bluuebunny/crossref_metadata_2025_split huggingface dataset:
The social calls of Kuhl's pipistrelles Pipistrellus kuhlii (Kuhl, 1819): structure and variation (Chiroptera: Vespertilionidae)
Authors: Russo Danilo , Jones Gareth 
Published: February 2006

AbstractThe aim of this study was to describe the structure of social calls produced by Kuhl's pipistrelles Pipistrellus kuhlii. Bats foraging around street lamps in the Campania region, Southern Italy, were recorded. Calls were produced by bats during chases and, similarly to those of Pipistrellus pipistrellus, were probably used to repel conspecifics from hunting sites. Calls often had three components, lasted on average 34 ms and contained most energy at about 17 kHz. A positive correlation was found between the frequencies of maximum amplitude of echolocation and social calls. Social calls from two adjacent populations differed in their peak frequencies, and possible hypotheses for this variation are given. The structure of P. kuhlii social calls was compared with those of the 45 and 55 kHz P. pipistrellus phonic types. Kuhl's pipistrelle calls lasted longer and showed lower values of minimum and peak frequencies. These differences can help to discriminate between field recordings of P. kuhlii and P. pipistrellus where the two species occur sympatrically.
Paracrobeles psammophilus sp. nov. (Nematoda: Cephalobidae) from El Saler, Valencia (Spain)
Authors: Navarro Pilar , Lluch Javier 
Published: February 2006

Abstract Paracrobeles psammophilus sp. nov. (Nematoda: Cephalobidae) is described from soil of the Dehesa de El Saler (province of Valencia, Spain). This is the second record of a species of the genus Paracrobeles Heyns, 1968. The new species is characterized by rounded cheilorhabdions and the large spicules and gubernaculum of males.
Morphology of spermathecae in the estuarine crab Chasmagnathus granulata Dana 1851 (Grapsidae, Sesarminae)
Authors: López Greco L. S. , López G. C. , Rodríguez E. M. 
Published: February 2006

AbstractThe morphology of the spermathecae (seminal receptacles) was studied in the grapsid crab Chasmagnathus granulata, both from the macroscopic and the microscopic points of view. Female adult crabs were collected throughout the year. Once in the laboratory, the right spermatheca was fixed in Bouin solution; histological sections were stained with haematoxilin–eosin. The observations indicated that the spermathecae belonged to the ‘ventral type’ described by Diesel (1991), related to the ‘hard female’ mating system of C. granulata described previously. They presented two distinct zones: the inner one (white‐coloured), where the double layer oviduct opened ventrally; and the outer one, of translucent, ‘jelly‐like’ appearance, where the communication with the genital duct could be observed. The spermatozoa were only observed in the ‘jelly‐like’ zone, but not as discrete packets, suggesting that spermatozoa from different matings could mix in the spermathecae of C. granulata. The spermathecae also showed seasonal variation, with the lowest degree of development observed during autumn. Post‐moulted females always showed collapsed spermathecae.
Expansion of a grey seal (Halichoerus grypus) breeding colony: changes in pupping site use at the Isle of May, Scotland
Authors: Pomeroy P. P. , Twiss S. D. , Duck C. D. 
Published: February 2006

AbstractUntil the mid 1970s only a few grey seal Halichoerus grypus pups were born each year on the Isle of May, Scotland, but 1408 pups were born there in 1994. We examined changes in overall site use, individual pupping site fidelity and success in relation to local population density and topography. The area of the island used by seals for breeding has increased as the population increased. Between 1988 and 1994 an index of the proportion of the island's northern area occupied by seals increased from 0.48 to 0.65, while the average population density in these occupied areas decreased over the same period. Although seals have begun to breed in southern parts of the island that were unused previously, other apparently suitable breeding areas on the island remain vacant. Fine scale digital elevation models were constructed using a GIS to evaluate the topographic characteristics of occupied areas and assign topographic ‘costs’ to areas used by seals for breeding on the Isle of May. Seals were associated generally with areas close to the numerous access points from the sea. New areas occupied in the later years of the study had a higher topographical ‘cost’ than the traditional sites. Thus, in an expanding colony such as the Isle of May, areas colonized early in the colony's history were those close to access points and/or standing water and at low elevations. Subsequent expansion resulted in an increase in the areas occupied by seals, but these newly colonized areas were less suitable, and their occupiers were subject to increased topographic ‘costs’. Pup mortality rates were similar in areas of high and low breeding density. Aggressive behaviour between breeding females is the likely mechanism which acts to limit local animal density. Mothers marked at the Isle of May since 1987 returned there to breed with few exceptions, and most females that returned were faithful to their previous pupping sites (median distance between sites used in consecutive breeding seasons = 25 m). Site fidelity persisted even when a previous pupping was unsuccessful and most individuals' pupping locations did not change gradually with time. Comparison with other colonies suggests that the spatial scale of site fidelity is related to the scale of topographic variation within the breeding site.
Role of the statolith in functioning of the acceleration receptor system in squids and sepioids
Authors: Arkhipkin Alexander I. , Bizikov Vyacheslav A. 
Published: February 2006

AbstractMorphology of statoliths and anatomy of statocysts were studied in five species of Gonatidae, Moroteuthis robusta (Onychoteuthidae) and Galiteuthis phyllura (Cranchiidae) from the northern Bering Sea, and Todarodes pacificus (Ommastrephidae) from the Pacific waters near Japan. A special experiment was carried out in order to observe statolith mobility on the macula statica and possible endolymph flows within the statocyst in freshly caught gonatid squid Berryteuthis magister. It was found that the statolith may deviate at small acute angles around three axes running through its centre of rotation (located near the spur) without any visual damage of its attachment area to the macula. This finding enabled us to re‐consider previous theories and to create a new model of the squid statocyst functioning with the statolith as detector of multidimensional movement. Two types of statolith morphology are distinguished: demersal type statoliths characteristic of near‐bottom decapods, and pelagic type statoliths characteristic of all pelagic squids and not dependent on their systematic position. Phylogenetic and ecological features of the statocyst and statolith structure are established. Possible evolutionary trends in development of different types of statocysts in decapods are discussed.
Tropical tree diversity, forest structure and the demography of a frugivorous rodent, the spiny rat (Proechimys semispinosus)
Authors: Adler Gregory H. 
Published: February 2006

AbstractPopulations of the Central American spiny rat Proechimys semispinosus isolated on eight small islands in Panama were sampled monthly for 1 year to examine the relationships of demography to tree species composition and forest structure. Demography was characterized by calculating seven variables from the monthly census data. Tree species composition was determined by marking, measuring and identifying all trees ð 10 cm in diameter at breast height (dbh) on each island. Forest structure (tree stature, density and species richness) was quantified by measuring seven variables at each of the 470 sampling stations. Bivariate correlations were computed between spiny rat demography and tree species composition and forest structure. To examine whether islands with more similar tree species composition or forest structure supported P. semispinosus populations with more similar demography, dendrograms based on complete‐linkage cluster analysis were constructed. Spiny rat densities were correlated positively with the density of large‐fruited fig trees and non‐linearly to an index of forest age based on tree species composition. Spiny rat densities were not related to any structural variable. Dendrograms based on cluster analysis showed that spiny rat demography did not map onto forest structure, overall tree species composition or any group of selected tree species except figs Ficus spp. Thus, islands with more similar fig tree composition contained spiny rat populations with more similar demography. Tree species composition, which partly determines resource abundance, is apparently more important than forest structure in influencing spiny rat demography. Proechimys semispinosus has a temporally and spatially variable demography, and this flexible demography, in concert with an ability to use diverse resources, presumably promotes abundance and persistence in heterogeneous tropical forests and may contribute to the ubiquity of this rodent.
Ovarian structure and oogenetic cycle in the millipedeCatamicrophyllum caifanum(Diplopoda: Iulidae)
Authors: Warburg M. R. , Gealekman Olga 
Published: February 2006

AbstractThe ovaries and oocytes of a iulid millipedeCatamicrophyllum caifanumVerhoeff 1920, were studied in an oak woodland and a planted pine forest in the Mediterranean region in northern Israel. The changes in the stages and number of oocytes are described throughout the activity period of this millipede: October–February. Four stages of female germ cell development could be distinguished: (1) the early stages of oogenesis when the female germ cells (= oogonia) are still embedded in the germ layers of the ovarian epithelium; (2) two sizes of previtellogenic oocytes entering the ovarian lumen are distinguishable. Small ones (< 0.1 mm) observable only in microscopic sections, and larger ones (0.2–0.45 mm) that could be seen under the dissecting microscope. The small previtellogenic oocytes were present in the ovary throughout the study period. The oocytes apparently undergo vitellogenesis during autumn; (3) with the accumulation of yolk, a third stage consisting of small, medium and large vitellogenic oocytes can be discerned; (4) the mature, post‐vitellogenic oocytes, elliptic in shape and yellowish in colour, appear towards the end of autumn. In winter only post‐vitellogenic oocytes are found, disappearing from the ovary towards the end of winter. The number of mature, post‐vitellogenic oocytes is positively correlated with the female's body size.Catamicrophyllum caifanumhas therefore an annual oogenetic cycle breeding once yearly during winter. This, together with the fact that its ovary contains oocytes belonging to different stages (= generations), indicates that it can breed at least four and possibly up to seven times during its lifetime.
Mouse (Mus musculus) stocks derived from tropical islands: new models for genetic analysis of life‐history traits
Authors: Miller Richard A. , Dysko Robert , Chrisp Clarence , Seguin Renee , Linsalata Luann , Buehner Gretchen , Harper James M. , Austad Steven 
Published: February 2006

AbstractFounder effects, together with access to unoccupied ecological niches, may allow rodent populations on isolated islands to evolve constellations of life‐history traits that distinguish them from their mainland relatives, for example in body size, litter size, and longevity. In particular, low intrinsic mortality risks on islands with reduced predator numbers and not subject to harsh winter climates may in principle support the development of stocks with extended longevity. Conversely, the conditions under which laboratory rodents are typically bred are thought to select for genotypes that produce large, rapidly maturing races with high early reproductive rates but diminished longevity. To test these ideas, and to generate new mouse stocks suitable for genetic and molecular analysis of the processes that time life‐history events, we have developed specific pathogen‐free stocks from mice trapped from three distinct populations: the U.S. mainland (Idaho) and the tropical Pacific islands Majuro and Pohnpei. Mice from all three locations were found to be shorter and lighter, to have smaller litters, and to have higher faecal corticosterone levels than mice of a genetically heterogeneous stock derived from four common laboratory inbred strains. Among the wild‐derived stocks, mice from Pohnpei and Majuro were significantly lighter and shorter than Idaho‐derived animals, even in populations kept from birth under identical housing conditions. Litter size and reproductive success rates did not differ significantly among the three wild‐derived stocks. Although further work will be needed to see if, as predicted, the wild‐derived stocks differ from one another and from laboratory mice in longevity, these stocks provide useful tools for genetic dissection of factors that regulate body size and reproductive success.
Clustering of colonies in an expanding population of New Zealand fur seals (Arctocephalus forsteri)
Authors: Bradshaw Corey J. A. , Lalas Chris , Thompson Caryn M. 
Published: February 2006

AbstractNew Zealand fur seals in the New Zealand area are increasing in number following earlier depletion by Polynesians and Europeans. Otago Peninsula, South Island is a region where recent re‐colonization has occurred. We identified 27 breeding and 41 non‐breeding colonies in 1998. At higher densities the shortage of space in breeding colonies may initiate emigration by first‐time breeders to suitable sites nearby. This hypothesis assumes philopatry (repeated return to a natal site) and site fidelity (repeated return to a non‐natal site). We quantified the rate of increase in pup production at Otago Peninsula since the early 1980s using annual counts of fur seals ashore from 1994 to 1998 and data on pup numbers before 1994 from the literature. The exponential rate of increase (b) ranged from 0.22 to 0.30 (95% confidence interval) and the average (arithmetic) rate of annual increase (r) was 0.30. To search for evidence of philopatry, site fidelity and immigration, relationships between counts of pups established colonies in 1996–1998 were measured and found to be highly correlated. We then tested whether new breeding colonies were established nearer to existing breeding colonies than would be expected by chance. There was significant spatial clustering of new breeding colonies around the 6 focal (established) colonies. We found no evidence for an association between the appearance of new colonies and r at nearby established colonies. Increasing numbers of fur seals on Otago Peninsula have resulted in the rapid proliferation of colonies, and their clustering is indicative of a ‘spill‐over’ effect where young individuals choose to breed near to established breeders.
Helpers provide no detectable benefits in the European badger (Meles meles)
Authors: Woodroffe Rosie , Macdonald David W. 
Published: February 2006

AbstractMany studies of co‐operatively breeding vertebrates have shown that social groups which contain more helpers experience higher reproductive success. Few of these studies, however, have demonstrated that this is a causal relationship. Using data on a co‐operatively breeding population of European badgers Meles meles, this study shows that the relationship between helper number and group reproductive success is a spurious one generated through the effect of territory quality. Within this population, most variation in cub production, growth rate and survival is explained by variation in food availability between years and between territories. Unusually for mammals, juvenile mortality is markedly higher in females than in males. After controlling for such effects, helpers appear to have only negative effects upon group reproductive success, and mothers with helpers are in poorer condition at the end of the breeding period than those without helpers. A high proportion of helpers are sexually mature females which have failed to breed as a result of intense competition for resources. Under such circumstances, alloparental care represents a low‐cost, low‐benefit behaviour which may mitigate the negative impact that non‐breeding group members have upon the reproductive success of their close relatives.
Developmental pattern and larval stages of Polystoma indicum Diengdoh & Tandon, 1991 (Monogenea: Polystomatidae) in rhacophorid anurans
Authors: Dutta Mamoni , Tandon Veena 
Published: February 2006

AbstractThe developmental pattern of Polystoma indicum Diengdoh & Tandon, 1991 occurring in the urinary bladder of the frogs Rhacophorus nigropalmatus, R. reinwardtii and Polypedates leucomystax from Meghalaya (north‐east India) was studied. Non‐ciliated larval stages were recovered in the gyrodactyloid‐I and post‐gyrodactyloid‐I stage mostly from the branchial chambers of the tadpoles; only rarely were they found in the intestines. These stages possessed features of bladder‐destined forms and showed a gradual acquisition of 2, 4 and then 6 opisthaptoral suckers, coupled with an increase in the size of the body and various structures. While a conspicuous increase was noticeable in the dimensions of the hamuli, the size of the microhooks remained almost the same from the 2‐suckered larval stage to the adult. The larval migration to the final destination seems to follow an external route leading to the cloaca of the metamorphosing host. The prevalence data of both the larvae and the adult flukes indicate a preference towards R. nigropalmatus amongst the three rhacophorid host species. The gyrodactyloid‐II, i.e. neotenic larvae were not encountered at all either on the external gills of the very young tadpoles or even in the branchial chambers of the older ones.
Extreme body size variability in the golden silk spider (Nephila edulis) does not extend to genitalia
Authors: Uhl Gabriele , Vollrath Fritz 
Published: February 2006

Abstract Nephila edulis is a spider with large body size variability in males and females. Genital characters show negative allometric values compared to somatic characters. In males, the embolus (the most important structure for sperm transfer) had a significantly lower coefficient of variation than body size. This suggests that male genitalia are under stabilizing selection favouring intermediate size. Female N. edulis showed a trend similar to males regarding allometric values in genitalia. In females, however, the variation coefficient in a specific genital character crucial for successful copulation did not differ from that of indicators for overall body size. This suggests that in Nephila the genitalia of the females experience less stabilizing selection than those of the males. In male and female genitalia, the mode of selection seems to cause developmental instability not in degrees of fluctuating asymmetry but in the degree of data scatter which indicates a lower coefficient of determination.
Movements and group structure of giraffe (Giraffa camelopardalis) in Lake Manyara National Park, Tanzania
Authors: van der Jeugd Henk P. , Prins Herbert H. T. 
Published: February 2006

AbstractMovements and group structure of giraffe Giraffa camelopardalis were studied in Lake Manyara National Park, northern Tanzania. The giraffe population in Manyara had increased from 60 to 85 individuals between the early 1980s and 1991. This increase may have been the result of an increase in browse availability as a result of a dramatic decline in elephant numbers, and bush encroachment following a series of anthrax epidemics that killed impala. Giraffe densities in Manyara are high compared to other areas within the Masai ecosystem, and Manyara probably serves as a dry season refuge. Females were found in small, yet unstable groups, while males associated randomly with each other. Neither males nor females were confined to single localities, although home ranges were small compared with studies in areas with low giraffe densities. In one area within the park a more stable group was found, and resident males who were probably defending a temporary harem, engaged in necking contests with immigrant males. A comparison with other studies showed that giraffe density, home‐range size, mobility and group stability differ across different habitats. The tendency that more stable groups are found in high density areas might be taken as evidence for the occurrence of resource defence polygyny in such areas.
A comparative study of morphometry in shell‐bearing molluscs
Authors: Tokeshi M. , Ota N. , Kawai T. 
Published: February 2006

AbstractA 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≊ 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.
Spalacopus cyanus (Rodentia: Octodontidae): an extremist in tunnel constructing and food storing among subterranean mammals
Authors: Begall Sabine , Gallardo Milton H. 
Published: February 2006

AbstractBurrow 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.