of P. littledalei has three overlapping components and is both shorter (53 ± 5 ms) and lower in dominant frequency (7.7 ± 0.1 kHz) than that of P. brantsii. The frequency bandwidth of P. littledalei calls (10.2 ± 0.7 kHz) is significantly higher than that of P. brantsii (6.8 ± 0.4 kHz). These significant distinctions are attributed to habitat preferences of the two species. Our data support the acoustic adaptation hypothesis in that P. littledalei, which inhabits a more closed habitat, has calls which are lower in frequency than P. brantsii calls, but contrary to the hypothesis, P. brantsii calls do not show greater frequency modulation than those of P. littledalei. Despite these differences, the alarm calls of the two species are both high-pitched, and may have converged in structure to be difficult for predators to locate.

Cerci are paired, sensory appendages extending from the terminal abdominal segment of crickets. While the cerci are acutely sensitive to air currents and thereby function in the detection of potential predators, they are also known to play a role in co-ordinating movements of males and females during copulation. The role of the male's cerci at four stages of the mating sequence (courtship, copulation, mate guarding and spermatophore removal) was examined by experimentally removing the cerci of male decorated crickets Gryllodes sigillatus and comparing their mating success with that of control males. The mating success of cercectomized males was significantly reduced relative to control males, primarily because of their greater inability to induce females to mount. Even when they succeeded in securing an initial mount, cercectomized males took significantly longer to transfer a spermatophore than did control males. Cercectomy had no influence on the efficacy of post-copulatory mate guarding by males, nor did females discriminate against cercectomized males by removing their spermatophores sooner than those of control males. We conclude that the primary function of the male's cerci in sexual interactions in G. sigillatus is to provide tactile stimuli to females that either elicit or guide their mounting response.

The Australian sleepy lizard Tiliqua rugosa forms socially monogamous pair bonds for 6 to 8 weeks each spring before mating occurs. This behaviour could not be explained by any hypothesis involving males helping to rear their young, because pairs split up soon after mating, and males seem to have no contact with the offspring of their partners. Short monogamous associations in other lizard species are often interpreted as mate guarding by the male to assure paternity. The mate guarding hypothesis was tested by experimental separation of pairs at various times during the pairing season. Data from 73 trials indicated that males were more likely to return to females than vice versa, and that the tendency of males to return to females increased as the time of mating approached. Also, reunion was more likely in pairs that had a greater tendency to remain together during the season. These results are consistent with predictions that the monogamous relationship is a form of mate guarding by males. However, the incidence of females re-uniting with males, and the long duration of pair bonds before mating occurs are not predicted by a mate guarding hypothesis. There may be additional explanations for monogamous pairing in the sleepy lizard.

The Brazilian tree-frog Corythomantis greeningi inhabits the Caatinga, a semi-arid habitat. This species exhibits putative adaptations to a dry environment, including a flat head, co-ossification of the cranial skin, and phragmotic behaviour (retreat to crevices using the head to seal the entrance). Real frogs were compared with agar models to study water balance under simulated Caatinga conditions and to investigate the ability of C. greeningi to find small water sources. The benefits of skin co-ossification were also studied by comparing agar models with and without nail polish on the head. Tree-frogs repeatedly preferred a humid test tube out of 10 possible choices, and adopted phragmotic behaviour inside it. In both agar models and tree-frogs, total water evaporation increased with body size, but relative water loss was higher in smaller individuals. The presence of nail polish on agar models barely reduced water loss, suggesting that cranial skin co-ossification has a small role in water economy. Although both models and tree-frogs evaporated about 90% more water when exposed than when phragmotic, tree-frogs evaporated about 50% less water than agar models at any test condition. We conclude that reduced skin permeability, phragmotic behaviour and a keen capacity to identify humid crevices, explain the success of this species in a semi-arid habitat.

The development of the male duct and spermatheca is studied in three species of the marine Limnodriloidinae (Tubificidae): Limnodriloides rubicundus; Tectidrilus bori; Thalassodrilides ineri. All tubificids are hermaphroditic with paired male ducts, female ducts and, as a rule, spermathecae. The male duct comprises a funnel, followed by a vas deferens, an atrium and, frequently, a copulatory structure. There may also be a diffuse or compact prostate gland in association with the male duct. In the three species studied, the funnel and vas deferens originate from peritoneal (mesodermal) cells in the posterior septa of the testes segment. The atrium develops from an invagination of the epidermis (ectoderm). The vas deferens and atrium subsequently connect to each other, and a continuous duct from the testes segment to the exterior is formed. The prostate gland originates from large peritoneal cells occurring in a delimited area on the outer surface of the atrium; other small peritoneal cells surrounding the whole atrium give rise to muscle fibres. The spermatheca develops from an invagination of the epidermis, and is thus of ectodermal origin. The morphology and position of the genital ducts have been and are important for the classification of the oligochaetes. However, different parts of the male duct have been named without regard to whether they are homologous or not. One way to establish stronger primary hypotheses of homology is to study the detailed morphology and/or the development of the genital ducts.

The ecology and feeding biology of two shell-burrowing polydorids associated with hermit crabs from the Philippines were investigated. Polydora umangivora and P. robi were found in shells of 15 and 28 gastropod species, respectively, occupied by nine hermit crab species. Polydora umangivora constructs U-shaped burrows in the outer shell while P. robi constructs burrows in the apex of the shell, extending to an opening along the columella of the upper body whorls. Polydora umangivora and P. robi preyed upon the embryos of three and seven species, respectively, of diogenid hermit crabs collected in the field. In laboratory feeding trials, P. robi ingested up to 230 developing eggs and 70 embryos of Calcinus gaimardii over a 6-h period. The impact of embryo predation is more apparent in hermit crab species that produce small broods of eggs (Paguristes runyanae) than in species that produce large broods of eggs (Calcinus gaimardii). Polydora robi transports the embryos to the mouth by a combination of muscular and ciliary action of the palps; ingestion follows breakage of the attachment stalk between embryo and pleopod seta. Invertebrates known and suspected to feed on host hermit crab eggs are reviewed and the evolution of polydorid/hermit crab symbioses is discussed.

The diet of striped possums Dactylopsila trivirgata inhabiting the tropical forests of far north Queensland, Australia, was investigated by observing foraging behaviour and analysing stomach samples collected opportunistically from dead animals. In contrast to non-dactylopsiline petaurids, which frequently use plant exudates as well as invertebrates, observations on the foraging behaviour of D. trivirgata indicate that it is an opportunistic forager feeding mainly on invertebrates. Animals occasionally fed on plant exudates but these contributed little to the diet. Nine different orders of invertebrates were present in stomach samples, with wood boring coleopteran and lepidopteran larvae, and adult hymenopterans and isopterans being most frequently represented in the diet. This is consistent with the unusual morphological characteristics of D. trivirgata's, such as their elongated fourth finger and powerful jaws, which appear to be adaptations for extracting prey such as wood-boring larvae. Two of the important prey taxa in the diet (alates of Formicidae, and larvae of Cerambycidae) had a very high fat content (44% and 40% of dry weight, respectively) suggesting that the animals may target prey of high nutritional value. Anatomical investigations indicated that, relative to body weight, the digestive tract of D. trivirgata was shorter than that of most other petaurids. These data further support the idea that D. trivirgata is more reliant on invertebrates than other members of the family Petauridae.

Can variation in egg size explain the local variation in tadpole growth and development of the common frog Rana temporaria or are other mechanisms, e.g. microevolution, involved? To study this, tadpoles were raised in outdoor tanks. Each tank housed tadpoles from one clutch. Eggs were collected during 2 years from six different ponds and their sizes were measured. Large eggs gave rise to tadpoles that grew and developed faster than those hatched from small eggs. Tadpoles from large eggs thus metamorphosed earlier but, because they grew for a shorter time, size at metamorphosis was not affected by initial egg size. Tadpoles from different ponds differed in strategy; after correcting for egg size effects, tadpoles from some ponds tended to metamorphose earlier and at a larger size than those from others. These ponds occasionally dry out during or before the tadpoles' period of metamorphosis. I argue that the detected pond differences are genetically based and represent a case of microevolution.

The fatty acid compositions of yolk lipids of eggs collected in the wild from five species of ducks (Anatidae) showing a range of dietary preferences, the king eider Somateria spectabilis, the lesser scaup Aythya affinis, the mallard Anas platyrhynchos, the green-winged teal Anas crecca and the gadwall Anas streperi, are reported. For all five species, the fatty acid profiles conformed to a similar pattern, characterized by relatively balanced proportions (w/w) of arachidonic (6.7–9.1%) and docosahexaenoic (5.9–7.0%) acids in yolk phospholipid. This contrasts markedly with the yolk phospholipid of current commercially-reared ducks where the proportion of arachidonic acid can be 10 times greater than that of docosahexaenoic acid. It was most notable that the similarities in yolk fatty acid profiles among the different species of wild ducks were achieved despite the considerable interspecies variation in dietary modes. It seems that, in this instance, genetic factors deriving from a common phylogeny may be more important than dietary differences in determining the fatty acid composition of yolk.

Physical characteristics of roost sites used by the lesser long-eared bat Nyctophilus geoffroyi and Gould's wattled bat Chalinolobus gouldii were investigated in a farmland–remnant vegetation mosaic and adjacent forested floodplain in south-eastern Australia. A total of 45 individuals of N. geoffroyi and 27 C. gouldii were fitted with radio-transmitters, resulting in the location of 139 and 89 roosts, respectively. Male N. geoffroyi roosted in trees, fallen and decayed timber and artificial structures. These roosts were low to the ground, mainly under bark and in cracks in timber. Roosts of female N. geoffroyi were located higher above ground, and all within trees. Maternity roosts were predominantly located in large dead trees, approximately twice the diameter of roost trees used by females outside the breeding season. No maternity roosts were found under bark, despite half the roosts used by non-breeding females being located in these situations. Both sexes roosted primarily in dead timber and used cavities where the narrowest dimension of the entrance was 2.5 cm. Most roosts of C. gouldii were in dead spouts on large, live river red gum Eucalyptus camaldulensis trees. Intraspecific differences in roost characteristics were less pronounced for this species. Despite access to the same roosting opportunities, there were marked differences in roost selection between N. geoffroyi and C. gouldii. Both species favoured large diameter trees, but differed significantly for all other measured variables: type of roost structure, condition of roost tree (live or dead), height of roost tree, height of roost, and entrance dimensions. Although these species are among the most widespread bats in Australia and are often considered to be habitat ‘generalists’, both displayed a high level of discrimination in the roosts used. Clearly, roosting requirements are a complex and important issue in the conservation of even the most common species of bats.

A survey of freshwater snails on Mafia Island has been conducted that mapped the distribution and, by using a timed searching strategy, documented the relative levels of abundance of species. Twenty-five freshwater habitats around the island were surveyed; snails were found in 15 sites (60%). From the total number of snails collected (n=240), prosobranchs (59%) outnumbered pulmonates (41%). Potential intermediate hosts of urinary schistosomiasis were encountered and these Bulinus species were further characterized by analysis of six enzyme systems (GPI, PGM, MDH, HBDH, GDH & AcP), by inspection of DNA sequence variation within mitochondrial cytochrome oxidase sub-unit I (COI) and nuclear ribosomal internal transcribed spacer (ITS). Three species of Bulinus were found: a single B. africanus group taxon, B. nasutus, and two B. forskalii group taxa, B. forskalii and a species presently identified as Bulinus sp. in this paper. The genera Pila, Lanistes and Bulinus were widespread across the island and dominated the fauna. The remaining taxa were found in lower numbers and often only at single sites. Three prosobranchs: Lanistes purpureus, Pila ovata and Melanoides tuberculata were found. In addition to Bulinus, the pulmonates included a small discoidal planorbid (?)Ceratophallus and an ancylid (a freshwater limpet). The factors that shape the dispersal and distribution of molluscs on Mafia were considered. Water chemistry could be an important variable as both pH (mean 6.37±0.99 SD) and conductivity (mean μS=149±135 SD) were significantly different from similar habitats on neighbouring Zanzibar Island (P<0.001). The Mafian fauna is clearly associated with that of mainland Africa and Madagascar.

The extant lungfish, including three genera, the Australian, South American and African lungfishes, retain a dentition that appeared first in the Devonian, in some of the oldest members of this group. The dentition consists of permanent tooth plates with persistent cusps that appear early in development of the fish. The cusps, separate early in development, form ridges that are arranged in a radiating pattern, and fusion of the cusps to each other and to the underlying jaw bone produces a tooth plate. The lungfish dentition is based on a template of mantle dentine that surrounds bone trabeculae enclosed in the tooth plate. The mantle layer is covered by enamel. In most derived dipnoans, this framework encloses two further forms of dentine, known as interdenteonal and circumdenteonal dentines. The tooth plates grow in area and in depth without evidence of macroscopic resorption of dentines or of enamel. Increase in size and changes in shape of lungfish tooth plates is actually achieved by a process involving microscopic remodelling of the bone contained within the margin of each tooth plate, and the later addition of new dentines and enamel within and around the bone. This is accomplished without creating weakness in the structural integrity of the tooth plate and bone complex, and proceeds in line with growth and remodelling of the jaw bones attached to the tooth plates.

The diet of the blackwidow spider Latrodectus lilianae (Araneae: Theridiidae) was studied in an arid shrub-steppe of south-eastern Spain during 1990–93. For the first 3 years, prey mummies attached to spider webs were collected once the spiders' activity period was finished, at the end of September. In the fourth year, webs were marked and checked bi-weekly from April to September during the activity period of the blackwidow spider. We identified 2106 prey items from 164 webs. Most prey were Tenebrionidae and Oniscidae, which together represented from 65.4% to 82.0% in frequency and from 78.6% to 92.0% in biomass of all prey. An analysis of selectivity comparing prey availability from prey collected in pitfalls and those collected in the webs showed that spiders preferred Tenebrionidae and Oniscidae. However, an analysis of prey size reflects also that spiders mostly selected prey ranging from 12.5 to 22.5 mm long, suggesting that prey size, rather than taxon, determines prey capture. Other predatory arthropods, as well as five small lizards, were found as prey of the blackwidow spider. This suggests that the blackwidow spider may play an essential role in regulating the food web and trophic structure in this community by preying on other species that potentially compete with or prey upon blackwidow spiders.

From what is known about the discovery of the gerenuk Litocranius walleri, the type locality is here restricted to the vicinity of Chisimaio, Somalia. Two discrete subspecies can be recognized. The smaller L. w. walleri occurs in north-east Tanzania, Kenya, southern Somalia and southern Ethiopia. The larger L. w. sclateri is restricted to Djibouti, northern Somalia and adjacent parts of northern Ethiopia and is present in very few protected areas.

During the 20th century, Mediterranean landscapes underwent extensive changes. In particular, decreasing grazing pressure combined with abandonment of agricultural uplands favoured the development of Mediterranean forests with a corresponding reduction of open habitats and landscape diversity. In some parts of the Mediterranean basin, including our study area, the reduction of open landscapes took place at the same time as a rapid decline in rabbits as a result of myxomatosis. This study assesses the impact of past changes in landscape and rabbit density on the density and the breeding performance of the eagle owl Bubo bubo, one of the largest predators of Mediterranean ecosystems. Eagle owl density, nest site structure and composition at the landscape level, diet and fecundity of 35 eagle owl nesting territories was analysed for 27 years. The study area is characterized by two distinct areas, the border of the massif and the interior, in which past changes acted differently. Eagle owls in the interior were simultaneously affected by the loss of rabbits, a shift to smaller prey, and by open areas reverting to forest. All of these factors reduced the foraging efficiency of the owls. When myxomatosis decimated the rabbit population, owls in the border area switched to other mammals, birds and fish, whereas in the interior, alternative prey were less abundant. The main impacts of reduced prey availability and landscape diversity on interior pairs were: (1) lower density of breeding pairs; (2) lower diversity in landscape structure and closer habitats; (3) lower richness and diversity in the diet; (4) later egg-laying dates; (5) lower productivity.