bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of food and density on growth and metamorphosis in larval wood frogs (Rana sylvatica) from central Labrador
Authors: Murray Dennis L.
Published: August 2008

Two experiments were performed on Rana sylvatica tadpoles from central Labrador to test for effects of food and density on growth and metamorphosis. In an experiment examining for the presence of diffusible growth inhibitors, one group of tadpoles was given water treated by adding a high density of sibling tadpoles, and another group was given filtered lake water. No diffusible growth inhibitors existed in this population, as body weight measured weekly, weight at metamorphosis, and duration of larval stage did not differ between control and treated groups. In a food-density experiment, effects of food and larval density were examined by subjecting tadpoles at four different densities to four food levels, creating a 4 × 4 food–density matrix. Food and density both affected growth rate, weight at metamorphosis, and duration of larval stage. Socially governed negative density-dependent interactions are either nonexistent in northern populations, or were completely masked by slight positive effects of grouping. Results suggest that northern larvae differ in life-history strategy from southern populations, and the possibility of overwintering in immature stages of high-latitude populations is discussed.
Variability in the life history of Unionicola crassipes, a sponge-associated water mite (Acari: Unionicolidae)
Authors: Proctor Heather C. , Pritchard Gordon
Published: August 2008

The life history of a member of the widely distributed Unionicola crassipes complex (Acari: Unionicolidae) in a foothills pond in Alberta, Canada, differs from those previously described for this taxon. Two years are required for a female to develop from an egg to an ovipositing adult. Fertilized females overwinter and oviposit in the sponge Eunapius fragilis in early May. Larvae emerge in late May to early June and parasitize chironomids of the genus Tanytarsus. Engorged larvae drop from their insect hosts and return to sponges for the protonymph resting stage. Active, predaceous deutonymphs develop from protonymphs in early summer. Deutonymphs overwinter and enter the tritonymph resting stage, also in sponges, in early May. Summer adults emerge from the tritonymph stage in late May to early June. Males emerge first, but there is an overall female bias to the sex ratio of emerging adults. Growth of sclerotized and unsclerotized parts occurs in adults over the summer, during which time females appear to suffer greater mortality than males, because the sex ratio is 1:1 in September. It is primarily mated females that overwinter for a second time. A population decline in the summer of 1987 was correlated with degeneration of sponges; variation in the life histories of sponge-associated water mites is discussed in light of this correlation.
How does benthic living affect body volume, tissue composition, and density of fishes?
Authors: Webb Paul W.
Published: August 2008

Tissue composition, tissue density, and body density of two benthic fish, plaice (Pleuronectes platessa) and father lasher or shorthorn sculpin (Myoxocephalus scorpius), and a benthopelagic fish, the whiting (Merlangus merlangus), were measured. Since the fish were not identical in absolute size, data on composition were normalized by dividing body and tissue volumes by the cube of the total length of the fish. For body volume, this normalized volume (volume × length−3) is analogous to the condition factor (mass × length−3), and hence is called the volume condition factor. Normalized tissue volumes are called relative volumes. Volume condition factor was 13 L∙m−3 for lasher. Plaice and whiting have compressed body cross sections compared with that of lasher, which were associated with lower volume condition factors of 8.1 L∙m−3 for plaice and 9.1 L∙m−3 for whiting. Plaice are highly compressed to reduce drag and facilitate station holding on current-swept substrates. The reduced relative volume of plaice was associated with reduced visceral volume, which may correlate with reductions in rates of energy and material processing. This may represent a cost of low-drag forms for benthic fish. Whiting were neutrally buoyant, but carcass density was 1061 kg∙m−3. The densities of plaice and lasher were 1069 and 1074 kg∙m−3, respectively. Tissue densities and composition were variable among the three species. Benthic species showed neither consistently high tissue densities nor consistently larger proportions of high-density tissues. Therefore, benthic fish do not appear to maximize body density, which could improve passive station-holding ability in currents. Density may not be maximized because of higher locomotor costs when fish swim off the bottom. Increasing density may not be essential, since other factors, such as high friction coefficients, could have larger effects on station-holding performance.
The Eimeriidae (Apicomplexa) of raptors: review of the literature and description of new species of the genera Caryospora and Eimeria
Authors: Upton Steve J. , Campbell Terry W. , Weigel Maure , McKown Richard D.
Published: August 2008

Four new species of Coccidia (Apicomplexa: Eimeriidae) are reported from North American raptors. Caryospora kansasensis sp.nov., in the feces of Swainson's hawk, Buteo swainsoni, has ovoid oocysts which measure 37.2 × 32.6 (32.8–40.0 × 29.6–36.0) μm. Caryospora lindsayi sp.nov., from the red-tailed hawk, Buteo jamaicensis, has subspherical oocysts measuring 33.7 × 31.6 (31.2–36.0 × 30.4–32.8) μm. Eimeria megabubonis sp.nov. from the feces of the great horned owl, Bubo virginianus, has ovoid oocysts measuring 32.7 × 28.9 (28.8–36.0 × 27.2–32.0) μm. Eimeria varia sp.nov., from the barred owl, Strix varia, measures 33.1 × 30.5 (31.2 × 36.0 × 28.0–32.0) μm. In addition to the above new species, Caryospora arcayae Volcań and Medrano, 1984 is recorded for the first time from North America and is redescribed from a new host, the broad-winged hawk, Buteo platypterus. Oocysts of Caryospora uptoni and Eimeria bubonis, as well as sporocysts of Sarcocystis/Frenkelia spp., were also found. A table is provided listing key features of the known species of Caryospora and Eimeria of raptors.
Ancyracanthopsis winegardi n.sp. (Nematoda: Acuarioidea) from Pluvialis squatarola (Aves: Charadriidae) and Ancyracanthus heardi n.sp. from Rallus longirostris (Aves: Rallidae), and a review of the genus
Authors: Wong P. L. , Anderson R. C.
Published: August 2008

Ancyracanthopsis winegardi n.sp. from under the koilin lining of the gizzard of Pluvialis squatarola (L.) can be distinguished by its ptilina which extend from the dorsoventral sides of the oral opening to the lateral sides; each ptilinum is divided into four lobes. In addition, the left spicule has a narrow process forming a truncated distal end and the right spicule has a conical protuberance on the left side near the distal end. Evidence is presented that fiddler crabs (Uca spp.) may serve as intermediate hosts of A. winegardi in the Gulf coast. Ancyracanthopsis heardi n.sp. from under the koilin lining of the gizzard of Rallus longirostris Boddaert can be distinguished by its ptilina which extend from the dorsoventral sides of the oral opening to the lateral sides; each ptilinum is divided into five or six serrations. In addition, the distal end of the left spicule is flat and expanded dorsally, and the right spicule is crescent-shaped and markedly tapered. Ancyracanthopsis now comprises eight known species, four occurring in the New World (i.e., A. coronata (Molin, 1860a); A. quadripartita (Clapham, 1945); A. winegardi n.sp.; A. heardi n.sp.), three in the Old World (i.e., A. parvialatus (Belopolskaya, 1953); A. petrovi Guschanskaya, 1950; A. schikhobalovi (Guschanskaya, 1950)), and one in Asia (A. buckleyi Ali, 1971).
Cold hardiness of tree-hole mosquitoes in the Great Lakes region of the United States
Authors: Copeland Robert S. , Craig Jr. George B.
Published: August 2008

We examined cold hardiness of the overwintering stages of five species of North American tree-hole mosquitoes through laboratory experiments and field observations. Among the species that overwinter as larvae, fall-collected individuals were freeze tolerant, whereas all summer-collected larvae were killed by freezing. Cold hardiness varied among species and among larval stages within species. The order of diminishing cold tolerance was Orthopodmyia alba, Anopheles barberi, and Orthopodomyia signifera. Some O. alba larvae survived freezing at −25 °C, the lowest temperature reported to be survived by an aquatic animal in ice. Prolonged (up to 16 days) and multiple (four) exposures to −15 °C had no effect on survival of O. alba third-instar larvae, but increased mortality of second instars of O. alba and A. barberi. Species were more tolerant of cold when frozen in rot-hole water in which they are commonly found in nature than in "pan" water in which they rarely occur. Both photoperiodically induced dormancy and prefreezing exposure to low temperature were necessary for the establishment of cold hardiness in laboratory-reared A. barberi. Eggs of Aedes triseriatus and Aedes hendersoni were more cold hardy than larvae of Orthopodomyia and Anopheles. Neither preconditioning to cold nor dormancy was necessary for survival at −15 °C for 24 h. Females that had survived temperatures to −25 °C as eggs showed no impairment of reproductive capability.
Enamel thickness of rooted and rootless microtine molars
Authors: Grayson Donald K. , Maser Chris , Maser Zane
Published: August 2008

Of the 10 genera of North American microtines, the molars of 4 become rooted in adults and thus do not grow continuously; the molars of the remaining 6 do not develop true roots and grow throughout the life of the animal. Continuously growing molars lengthen rapidly, but rooted molars do not. We hypothesize that the life of the molars in voles with rooted molars is increased by tooth enamel that is thicker than in voles with continuously growing molars. Measurements of the enamel thickness in Microtus and Clethrionomys support this hypothesis.
An assessment of the phylogeny of the Branchiobdellida (Annelida: Clitellata), using PAUP
Authors: Gelder S. R. , Brinkhurst R. O.
Published: August 2008

Analyses using PAUP (phylogenetic analysis using parsimony) were conducted on a matrix of 24 taxa and 26 characters. The taxa included generalised descriptions of a haplotaxid and a lumbriculid oligochaete as outgroups with a hypothetical branchiobdellidan ancestor and 21 genera as ingroups. The branchiobdellidan taxon is a monophyly, and using anatomical characters only, is composed of three suprageneric assemblages. The taxonomic rank of the taxon and assemblages cannot be determined until they have been compared with cladistic analyses on other closely related clitellate groups. In the meantime the currently accepted ordinal rank of Branchiobdellida and the major branchiobdellidan families should continue to be used, with the latter reflecting the assemblages of the genera in our analyses: Branchiobdellidae (including Holtodrilus n.gen., Sinodrilus n.gen., and Xironodrilus), Bdellodrilidae (including Caridinophila and Hidejiodrilus n.gen.), and Cambarincolidae. An analysis with two zoogeographical characters in the matrix caused the genera to be divided into their respective North American and Eurasian groups; however, the North American Triannulata appeared constantly in the latter group. The genera in the Branchiobdellidae, as defined by us, are found in both geographical regions, and predictably the assemblage was split in two.
Effects of temperature fluctuations and photoperiod on hatching in the parasitic copepod Salmincola edwardsii
Authors: Poulin Robert , Conley David C. , Curtis Mark A.
Published: August 2008

In laboratory experiments, we studied the effects of the day–night cycle (photoperiod and temperature fluctuations) on the initiation of hatching and hatching rate in egg sacs of the copepod Salmincola edwardsii, ectoparasitic on brook trout (Salvelinus fontinalis). Pairs of egg sacs were removed from adult female copepods; for each pair, one sac was placed under experimental conditions and the other one was kept under constant conditions, providing an ideal control. Photoperiod had no significant effect on the initiation of hatching or hatching rate. The observed effects of temperature fluctuations were associated with water temperature itself, and appeared independent of whether it was fluctuating or constant. We conclude that hatching in S. edwardsii is not rhythmical but spontaneous, showing no relationship with daily changes in host vulnerability.
Reproduction and year-class strength of the Atlantic tomcod (Microgadus tomcod) in the Sainte-Anne River, at La Pérade, Quebec
Authors: Fortin Réjean , Léveillé Martin , Laramée Paul , Mailhot Yves
Published: August 2008

Experimental catches of a fyke-net fishery operated in the Sainte-Anne River during the 1980–1981 to 1983–1984 spawning seasons showed that although the majority of adult tomcod migrate upstream during rising tide, significant numbers do so against the tidal current. Most spawners return to the Saint Lawrence River during a falling tide. In the first 2 years, peak upstream migration occurred during the second half of December, and in the last 2 years, early in the second half of January. The date of peak upstream migration is significantly correlated with September and October air temperature in the summer habitat. Peak downstream migration of spawned-out adults occurred during the second half of January in 3 years and on 1 February in 1 year. The peak of the upstream and downstream migration of males and females generally occurred on the same dates. The spawning period extends minimally from mid-December to mid-February, but probably peaks close to the maximum of the downstream migration. The length and age composition of the Sainte-Anne River tomcod spawning stock remained relatively stable between the 1980–1981 and the 1983–1984 seasons. For the 1975–1976 to 1981–1982 period, the environmental variable to which year-class strength showed the highest parametric correlation was mean December Sainte-Anne River discharge. Stronger year-classes were produced in years of high water levels and discharge during the spawning period.
Life on the edge: the ecology and life history of the tropidurine iguanid lizard Uranoscodon superciliosum
Authors: Howland Jeffrey M. , Vitt Laurie J. , Lopez Pamela T.
Published: August 2008

An Amazonian population of the iguanid lizard Uranoscodon superciliosum was studied in lowland tropical wet forest in central Pará, Brazil. These nonheliothermic lizards are restricted to densely vegetated habitats near (often over) water, particularly riverbanks and small forest streams, where they utilize small-diameter perches and feed on a wide variety of invertebrates, apparently at the water's edge. They mature at moderate to large size at an age of about 1.5 years. Production of moderate-sized clutches of eggs is seasonal, and reproduction and fat storage both cycle in association with rainfall and flooding. Although they occur in fairly high densities, social interaction is uncommon and sexual dimorphism is not pronounced. The ecology and life history of this lizard seem to be strongly influenced by the unusual habitat specialization.
Postembryonic expression of the serotonin phenotype in Helisoma trivolvis: comparison between laboratory-reared and wild-type strains
Authors: Diefenbach Thomas J. , Goldberg Jeffrey I.
Published: August 2008

In a laboratory-reared albino strain of the snail Helisoma trivolvis, the number of neurons expressing the serotonin phenotype increases markedly during postembryonic life. To address whether these latent changes occur selectively in the laboratory-reared strain, postembryonic expression of serotonin immunoreactivity was directly compared in laboratory-reared and wild-type specimens. The spatial pattern of serotonin-immunoreactive neurons was generally the same in the two strains. In contrast, the time course over which this pattern was generated was more prolonged in the wild types than in the laboratory-reared strain. The cerebral, left parietal, and visceral ganglia of laboratory-reared animals completed their postembryonic acquisition of serotonin-immunoreactive neurons by stage P10. Acquisition of serotonin-immunoreactive neurons after stage P10 occurred only in the pedal ganglia. In the wild types, addition of serotonin-immunoreactive neurons continued at least until stage P20 in all of the ganglia examined. Analysis of serotonergic clusters within the cerebral and pedal ganglia revealed distinct developmental patterns for individual clusters. Therefore, the acquisition of the serotonin phenotype during postembryonic life is a normal component of nervous system development in wild-type H. trivolvis.
Observations of aggregating behaviour in adult male polar bears (Ursus maritimus)
Authors: Derocher Andrew E. , Stirling Ian
Published: August 2008

Polar bears (Ursus maritimus) are usually considered a solitary species, but between 50 and 60% of the adult male polar bears captured on land during the ice-free period in western Hudson Bay were sighted in aggregations with a mean size of 4 and a range of 2–14 individuals. The mean weight of aggregating adult males was significantly greater (approximately 60 kg) than the mean weight of nonaggregating adult males, but there were no significant differences in the mean age. Aggregations occurred throughout the ice-free period (August–October) and were most common at prominent points along the coast or nearby islands. Some locations were used over several years. The lack of competition for food and the absence of breeding activity during the ice-free period produce conditions that may facilitate aggregating. Familiarity with conspecifics may yield benefits by reducing the severity and frequency of competition for resources on the sea ice.
Morphometric variation within and between populations of the pine aphid, Cinara nigra (Wilson) (Homoptera: Aphidoidea: Lachnidae), in western North America
Authors: Foottit R. G. , Mackauer M.
Published: August 2008

Morphological variation in Cinara nigra (Wilson), found on Pinus contorta Dougl. ex Loud, throughout western North America, was characterized with the aid of univariate and multivariate statistical methods. Within-population variation in one sample collected near Edson, Alberta, was examined. Correlation and principal component analysis revealed patterns of interdependence among characters as well as patterns of size and size-related shape variation in 52 characters. To examine morphological variation between 19 geographic samples, this initial set was reduced in two steps to 49 and 32 characters, respectively; the reduction did not result in a significant loss of information content. No geographic pattern in clusters of samples was revealed either by the ordination of sample centroids or by UPGMA cluster analysis of the Mahalanobis D values. The taxonomic implications of this morphometric analysis are discussed, in particular the usefulness of various morphological attributes for species discrimination.
Activity and movement patterns of juvenile Atlantic cod, Gadus morhua, in Conception Bay, Newfoundland, as determined by sonic telemetry
Authors: Clark Donald S. , Green John M.
Published: August 2008

We studied the movements and activity patterns of individual 3-year-old (28–33 cm total length) Atlantic cod, Gadus morhua, in Conception Bay, Newfoundland, using sonic telemetry. Cod tracked between June and early September (summer) were wide ranging (> 3 km/day), nocturnally active, and migrated daily between deep (30 m) cold water where they were inactive and shallow (< 15 m) warm water where they fed. Cod tracked between mid-September and December (autumn) stayed in shallow (< 20 m) water where they were active in relatively small (545.3–2581.6 m2) home ranges during daylight hours and inactive at consistent resting sites at night. Home ranges were over sand whereas resting sites were generally in rocky areas. The seasonal change in migratory behaviour coincided with the disappearance of the shallow (< 30 m) summer thermocline. When the water column became isothermal over the depth range of juvenile cod, they remained in shallow feeding areas throughout the diel period. We suggest that the summer diel migration is a strategy to increase energetic efficiency. Literature on the feeding behaviour of cod and on the predation of juvenile cod suggests that the switch from nocturnal to diurnal activity may be an antipredator strategy. However, more information on the feeding behaviour of cod is required before this hypothesis can be adequately evaluated.
Molt patterns in the tree swallow (Tachycineta bicolor)
Authors: Stutchbury Bridget J. , Rohwer Sievert
Published: August 2008

The pattern and timing of molt was examined in 386 museum specimens of tree swallows (Tachycineta bicolor). The primaries were the first flight feathers to begin molt, with the secondaries and rectrices beginning soon after. Body molt began with the back, breast, and belly; the crown, chin, and rump regions were the last to molt. Flight feather molt began in mid-July and was completed by November. Birds from western populations began molt of the primaries later than birds from eastern populations. Birds in juvenal plumage had a complete molt of the primaries, secondaries, and rectrices, and in the eastern population tended to begin molting later than adults. Body molt took place primarily from mid-July through late October; however, from February to April, 34% (21/64) of birds sampled were actively molting chin feathers, and 5% (3/64) were molting crown feathers. The main period of molt (mid-July to mid-November) coincides with fall migration, and there was no evidence for interrupted molt during this time. A comparison of North American swallows suggests that species with northern winter ranges may be constrained to complete molt before winter, whereas species with more southern winter ranges have a protracted molt that is completed on the wintering grounds.
Development of Porrocaecum ensicaudatum (Nematoda: Ascaridoidea) in terrestrial oligochaetes
Authors: McNeill Marilyn A. , Anderson R. C.
Published: August 2008

Development of Porrocaecum ensicaudatum (Zeder, 1800) in the egg was studied at 5–10, 23–26, and 32–35 °C. Embryonic development occurred at 23–26 and 32–35 °C, but ceased at 5–10 °C. Development resumed in eggs transferred from the cold temperature to 23–26 °C. First-stage larvae moulted within eggs and second-stage larvae were infective to the terrestrial oligochaetes Eudrilus eugeniae (Kinberg) (Eudrilidae) and Eisenia fetida (Savigny) (Lumbricidae). In earthworms, second-stage larvae developed in the ventral blood vessel and moulted there 21–23 days postinfection. Third-stage larvae were infective to the definitive host after 4–5 weeks of development and remained infective for at least 1 year. Larvae were nonpathogenic to earthworms.
Development of Porrocaecum ensicaudatum (Nematoda: Ascaridoidea) in starlings (Sturnus vulgaris)
Authors: McNeill Marilyn A. , Anderson R. C.
Published: August 2008

Laboratory-raised starlings (Sturnus vulgaris L.) were experimentally infected with third-stage larvae of Porrocaecum ensicaudatum (Zeder, 1800) from earthworms. Within 2 h postinfection, larvae penetrated the koilin matrix of the gizzard and moulted in 36 h. Larvae appeared to avoid host response by remaining in the relatively inert koilin matrix. Fourth-stage larvae moved directly from the gizzard into the duodenal mucosa 48 h postinfection. The final moult occurred in the intestinal wall 11 days postinfection. Development of fourth-stage and adult worms in the tissues elicited a localized granulomatous inflammatory response. Adult worms emerged from the intestinal mucosa at 28 days and were found thereafter in the intestinal lumen. Eggs were first detected in the faeces of infected starlings 33 days postinfection and longevity of P. ensicaudatum in the definitive host was approximately 70 days. Challenge infections showed that starlings were susceptible to repeated infection. The number of adult P. ensicaudatum that matured in the intestine was independent of the number of larvae ingested. Clinical signs were not observed throughout the course of infection.
RNA/DNA ratios in white muscle as estimates of growth in rainbow trout held at different temperatures
Authors: Ferguson Moira M. , Danzmann Roy G.
Published: August 2008

The concentrations of RNA, DNA, and protein in white muscle from 240 uniquely tagged rainbow trout (Oncorhynchus mykiss) held at three temperatures (5, 8 (control), and 11 °C) were measured. Both RNA and RNA/DNA ratios were better predictors of recent length- and weight-specific growth rates than they were of absolute fish size. Furthermore, RNA concentrations were better predictors of growth than RNA/DNA ratios. The strength of the regression between either RNA/DNA ratio or RNA and growth rate did not differ consistently among temperatures. Fish reared at warmer temperatures had lower concentrations of RNA for both a given growth rate and a given DNA concentration compared with cold-reared trout. Warm-reared fish also had lower concentrations of DNA and higher protein/DNA ratios than cold-reared trout when fish size was standardized. The concomitant decrease in both RNA and DNA concentrations resulted in marginally lower RNA/DNA ratios in warm-reared fish.
Metabolic effects of the expression of a phosphoglucomutase locus in the liver of rainbow trout
Authors: Ferguson Moira M. , Danzmann Roy G. , Allendorf Fred W. , Knudsen Kathy L.
Published: August 2008

We examined the lengths, weights, condition factors, and hepatosomatic indices of juvenile rainbow trout (Oncorhynchus mykiss) from four full-sib families, each segregating at the temporal regulatory locus Pgm1-t, and the concentrations of RNA, DNA, and protein in their livers and white muscle. In three families, fish with phosphoglucomutase-1 (PGM1) activity in liver (Pgm1-t(b) fish) are significantly longer than their full-sibs lacking activity for liver PGM1 (Pgm1-t(a) fish). Hepatosomatic indices tend to be higher in the Pgm1-t(b) fish than in their Pgm1-t(a) siblings. RNA/DNA ratios in the liver of Pgm1-t(b) fish are significantly higher than those of Pgm1-t(a) fish in two families and marginal in a third. However, no significant differences were detected in a parallel analysis of nucleic acids and protein in white muscle, where PGM1 is expressed in all fish. In a separate experiment, Pgm1-t(b) fish were significantly heavier in all five families, had significantly higher condition factors in two families, and had marginally lower standardized oxygen consumption rates in three families.
Catecholamine-containing, serotonin-like, and FMRFamide-like immunoreactive neurons and processes in the nervous system of the early actinotroch larva of Phoronis vancouverensis (Phoronida): distribution and development
Authors: Hay-Schmidt Anders
Published: August 2008

The distribution and development of neurons and nerve processes containing the putative neurotransmitters catecholamines (CA), serotonin-like immunoreactivity (5-HT-ir), and FMRFamide-like immunoreactivity (FMRFamide-ir) have been investigated by means of glyoxylic acid induced fluorescence in CA and antibodies against 5-HT and FMRFamide in the 0- to 6-tentacle actinotroch larvae of Phoronis vancouverensis Pixell, 1912. CA and 5-HT-ir were observed in the apical ganglion at all stages (beginning at the early 0-tentacle stage); FMRFamide-ir appeared first at the late 0-tentacle stage. The CA-containing cells are located in a ring at the periphery of the apical ganglion, whereas the 5-HT-immunoreactive cells form a U-shaped area in the centre of the epistome. In late 0-tentacle stages, CA, 5-HT-ir, and FMRFamide-ir are found in processes along the future ciliary band of the tentacles and the margin of the epistome. At the 2-tentacle stage, processes are observed in the apical ganglion extending from the neuropil towards the tentacles and the margin of the epistome. At the 4- to 6-tentacle stage, processes loosely concentrated in large bundles are found along the epistome margin projecting on the ventral side of the mesosome towards the tentacles (CA, 5-HT-ir, and FMRFamide-ir), extending from the apical ganglion towards the tentacles (5-HT-ir and FMRFamide-ir), along the ciliary band of the tentacles (CA, 5-HT-ir, and FMRFamide-ir), and along the posterior ciliary band (CA, 5-HT-ir, and FMRFamide-ir).
Relationships between reproductive output and shell morphometrics of the pill clam, Pisidium casertanum (Bivalvia: Sphaeriidae)
Authors: Kilgour Bruce W. , Mackie Gerald L.
Published: August 2008

Specimens of Pisidium casertanum were collected from 15 locations across southern, central, and eastern Ontario to determine if variation in the numbers of shelled larvae produced by adults was related to variation in shell morphometrics. More than 90% of the variability in shell morphometrics was related to shell length and site of origin. Approximately 40% of the variation in numbers of shelled larvae produced by adults was not related to shell length and site of origin. Results showed that individuals that are lower, wider, and have a more rounded anterior end produce more shelled larvae than individuals that are higher, narrower, and have an elongated anteroventral margin. Low correlation coefficients for the model describing the relationship between the number of shelled larvae and shell morphometrics suggests that it would be difficult to use shell measurements to predict the production of shelled larvae by adults.
Caractéristiques de la reproduction du myocastor (Myocastor coypus M.) mâle dans la région du marais Poitevin
Authors: Dagault N. , Saboureau M.
Published: August 2008

The study of the male reproductive function in coypu population living in Poitou marshlands (central-west France) showed that testicular mass is nearly constant throughout seasons. The demonstration of positive correlations between the evolution of (i) testicular mass and body mass and (ii) testicular mass and age corroborated that the testicular function is continuous and that animals are able to breed all over the year. Changes in endocrine testicular activity, measured by plasma testosterone concentrations (T), showed a great variability from year to year. Nevertheless, a decrease of testicular endocrine activity in wild animals, at the end of autumn and the beginning of winter, seemed to be due to a decrease in food availability. This last point was confirmed by an experimental study: (i) a 50% reduction of available food in winter provoked a decrease of T and (ii) after refeeding ad libitum, T was rapidly restored to high values.
Neospora caninum (Protozoa: Apicomplexa) infections in rats
Authors: Lindsay David S. , Dubey J. P.
Published: August 2008

The susceptibility of laboratory rats (Rattus norvegicus) to experimental inoculation with tachyzoites of Neospora caninum was examined. Groups of female rats were intramuscularly injected with 0, 2, or 4 mg of methylprednisolone acetate (MPA) 7 days prior to, and on the day of, subcutaneous inoculation with 0 or 1.5 × 105 tachyzoites. Clinical signs of disease or deaths did not occur in rats given nothing or only N. caninum tachyzoites. Rats given only 4 mg MPA failed to grow as well as rats given nothing or only N. caninum tachyzoites but were otherwise healthy. All of 20 rats given 4 mg MPA and tachyzoites died of hepatitis and pneumonia within 12 days postinoculation. Hepatic necrosis was the most striking lesion seen in these rats, and other milder lesions consisted of pneumonia, encephalitis, and myositis. The response of rats given 2 mg MPA and tachyzoites was less severe. Three of 20 rats died with encephalitis, myositis, hepatitis, and pancreatitis. Mild lesions, but no N. caninum tachyzoites, were seen in 3 of 14 rats inoculated only with tachyzoites. Rats given the 4 mg MPA treatment and inoculated with N. caninum tachyzoites appear to be suitable subjects for examining acute neosporosis and could be used in studies designed to examine treatment of acute disease.
Comment—Bergmann's rule is invalid: a reply to V. Geist
Authors: Paterson James D.
Published: August 2008

In a previous note, Geist attempts to prove that Bergmann's rule lacks both an empirical and a theoretical basis, and hence should be discarded (V. Geist. 1987. Can. J. Zool. 65: 1035–1038). It is noted that Geist has made a number of errors in interpreting the data and the theoretical material relating to the rule, and Searcy's arguments in particular have been distorted. It is concluded that Geist has confounded his data set with unrecognized multiple causality, a lack of critical analysis of biological relevance, inadequate partitioning of the data set, and misinterpretation of a physiological relationship. The conclusion that Geist has not proved Bergmann's rule to be invalid is justified.
Bergmann's rule is invalid: a reply to J. D. Paterson
Authors: Geist Valerius
Published: August 2008

Paterson's critique misdefines Bergmann's rule, contains contradictions, misrepresents empirical observations and the writings of others, draws the logarithms of log-transformed data, invokes a hypothesis that would make wolves change subspecific status with migration, and ends by presenting an untestable reformulation of Bergmann's rule. Paterson's critique throws no new light on Bergmann's rule, nor does it invalidate Geist's conclusion that Bergmann's rule has neither empirical nor theoretical justification.
Origin and biogeography of the beetles (Coleoptera) of the Galápagos Archipelago, Ecuador
Authors: Peck Stewart B. , Kukalová-Peck Jarmila
Published: August 2008

The Galápagos Archipelago is a model system for estimating the dynamics of biotic dispersal to, evolutionary differentiation in, and ecological structuring of oceanic islands. The islands, 800–1000 km west of the coast of Ecuador, have been available for terrestrial colonization for about 3 million years. After 150 years of sporadic study, the beetle fauna is still poorly known, but at least 54 families, 214 genera, and 366 species are present. Comparatively few families (10) contain endemic genera (13) that may represent early colonizations. Species flocks occur in usually flightless members of seven genera. Adaptive radiation, as seen in Darwin's finches, is evident in three genera of tenebrionids. The species are 24% native (i.e., they have naturally dispersed from Central or South America), 67% being endemic to one or more islands, and 9% have been introduced by man. Virtually nothing is known of the bionomics of the species. The fauna of 335 native and endemic species is estimated to have originated from at least 257 successful ancestral colonizations. Over 3 million years this is an average rate of one successful colonization every 11 700 years, and 1.4 new species per ancestral colonization. Most of the colonists reached the islands either through the air as "aerial plankton" (60%) or by rafting on oceanic flotsam (39%) from Central or South America. Extinctions were more prevalent in "glacial-arid" periods, and colonizations more prevalent in "interglacial-humid" periods. The rate of species introduction has increased with human visitation and colonization. The factors suppressing species proliferation in Galápagos beetles, compared with those in other insular areas, seem to be as follows, in probable order of importance: lack of strong ecological diversity, proximity to mainland areas, proximity of main islands to each other, geological youth, and recent development of a more suitable (wetter) climate. An appendix presents new beetle records for the islands. Lobopoda brunneipennis Campbell (Alleculidae) is placed in synonomy under Lobopoda galapagoensis Linell.
Reproductive bionomics of some shallow-water lysianassoids in the Saint Lawrence Estuary, with a review on the fecundity of the Lysianassoidea (Crustacea, Amphipoda)
Authors: Sainte-Marie Bernard , Lamarche Gabriel , Gagnon Jean-Marc
Published: August 2008

The life history and fecundity of five shallow-water lysianassoids from the Saint Lawrence Estuary were examined. Orchomenella minuta and Or. pinguis are annual and iteroparous (two broods), Psammonyx terranovae is iteroparous (two broods) and probably biennial, and Anonyx sarsi and Onisimus litoralis are biennial and semelparous. Females of A. sarsi and On. litoralis cease feeding on bait shortly before or after oviposition, whereas females of the iteroparous Or. pinguis stop feeding on bait only when broods are in the latest stages of embryo development. These ontogenetic changes may result from gut constriction caused by developing ovaries and broods, or may be due to behavioural changes. Data on the fecundity of the Lysianassoidea are reviewed, and it is concluded that deep-living species are probably much less fecund than shallow-living species. Anonyx nugax, Or. pinguis, and A. sarsi are more fecund than other lysianassoids, possibly because of their high-risk carrion-feeding and suprabenthic foraging activities.
Isolation and characterization of antifreeze proteins from smelt (Osmerus mordax) and Atlantic herring (Clupea harengus harengus)
Authors: Ewart K. Vanya , Fletcher Garth L.
Published: August 2008

Antifreeze proteins (AFPs) from smelt (Osmerus mordax) and Atlantic herring (Clupea harengus harengus) were isolated using gel filtration, ion exchange chromatography, and high performance liquid chromatography. The AFPs of smelt appeared to consist of at least six components and those of Atlantic herring, of at least two components. The relative molecular masses of these antifreezes were 24 000 and 14 600, respectively. Amino acid analysis showed both proteins to be cystine-rich, type II AFPs like those of the sea raven (Hemitripterus americanus). In addition, smelt AFPs were found to be immunologically similar to those of the sea raven. The smelt AFPs differed from those of Atlantic herring and sea raven in that they contained a small amount of glucosamine (~3%). The activity levels of the smelt and herring AFPs were reduced in the presence of dithiothreitol, indicating the functional importance of intact disulfide bonds.
Radiotelemetry of body temperatures of free-ranging snapping turtles (Chelydra serpentina) during summer
Authors: Brown Gregory P. , Brooks Ronald J. , Layfield James A.
Published: August 2008

We wished to determine whether free-ranging snapping turtles (Chelydra serpentina) would use aquatic and atmospheric basking to maintain body temperature at the mean temperature (28–30 °C) selected by snapping turtles placed in a controlled aquatic thermal gradient. Body temperatures from eight adult snapping turtles in three different lakes in Algonquin Provincial Park were monitored by radiotelemetry during July and August 1987. Mean body temperature of all eight turtles over the study period was 22.7 °C, and mean temperature of every individual was well below the reported mean selected temperature for this species. The turtles did not maintain body temperatures near the available maximum environmental temperature. The mean body temperatures of the turtles were not significantly different among the three study lakes although these lakes had different physical characteristics. Similarly, there were no significant differences, among individual turtles, between air temperatures or operative environmental temperatures recorded concurrently with their body temperatures Nevertheless, mean body temperatures differed significantly among individuals; foraging tactics, metabolic rates, and home range structure may account for these differences.
Postmating barriers to gene flow among species and subspecies of tsetse flies (Diptera: Glossinidae)
Authors: Gooding R. H.
Published: August 2008

Postmating barriers to gene flow between closely related species and subspecies of tsetse flies include (i) reduced fecundity of hybridized and hybrid females and (ii) sterility of hybrid and backcross males, owing mainly to incompatibility between X and Y chromosomes from two different taxa or, possibly, incompatibility between the X from one taxon and autosomes from the other. There are also maternally inherited factors that confer unidirectional sterility upon males; these factors may influence the direction of gene flow. When Glossina morsitans morsitans and Glossina morsitans centralis are crossed, these factors appear to be unstable and lose their effectiveness as barriers to gene flow when hybrid females, from several consecutive generations, are backcrossed to G. m. centralis. In hybrid females of the morsitans group, intrachromosomal recombination is suppressed in the X chromosomes, but it may occur at near normal levels in at least part of linkage group II. Some backcross flies with chromosomes composed of segments from two different taxa are fertile. Naturally occurring hybrids have been found, but it appears that hybridization zones are narrow. It remains to be determined whether introgression of genes plays a significant role in the evolution of tsetse flies.
Induced hybrid sterility by injection of streptococcal L-forms into Drosophila paulistorum: dynamics of infection
Authors: Ehrman Lee , Somerson Norman L. , Kocka John P.
Published: August 2008

Intracellular symbionts are common among insects, and all semispecies of the neotropical Drosophila paulistorum complex contain them. Symbionts of D. paulistorum, identified as group D streptococcal L-forms (cell wall deficient), are involved in male sterility that results from crosses between semispecies. This is one of three reproductive isolating mechanisms that maintain the six semispecies. When extracts of Mesitas strain of the Andean-Brazilian semispecies are injected into females of the Santa Marta strain of the Transitional semispecies, the females, mated with Santa Marta males, produce male progeny that are sterile.
Speciation by hybridization in phasmids and other insects
Authors: Bullini Luciano , Nascetti Giuseppe
Published: August 2008

Speciation by hybridization in insects has been recently recognized on the basis of isozyme and chromosome studies showing that several species, either diploid or polyploid, have genomes that combine the genes and chromosome sets of two (or more) bisexual species. Until this evidence became available, thelytokous invertebrates were all considered uniparental derivatives of bisexual species. In this paper, we review examples including the stick insects Bacillus whitei, B. atticus, B. lynceorum, Leptynia hispanica D, Clonopsis gallica, Carausius morosus; the grasshopper Warramaba virgo; some Otiorrhynchus weevils; the planthopper Muellerianella 2-fairmairei–brevipennis; and black flies of the genera Gymnopais and Prosimulium. For several species (e.g., Warramaba virgo and Bacillus whitei), both parental taxa have been recognized, and their hybrid origin has been genetically assessed. In others (e.g., B. atticus), only one of the bisexual parental species has been detected; but their hybrid origin is supported by strong evidence, at both the isozyme and chromosome levels. For other supposed hybrid species (e.g., Clonopsis gallica, Carausius morosus), no bisexual ancestors have been detected, possibly because competition with their hybrid derivatives has made them rare or extinct. Insect hybrid species may differ in their mode of reproduction (apomictic or automictic thelytokous parthenogenesis, gynogenesis), degree of ploidy, and genetic structure (level of heterozygosity, clonal variation). The parallels between insect and vertebrate hybrid species, in which this phenomenon has been recognized and widely studied in the past 50 years, are drawn. The main problems involved in the origin and evolution of hybrid species are discussed, with particular regard to (i) changes in the maturation divisions allowing the transmission of the hybrid genome to the next generation, and (ii) their successful adaptation. The "spontaneous" and "hybrid" theories for the origin of unisexual forms are compared, with regard to hybrid species. An origin of hybrid species from occasional parthenogenetic development of hybrid eggs produced in areas of extensive interspecific hybridization (e.g., disturbed habitats) is suggested. Hybridization would not itself cause changes in the maturation divisions (which are controlled by genes of tychoparthenogenetic eggs) but only favour their selection through heterosis. The role of the so-called "heterotic" advantage (resulting from high levels of heterozygosity) and "demographic" advantage (resulting from all-female reproduction) in the evolutionary success of hybrid species is discussed. It is concluded that habitat disturbance by man is favouring both the onset of hybrid species and their successful spread.
Introgressive hybridization in Heteroptera: the example of Limnoporus Stål (Gerridae) species in western Canada
Authors: Spence John R.
Published: August 2008

Populations of the pondskaters, Limnoporous dissortis and Limnoporous notabilis, hybridize extensively in the Cordilleran region of western Canada. In laboratory crosses using L. dissortis from central Alberta and L. notabilis from southwestern British Columbia, most eggs are fertilized and begin development, but only ca. 50% of the eggs hatch and nearly all F1 hybrid adults are males. F1 hybrid males are fertile in backcrosses to females of both species, although egg hatch is reduced and mainly male progeny result from crosses to females of the paternal species. These species both have an XO sex chromosome system, and the foregoing results suggest that either products of genes on X chromosomes of the two species are incompatible or that they are incompatible with heterospecific cytoplasmic elements. Males of L. dissortis are more successful at interspecific copulations than are those of L. notabilis, perhaps because they more frequently adopt aggressive mating behaviour that circumvents premating barriers. Although gene pools of these two species are partially isolated by both pre- and post-mating barriers, there has been large-scale exchange of genes at autosomal loci, and significant introgression occurs over a large geographic area. Introgression is asymmetric, with genes of L. dissortis tending to flow disproportionately into L. notabilis populations, reflecting differences between the species in mating behaviour and dispersal tendencies. Because these two species are not closest relatives, I conclude that reticulations can be important considerations in the evolution of semiaquatic bugs. A literature survey shows that interspecific hybridization occurs in a number of heteropteran families, although partial barriers to gene flow are common.
Hybridization in natural populations of ground beetles (Coleoptera, Carabidae)
Authors: Mossakowski Dietrich , Braun Sabine , Roschen Axel
Published: August 2008

We investigated 13 populations of the carabid subgenus Chrysocarabus in the Spanish mountains Sierra de Urbasa and Sierra de Andia. In some areas there were up to 16% hybrids between Carabus lineatus and Carabus splendens. Hybrids are best distinguished as individuals having combinations of morphological characters that are diagnostic for both species. Multivariate discriminant analysis showed a gap between the parental species, but hybrids were either C. lineatus-like or C. splendens-like. Experimentally produced hybrids lie in the same range as natural hybrids. Electrophoretic studies have interpretable results for eight enzymes, but only one sex-linked locus (G-6-pd) was fixed for alternative alleles in the parental species, allowing identification of only female hybrids. Analysis of proteolytic enzymes from the gut revealed one fixed difference for chymotrypsin, but the locus for this enzyme is sex-linked. Trypsin appears polymorphic at several loci and is not useful for identifying hybrids. The geographical range of overlap and hybridization is large when compared with dispersal abilities of C. lineatus and C. splendens. We suggest that the hybrid zone is broken up into a number of subzones defined by differences in habitat structure and related to specific ecological requirements of the parental species. Within each of these zones, theory developed from study of narrow hybrid zones may apply.