bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Natural Variation in Sex Ratio and Habitat Structure On Mate-Guarding Decisions in Amphipods (Crustacea)
Authors: Dick Jaimie T.A. , Elwood Robert W. 
Published: April 2008

AbstractWe employed field-based studies, with complementary laboratory-based studies, to investigate social and environmental influences on tactical mate-guarding decisions in amphipods (Crustacea). Firstly, we investigated variation in precopulatory mate-guarding duration in Cammarus duebeni celticus in relation to the social structure of natural populations. Variation in population density of up to two orders of magnitude had no effect on precopula duration, whereas guarding durations increased as the sex ratios of the populations became more male biased. That is, males have some ability to assess the probability of other males taking females into precopula and are prepared to guard for longer as this threat of male: male competition increases. A field demonstration of tactical shifts in reproductive behaviour in response to pertinent social conditions is thus provided. Secondly, the 'habitat segregation' hypothesis, which proposes that positive size-assortative pairing in amphipod populations arises due to variation in the use of micro-habitats, was tested in natural field populations and under laboratory conditions in Echinogammarus marinus. This was necessary in order to distinguish any purely environmental determinants of size-assortment from the role of active decisions by males concerning mate choice and male: male competition. The hypothesis was rejected on the grounds that size-assortative pairing arises under both heterogeneous and homogeneous environmental conditions. Further, in both study species, male and female body size were positively correlated with precopula duration. Thus, indirect competition for access to large, fecund females, based on the timing of male entry into precopula, together with direct aggression, provides the explanation for size-assortative pairing in amphipods.
Band Structure and Failures of Reproductive Suppression in a Cooperatively Breeding Carnivore, the Slender-Tailed Meerkat (Suricata Suricatta)
Authors: Doolan Sean P. , Macdonald David W. 
Published: April 2008

Abstract
The extent to which band structure influences the distribution of breeding activity is unknown for the slender-tailed meerkat Suricata suricatta, a cooperatively breeding mongoose. Here we present the residence histories of three focal bands monitored over ten band-years in the southwestern Kalahari, with less detailed data derived from non-focal bands for a further 20 band-years. Mean total band size early in the breeding season was 10, and mean size excluding juveniles was 6.7. Despite a tendency towards females among juveniles, and males among yearlings and adults, sex ratios within each age class did not significantly deviate from unity, but at the population level there were significantly more adult males than reproductive females. A large proportion (71.6%) of adult females bred, and failures of reproductive suppression occurred in 40% of band years. This incidence was high in all years and was not obviously related to environmental conditions. Bands with more than one reproductive female contained significantly more adults and adult females than bands with only a single reproductive female. There was a strong correlation between numbers of reproductive females and numbers of adult females in a band. Most (68%) subordinate females which bred were aged three years or more. Reproductive competition was strong and there was a negative correlation between numbers of adult females, breeding females or adult males and per capita juvenile production. Meerkat bands are unusual among cooperative breeders because many individuals were non-kin and the relative constancy in band size within and between years masked a high turnover of membership: all animals of known origin aged three years or older, were immigrants, although philopatry was commoner among younger animals. Our data show that meerkats employ a range of reproductive strategies: bands exhibiting a spectrum of reproductive suppression coexist, and individuals respond to the opportunities afforded by their social environments.
Habitat Choice, Habitat Matching and the Effect of Travel Distance
Authors: Kennedy Martyn , Gray Russell D. 
Published: April 2008

Abstract
The Ideal Free Distribution was developed to predict the distribution of organisms at a habitat level. The theory of the Ideal Free Distribution assumes that travel between resource sites has a negligible affect on the distribution of organisms. In this experiment we tested whether the Ideal Free Distribution, and in particular its prediction of habitat matching, is robust to violations of this assumption. In an experiment with free-living ducks we manipulated the distance between two food sites. We used two conditions, one with 16 m between the two food sites and another with 45 m between the resource sites. We found that the distribution of organisms became less extreme with increased travel distance. This result is probably due to two effects: that travel distance caused a decrease in the ducks' ability to discriminate between the sites' profitabilities and by a decrease in the number of ducks travelling between the resource sites with increased distance. The decreased number of ducks travelling alone can explain only a relatively small amount of the change in the distribution. The decrease in discriminability may be due to either (or both) the increased distance causing a decrease in the foragers' ability to visually judge the relative profitabilities of the sites or by a decrease in switching rate associated with travel distance (if physical sampling of a site is needed to gather information). Because even a minor change in travel distance can cause a significant change in the distribution of foraging organisms, caution is urged about making extrapolations from experiments at a small spatial scale to the habitat level.
Agonistic Interventions in Wild Mountain Gorilla Groups
Authors: Watts David P. 
Published: April 2008

AbstractData on a large sample of interventions that individuals in two mountain gorilla (Gorilla gorilla beringei) groups made in agonistic interactions between others corroborate and extend earlier analyses in several ways. Related females supported each other as often as those in some female-bonded primates and maintained alliances while they resided together. Most unrelated females rarely supported each other, but some developed alliances. Females mostly supported other females with whom they had affinitive relationships against those they often engaged in dyadic aggression. They showed reciprocity in support, and often intervened against individuals who, in turn, often intervened against them. But even female coalitions that outnumbered their opponents by more than two-to-one had limited effectiveness, largely because males intervened in many female contests to control aggression. By rendering coalitions ineffective, males contribute to a combination of factors (e.g. low potential to gain from cooperation in contest feeding competition) that limit the benefits of female philopatry. Male curtailment of female aggression may influence female mate choice. Co-resident mature males in the study groups competed to control female aggression. High-ranking males curtailed aggression to females by subordinates, although two males formed an alliance against two others in their group. Immature animals mostly received defensive support against larger individuals and did not receive support from adults that could lead to a nepotistic dominance system.
Social Interactions in Two Sympatric Salamanders: Effectiveness of a Highly Aggressive Strategy
Authors: Anthony Carl D. , Wicknick Jill A. , Jaeger Robert G. 
Published: April 2008

Abstract
In terrestrial plethodontid salamanders, aggressive behaviour is thought to function in the spacing of territorial residents among contested cover objects on the forest floor. Such behaviour, when exhibited toward heterospecifics, plays an important role in the competitive interactions between species. We compared levels of aggressive behaviour in intra- and interspecific contexts in two species of sympatric salamanders (Plethodon ouachitae and P. albagula) that have similar ecological requirements but differ in adult size. We also tested the effectiveness of such behaviour in holding cover objects (territorial foci) in the laboratory and on the forest floor. We predicted that if one species were more aggressive than the other, then that species would have greater success in obtaining and holding cover objects. In laboratory trials, residents of P. ouachitae (the smaller species) were extremely aggressive in both intra- and interspecific contexts. Individuals of P ouachitae delivered bites at a rate 14 times that of previously studied species of Plethodon and were significantly more likely to escalate to biting when tested as territorial residents (in intra- and interspecific trials) and as intruders (in interspecific trials). Plethodon albagula exhibited a lower level of aggression, similar to other species of Plethodon. In laboratory trials, in which salamanders competed for cover objects of differing quality, residents of P. ouachitae were effective in expelling conspecific intruders, and they were marginally effective at expelling intruding P. albagula. Residents of P. albagula were less effective in expelling conspecific intruders and did not expel intruding P. ouachitae. We conclude that the extreme aggression exhibited by P. ouachitae enabled it to expel intruders from artificial cover objects and to invade cover objects held by larger heterospecific residents. Field data supported intraspecific defence of cover objects by P. ouachitae, but results for P. albagula were inconclusive. These results are consistent with the geographic distributions of these species (P. ouachitae typically outnumbers P. albagula in the Ouachita Mountains) and provide an example of a behavioural mechanism overcoming a size-related disadvantage.
The Function of Green Plants in Nests of European Starlings (Sturnus Vulgaris)
Authors: Gwinner Helga 
Published: April 2008

AbstractEuropean starlings add fresh green plants to their dry nest material. Male starlings of our 60-nest-box colony carried 68 different plant species into their nests. Some males were polygynous and had 3-6 clutches, others were monogynous and had 1-2 clutches per reproductive season. The 'nest protection hypothesis' proposes that insecticidal compounds in green plants reduce the parasite load of the nests. The 'courtship hypothesis' predicts that carrying nest greenery is a courtship activity to attract females. The aim of this study was to collect field data suitable for distinguishing these two hypotheses. 1. Some plant species occurred more often in the nest-boxes than expected from their frequency in the nest-box environment. A significant number of these preferred plants were rich in volatiles, some of which are said to be insecticidal. But volatiles could also attract females and/or influence their breeding activity and the chicks' development directly. 2. The males carried greenery into their nest boxes maximal around 5 days before the onset of laying, when pair formation took place, and ceased this behaviour with egg deposition. The total amount of greenery deposited in a nest-box was a function of the number of days of courtship a male needed to attract a female. 3. Polygynous males deposited the same amount of greenery in their first nest as monogynous males. In additional nests polygynous males deposited more greenery. However, this was due to the fact that these additional nests were advertised for a longer time.
Description of the Male of Amphiporeia Gigantea Bousfield (Amphipoda, Haustoriidae)
Authors: Glennon Thomas A. 
Published: April 2008

AbstractThe male of Amphiporeia gigantea Bousfield, previously unknown to science, is described from samples containing females of the same species and 4 other species of haustoriids, collected on Georges Bank in November 1975. The reproductive morphology within Amphiporeia is briefly compared and contrasted with known reproductive morphology and behavior within the subfamily Pontoporeiinae.
Effects of Starvation Upon Survival, Growth and Molting Interval of the Larvae of the Spiny Lobster Panulirus Japonicus (Decapoda, Palinuridea)
Authors: Mikami Satoshi , Takashima Fumio 
Published: April 2008

Abstract
The effects of starvation upon survival, growth and molting interval of newly hatched spiny lobster (Panulirus japonicus) larvae were examined. Newly hatched phyllosoma larvae were divided into five groups, which were starved for 2, 10, 24, 48 and 72 hours. The effects of starvation after hatching appeared to be restricted to lengthening of the first molting interval. First molting was delayed by a time proportional to the starvation period. This result indicates optional preparation of food organisms before phyllosoma larvae hatch out.
Postmarsupial Development of Munnopsurus a Tlanticus (Bonnier, 1896), a Dominant Asellote Isopod From the Upper Continental Slope of the Bay of Biscay
Authors: Elizalde Marta , Claude Sorbe Jean 
Published: April 2008

AbstractThe asellote isopod Munnopsurus atlanticus is a dominant species in the bathyal suprabenthic assemblages from the south margin of the Cap-Ferret Trench; it is therefore a valuable subject for studies of postmarsupial development and population biology in bathyal Isopoda. In this introductory paper, its postmarsupial development is described on the basis of size frequency analysis and morphological discrimination. Eight developmental stages are recognized within the Biscayan population: mancas 1-2; manca 3, juvenile and copulatory males; manca 3, juvenile, preparatory and brooding females. The number of successive instars depends on the sex of the individuals; at least 8 instars for the females and 5 instars for the males. The female may be iteroparous, reverting to a preparatory condition before brooding once more. The larger adults are found over muddy sediments, probably reflecting more favourable environmental conditions for growth increment in the deepest part of the investigated area.
Population Biology of the Red Swamp Crayfish Procambarus Clarkii (Girard, 1852) in Southern Portugal
Authors: Adao Helena , Marques Joao Carlos 
Published: April 2008

AbstractPopulation structure and recruitment of Procambarus clarkii were studied from 1989 to 1991 in a freshwater reservoir in southern Portugal. Two distinct recruitment periods were observed, the main one from October to February and a less significant one during spring and summer. With regard to population structure, juveniles were clearly dominant in January and February. The present results suggest that more than one generation per year may occur under favourable climatic conditions.
Feeding of Copepodite and Adult Stages of Eudiaptomus Gracilis (G.O. Sars, 1863) (Copepoda, Calanoida) On Mixed Plastic Beads
Authors: Zánkai Nóra P. 
Published: April 2008

AbstractSize selection of Eudiaptomus gracilis copepodites (CI-CV) and adults was studied in feeding experiments with beads of 1-84 μm diameter. Concentration of particles ranged between 1.3-2.1 x 107 beads ml-1, i.e. it was similar to the natural particle concentration. Animals were collected in Lake Balaton and acclimated to laboratory conditions for a few days before the experiments. On average, 91% of the experimental animals ingested beads. Almost each of the bead-ingesting animals took in 1 μm beads. Young copepodites had a narrow size spectrum (1-12 μm), whereas old copepodites and adults had broader spectra (1-39 μm). The number of ingested beads varied widely in each stage and among the individuals of the same stages. Diameter of the largest ingested bead, average number of beads in the guts, and clearance rate increased linearly with dry weight of the different stages (p < 0.001). Clearance rates were different for various particle sizes. Relatively high clearance rates were obtained for 6 μm and 10-12 μm beads in each stage. Moreover, older copepodites had higher clearance rates for beads of 20 and 25 μm diameter, and clearance rates of adults increased for larger than 30 μm particles. CI copepodites selected for particles of 4-12 μm diameter, and their selectivity increased with the increasing bead size within this range. Older stages selected only for beads larger than 12 μm, whereas adults did only for beads larger than 22 μm.
A New Species of Haloniscus Chilton, 1920 From New Caledonia (Isopoda, Oniscidea)
Authors: Taiti Stefano , Ferrara Franco , Iliffe Thomas M. 
Published: April 2008

AbstractA new species of a blind terrestrial isopod, Haluniscus anophthalmus, from anchialine waters in a cave on the Isle of Pines, New Caledonia, is described. The systematic position of the genus Haloniscus is discussed.
Diaphanosoma Dumonti Sp. Nov. (Cladocera, Daphniiformes, Sididae) From China
Authors: Korovchinsky Nikolai M. 
Published: April 2008

AbstractThe description of a new species, Diaphanosoma dumonti, is based on parthenogenetic females collected in Shensi province, China. Individual and morphological variability due to age as well as size frequency distribution, are also analyzed.
Peracarid Crustaceans (Malacostraca) From a "Time-Series Station" in the Westwind Trough of the New-Polynya (Greenland): a Benthic Response To Productivity?
Authors: Brandt Angelika 
Published: April 2008

AbstractDuring the expedition ARK IX-2/3 with RV "Polarstern" to the Northeast Water Polynya (NEW-Polynya), off Greenland, a station in the Westwind Trough was revisited sever times. Successful samples were taken by means of a box corer seven times over 2 months (May-July 1993) and by an epibenthic sledge (EBS) five times over a period of six weeks. One-hundred-and-thirty-one species from 78 genera and 40 families comprising a total of 13 280 individuals were collected with the EBS. The most abundant taxon at this station were the Cumacea. Amphipoda were most diverse. A change in peracarid composition and abundance occurred between the stations sampled over the two months, especially in the box corer samples. For seven isopod species developmental stages were determined and compared. Although no clear difference in stage composition of the species investigated was observed between stations, within some species the number of immature, preparatory, and ovigerous females was high. This might indicate an active period of reproduction during early summer, during times of favourable food supply. High abundance of Peracarida was found shortly after a sedimentation event of chlorophyll (phytoplankton and ice algae), observed in the upper sediment layer, possibly reflecting a benthic response to productivity.
Pattern of Mandibular Morphology in Anostraca With Some Taxonomical Remarks
Authors: Mura Graziella 
Published: April 2008

AbstractOccasional reports on mandibular morphology in some Anostracans by means of optical (Ocioszynska-Bankierowa, 1933; Lynch, 1937; Linder, 1941; Mahoon, 1960; Fryer, 1966) and SEM microscopy (Tyson & Sullivan, 1981; Fryer, 1983; Schrehardt, 1987; Mura, 1991; Mura & Del Caldo, 1992, 1993) posed the question whether this character might be taxonomically relevant. This view was supported by the findings of Edwards (1980) on cladocerans, and of Martin (1988) on conchostracans, thus suggesting to perform a wider inquiry. This SEM study examined the morphology of the molar surfaces in a large number of representatives of the 8 existing Anostraca families, in order to obtain further information. The results are contrasting, and vary depending on the families considered. The observed differences, when present, are detectable only at the genus level and never extend to species, except on rare occasions (for example in the branchinectids). The observations concern both shape and ornamentation (number of teeth and spines at the posterior tips and on the dorsal margins, texture of the transition area, extension of the antero-ventral area, and so on). The most evident variation was expected between non-related genera, but this was shown to be invalid in many cases, and did not depend on the systematic position of the taxa examined. Moreover, even within a family, intergeneric diversity was frequently not observed (like in chirocephalids and branchipodids). Finally, intraspecific variation was also recorded, at least for those species where a great number of specimens was available for study.
A New Species of Probopyrus (Isopoda, Bopyridae), Parasite of Macrobrachium Americanum Bate, 1868 (Decapoda, Palaemonidae)
Authors: Román-Contreras Ramiro 
Published: April 2008

AbstractA new species of Probopyrus Giard & Bonnier, 1888, parasitizing the freshwater shrimp Macrobrachium americanum Bate, 1868, is described. Probopyrus markhami new species, differs from other American species of the genus by having, in the female, the body almost as wide as long, pleopods not projecting beyond the pleon edge, distortion angle seven degrees, brown reticular pigmentation, third maxilliped palp pyramidal-shape, and anterolateral angles of head with a short acute process.
Reproduction Saisonnière Chez Hemilepistus Reaumuri (Audouin, 1826), Isopode Terrestre Des Zones Semi-Arides
Authors: Nasri Karima , Mocquard Jean-Pierre , Juchault Pierre , Souty-Grosset Catherine 
Published: April 2008

AbstractIn Hemilepistus reaumuri (Audouin, 1826), a monogamous desert isopod, control of reproduction by external factors is studied in females from a Tunisian population. In the wild, females perform only one brood (in May). In contrast to isopods submitted to temperate climates (long day species), H. reaumuri is unsensitive to photoperiod. Onset of reproduction is dependent on temperature: it occurs only when temperature is higher than 15°C (between 15°C and 20°C). Moreover, at 25°C, the lag time of the onset of reproduction is shortened by 50% in comparison with the delay obtained at 20°C. Whereas an isolated female remains in sexual rest, the presence of a male (even separated from the female by a wire netting) speeds up vitellogenesis following by moult. The beginning of burrow digging is well correlated with the initiation of reproduction (second phase of vitellogenesis).
Sphaeronella Squamosa N. Sp. (Copepoda, Nicothoidae), a New Parasite of the Ostracod, Codonocera Sp
Authors: Lim Dong-Hyun , Yoo Kwang-Il 
Published: April 2008

AbstractA new species of parasitic copepod, Sphaeronella squamosa, is described from its ostracod host, Codonocera sp.