bluuebunny/crossref_metadata_2025 huggingface dataset:
Life in the trees: the ecology and life history of Kentropyx striatus (Teiidae) in the lavrado area of Roraima, Brazil, with comments on the life histories of tropical teiid lizards
Authors: Vitt Laurie J. , Carvalho Celso Morato de
Published: July 2008

The ecology and life history of the tropical teiid lizard Kentropyx striatus were studied in a grassland of northern Brazil, the lavrado area. The area, located nearly at the equator, experiences a prolonged dry season with a wet season extending from May to September. Total annual rainfall averages 1750 mm. Lizards were nonrandomly distributed among habitat patches and microhabitats. Most individuals were in trees and shrubs surrounding temporary and permanent water. Most individuals were observed active during late morning, the time period during which feeding and social interactions were observed. Lizards bask to achieve active body temperatures averaging 35.7 ± 0.23 °C. Body temperature is correlated with both substrate and air temperatures; foraging lizards maintained higher temperatures than basking lizards regardless of whether they were in sun, and lizards sampled when there was cloud cover had lower body temperatures than those sampled when sun was available. Females reach sexual maturity at 74 mm snout–vent length (SVL), produce 3–9 eggs per clutch, reproduce more than once per season, and commence reproduction during the wet season. Lizards hatch from eggs at 31 mm SVL. Maturity appears to be reached in 1 year or less. Overall, female reproductive characteristics are similar to those of other tropical teiid lizards that have been studied, with body size explaining much of the variance in reproductive characteristics across species. There is pronounced sexual dimorphism, with males larger in body size as well as certain other characteristics independent of body size. Sexual dimorphism appears to be a consequence of sexual selection. The diet is varied, but is dominated volumetrically by frogs, eruciform larvae, and spiders. Lizard body size accounted for only 5.5% of the variance in prey size and there was no difference in prey size due to sex. The occurrence of frogs and lizards in K. striatus stomachs suggests that teiid lizards may influence the structure of lizard and frog assemblages. The similarity of K. striatus to other studied tropical teiids in reproductive characteristics, morphology, activity period, activity temperatures, and diet underscore the conservative nature of the ecology of teiid lizards, presumably a consequence of their mode of prey acquisition.
The leucocytozoids of the avian families Anatidae and Emberizidae s.l., with descriptions of three new Leucocytozoon species
Authors: Bennett Gordon F. , Squires-Parsons Deborah
Published: July 2008

Leucocytozoon simondi from the Anatidae is redescribed for the first time since its original description by Mathis and Léger in 1910. The leucocytozoids of four of the five subfamilies of the Emberizidae are reviewed and Leucocytozoon cambournaci of the Emberizinae is resurrected from synonymy and redescribed. Leucocytozoon icteris n.sp., Leucocytozoon parulis n.sp., and Leucocytozoon thraupis n.sp. are described from the Icterinae, Parulinae, and Thraupinae, respectively.
Host effects on Romanomermis (Nematoda: Mermithidae) parasites of snowpool Aedes mosquitoes (Diptera: Culicidae)
Authors: Blackmore Mark S.
Published: July 2008

Host effects on mermithid nematodes (Romanomermis sp.) were studied in four populations of snowpool Aedes spp. mosquitoes (Diptera: Culicidae) in western Wyoming. Two factors associated with nematode fitness, survival and adult size, were examined in relation to species and parasite load of the hosts. The proportion of entering parasites that successfully emerged from hosts was relatively high in Aedes impiger, Aedes increpitus, Aedes pullatus, and Aedes punctor, none of which produced melanotic encapsulations of parasites. Emergence success at all localities was lowest in Aedes nevadensis and Aedes hexodontus, species that commonly encapsulated nematodes. Proportionately fewer parasites were encapsulated per host as parasite load increased, and encapsulation by Ae. nevadensis and Ae. hexodontus occurred less frequently in populations in which these species constituted most of the available hosts. Mean adult lengths varied between populations but did not differ between postparasites from different mosquito species within the same site. Total volume of nematodes per host was independent of parasite load but size of individual parasites decreased with increasing parasite load. This suggests intraspecific competition for finite resources in superparasitized hosts.
The relationship between annual survival rate and migration distance in mallards: an examination of the time-allocation hypothesis for the evolution of migration
Authors: Hestbeck Jay B. , Nichols James D. , Hines James E.
Published: July 2008

Predictions of the time-allocation hypothesis were tested with several a posteriori analyses of banding data for the mallard (Anas platyrhynchos). The time-allocation hypothesis states that the critical difference between resident and migrant birds is their allocation of time to reproduction on the breeding grounds and survival on the nonbreeding grounds. Residents have higher reproduction and migrants have higher survival. Survival and recovery rates were estimated by standard band-recovery methods for banding reference areas in the central United States and central Canada. A production-rate index was computed for each reference area with data from the U.S. Fish and Wildlife Service May Breeding Population Survey and July Production Survey. An analysis of covariance was used to test for the effects of migration distance and time period (decade) on survival, recovery, and production rates. Differences in migration chronology were tested by comparing direct-recovery distributions for different populations during the fall migration. Differences in winter locations were tested by comparing distributions of direct recoveries reported during December and January. A strong positive relationship was found between survival rate and migration distance for 3 of the 4 age and sex classes. A weak negative relationship was found between recovery rate and migration distance. No relationship was found between production rate and migration distance. During the fall migration, birds from the northern breeding populations were located north of birds from the southern breeding populations. No pattern could be found in the relative locations of breeding and wintering areas. Although our finding that survival rate increased with migration distance was consistent with the time-allocation hypothesis, our results on migration chronology and location of wintering areas were not consistent with the mechanism underlying the time-allocation hypothesis. Neither this analysis nor other recent studies of life-history characteristics of migratory and resident birds supported the time-allocation hypothesis.
Redescription of the duck leech, Theromyzon rude (Baird, 1869) (Rhynchobdellida: Glossiphoniidae)
Authors: Oosthuizen J. H. , Davies Ronald W.
Published: July 2008

The identification of the species of Theromyzon in North America and worldwide is based on the number of annuli separating the male and female gonopores. The first species identified from North America (Glossiphonia rudis) was not fully described but, based on the collection of a specimen from the same site, T. rude was subsequently thought to have three annuli between the gonopores. The syntypes of G. rudis were examined. One was identified as Placobdella ornata and the second as a Theromyzon which becomes the holotype of G. rudis on which a new description of T. rude is presented. Theromyzon rude has the gonopores separated by two annuli. The male atrium is spherical, with the undifferentiated terminal ends of the paired male ducts joining before entering the atrium. The vagina is short and vertical. Specimens of Theromyzon with three annuli between the gonopores and previously identified as T. rude clearly must belong to a different species.
Carabodes of the eastern United States and adjacent Canada (Acari: Oribatida: Carabodidae)
Authors: Reeves R. Marcel
Published: July 2008

Adults of four new species of Carabodes, C. chandleri, C. erectus, C. interruptus, and C. pentasetosus, and the immatures of C. erectus, are described. All have been collected from a variety of forest-floor habitats, with C. chandleri, C. interruptus, and C. pentasetosus more common in leaf litter, and C. erectus preferring polyporous fungi. All four species are widely distributed in eastern North America, with C. chandleri, C. erectus, and C. interruptus more abundant in samples from the Appalachian Mountains and C. pentasetosus in those from the Atlantic coastal plain. Thelytokous parthenogenesis is suspected to occur in C. pentasetosus n.sp. and Carabodes granulatus Banks. A key to the 19 species of Carabodes found in North America is provided.
Size and species selection of zooplankton by larval and juvenile walleye (Stizostedion vitreum vitreum) in Oneida Lake, New York
Authors: Graham Donna M. , Sprules W. Gary
Published: July 2008

Young-of-the-year walleye (Stizostedion vitreum vitreum) ranging from 7 to 38 mm in total length were collected from Oneida Lake, New York, from 14 May to 11 June, 1989. Stomach contents were analyzed to document feeding strategies employed during their early life stages. A distinct change in both type and size of prey was evident as the walleye progressed through their first 4 weeks of life. The diet of 10- to 13-mm walleye consisted of 77.3% (by number) cyclopoid copepods; walleye 13–19 mm in total length consumed calanoid copepods (96.1%), while the diet of older juveniles, 29–38 mm in total length, consisted of mostly cladocerans (Daphnia spp.) (88.3%). The smallest size class of fish consumed zooplankton 0.50–1.50 mm long, the second class of fish consumed 1.25- to 2.00-mm zooplankton, and the third class consumed 1.5- to 2.00-mm zooplankton. Electivity calculations from both field and laboratory studies revealed that these changes were a result of active selection by the young walleye. The smallest walleye consumed zooplankton as large as their mouth gapes would allow. As the larvae increased in size they began to consume zooplankton of intermediate size (mouth gape approximately 2.0 mm) and remained consistent in their choice thereafter. We suggest that young-of-the-year walleye foraged in a manner that optimized growth. Both species and size of zooplankton were important components of their feeding strategy.
Developmental abnormalities in triploid hybrids between tetraploid and diploid tree frogs (genus Hyla)
Authors: Mable Barbara K. , Rye Leslie A.
Published: July 2008

Crosses between tetraploid female grey tree frogs, Hyla versicolor, and diploid males of the same genus may provide information on developmental differences between the parental species. Crosses with Hyla cinerea males in 1988 produced a large number of vigorous offspring, but abnormalities in eye development indicated some incompatibility of the parental genomes. The degree of eye development of the hybrids varied, ranging from completely absent to fully functional. Repetition of this cross combination in 1989 resulted in similar variation in eye formation. Histological sections through developing eyes indicated that the abnormalities may be related to improper formation of the cornea, improper orientation of the lens, or lack of lens induction. This may reflect differences in the timing of development between the two parental species.
Dynamics of fat and protein reserves during winter and spring migration in greater snow geese
Authors: Gauthier Gilles , Giroux Jean-François , Bédard Jean
Published: July 2008

We studied the dynamics of fat and protein reserves in greater snow geese (Chen caerulescens atlantica) during winter and spring migration, and examined the influence of a recent expansion of their staging grounds and change in habitat use on fat and protein storage. We collected 63 geese during the winter of 1989–1990 at Bombay Hook National Wildlife Refuge in Delaware, 158 geese in spring 1989 and 1990 at Lake Saint-Pierre and Cap-Saint-Ignace along the St. Lawrence River in southern Quebec, and 17 geese at the end of the 1990 migration on By lot Island, N.W.T. In both sexes, protein reserves did not change in winter but fat declined from a peak in December to a low point in early March, just before spring migration. Geese collected 3 weeks later at Lake Saint-Pierre (800 km north) had considerably larger fat reserves (90% larger in females and 40% in males). Geese accumulated large fat reserves at both sites along the St. Lawrence River. Although geese staged for a shorter period at Lake Saint-Pierre (a recently used area), males stored as much fat as those staging at Cap-Saint-Ignace and females only slightly less. A small amount of protein was stored between late winter and the end of staging. Spring conditioning of geese along the St. Lawrence River seems to have improved over the past decade. We found weak evidence that larger females stored more fat. The cost of migrating from the St. Lawrence to Arctic nesting grounds (2900 km) is considerable, as half of the fat reserves accumulated in spring were used for the migration. There is no evidence of fat or protein storage between the St. Lawrence estuary and the Arctic nesting grounds.
Cytoskeleton of Euplotes focardii: morphology and morphogenesis
Authors: Serrano Susana , Sola Ana , Guinea Almudena , Arregui Lucia , Fernàndez-Galiano Dimas
Published: July 2008

New data are given about the infraciliature, cytoskeleton, and morphogenesis during cell division in Euplotes focardii. Our observations indicate slight variability in the dorsal and ventral infraciliary pattern. The oral infraciliature is composed of a paroral complex formed by 29–34 oblique rows of kinetosomes and an adoral zone of membranelles in which three parts can be distinguished according to the number of rows and the infraciliary composition of the paramembranelles. Besides the complex microtubular cytoskeleton connected with the dorsal and ventral somatic infraciliatures, characteristic of the genus Euplotes, we observe two argentophilic zones in the anterior zone of cirrus 6 and between the posterior part of the paroral complex and the adoral zone of membranelles. The process of cell division is generally similar to that described in other species of Euplotes, but the somatic origin of cirrus 1 and the origin of the left marginal cirri from a single primordium should be noted. Finally, in E. focardii we observe the development of systems of microtubular bundles, which are probably connected with the movements of the ventral cirri during morphogenesis.
Facial anatomy and potential function of facial structures for sound production in the harbor porpoise (Phocoena phocoena) and Dall's porpoise (Phocoenoides dalli)
Authors: Curry Barbara E.
Published: July 2008

Structural modifications of the odontocete skull and nasal passages have shifted the position of the facial bones and associated soft anatomy to the dorsal aspect of the head. The facial structures of true porpoises, Phocoenidae, are highly specialized. Facial regions of 18 Phocoena phocoena and 3 Phocoenoides dalli specimens were dissected and described. In addition, heads of three phocoenid specimens were serially sectioned. Comparison to delphinid facial anatomy demonstrates that nasal passages, associated diverticula, and facial muscles of these phocoenid species are homologous to facial structures of delphinids, with several notable exceptions. The blowhole ligament and its posterior septum appear to be separate branches of the same structure; the structure of the blowhole ligament of delphinids may be a derived condition associated with the loss of the posterior septum. The potential functions of phocoenid facial structures are examined. Phocoenid nasal passages are capable of complex airflow. Sound transmission in phocoenids is suggested to be different from that in delphinids.
Biochemical genetic variation in odd-year pink salmon (Oncorhynchus gorbuscha) from Kamchatka
Authors: Varnavskaya Nataly V. , Beacham Terry D.
Published: July 2008

Electrophoretic analysis was conducted at 17 loci for eight populations of pink salmon spawning in odd years from the east coast of Kamchatka and one population from the Fraser River drainage in British Columbia. Heterogeneity in allelic frequencies among the Kamchatkan populations was observed at 5 loci (ADA, GPD, MDH-1,2, PGDH, and PGM). Substantial heterogeneity in allelic frequencies was observed between Kamchatkan populations and the Fraser River population. Cluster analysis, based on 5 loci surveyed in previous studies, indicated that pink salmon from the Fraser River and southern British Columbia were distinct from more northerly spawning populations in British Columbia, Alaska, and Kamchatka. The concept of a "fluctuating stock" population structure of pink salmon or random mixing during spawning over a large geographic area was not supported by observed patterns of genetic variation.
Phenotypic plasticity of the montane vole (Microtus montanus) in unpredictable environments
Authors: Negus Norman C. , Berger Patricia J. , Pinter Aelita J.
Published: July 2008

From 1987 to 1989, the cohort dynamics of Microtus montanus populations were studied at two montane meadow sites approximately 160 km apart, in northwestern Wyoming. The 1987 and 1988 breeding seasons differed markedly from each other. In 1987, melt off occurred in April, and the first cohort was born in May (cohort 1). The entire breeding season was favorable owing to frequent rainfall throughout the summer. Cohort 1 animals grew rapidly and females began breeding at 4–5 weeks of age. Likewise, cohort 2 (June) animals exhibited rapid growth and females were breeding at 7–8 weeks of age. Cohort 3 (July and August) animals grew more slowly and most entered the winter as prepubertal animals of subadult size. At the end of the summer, cohort 3 animals represented >70% of the voles recruited during the breeding season. In 1988, following melt off in late April, precipitation was below normal and the situation intensified to severe drought through the summer. The growth rates of cohort 1 and 2 animals were significantly lower than 1987 growth rates, and very few females attained sexual maturity. At the end of the summer, cohort 3 animals represented <25% of the total recruitment at both study sites. Such apparent phenotypic plasticity of growth and maturation appears to be an evolved adaptive strategy that is responsive to several environmental cues. Both study sites, although widely separated, exhibited virtually identical patterns throughout the study.
Fetal growth and the condition of pregnant northern fur seals off western North America from 1958 to 1972
Authors: Trites Andrew W.
Published: July 2008

Annual estimates of the condition of pregnant northern fur seals (Callorhinus ursinus) and the size of their fetuses were determined from over 2600 samples collected in the North Pacific from 1958 to 1972. A condition index related the observed mass of pregnant females (adjusted for fetal mass) to their predicted mass (calculated from body length). It showed that females carrying male fetuses were in poorer condition than those carrying female fetuses. It also showed that the mean condition of pregnant females improved from 1958 to 1964, but dropped sharply in 1965. Body condition remained poor until 1972, when it plunged again. Fetal mass declined throughout the 1960s, unlike body length, which changed very little. It is suggested that fetal growth, particularly mass, is a sensitive indicator of feeding conditions during the last trimester of pregnancy while pregnant females are in the Gulf of Alaska and Bering Sea. It is further speculated that the condition index for adults reflects overall feeding conditions experienced throughout the annual migration.
Rapid change in suitability of white spruce for a specialist herbivore, Zeiraphera canadensis, as a function of leaf age
Authors: Quiring D. T.
Published: July 2008

Field studies were carried out over 2 years to determine the effect of age of white spruce (Picea glauca) leaves on the development of the spruce bud moth, Zeiraphera canadensis Mut. &Free. (Lepidoptera: Tortricidae). In both years developing buds remained suitable for first-instar larvae for only 4–5 days after bud burst, after which survivorship decreased significantly. Individuals that survived on flaring shoots were smaller than those placed on newly burst buds. Although leaf contents of water, nitrogen, and several minerals were inversely related to leafage, only declines in N and P content were associated with the rapid change in host suitability. Differences in N and P contents were small, however, suggesting that the rapid decline in host suitability was also due to the influence of other, unmeasured factors. When larvae were placed on foliage of the same age, their survival was similar on trees in half-sib families with high or low susceptibility to Z. canadensis. Thus, variations in susceptibility of white spruce to Z. canadensis might be associated with differences in host-plant phenology but are not due to differences in nutritional quality. This study demonstrates that the phenological window for establishment of newly emerged folivores may be shorter than is commonly thought.
Innate recognition of flowers by bumble bees: orientation of antennae to visual stamen signals
Authors: Lunau Klaus
Published: July 2008

The innate behaviour of flower-naive bumble bees (Bombus terrestris, Bombus lucorum) was observed at artificial flowers that consisted of a corolla and a guide area. A set of key stimuli was found to release a sequence of reactions, including the bee's approach, antennal reaction, and landing. For each reaction a binary choice between visual and olfactory signals was presented at the artificial flowers. Approach from a distance was released by the spectral purity of the corolla colour. The antennal reaction, which is the first antennal contact at an artificial flower, and occurs while the bumble bee is in flight, was oriented toward those areas with colours of the highest spectral purity. The landing reaction was released by visual and olfactory signals from the areas contacted during the antennal reaction. The combined presentation of visual signals from the anthers and olfactory signals from the pollen most effectively promoted landing. The antennal reaction allows precise alignment for landing and the antennal tips contact the visually conspicuous guide areas. This leads to effective perception of visual and olfactory stimuli from the guide area. The pollen and anthers, as well as the floral guides, which act as landing signals, of entomophilous flowers (Linaria vulgaris, Melampyrumpratense) possess olfactory qualities. In contrast, the pollen of one anemophilous plant (Pinus cedrus) exhibits no such qualities.
Temporal and geographic variation in the social structure of female sperm whales
Authors: Whitehead Hal , Kahn Benjamin
Published: July 2008

The social structure of female sperm whales (Physeter macrocephalus) was examined from data collected during studies of identified individuals off the Galápagos Islands in 1985, 1987, and 1989, off the Seychelles Islands in 1990, and off mainland Ecuador in 1991. Three levels of social organization were examined in the Galápagos Islands studies. "Units," permanent associations between individuals, showed no significant deviation from a mean size of 13 individuals. "Groups," temporary associations between units lasting a few days, had a mean size of 24 individuals. Group size was lower in 1987 (an "El Niño" year) than in 1985 or 1989, but this difference was not statistically significant. "Aggregations" of groups in the same general area lasting periods of hours were significantly larger in 1985 (mean of 77 individuals) than in 1987 (mean of 47 individuals). There are significant differences between areas in aggregation sizes but not in group sizes. Groups appear to aggregate frequently off the Galápagos Islands, occasionally off mainland Ecuador, and very rarely off the Seychelles Islands. These temporal and geographic differences in sizes of groups and aggregations in sperm whales are probably caused by variations in the distribution and abundance of their food, but responses to recent exploitation may also be a factor.
Reconstructing reproductive histories of black bears from the incremental layering in dental cementum
Authors: Coy Pamela L. , Garshelis David L.
Published: July 2008

Known reproductive histories of female radio-collared black bears (Ursus americanus) in Minnesota were matched against the spacing of growth layers in stained thin sections of their teeth. Light-staining bands of cementum, deposited during the summer months, were relatively narrow during years when females were raising cubs. Because females in this study never successfully reared cubs in 2 consecutive years, narrow light bands were bordered by wider bands, causing the intervening dark-staining fall–winter annuli to appear paired. Adult males exhibited similar pairing of dark annuli, caused not by altered annular spacing but by deposition of distinct summer accessory lines. Paired dark annuli in females accurately reflected known cub-rearing records, although it was more difficult to determine the years of cub production (reading teeth from the outer annulus inward) than the ages of females when they produced cubs (counting annuli outward from the dentin–cementum interface). The distribution of ages of first reproduction gleaned from teeth of harvested females coincided with that of females with known reproductive histories, indicating that teeth currently collected from harvested black bears by management agencies across North America could provide reasonably good accounts of both present and past reproductive rates.
Taxonomic notes on the Oreochromis niloticus subspecies-complex (Pisces: Cichlidae), with a description of a new subspecies
Authors: Seyoum Seifu , Kornfield Irv
Published: July 2008

Relationships among the seven recognized subspecies of the widespread African cichlid Oreochromis niloticus (L.) were investigated using restriction endonuclease analysis of mitochondrial DNA. Changes in nomenclature are based on estimates of sequence divergence and concordant results from phenetic, cladistic, and maximum likelihood analyses of molecular character sets. Oreochromis niloticus cancellatus and O. n. filoa are reassigned to O. cancellatus as O. c. cancellatus and O. c. filoa, respectively. The tilapiine fishes of Lake Tana, Ethiopia, previously assigned to O. n. cancellatus, are here described as Oreochromis niloticus tana subsp.nov. in recognition of their distinctive molecular phenotypes.
Determination of gender in cetaceans by the polymerase chain reaction
Authors: Palsbøll Per J. , Vader Anna , Bakke Ingrid , El-Gewely M. Raafat
Published: July 2008

We determined the gender of a variety of cetacean species, including both ondotocetes and mysticetes, using the polymerase chain reaction for amplification of the sex chromosome specific regions ZFY/ZFX and SRY. This quick and simple method requires extremely small amounts of tissue, and therefore allows gender to be determined from skin biopsies taken from free-ranging specimens. In the fin whale, Balaenoptera physalus, no gender-specific bands were observed when the ZFY/ZFX system was used, but when the SRY system was used, sex was accurately determined. Previous studies in other mammals have also shown the SRY system to be more reliable in sex determination. We therefore recommend amplification of the SRY region alone or in parallel with the ZFY/ZFX regions, as described here, as a test for gender in cetaceans and other mammals.
Validité de l'analyse des sacs fécaux pour l'étude du régime alimentaire des jeunes au nid de la linotte mélodieuse (Carduelis cannabina)
Authors: Eybert M. C. , Constant P.
Published: July 2008

Diet was studied in nestlings of the European Linnet (Carduelis cannabina L.) by analysing fecal sacs, the only method that allows continuous sampling of the diet to the end of the nesting period. The validity of the method was tested by comparing the results of the analysis with the composition of the stomach contents of nestlings that died during nesting. This study was carried out in a moor surrounded by hedges, at Campénéac, in Brittany, France. There is a strong correlation between the mean composition of the fecal sacs and that of the stomach contents, but biases were found. Animal matter, which represents a minimal fraction of the food and is given only occasionally to the chicks during the first days of feeding, leaves practically no traces in fecal sacs. Moreover, a few species of seeds that are almost completely assimilated, e.g. Brassica napus and Euphorbia helioscopia, can be greatly underestimated in the analysis of fecal sacs. As these species may be at certain times the preferred food of the chicks, specific correction factors have been calculated to compensate for the biases. Our results indicate that by analysing the fecal sacs one can quickly identify and quantify the diet of nestlings and that with a relatively small number of samples; it constitutes therefore a reliable and rapid technique.[Journal translation]
Pathogenicity of larval Protocalliphora (Diptera: Calliphoridae) parasitizing nestling birds
Authors: Whitworth Terry L. , Bennett Gordon F.
Published: July 2008

Controlled tests showed that feeding by larvae of several species of Protocalliphora lowered haematocrit and haemoglobin levels of nestling magpies and bank swallows. Subsequent studies showed that natural populations of nestling magpies and Bank Swallows infested by P. asiovora and P. chrysorrhoea, respectively, experienced significantly reduced blood levels at the P0.05 and P0.01 levels except in the youngest nestlings. Despite the presumed heavy blood loss, most nestlings are not killed by larvae of Protocalliphora. Studies of natural populations of Protocalliphora in 48 species of birds indicate that the larval populations are usually too small to kill or seriously injure most nestlings.
A new freshwater moss animal in the genus Plumatella (Ectoprocta: Phylactolaemata: Plumatellidae) from New England (U.S.A.)
Authors: Smith Douglas G.
Published: July 2008

A new species of phylactolaemate ectoproct is described from New England. The new species is characterized by a thick hyaline ectocyst, which is transparent throughout the colony, and a round floatoblast. Other features of the floatoblast and the surface morphology of the sessoblast fenestra distinguish this species from its apparently closest relatives, Hyalinella orbisperma and Hyalinella vaihiriae. It is proposed that along with the two above-mentioned forms the new species described evolved from a Plumatella repens-like ancestor. The new species is confined to near-pristine environments in several types of lentic to near-lotic habitats having in common weak acidity. The discovery of the new species, which contains characters common to both Hyalinella and Plumatella, further stresses the need to reevaluate the genus Hyalinella.
Adult population dynamics and reproductive effort of the fishing spider Dolomedes triton (Araneae, Pisauridae) in central Alberta
Authors: Zimmermann Manfred , Spence John R.
Published: July 2008

A combination of simple enumeration and more intensive Jolly–Seber and Manly–Parr mark–recapture estimation was required to give a complete picture of the population dynamics of adult Dolomedes triton on a small pond in central Alberta. The total number of spiders marked was 142 in 1986 and 210 in 1987, and annual adult emergence, using the population size estimates of the two mark–recapture methods, amounted to ca. 150 and 230 individuals in 1986 and 1987, respectively. The sex ratio was not different from 1:1 in 1986, but in 1987 more than twice as many males emerged than females. Males had significantly shorter observed residence times (life-spans) than females. Contrary to longevity estimates based on the survival probabilities given by the Jolly–Seber model, which were close to those based on enumeration, Manly–Parr survival estimates were strongly biased and even yielded impossible estimates of adult longevity. In both years the median date of male emergence preceded that of females by 5–10 days. Male population size decreased dramatically during the interval when the density of the female population increased, supporting the hypothesis that cannibalism by females is a major source of male mortality. Seventy and 55% of marked females produced egg sacs in 1986 and 1987, respectively. First egg sacs contained 472 ± 18.5 (SE) eggs. Four times as many nursery webs were found in 1986 as in 1987, suggesting that significant losses in female reproductive success occur during the period of egg sac care.
Caractéristiques de la coquille des oeufs chez la souche hybride (ovipare × vivipare) du lézard Lacerta vivipara
Authors: Heulin Benoît , Arrayago Maria Jesus , Bea Antonio , Brana Florentino
Published: July 2008

The lizard Lacerta vivipara has both oviparous and viviparous populations. Experimental crossbreedings (oviparous strain × viviparous strain) in the laboratory have previously allowed us to obtain a hybrid strain. Hybrids have also laid eggs in the laboratory. The aim of the present study was to determine the eggshell characteristics of the hybrid and to compare them with the characteristics previously studied in the oviparous and viviparous strains. The mean thickness of the eggshell is 21 μm for the hybrid, 40 μm for oviparous eggshell, and 9 μm for the viviparous eggshell membrane. Mean dry mass of the eggshell is 3 mg for hybrids, 5 mg for the oviparous strain, and 0.6 mg for the viviparous strain. Ash mass of the eggshell is 0.79 mg for hybrids, 1.05 mg for the oviparous strain, and 0.22 mg for the viviparous strain. Fibrils were observed in both oviparous and hybrids' eggshells and in the viviparous eggshell membrane. The outer surface of the hybrids' eggs presents both places with a calcareous layer (61%) and places where fibrils are not covered with a calcareous layer (39%). These incompletely calcified eggshells are intermediate between the oviparous eggshells (complete calcareous layer) and the regressed eggshell membrane (fibrils with minor traces of calcite) observed during the gestation of the viviparous lizards. This situation is of considerable interest for further experimental studies dealing with physiological and genetic aspects of the evolution of viviparity.
Gray whale foraging on ghost shrimp (Callianassa californiensis) in littoral sand flats of Puget Sound, U.S.A.
Authors: Weitkamp Laurie A. , Wissmar Robert C. , Simenstad Charles A. , Fresh Kurt L. , Odell Jay G.
Published: July 2008

Gray whales (Eschrichtius robustus) residing in Puget Sound, Washington, U.S.A., in 1990 and 1991 created feeding pits on littoral sand flats dominated by ghost shrimp (Callianassa californiensis). The whales removed an extensive biomass of shrimp from the pits. Ghost shrimp standing stock was 2–5 times lower inside than outside feeding pits, equivalent to a removal of 3–6 kg of shrimp per pit. An estimated 2700–3200 feeding pits were present on 19 km of sand flat in 1990, while 19 000 feeding pits were documented over the same region in spring and summer, 1991. We estimated that 10–12 and 75 t of shrimp were removed from the pits in 1990 and 1991, respectively. Ghost shrimp represent an energetically valuable prey for gray whales, providing 2–15 times higher standing stocks than any other reported prey. We discuss our results in the context of conflicts with human activity, impacts on the littoral community, and the significance of an expanding gray whale population.
Genetic variation in male Yellow-headed Blackbirds from the northern Great Plains
Authors: Twedt Daniel J. , Bleier William J. , Linz George M.
Published: July 2008

Electrophoretic differences at 15 presumptive loci were used to assess allelic frequencies, heterozygosities, and polymorphism for male Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) collected in east-central Alberta, north-central North Dakota, and east-central South Dakota. Five loci were polymorphic and mean heterozygosities ranged from 0.119 to 0.133. Significant differences were detected among these geographic populations of Yellow-headed Blackbirds, primarily due to differences in the allelic frequencies of isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase. Differences detected were not sufficient to uniquely identify the geographic origin of Yellow-headed Blackbrids.
Enzymologie du tractus digestif de la modiole hydrothermale Bathymodiolus thermophilus (Mollusque Bivalve)
Authors: Pennec Marcel Le , Martinez Jean-Claude , Donval Anne , Herry Angèle , Beninger Peter
Published: July 2008

Although the structure and ultrastructure of the digestive tract of the hydrothermal vent mytilid Bathymodiolus thermophilus conform to those of other bivalves, enzymological data are lacking. To address this question, digestive enzyme assays and histoenzymological tests were performed on different regions of the digestive tract: labial palps, oesophagus, stomach, digestive gland, intestine, and rectum. Carbohydrases, mainly present in the digestive gland and the stomach, were the most active of the 33 enzymes studied. These enzymes would allow substantial digestion of particles from the immediate environment as well as those descending from the photic zone. Acid phosphatases present in all the compartments of the digestive tract indicate intracellular digestion, whereas alkaline phosphatase activity, mainly in the digestive gland and the stomach, demonstrates absorption phenomena. We conclude that, in addition to the nutrient supply furnished by chemoautotrophic bacteria in the gill bacteriocytes, the digestive tract is functional and provides at least some of the nutritive requirements of this species.
Cardiovascular responses to diving and involuntary submergence in the rhinoceros auklet (Cerorhinca monocerata Pallas)
Authors: Stephenson Richard , Hedrick Michael S. , Jones David R.
Published: July 2008

Cardiovascular responses during diving behaviour were recorded via a cannulated carotid artery in five rhinoceros auklets. Heart rate and mean arterial blood pressure were unchanged from predive values during both escape and feeding dives. The responses to feeding dives and escape dives did not differ. Acidosis, accompanying elevated steady-state plasma lactate levels during escape diving activity, was partially compensated by lung ventilation between dives. The absence of progressive accumulation of lactate in the blood implies that an aerobic steady state was attained, despite the short intervals between dives (2.4 ± 0.4 s). Arterial blood oxygen tension was maintained at reduced levels (50–60 mmHg; 1 mmHg = 133.322 Pa) for up to 32 min of continuous escape diving activity. Immersion of restrained auklets or capture of diving auklets in a net provoked a rapid and intense bradycardia. Growth of hand-reared auklet nestlings peaked at a time corresponding to the natural fledging age for this species but the urge to leave the nest box was not triggered by reduced food availability, as has been suggested for wild semi-precocial alcids. Potential pitfalls in the maintenance and use of alcids in physiological research are discussed.
Effect of the rat tapeworm, Hymenolepis diminuta, on the coprophagic activity of its intermediate host, Tribolium confusum
Authors: Evans W. S. , Hardy M. C. , Singh Renate , Moodie G. E. , Cote J. J.
Published: July 2008

Populations of Tribolium confusum that had been fed continuously (satiated) or starved for 48 h were separated into groups of 10 beetles each. Each group was placed in a test arena (diameter 90 mm) that contained two infective baits (feces from rats infected with patent Hymenolepis diminuta) and two baits from uninfected rats and allowed to forage for 120 or 240 min. The number of beetles aggregated in the immediate region of each bait was recorded every 20 min until the experiment was terminated. During the first 180 min the distribution of the beetles in the starved populations invariably favoured (P < 0.025) the infective baits. A similar trend was observed with satiated beetles but the difference in beetle distribution was significant (P < 0.001) only at the 100-min observation time. With both starved and satiated populations the differences in distribution between bait types were not significant after 180 min.
Ecdysis and other aspects of metamorphosis in rove beetles with exarate or obtect pupae (Coleoptera: Staphylinidae)
Authors: Frania Henry E.
Published: July 2008

Based on actual observations of ecdysis or examination of exuviae of early- and (or) last-instar larvae of species in the Staphylininae (sensu latu), Paederinae, Steninae, Tachyporinae, Oxytelinae, Omaliinae, and Aleocharinae, it is shown that ecdysis from one larval instar to the next and larval–pupal ecdysis occur in about the same manner in all of these subfamilies. Newly emerged pupae of all Staphylinidae are exarate; pupae of the subfamily Staphylininae then become obtect. These findings refute a previous claim that larval–pupal ecdysis occurs differently in the Staphylininae and Paederinae than in other Staphylinidae. Larvae of Staphylininae and Paederinae have divided abdominal terga and sterna; this might facilitate ecdysis, but not as previously thought. The emerging larva or pupa remains connected to the old larval cuticle by the everted lining of the old larval foregut until near the end of ecdysis; this could be a necessary feature of ecdysis in Staphylinidae. Pupal chaetotaxy could affect how active the pupa is when disturbed.
Viability of glochidia of two species of Anodonta exposed to low pH and selected metals
Authors: Huebner J. D. , Pynnönen K. S.
Published: July 2008

Mature glochidia were stripped from the gills of gravid mussels and exposed to low pH (3 – 6.5), aluminum (150 – 3000 μg/L), aluminum (300 μg/L) at low pH (3–6.5), zinc (5 – 30 000 μg/L), cadmium (50–3000 μg/L), or copper (5 – 1500 μg/L) for 6 days. Viability was tested after 24, 48, 72, and 144 h by observing the ability of the glochidia to close when exposed to an irritant, 2.5 M KCl. Effective concentrations needed to reduce the closure response to 50% (EC50) under the experimental conditions were calculated using probit analysis. The relative toxicities (based on 48-h EC50s) of the metals to Anodonta cygnea glochidia were Cu (EC50 = 5.3 μg/L) > Cd (EC50 = 46.8 μg/L) > Zn (EC50 = 69.1 μg/L) > Al. The EC50 for pH was 4.34 for A. cygnea and 4.69 for Anodonta anatina. In 300 μg/L Al, the EC50 for pH for A. cygnea was 4.46. The ability of glochidia to close their valves is considered a reliable measure of viability, as this action is necessary for the larvae to complete the obligate ectoparasitic stage of their life cycle. Decrease in glochidial viability is suggested as a possible explanation for the disappearance of unionids from acid- and metal-contaminated waters.
Neuromuscular analysis of the chela-closer muscle associated with precopulatory clasping in male snow crabs, Chionoecetes opilio
Authors: Govind C. K. , Read A. T. , Claxton W. T. , Elner R. W.
Published: July 2008

Male snow crabs, Chionoecetes opilio (Majidae), use their modified chelae to retain females for weeks before copulation. Consequently, adaptations for such sustained activity were examined in the chela-closer muscle responsible for clasping. Based on an allometric increase in the ratio of chela size to carapace width, male snow crabs were categorized as morphometrically mature or immature, the former displaying precopulatory clasping more readily than the latter. However, the two types were similar in terms of the properties of the chela-closer muscle, which was examined in this study. The motor pattern during clasping consisted of low-frequency firing of one of the excitor motoneurons, which gives rise to small synaptic potentials. The other excitor motoneuron, which produces large synaptic potentials, fired only when the female struggled during the embrace. The synaptic potentials of both axons showed little if any fatigue at these low firing frequencies. The neuromuscular terminals of these motoneurons displayed areas of synaptic contact larger than most found in other tonically active crustacean muscles. The majority of these synapses had an active site for transmitter release denoted by a dense bar, with many containing more than three dense bars. The closer muscle had typically slow features, with 10 or 11 thin filaments surrounding a thick filament, and sarcomere lengths of 9 – 10 μm. Overall, the closer muscle with its slow-fiber composition, tonic motoneurons, and neuromuscular synapses is well suited to sustained, low-level activity such as precopulatory clasping.
Relationships of foetal haemoglobin level to age of newborn fallow deer (Dama dama)
Authors: Schreiber Arnd , Braza Francisco , José Cristina San , Aragón Santiago
Published: July 2008

The relative proportions of foetal and adult haemoglobins were quantified by densitometry of isoelectric focusing patterns in blood samples from 157 fawns from a free-living population of fallow deer (Dama dama) in Coto Doñana National Park, southwestern Spain. During the first week of life, the ratio of adult to foetal haemoglobin concentration increases with age. The proportion of foetal haemoglobin to total haemoglobin in peripheral blood proved a better indicator of age than morphological characteristics based on the persistence of natal traits in the fawns external phenotype. The erythrocytes of even the youngest fawns contained some adult haemoglobin, the mean percentage of adult haemoglobin in offspring less than 24 h of age being 13.7% in the reproductive season of 1989 (n = 28) and 7.18% in 1990 (n = 25). Half of the fawns whose blood contained less than 3% adult haemoglobin failed to survive past the first weeks of life (even when body mass was not below average), whereas not a single fawn with more than 5% adult haemoglobin on its first day of life was subsequently found dead. Even when the effects of sexual dimorphism in body size are taken into account, the blood of male fawns contained less adult haemoglobin at a given age than that of females, as was evident from significantly lower levels of adult haemoglobin when referenced to several body size covariates such as body length, shoulder height, hind-foot length, and body weight.
Defence against intraspecific usurpation by paper wasp cofoundresses (Polistes fuscatus, Hymenoptera: Vespidae)
Authors: Gamboa George J. , Wacker Tracy L. , Duffy Kimberly G. , Dobson Scott W. , Fishwild Thomas G.
Published: July 2008

We conducted extensive field observations (369.6 h) and surveys of 36 preworker, multiple-foundress colonies of the social wasp Polistes fuscatus. We observed 48 intrusions by foreign conspecifics in 18 of 36 colonies. The rates of intrusion by foreign females, about 1 intrusion per colony each day, did not differ among observations conducted approximately 22, 39, and 48 days after nest initiation. Thus, it appears that usurpation pressure is both intense and constant throughout the preworker stage of the colony cycle. None of the observed intrusions resulted in the replacement of resident foundresses, although surveys revealed that 2 of 36 multiple-foundress colonies were usurped. All 48 intrusions were by females that were unlikely to be closely related to the colonies they attempted to usurp. Resident foundresses exhibited highly intolerant behaviour toward intruders, and evicted them within 40 s of their landing on the nest. There was a pronounced division of labour between queens and subordinates in colony defence. When present together on the nest, queens were significantly more involved than their subordinates in repelling intruders. The vast majority of intruder evictions did not involve cooperation or joint effort by cofoundresses. Therefore, the ability of multiple foundresses to successfully defend against usurpation is probably due to the decreased probability that their nest is left unattended.