A comparative study was conducted on the ontogenetic variation in morphometry of a total of 29 shell-bearing molluscan species occurring on an intertidal stony shore in south-western Japan. The relationships between shell size and total weight and between shell size and flesh weight were all highly significant on logarithmic scales with the slopes having values of about three. The arcsine-transformed proportion of shell weight out of total weight varied among and within different morphological/taxonomic groups, ranging from 58.6% in Acanthochiton defilippi to 76.4% in Nerita albicilla. The allometry of shell weight was analysed by regressing the arcsine transformed values of the proportion of shell weight against total weight in each species. The slope (β) of the regression varied substantially among different taxa, with all three possible cases, i.e. β > 0, β [ape ] 0 and β < 0, being observed. Thus, depending on molluscan species, the proportion of shell mass either (1) increases, (2) does not change, or (3) decreases with increasing body mass. Variation in the value of β was to some extent explained by the proportion of shell mass of young individuals of each species; species with relatively high proportions of shell mass in small individuals tended to have low β. Interspecifically, it was shown that shell mass scaled in proportion to body mass for this assemblage of 29 species. Consideration was given to the theoretical background of variation in shell morphometry, with particular reference to the shell as a defence structure.

The idea that the size of animal populations may be regulated by factors intrinsic to them, such as behaviour, has a long history in ecology. Although this idea is now rejected as a general mechanism, it may apply in some species where females are damaged during courtship attempts, such as the Mediterranean tortoise Testudo hermanni. The sex ratios (adult males : adult females) of most dense Greek populations were more extreme (over 1.5:1) than could be accounted for by the earlier age at maturity of males, and some ranged to over 6:1. The sex ratio was correlated with the population density of adult males and the frequency of courtship attempts on females, and negatively correlated with the longevity of females. A high population density of males limits the density of adult females. This intrinsic regulation of population size is a consequence, rather than a goal, of a particular type of courtship behaviour (persistent thrusts by the male using a tail with a sharp terminal spur) in T. hermanni. Existing population densities at many Greek sites are probably unnaturally high, owing to the reduction of natural predators.

The dive duration of 16 underyearling (6–12 months old) southern elephant seals Mirounga leonina during their second trip to sea was investigated using geolocating time–depth recorders. Underyearling seals had a lesser diving ability, with respect to duration and depth, than adult southern elephant seals. Individual underyearlings dived for average durations of up to 20.3 min and depths up to 416 m compared to durations and depths of 36.9 min and 589 m, respectively for adults. Dive duration was positively related to their body mass at departure, indicating that smaller seals were limited to shorter dive durations, perhaps as a result of their lesser aerobic capacity. All seals often exceeded their theoretical aerobic dive limit (average of 22.1 ± 18.1%). The number of dives exceeding the theoretical aerobic dive limit was not related to mass, suggesting that factors other than mass, such as foraging location or prey availability, may have been responsible for differences in diving effort. Foraging ability, indicated by the ability of the seals to follow vertically moving prey, was positively related to seal mass, indicating that small mass restricted foraging ability. The shorter dive durations of the smaller seals inferred that they had shallower dive depths in which to search for prey, thus restricting foraging ability. Although foraging ability was restricted by size, foraging success was found to be inversely related to mass, the smaller seals gaining a higher proportion of blubber than larger seals during their foraging trips. Thus, despite smaller seals being restricted to shallower depths and shorter durations, their foraging success was not affected.

During an intensive meiofauna sampling campaign in intertidal seagrass beds along the Caribbean coast of the Yucatán Peninsula (Mexico), 131 specimens of Lightiella incisa (Cephalocarida, Crustacea) were recovered from the sediment. Two-thirds of the specimens were adults, one-third were pre-adults. This collection is the first record of this minute primitive crustacean in the western part of the Caribbean Sea, and extends the known range 3000 km from the type locality of Hastings Bay, Barbados. A detailed sampling protocol and environmental data made it possible to study the microhabitat preferences of this species, and perhaps for cephalocarids in general for the first time. The vertical distribution of L. incisa in the sediment showed a maximum density in deeper layers, i.e. 3–4 and 4–5 cm depth. Nitrate and nitrite concentrations seem to be most closely related to the distribution of L. incisa. It was clear that L. incisa followed polychaetes to deeper sediment layers. In this study we state that L. incisa is an endobenthic species occupying anoxic sediments oxygenated by bioturbation (e.g. Polychaeta) rather than being an animal living in the oxygenated top layers.

Mortality is the most extreme effect of ultraviolet-B radiation (UV-B; 280–315 nm) on living organisms, but sublethal effects of UV-B may also be important. Moreover, there may be population differences in response to UV-B, but this aspect has not been well explored for animal populations. Amphibians have been a model system for studying the detrimental effects of UV-B. However, previous research on the effects of UV-B on amphibians has mainly focused on embryos. Few studies have investigated how UV-B affects larvae. We examined potential sublethal effects of UV-B on the long-toed salamander Ambystoma macrodactylum from two different populations. Observational data from field transects indicated that larvae are potentially exposed to UV-B in their natural habitat. Choice tests indicated that larvae select shaded regions more often than those in the sun, but do not directly distinguish between regions with high and low UV-B. Laboratory experiments indicated a survivorship difference between individuals from low- and high-elevation sites. When exposed to relatively low levels of UV-B individuals from low-elevation sites experienced higher mortality than controls (no UV-B). There were no differences in mortality between UV-exposed and non-exposed larvae from the high-elevation population. Although mortality of UV-B exposed larvae was not significantly different from controls in the high-elevation population, sublethal effects on growth were observed. Individuals from the high-elevation site grew significantly less when exposed to UV-B than individuals shielded from UV-B. Our study demonstrates that larval A. macrodactylum are exposed to UV-B in nature, that UV-B exposure can cause mortality as well as having sublethal effects on growth and that there are potential population differences in sensitivity to UV-B radiation.

The shallow, offshore, hypersaline (∼ 60‰), benthic marine environment of Shark Bay, Western Australia, is dominated by the cockle Fragum erugatum. This small (< ∼ 11 mm long) bivalve occurs in large numbers (4000/m2) and probably completes its life cycle in 1 year. Cyclones with a periodicity of ∼ 50 years have, over the last 5000 years, deposited huge numbers of the shells of F. erugatum onto the shore as windrows, creating the unique Shell Beach, or Hamelin Coquina. In most anatomical respects, F. erugatum is a typical cockle, with a powerful digging foot, siphons formed by fusion of the inner mantle folds only, plicate ctenidia with a ciliation of type C(1) and powerful rejectory currents on the visceral mass and mantle. It is thus able to collect filterable material and digest it. The labial palps are, however, reduced, allowing the ingestion of only the finest particles of food via the acceptance tracts in the ctenidial axes and distal oral grooves. The waters of Shark Bay are hypersaline and oligotrophic, so what is the food source that supports such large numbers of filter-feeding bivalves? Fragum erugatum possesses symbiotic zooxanthellae, as do its close relatives the giant clams (Tridacnidae), and probably obtains the same nutritional benefits from the association, which may facilitate survival in the hyperosmotic environment of Shark Bay. The association between giant clams and their zooxanthellae enhances shell growth and results in a long life expectancy and gigantism. Conversely, in F. erugatum the association facilitates a large population size (but short life expectancy), allowing it to dominate a unique, hypersaline, oligotrophic environment. Like giant clams, F. erugatum possesses a zooxanthella tube system linking the digestive diverticula of the stomach with the kidneys. Either accidentally or periodically, ingested zooxanthellae are transferred from the gut, via this tube, along with senescent zooxanthellae from the blood haemocoel, to the kidney tubules for lysosomal hydrolysis and eventual expulsion. In the light of this discovery, the functioning of the recently confirmed zooxanthella tube system in the Tridacnidae needs re-examination and re-evaluation.

Many hypotheses have been proposed to account for geographic variations in species diversity. In general these relate to some aspect of climate, particularly climatic variables measuring available or potential energy, but while these relate directly to plant diversity they may only indirectly affect mammal species richness. We have examined these relationships by mapping and correlating mammal species richness in southern Africa (n= 285 species) with 15 climatic variables, two topographic variables, and woody plant species richness (n = 1359 species). The effect of area on richness was held a constant by using an equal-area grid cell matrix superimposed on species range maps, with each grid cell equal to 25 000 km2. We found that variability in the plant species richness alone accounts for 75% of the variability in mammal species richness. Of the climatic variables, only thermal seasonality approaches this figure, accounting for 69% of the variability, while annual measures of temperature, precipitation or energy account for only 14–35% of variability. Differences from North American mammal diversity studies, where annual temperature, and hence annual potential evapotranspiration (PET), have been found to be more important, are attributed in part to southern Africa's climate and vegetation being largely temperate to tropical, as opposed to temperate to polar in North America. By distinguishing different types of mammal based on size, spatial and dietary guilds, other differences emerge. Strong correlations with annual temperature exist only for large mammals, accounting for 60–67% of the variability in species richness of large mammals compared with <20% for small mammals. Small mammals are strongly correlated with other climatic or vegetation parameters, especially plant richness and thermal seasonality; frugivorous and insectivorous mammal richness is correlated with thermal seasonality and minimum monthly PET; and arboreal and aerial species richness is correlated with plant richness, thermal seasonality and minimum monthly PET. Up to 77% of the variability in richness of arboreal, frugivorous and insectivorous species can be explained by woody plant richness, compared with only 38–48% of the variability in terrestrial herbivores. It is clear from this that different kinds of mammals are differentially affected by climatic and environmental factors, and this explains some of the discrepancies found in earlier studies where no distinction was made between different sizes or guilds of mammal. This result has implications both for the conservation of mammalian communities at the present time and for understanding the evolution and structure of mammalian communities in the past.

The relationships between landscape, land-use and the number of territories of eight species of birds, most with declining populations, were studied over 3 years in an area of largely arable agriculture in eastern England. Two species, skylark Alauda arvensis and yellow wagtail Motacilla flava, established territories within crops. More than half of skylark territories were in autumn-sown cereals, but densities were higher in set-aside and spring-sown crops, while a conservation grassland cut for hay in late July held the highest density. Skylarks did not switch territories in winter cereals for other crops as the breeding season progressed. Weak preferences were found for spring-sown crops and weak avoidance of autumn-sown crops (i.e. there were fewer territories than expected from the area under autumn-sown crops). Skylarks showed preferences for set-aside and conservation grassland but other grassland was avoided. Skylark numbers were negatively associated with hedgerow length within tetrads. Most yellow wagtails nested in spring-sown crops, especially potatoes, for which there was a strong preference; most territories were in the largest fields. More than 75% of territories of turtle dove Streptopelia turtur were associated with residential areas, scrub and woodland, with hedges used much less often than expected from their occurrence. Grass was a strongly preferred land-use. Linnets Carduelis cannabina were mainly located in small areas of scrub and there was an association with winter oil-seed rape. Common whitethroats Sylvia communis showed preferences for hedges, especially for tall hedges, though many territories were situated in field boundaries with only scattered shrubs. Lesser whitethroats S. curruca preferred only tall hedges. Both species had more territories adjacent to grass than expected, with common whitethroat also showing a preference for winter oil-seed rape. Yellowhammers Emberiza citrinella declined over the 3 years of the study. Territories were strongly associated with tall hedges, but preferences for crops were weak. The small number of reed bunting E. schoeniclus territories were almost all by water, with a preference for adjacent grass. Possible mechanisms for reversing the downward trends of bird populations on farmland are discussed.

The spatial and temporal compositions of rodent communities in habitats of the Badia region of north-east Jordan were investigated between 1996 and 1997. Live grid-trapping and spot-lighting techniques were employed to estimate rodent densities. Sixteen environmental variables including soil content, vegetation cover and relief were recorded within the study sites. TWINSPAN was used to derive six habitat classes based on the similarity of their rodent communities. These were hammada, harrat, marab, wadi and two types of sand dunes. The derived classifications were similar to the original categorization of habitat types based on ground-truthed observations of the sites selected from satellite imagery. Multivariate statistical analyses (TWINSPAN and DECORANA) revealed three major rodent groups in relation to local habitat types: (1) petrophiles: Gerbillus dasyurus, Acomys russatus and Meriones tristrami; (2) open hammada-dwelling species: Jaculus jaculus, Gerbillus henleyi and Meriones crassus; (3) psammophiles: Meriones libycus, Gerbillus nanus and Gerbillus cheesmani. Species richness was highest in marabs and lowest in red sand dunes. Species diversity (Hill's index) was highest in sand dunes and lowest in red sand dunes. Rodent biomass was highest in sand dunes and lowest in wadis. CANOCO showed rodent community composition to be correlated with vegetation parameters and soil content. TWINSPAN grouping and DECORANA ordination of rodent species provides some evidence for habitat preference, size disparity and competition as mechanisms of resource partitioning facilitating coexistence.

Sperm length varies considerably amongst closely related species and the variation can be positively related to interspecific variation in the risk of sperm competition. In addition, a comparative study has shown that traits involved in sexual selection may often be sex linked. This study examined the quantitative genetics of sperm length in the yellow dung fly Scathophaga stercoraria (L.). There was a significant heritability of sperm length, h2 = 0.673. In addition, a significant non-linear epistatic interaction between determinants on the X chromosome and on the autosomes was identified in a three-generation breeding experiment. The ratio of the additive to epistatic components was approx. 5 : 1, though this is probably an overestimate, and the total proportion of the variance in sperm length accounted for by these genetic factors was > 80%. I argue that selection acting in both males and females is relevant for the evolution of this trait.

An analysis of 59 droppings of the greater noctule Nyctalus lasiopterus, collected either during direct handling of the bat or from the bat-boxes used as shelters in the Pian di Novello Natural Reserve (Tuscany, Italy), has shown that it is a partial carnivore. The content of the samples, collected in October and November of 1995 and in September and October of 1996 and 1997, consisted mainly of bird feathers identified as those of the robin Erithacus rubecula and the blue tit Parus caeruleus. The presence of feathers during the 3 consecutive years of the study period confirms that the diet of the greater noctule in this area is not based exclusively on arthropods as was previously suggested.

Burrow systems of two coastal populations (El Alamo and Los Maitenes) of the social octodontid rodent Spalacopus cyanus were studied in central Chile. Tunnel systems were estimated to be up to 600 m long, ran at a depth of 15 cm and had a diameter of 6 cm. Tunnel openings were usually unplugged, and a minor preference toward southern and south-eastern direction of entrances was apparent. Nests, frequently found in the root system of Berberis actinacantha at a depth of 30 cm, consisted of grasses, roots and plastic bags. Nests serve for sleep, care of the pups and as latrines. Many staphylinid beetles of the genus Edrabius and other invertebrates were found in the breeding nests. Food chambers contained up to 13.2 kg of bulbs of the geophyte Dioscorea longipes collected by a single colony consisting of 26 animals (including 10 adults) and were frequently found at El Alamo. However, no bulbs were found at Los Maitenes, where the coruros forage above ground on leaves of Convolvulus arvensis within a radius of about 10 cm of the entrances. Apparently, the burrow design is also affected by food availability, soil quality, and colony size.

The density of nests of the magpie goose Anseranas semipalmata on the Mary River floodplain fluctuated markedly during 1988–93, failing almost completely in unfavourable (El Niño) years. Nest density and timing of nesting were strongly correlated with variations in the time of onset of the wet season, but were much less sensitive to rainfall quanta in the mid- to late wet season. Nest densities were higher and nesting was initiated earlier in breeding seasons preceded by sustained rainfalls during the transition from dry to wet seasons. Clutch sizes were slightly larger in years of early wet-season onset. Within seasons, later clutches contained fewer eggs and the eggs were smaller, probably as a consequence of later nesting by younger birds. Second clutches from a small sample of marked re-nesting birds and a pulse of nesting after flooding losses, contained similar numbers of eggs to first clutches, but the eggs were larger. Dependence of nesting on events occurring months before clutch initiation, when birds are using habitats distant from nesting colonies, illustrates the importance of integrated management of floodplain systems to meet year-round habitat needs, and the risks posed by homogenization of wetlands by improvement of pasture for grazing.

In this study, glycogen distribution during the development of larval salivary glands in two Drosophila species (D. melanogaster and D. auraria) was examined using the osmium tetroxide–potassium ferrocyanide technique at the ultrastructural level. Glycogen particles are found in big clumps in the salivary gland cells of D. melanogaster during the early third instar, mainly at the basal part of the cells; they are also found as scattered particles in the cytoplasm and very close to the apical plasma membrane during the secretory activity at this developmental stage. During the middle third instar, where the production of ‘glue’ secretory granules begins, glycogen particles are mainly scattered and they are seen near the Golgi complexes and secretory granules. No glycogen particles are seen during the late third instar and secretion of ‘glue’ secretory granules. Re-formation of glycogen begins after spiracle eversion. In the larval salivary gland cells of D. auraria, glycogen particles (scattered and in clumps) are seen in every developmental stage. In the larval fat body cells of both species, many huge clumps of glycogen particles are seen, independent of the developmental stage. These results indicate that glycogen provides an important source of energy during development of Drosophila salivary glands, but different species use glycogen at different metabolic pathways, according to their needs.

This study examines the behavioural responses to ultrasound in 52 species from the family Cicindelidae using both tethered flight and non-flight assays. Tethered flying tiger beetles respond to trains of bat-like ultrasonic pulses with a short-latency, multi-component behaviour. There was no variation in the nature of the behavioural responses regardless of geographical distribution or phylogenetic position. Lowest mean behavioural thresholds lie predominantly between 30 and 45 kHz. Sensitivity, however, varies widely, and several species do not respond at all in these assays. The lowest thresholds for responders are most often between 70 and 80 dB SPL. Almost all subgenera of North American tiger beetles in the genus Cicindela have at least some species with low-threshold acoustic behaviour. The single exception is the large subgenus Cicindela where all species are completely unresponsive or have very high thresholds. There was little relationship between habitat and responsiveness to ultrasound, but there is a strong correlation with seasonal activity – species with adults active in the spring and autumn (all in the subgenus Cicindela) do not show ultrasound-triggered behaviour whereas summer-active species generally do. Superimposing these data on a current phylogeny of the North American tiger beetles suggests that acoustic behaviour (and hearing) is a shared primitive trait among the taxa examined here and that there have been at least five independent losses of this character.

Fox culling practices in three contrasting rural regions (1280–2320 km2) of Britain were investigated by questionnaire surveys of landowners and tenant farmers. Between 50 and 52% of all farmers identified in each region contributed to the survey (total number of replies = 1123). Fox culling was widespread in all regions, with 70–95% of farmers involved either directly or indirectly as hosts. Motivation for culling foxes and the methods employed reflected regional variation in agricultural and game-shooting interests. Social factors associated with fox-hunting for sport also played an important role in one region. The contribution to the total fox cull made by communally organized groups operating over large tracts of farmland, and the efforts of individual farmers at a local scale, also varied regionally. The numbers of foxes culled were close to published estimates of annual productivity in British fox populations. Deliberate culling was therefore likely to be the chief cause of fox mortality in these regions. The marked differences in culling practices between these regions provide a strong case that the impact of culling on fox population dynamics must be assessed for regions of this size, as well as at a more local scale. Studies at a national scale (e.g. the whole of Britain) are probably of little biological or sociological significance. The success of different interest groups in achieving their aims, and the consequences of any change in culling practices must also be considered at a similar geographical scale.

Reproductive data on individually known free-ranging red-necked wallabies Macropus rufogriseus banksianus were obtained over a 6 year period. Although this subspecies is essentially a non-seasonal continuous breeder, more young wallabies emerged permanently from the pouch in spring than in any other season. This partial seasonality of breeding was the combined result of seasonal variation in duration of pouch lives, a tendency for the first young of females to emerge permanently in spring, and seasonal variation in the incidence of reproductive interruptions. It is proposed that the adaptive significance of this partial seasonality is that it maximizes juvenile survival while maintaining a high reproductive rate.

Pristina silvicola and P. terrena spp. nov. are described from soil samples of the primary rain forest at the Brazilian Agroforestry Research Facility near Manaus, Brazil. Living and preserved specimens were studied. The species are among the smallest oligochaetes known (1–1.5 mm long) but they are conspicuous by their brilliant, highly refractile coelomocytes. Pristina silvicola is also described from sexually mature specimens. Its character combination invalidates Pristinella as a genus separate from Pristina. Both genera are reunited as Pristina. Pristina silvicola and P. terrena, species which lack a proboscis, share a character combination that is unique in the genus: stomach absent, first nephridia in segment VII, ventral chaetae uniform with upper tooth not longer than lower. They differ from one another in the shape of the brain and in other details of the chaetae.

Embryonic development time has been of long-standing interest to physiologists and ecologists because of its importance in understanding the behaviour and ecology of reproduction, and the evolution of reproductive strategies in animals. Yet, the relationship of embryonic development time to both neonate mass and incubation temperature remains poorly understood for most taxonomic groups. Here we define the relationship of embryonic development time to neonate mass (embryo mass at birth) and incubation temperature for a broad range of animals, ectothermic and endothermic, invertebrate and vertebrate, microscopic and gigantic. We begin by establishing the relationship of embryonic development time to neonate mass for a broad array of zooplankton, fishes and amphibians for temperatures from 5 to 20°C. Next, we compare the relationships of embryonic development time to neonate mass in these aquatic ectotherms to those for terrestrial ectotherms (reptiles) and endotherms (birds and mammals) in terms of degree-days. The similar nature of these relationships allows us to define embryonic development time as a function of neonate mass for many of the species considered here with a single equation in terms of degree-days for incubation temperatures ranging from 5 to 38°C. This relationship establishes a basis by which to compare differences in embryonic development time among species.

Spotlight transect surveys with distance sampling were used to estimate spring (pre-breeding) and autumn (post-production) fox Vulpes vulpes densities in three contrasting rural areas of Britain during 1995–97. This was the first attempt in Britain to measure and compare fox densities over large geographical areas (630–1460 km2). Mean post-production fox abundance was estimated to be 0.90/km2, 2.62/km2, and 0.59/km2 in mid-Wales, the east Midlands and East Anglia, falling to pre-breeding levels of 0.41/km2, 1.17/km2, and 0.16//km2 in spring. As relative measures of regional density, these estimates are strongly supported by independent indices of fox abundance, and by the simultaneous survey of two sympatric species, the badger Meles meles and brown hare Lepus europaeus, which demonstrate the absence of any terrain-related bias. Absolute abundance is less easy to verify, but estimates of spring density based on breeding earth censuses support the transect surveys. For two of the three regions, fox density was close to levels predicted by extrapolation on the basis of landscape, but in the third region (East Anglia), fox density was substantially below prediction. Thus, results failed to support a hypothesis that fox abundance can be predicted solely on the basis of landscape and its close correlates. Rather, they favoured a competing hypothesis that an independent factor determines fox abundance in some regions. A likely factor is culling by man.