bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of environmental temperature and Hymenolepis nana on histopathology of the small intestine of mice
Authors: Novak M. , McMillan E. , Evans W. S.
Published: August 2008

Uninfected and infected (Hymenolepis nana, eggs by stomach tube) 4-month-old Swiss–Webster male mice were maintained at 5, 21, or 35 °C for 4 or 10 days. Histological examination of their small intestines revealed that exposure to 5 °C produced acute catarrhal enteritis in uninfected mice, but in infected mice this sympton was reduced to a few edematic foci located in the submucosa. The hot environment caused a marked reduction in intestinal gland and goblet cell activity in uninfected mice. This condition was reversed in infected mice as, regardless of temperature, the worms invariably induced pronounced glandular hyperplasia. Temperature did not affect the host's cellular reaction to the parasite as the influx of inflammatory cells at the sites of infection was equally intense in all groups of mice.
Historical processes, evolutionary explanations, and problems with teleology
Authors: O'Grady Richard T.
Published: August 2008

Organisms are subject first to general, physical causes and then to restricted, biological causes. This internesting contains evolutionary causes that were once contingent but have since been incorporated into the inherited historical causality of descendants. These historical causes should be used as null hypotheses in evolutionary explanations. This is the approach of historical structuralism, which considers function to be an effect of structure and evolution to be structural change that may or may not involve functional change. Conversely, historical functionalism looks to function for evolutionary explanations. This produces an unacceptable appeal to teleological causation. Biological teleology is acceptable only as an explanatory analogy in nonhistorical studies, which do not address organisms' etiology. These treat organisms as machines but do not consider the implied teleology to be real. Neo-Darwinian explanations encounter the unacceptable teleology of historical functionalism when they cite adaptedness as an explanation for how an organism came to exist. This error is difficult to detect because of (i) incomplete theory structure and (ii) three types of "what for" questions in biology, two of which are legitimate, one of which is not. Another approach to evolutionary studies, ahistorical structuralism, avoids problems with teleology, but underestimates historical causality.
Myicola metisiensis (Copepoda: Poecilostomatoida), a parasite of the bivalve Mya arenaria in eastern Canada, redefinition of the Myicolidae, and diagnosis of the Anthessiidae n. fam.
Authors: Humes Arthur G.
Published: August 2008

The myicolid copepod Myicola metisiensis is redescribed from topotypes and other specimens found in Mya arenaria in Quebec and New Brunswick. The family Myicolidae comprises three closely related genera, Myicola, Ostrincola, and Pseudomyicola, all parasitic in bivalve mollusks. A new family, the Anthessiidae, includes five genera previously placed in the Myicolidae, Anthessius, Katanthessius, Neanthessius, Panaietis, and Rhinomolgus.
Estimating food availability for larval dragonflies: a cautionary note
Authors: Baker Robert L.
Published: August 2008

Fecal pellets produced by larvae of Enallagma ebrium and Ischnura verticalis given ad libitum feedings of enchytraeid worms were heavier than pellets produced by larvae given ad libitum feedings of Daphnia magna. Dependence of pellet weight on food type has marked implications for indices of food limitation for larval dragonflies.
Distant and near-range functions of harp seal underwater calls
Authors: Terhune J. M. , Ronald K.
Published: August 2008

Underwater vocalizations of harp seal (Phoca groenlandica) in the Gulf of St. Lawrence, were obtained during 10 breeding seasons between 1968 and 1983. No changes in their vocal repertoire were found. At high calling rates, vocalizations overlapped and the average sound levels increased. An individual's calls may be partly masked under these conditions. Sound levels of 140 dB re 1 μPa were received with no seal closer than 2 m from the hydrophone. Such sounds should be detectable (by other seals) from a distance of at least 2 km (uner ice cover). Recordings at points progressively farther away from the main herd detected calls continuously over a 60-km distance. Seals were in the water along these transects and presumably were in acoustic contact with each other. A seal searching for the heard would thus be searching for a large acoustic target rather than the relatively smaller on-ice herd. Calls also may be associated with courtship or mating. These would be involved with close-range communication. Harp seal calls are typically repeated at least twice but often more than 10–20 times. This repetition, the loudness of some calls, and the possible incorporation of clues to aid directional hearing may help overcome the masking problem encountered by these shorter range courtship or mating calls.
Enzyme activities in the Atlantic hagfish, Myxine glutinosa: changes with captivity and food deprivation
Authors: Foster Glen D. , Moon T. W.
Published: August 2008

Selected Krebs cycle enzymes and carbohydrate, amino acid, and lipid metabolizing enzymes were assayed in the muscle and liver of newly captured (April, 4 °C; August, 15 °C), fed (for 7 months), and food-deprived (for 7 and 11 months) hagfish, Myxine glutinosa. Seasonal differences were found in the glycogen content of the muscle and liver of newly captured hagfish (lower in the cold temperature), while consistently high levels were maintained in the fed group. Food deprivation decreased the content. All enzymes measured were found in both tissues, except glucose-6-phosphate dehydrogenase (liver only) and glycerol kinase (absent in both tissues). Activities of the enzymes were lower than teleost values, except for pyruvate kinase, citrate synthase, and 3-hydroxyacyl-CoA dehydrogenase, for which activities resembled teleost levels. Enzyme values from the fed fish (7 months) were generally the same as the newly captured group, and food deprivation increased phosphoenolpyruvate carboxykinase activities without altering other enzyme levels. These results support the view that hagfish are anoxia tolerant with low metabolic potential and demonstrate that the muscle and liver rely on carbohydrate and lipid reserves during fasting.
Evidence for a physiological gradient in the vestimentiferan trophosome: size–frequency analysis of bacterial populations and trophosome chemistry
Authors: Burgh M. E. de
Published: August 2008

Size of bacterial symbionts was compared in anterior and posterior trophosome tissue of four vestimentiferan worm species from hydrothermal vents. Analysis of size measurements indicated that there were more small bacteria in the anterior than the posterior trophosome. Bacterial division, though rarely seen, was more common in the anterior trophosome. Bulk chemical analysis of the two trophosome regions showed that sulfur (essential in the bacterial symbiont metabolism) and zinc were more concentrated in the anterior tissues, whereas 31 other major and minor elements were more concentrated in the posterior region. The existence and significance of a physiological gradient in the vestimentiferan trophosome is discussed.
Comparative gluconeogenesis in hepatocytes from salmonid fishes
Authors: Mommsen Thomas P.
Published: August 2008

Rates of gluconeogenic flux and substrate oxidation are assessed in isolated hepatocytes from three species of salmonid fishes: rainbow trout (Salmo gairdneri), coho salmon (Oncorhynchus kisutch), and sockeye salmon (Oncorhynchus nerka). Coho salmon displays the highest capacity for gluconeogenesis from lactate and alanine, but rates are well below those of eels. Enzyme compartmentation on isolated mitochondria shows that in trout and sockeye, phosphoenolpyruvate carboxykinase is almost entirely localized in the mitochondrion and the cytosol, respectively, while in the coho, 40% of phosphoenolpyruvate carboxykinase activity is associated with the cytosol. Freshly isolated salmonid hepatocytes are in negative glycogen balance. It is established here that at low (<250 μmol glucosyl units/g) glycogen concentrations a linear relationship exists between the rate of endogenous glucose production and the initial glycogen concentration. High rates of endogenous glycogen breakdown necessitate the use of radiotracers for determining gluconeogenic fluxes in fish hepatocytes. Rates of gluconeogenesis calculated from radiolabel experiments are compared with nonlabelled lactate and are determined not to be significantly different from each other. It is concluded that in fish hepatocytes, (i) radiotracer experiments give accurate estimates of gluconeogenesis, (ii) dilution of label at the oxalacetate level is insignificant, and, consequently, (iii) rates of 14CO2 production are a valid measure of true substrate oxidation.
Diel activity patterns in the breeding migrations of winter-breeding anurans
Authors: Pechmann Joseph H. K. , Semlitsch Raymond D.
Published: August 2008

Diel activity patterns in the breeding migrations of four winter-breeding anurans (Hyla crucifer, Pseudacris nigrita, Pseudacris ornata, and Rana utricularia) were examined at a breeding pond in South Carolina, U.S.A., using a terrestrial drift fence with pitfall traps. Traps were censused at 0600, 1200, 1800, and 2400 during six 24-h periods from 1982 through 1984. Census dates were selected during which the weather was expected to remain uniformly warm and rainy throughout all four time intervals. This allowed us to separate the effect of time of day on migratory activity from the effects of temperature and rainfall. There were significant differences in migratory activity among time intervals, but no significant differences among time intervals in either mean air temperature or rainfall. Males and females of all four species migrated to and from the pond primarily during the two night intervals. The absence of daylight appears to be a necessary trigger for migratory behavior in these anurans. Temperature and moisture conditions often limit their breeding migrations, and the failure to utilize suitable diurnal weather conditions represents an additional constraint. We suggest that the observed diel pattern of migratory activity may be an adaptation to avoid visual predators.
Behaviour and use of space by juvenile Columbian ground squirrels (Spermophilus columbianus)
Authors: Waterman Jane M.
Published: August 2008

The behavioural ontogeny of the Columbia ground squirrel (Spermophilus columbianus) was examined using livetrapped and marked individuals in a population in southwestern Alberta, Canada. Observations using scan and all-occurrence sampling recorded the activities and locations of individuals. Differences between sexes in the movement of juvenile squirrels were apparent after the first 10 days from emergence from the natal burrow. Males travelled further from the natal burrow, had larger home ranges, and shifted their activity centres more than did females. Females remained nearest their sisters and rates of play between sisters were the highest of all interacting pairs. Although there was no difference in the mean distance from the mother for males and females, females greeted their mothers three times more frequently than did brothers. The consequences of such different social and spatial experiences are discussed in light of female site fidelity and male dispersal.
Secondary sex ratio of the cyclic parthenogen Daphnia magna (Crustacea: Cladocera) in the Canadian Arctic
Authors: Barker David M. , Hebert Paul D. N.
Published: August 2008

Secondary sex ratios of the cyclic parthenogen Daphnia magna were studied in habitats near Churchill, Manitoba. Daphnia magna is believed to possess an environmentally mediated sex-determining system. Throughout the season females produced broods that were predominantly unisexual. The proportion of male offspring was low early in the season but rose to a value near 50% in each of four populations. It is hypothesized that after they have an initial series of female broods, individual females begin to alternate the sexes of their broods in response to an environmental cue. Such an alternation of brood sexes would explain the population sex-ratio pattern observed and would satisfy theoretical requirements for population and individual secondary sex ratios of 1:1. In studies on cladocerans, environmental cues inducing the sex-ratio response must be distinguished from cues with a sex-determining effect.
Interpretation of otoliths in stomach content analyses of phocid seals: quantifying fish consumption
Authors: Murie D. J. , Lavigne D. M.
Published: August 2008

Thirteen captive phocid seals (10 grey seals (Halichoerus grypus), 2 harp seals (Phoca groenlandica), and 1 ringed seal (P. hispida)) were fed Atlantic herring (Clupea harengus harengus) in experiments designed to examine the use of otoliths recovered in stomach contents to interpret food consumption of wild seals. The percentage of ingested otoliths recovered in the stomach contents decreased with the time elapsed after feeding; 100% of otoliths were recovered between 0 and 3 h after feeding and 0% were recovered by 12.9 h after feeding. Absence of otoliths in the large intestine of seals having fed 3 to 6 h previous indicated that unrecovered otoliths had been digested (i.e., a complete disappearance of whole otoliths) while in the stomach. A significant relationship was also evident between the state of digestion of a seal's stomach contents, as measured by the proportion of otoliths remaining in skull cases (skull-recovered otoliths), and the duration of time since it had fed. These relationships have potential application in the estimation of daily fish consumption of seals feeding in the wild.
Ultrastructural analysis of chorion formation in the silkmoth Bombyx mori
Authors: Papanikolaou A. M. , Margaritis L. H. , Hamodrakas S. J.
Published: August 2008

The formation of the chorion in the silkmoth Bombyx mori (Lepidoptera) is analysed in detail by means of electron microscopy. The secretion of the proteinaceous chorion layers is being accomplished by the follicular epithelial cells which surround the oocyte. The mature chorion exhibits a tripartite ultrastructure; the trabecular layer closest to the oocyte, the inner lamellar layer, and the outer osmiophilic layer. The trabecular layer is deposited first upon the vitelline membrane and further modified possibly by rearrangement and (or) changes of its constituent proteins. A thin porous (sieve) layer is firmly attached to the tips of the follicle cell microvilli and appears to be implicated in the process of secretion of chorion proteins. In early choriogenesis, chorion is a thin (0.7–6 μm) lamellate and simply organized zone becoming thicker (12–20 μm) and more complex as choriogenesis proceeds. Chorion lamellae consist of helicoidally twisted fibrils embedded in an amorphous matrix. A denaturing agent (urea) was used to derive more information concerning assembly of chorion fibrous lamellae. The agent does not seem to eliminate the lamellar organization of chorion although it does modify it. There are suggestions that the agent disrupts many weak interactions, causing conformational changes in the structure of chorion protein components. The surface of the mature chorion is sculptured by follicle cell imprints. Small holes, the aeropyles, which extend radially into chorion down to the trabecular layer presumably serve for respiratory purposes. An elaborate depression in the anterior pole of the chorion, the micropyle, serves for sperm entry.
Revision of the genus Syncuaria Gilbert, 1927 (Nematoda: Acuarioidea)
Authors: Wong P. L. , Anderson R. C. , Bartlett Cheryl M.
Published: August 2008

Syncuaria Gilbert, 1927 is revised and Skrjabinocara Kurashvili, 1940 placed in synonymy with it. Nine species are recognized: S. ciconiae Gilbert, 1927 (type species); S. buckleyi (Ali, 1957) n. comb.; S. decorata (Cram, 1927); S. longialula Wang, 1976; S. leptoptili (Gedoelst, 1916) (=S. parvepapillata Macko, 1962a, 1962b); S. bressoui Gretillat, 1970; S. hargilae (Baylis and Daubney, 1923); S. diacantha Petter, 1961; and S. squamata (Linstow, 1883) n. comb. Redescriptions of the latter five species are provided. Six other species are regarded as species inquirendae: S. calcarata (Molin, 1860), S. contorta (Molin, 1858), S. longeornata (Molin, 1860), S. rostombekovi (Kurashvili, 1940) n. comb., S. ardeae (Smith, Fox and White, 1908), and S. sturni (Ozerskaya, 1927). Syncuaria longevaginata (Molin, 1860) is transferred to Desportesius, resulting in D. longevaginatus (Molin, 1860) n. comb. Syncuaria squamata was found in 11 of 18 young of the year double-crested cormorants (Phalacrocorax a. auritus (Lesson)) from Lake Erie, Ontario, Canada, indicating that transmission of this species occurs on the breeding ground of its final host.
Les effets additifs de la syntaxe et de la forme des syllabes lors de la reconnaissance spécifique chez le Troglodyte (Troglodytes troglodytes)
Authors: Kreutzer Michel , Brémond Jean-Claude
Published: August 2008

Songs of Winter wrens have a characteristic pattern. We know that syntax is a factor involved in species recognition. In this study, we used different parts of a Winter wren song to construct abnormal syntax songs. Birds react specifically to these atypical signals, but the territorial reactions are significantly less intense than those to a normal song. To induce very weak territorial reactions, it is necessary to modify syntax and syllable shapes at the same time. Species recognition is subordinate to some acoustic cues, but each cue cannot, by itself, induce reactions as strong and reliable as all cues included in a normal song. Thus, Winter wren species recognition is the result of an additive process.
Oocyst age and excystation of Cryptosporidium parvum
Authors: Speer C. A. , Reduker David W.
Published: August 2008

The effects of temperature, tap water, and excysting fluid were tested on oocysts of Cryptosporidium parvum that had been stored for 14, 32, or 43 weeks at 4 °C. In preparations containing 14-week-old oocysts, sporozoites excysted in the presence of excysting fluid at 37 °C, but did not excyst in excysting fluid at 22 °C nor in tap water at 22 or 37 °C. In contrast, numerous empty oocysts but few or no sporozoites were present in preparations of 32- or 43-week-old oocysts incubated in excysting fluid or tap water at 22 or 37 °C. Sporozoites in tap water lysed soon after leaving the oocyst. Thus, sporozoites of C. parvum will excyst from young oocysts only in the presence of excysting fluid at 37 °C, whereas older oocysts deteriorate with an increase in age and apparently become susceptible to the harmful effects of a hypotonic environment.
Review of the Dasyhelea fasciigera species group (Diptera: Ceratopogonidae) with a revision of the Nearctic species
Authors: Borkent Art , Forster Leo
Published: August 2008

The Dasyhelea fasciigera species group is characterized by males having a gonostylus divided nearly to its base. Five species are present in the Nearctic region: D. tristyla Wirth, D. bifida Zilahi-Sebess, D. fasciigera Kieffer, D. crassiseta n. sp., and D. pollex n. sp. Each species is described and its distribution discussed; a key for the identification of the males of the Nearctic species is provided. A lectotype is designated for D. dentiforceps Tokunaga, from Japan.
The effects of amidantel (BAY d 8815) and its deacylated derivative (BAY d 9216) on wild-type and resistant mutants of Caenorhabditis elegans
Authors: Woods Robin A. , Malone Kathleen M. B. , Albuquerque Cheryl A. , Tomlinson George
Published: August 2008

The anthelmintic drugs amidantel (BAY d 8815) and its deacylated derivative (BAY d 9216) inhibited the growth of wild-type (N2) Caenorhabditis elegans but had little effect on development or reproductive capacity. Inhibition of growth correlated well with drug-induced paralysis, both becoming maximal at around 1.0 mM concentration of either drug. Egg laying was delayed by about 24 h and the rate of laying was only about 60–70% of the controls. However, the period during which eggs were laid was extended by a similar amount and the total number of eggs laid was the same for controls and drug-treated worms. Five drug-resistant mutants (T114, T22, T26, T216, and T226) were isolated following ethylmethanesulphonate mutagenesis. All were shorter than N2 at 96 h on drug-free medium; their growth was not further impaired by either of the anthelmintic drugs. All except T114 exhibited a normal pattern of sexual maturation. Cultures of T114 at 96 h contained many immature worms. This mutant also exhibited the most impaired motility, being severely uncoordinated in liquid suspension. The other mutants could swim normally but were noticeably slower than N2. Genetic analysis indicated that each mutant was the result of a single genetic lesion, that the mutants were recessive, and that there were two genes for amidantel resistance (adt1 and adt2). In vitro studies on representatives of each class (T114 and T22) indicated a defect in the acetylcholine receptor. T22 mutants showed a moderate decrease in sensitivity towards typical cholinergic agonists as well as the anthelmintic drugs, while T114 mutants were apparently devoid of functional pharmacological acetylcholine receptors.
Ontogenetic changes in predatory behavior of larval tiger salamanders (Ambystoma tigrinum)
Authors: Leff Laura G. , Bachmann Marilyn D.
Published: August 2008

The predatory behavior and selectivity of larval tiger salamanders was examined in a laboratory study. Larvae of three size classes, based on snout–vent length, were used in experimental trials conducted in three time blocks. Larvae of different sizes behaved differently. The number of behaviors exhibited per second, trial length, and consumption and miss rates varied significantly with larval size class. Electivity index values also varied with size class. Small larvae tended to lunge at prey most frequently. With the exception of the number of behaviors exhibited per second, time of day did not significantly influence these predation variables. Larvae were inefficient at prey capture as indicated by the greater number of failed than successful captures. Small larvae exhibited different foraging strategies from medium or large larvae, which exhibited similar strategies. These differences can be attributed to the state of limb development of the larvae. These ontogenetic foraging strategy changes may produce different effects on the aquatic community.
American cockroach (Periplaneta americana) hemocyte response to Entomophaga aulicae protoplasts
Authors: Martin F. R. , Nolan R. A.
Published: August 2008

Contact through protoplasmic extensions from the protoplasts was infrequently observed and cell–cell contact involving large surface areas was not observed when adult Periplaneta americana hemocytes were incubated with Entomophaga aulicae protoplasts in in vitro culture for up to 30 min. Such contact did not appear to alter the subsequent morphology of either the protoplast or the hemocyte. Coagulocyte, plasmatocyte, and granulocyte aggregates along with individual coagulocytes and granulocytes produced a melaninlike material upon incubation with protoplasts. Incubation of the hemocytes in the presence of protoplasts did not alter the affinity of hemocytes for Sephadex beads. The results of this study indicate that there was no detectable cell-mediated immune reaction of cockroach hemocytes to E. aulicae protoplasts. The role of the melaninlike material is unknown.
An analysis of multiple captures in Permoyscus with a critique on methodology
Authors: Bergstrom Bradley J.
Published: August 2008

Multiple captures obtained in Sherman traps are reported for Peromyscus maniculatus (66 intraspecific, 6 interspecific) and P. difficilis (12 intraspecific, 4 interspecific) in Colorado. Multiple capture frequency in P. maniculatus. (3.53%) was higher than in P. difficilis (1.94%), which probably resulted from the greater weights of P. difficilis. Only one case of injury or death was noted in 84 multiple captures. Multiple captures occurred in traps in which the treadles were significantly less sensitive to tripping than traps that captured single mice, which suggested that pairs of mice did not enter the traps simultaneoulsy. Adult mice were disproportionatley sampled in single captures because of the insensitivity of the tripping mechanism. For the same reason, immature mice were disproportionately sampled in multiple captures. These trap-related biases can create spurious age and sex associations within multiple captures. Trap bias should be tested explicitly before attempting to analyze multiple-capture data from single-capture traps. A "socially null" model of random encounter of traps by captured pairs fits many of the data presented here and is suggested as the appropriate null hypothesis for these analyses. If live-trapping data must be used to address questions of social behavior, the use of actual multiple-capture traps, preferably to study long-term associations between individuals, is suggested.
Behavioral responses of a herbivorous calanoid copepod to the presence of other zooplankton
Authors: Wong C. K. , Ramcharan C. W. , Sprules W. G.
Published: August 2008

Swimming behavior of the herbivorous calanoid copepod Diaptomus minutus consists of periods of rest interrupted by short jumps. Jumping frequency decreased in the presence of predatory copepods and increased in the presence of the herbivorous Daphnia pulex, a potential competitor. Because D. minutus is detected by vibration-sensitive predators when it jumps, its response in the presence of predators may be a prey defense mechanism. Since feeding by D. minutus takes place during the rest period and is interrupted by jumps, the response to the presence of D. pulex may indicate interference competition. The results demonstrate the behavioral flexibility of zooplanktonic organisms.
Meristic variation in a clone of the cyprinodont fish Rivulus marmoratus related to temperature history of the parents and of the embryos
Authors: Swain D. P. , Lindsey C. C.
Published: August 2008

Parents from one clone of the self-fertilizing cyprinodont fish Rivulus marmoratus were held at 25 or 30 °C, and their offspring were subjected to either a sustained temperature of 25 or 30 °C or to a temperature break (abrupt transfer in either direction between 25 and 30 °C) at various developmental stages. Effects of parental temperature before fertilization on meristic counts of offspring were determined both by comparing offspring produced either soon or long after parents had been transferred to a new temperature, and also by examining meristic responses of developing embryos to temperature breaks. Both line of evidence indicate that a parental temperature of 30 °C produces fewer vertebrae (0.31), pectoral rays (0.54), and caudal rays (1.11) than does one of 25 °C, in offspring reared under comparable temperature regimes. Neither line provides clear evidence of an effect of parental temperature on number of anal or dorsal rays in offspring. Responses of all five meristic series to temperature breaks in either direction were extralimitary (beyond the counts produced by sustained incubation at either temperature) and were satisfactorily fitted by an "atroposic" model described previously. Embryos transferred to fresh water during development tended to have higher meristic counts than those with sustained rearing in brackish water, but counts among embryos transferred to fresh water at different developmental stages differed significantly only for caudal rays. Only dorsal ray numbers differed significantly among embryos retained within parents for different times after fertilization. Previous studies claiming uniquely high thermolability of vertebral number in R. marmoratus are re-evaluated; thermolability of vertebral number in R. marmoratus is concluded to be within the range reported for other species.
Variations, selon la progression de l'hiver, dans le choix de l'habitat et du régime alimentaire chez trois groupes d'orignaux (Alces alces) en milieu agro-forestier
Authors: Joyal Robert , Bourque Claude
Published: August 2008

Three distinct groups of moose (Alces alces) were followed for one winter in settlement areas of northwestern Quebec to investigate changes in their choice of diet and habitat over the winter. No trend was observed in structure and plant composition of winter yards over the season. From December to March, each group used at least three different core areas intensively, these areas totalling 1.02 (first group), 1.28 (second group), and 2.48 km2 (third group). The size of the winter yards diminished in March but this decrease was not due to an increase in snow depth, which reached its maximum of 88 cm in February. The total areas used by the three groups were 1.7, 2.6, and 6.6 km2, respectively. No trend was found in the diet during the winter, except that trembling aspen (Populus tremuloides) was most heavily used by the three groups in March. Twenty-three species of browse were used but 6 species formed nearly 95% of the diet; balsam fir (Abies balsamea) and mountain maple (Acer spicatum) were almost completely absent from the diet.
Laboratory and field evidence for the avoidance of California voles (Microtus californicus) by western harvest mice (Reithrodontomys megalotis)
Authors: Heske Edward J. , Repp Jeanette M.
Published: August 2008

The hypothesis that western harvest mice (Reithrodontomys megalotis) would avoid the scent of large, behaviorally dominant California voles (Microtus californicus) was investigated in both laboratory and field experiments. Reithrodontomys megalotis chose to build nests in boxes containing clean pine shavings rather than those bearing the odors of M. californicus when presented with a choice in the laboratory. Microtus californicus were indifferent to R. megalotis odors. Both species were strongly attracted to conspecific odors. When presented with pairs of clean live traps and traps bearing California vole scent in the field, R. megalotis were captured at significantly greater frequency in the clean traps. This response was strongest when harvest mice were in breeding condition. Results of this study support the hypothesis that interspecific avoidance of voles by harvest mice is a likely mechanism contributing to spatial separation between these species at high vole densities.
Biochemical evidence of speciation in the cod genus Gadus
Authors: Renaud Claude B. , Speers Lawrence I. , Qadri Sami U. , McAllister Don E.
Published: August 2008

Isozyme data obtained from 13 enzyme systems encoded by 21 presumptive gene loci were used to investigate members of the cod genus Gadus; 10 loci were polymorphic. On the basis of our data we do not reject the view of conspecificity between the Baltic cod, G. morhua callarias, and the Atlantic cod, G. m. morhua, or between the ogac, G. m. ogac, and the Pacific cod, G. m. macrocephalus; the data do indicate that these two groups are specifically distinct.
Congruence of morphometric and cultural evolution in Atlantic island chaffinch populations
Authors: Lynch Alejandro , Baker Allan J.
Published: August 2008

Cultural and morphometric evolution of populations of chaffinches from the Azores, Madeira, and Canary Islands were compared using songs and external measurements from seven populations. Cultural evolution was assessed by computing distances among island syllable pools, based on presence or absence coding of syllables. Morphometric differentiation was assessed by computing average taxonomic distances among populations using data from Grant (P. R. Grant. Biol. J. Linn. Soc. 11: 301–332. 1979). Separate analyses of the syllable pool and morphometric distances using cluster and principal coordinates analysis revealed that populations within archipelagos are more similar to one another than they are to populations in different archipelagos. The Madeira population occupies an intermediate position, consistent with its geographic location between the Azores and Canaries archipelagos. Congruence of the patterns of morphometric and cultural evolution in these islands suggests to us that the differentiation has been influenced by a colonization history involving restricted gene and meme flow between archipelagos, subsequent drift, and possibly founder effects. Although directional selection has been implicated in the morphometric differentiation (Grant 1979), cultural evolution (like neutral gene evolution) does not seem to have been subject to selective forces.
The constraints on cephalopods: why squid aren't fish
Authors: O'Dor R. K. , Webber D. M.
Published: August 2008

The convergent evolution of cephalopods and fish has often been discussed on an anatomical basis, but recent advances in the knowledge of cephalopod life cycles, physiology, and biochemistry suggest that there are constraints on cephalopods that prevent them from competing directly with fish. These advances are reviewed against the background of detailed information on fish from the perspective that the basic inefficiency of the jet-propulsion system has required bioenergetic, physiological, and biochemical adaptations in squid which maximize their metabolic rates. Such "high-energy" adaptations are suggested to have resulted in the short life history and semelparous reproductive patterns that seem to characterize these coleoid cephalopods. Conversely, the physiology and biochemistry offish give them distinct advantages for long lives and iteroparity.
Hydrodynamics of swimming in the water boatman, Cenocorixa bifida
Authors: Blake R. W.
Published: August 2008

Locomotion of a small water boatman (Cenocorixa bifida, Corixidae) was investigated employing high-speed cinematography and hydromechanical modelling based on a blade-element approach. The animal is propelled by the synchronous rowing action of its hind legs. The propulsive cycle consists of a power stroke and a recovery stroke phase. Force, impulse, power, and hydromechanical efficiency were calculated for a representative power stroke during which the mean body velocity was about 8 cms−1. A distinction is made between quasi-steady resistive and unsteady inertial (added mass) forces. The mean and maximum resistive thrust forces were calculated to be about 2.4 × 10−5 and 5.7 × 10−5 N per limb, respectively. By equating the total impulse of the power stroke for both legs (2.4 × 10−6 N s) with that of the drag force acting on the body over the same period, a drag coefficient of approximately 1.07 is inferred for the body. This value is comparable to those obtained for certain insects that operate at similar Reynolds numbers to C. bifida. The unsteady added mass force that acts in the forward direction is positive (propulsive) over most of the stroke with a mean value of about 1.17 × 10−5 N per limb, corresponding to an impulse of approximately 5.9 × 10−7Ns. The total propulsive mean force and impulse acting in the forward direction amount to about 3.6 × 10−5N and 1.8 × 10−6N s per limb, respectively, so the impulse of the forwardly directed added mass force amounts to about half that of the resistive thrust force. The total work and mean power associated with generating the resistive thrust were calculated to be about 6.7 × 10−7 J and 1.33 × 10−5 W per limb, respectively. Dividing the mean body drag power (1.4 × 10−5 W) by the total mean resistive power from both legs gave a hydromechanical efficiency of 0.52. When the mean inertial power associated with moving the body (2.3 × 10−6 W) and the added mass power required to accelerate and decelerate the legs (1.95 × 10−5 W per limb) are taken into account, the power stroke propulsive efficiency falls to 0.42. Taking the energy required to power the recovery stroke into account gives an overall propulsive cycle efficiency of about 0.40. This value is about twice that calculated in a previous study for drag-based pectoral fin rowing in the angelfish and reasons for this are suggested.
Influence of temperature and other factors on the daily roosting times ofblack-billed magpies
Authors: Reebs S. G.
Published: August 2008

On 102 occasions from September 1984 to April 1985, the time of morning departure and evening arrival of a population of black-billed magpies (Pica pica) was recorded at a winter roost near Edmonton, central Alberta. The goal was to determine whether an effect of cold on daily roosting time could be observed and distinguished from that of other environmental factors. Multiple linear regression analysis on the data revealed that, all other things being equal, magpies left the roost later relative to sunrise, and returned to it earlier relative to sunset on colder days, and also (i) on longer days, (ii) on darker, cloudier days, (iii) in the second half of winter, when compared with the first half, and (iv) when fewer birds were using the roost. These results held true only before the occurrence of overt territorial behaviour in March, which coincided with a notable shift towards earlier departures and later arrivals. The larger amount of time spent in the roost by magpies when it was cold may be related to an increased predisposition to inactivity induced by cold temperatures, or to possible microclimatological advantages offered by the roost. The amplitude of this temperature effect may, however, be dependent on the birds' level of hunger. Indeed, the effect of temperature on roosting times was much weaker in the case of departure, i.e., after a long night of food deprivation, than it was in the case of arrival.
Digger wasp (Hymenoptera: Sphecidae) provisioning flights as a defence against a nest parasite, Senotainia trilineata (Diptera: Sarcophagidae)
Authors: McCorquodale David B.
Published: August 2008

The provisioning flights of six species of digger wasps (Oxybelus uniglumis, Crabro argusinus, Bembix americana, Philanthus gibbosus, P. inversus, and Cerceris echo) at one aggregation were species specific, providing a diverse array of patterns to the visually searching nest parasite, Senotainia trilineata. Flight diversity did not appear to reduce the probability of initial detection by the fly (a primary defence) because flights of all species were noticed and followed frequently. Flight responses by C. argusinus and P. inversus, after a fly had detected the flight, significantly reduced the probability of contact (a secondary defence). The observed diversity of responses to being followed probably played no role in these defences because S. trilineata contacted prey during a variety of flight types and individuals did not specialize on certain flight types.
Risk of predation and foraging behaviour in shoaling banded killifish (Fundulus diaphanus)
Authors: Godin Jean-Guy J.
Published: August 2008

While foraging for patchily distributed benthic prey in the laboratory, solitary and shoaling banded killifish reduced their per capita rate of feeding attempts and shortened the duration of their feeding posture (when sampling outside the food patches) in the presence of a predatory brook charr. This presumably allowed more time for predator vigilance and avoidance. Individual feeding rate was independent of shoal size, in either the presence or absence of a predator. Solitary fish thus incurred only a slightly greater predator-mediated relative cost of lost foraging opportunities compared with shoaling fish. Killifish therefore altered their foraging behaviour to reduce risk of predation in the presence of a predator and appeared to trade off risk of mortality and energy gain.
Sex differences in the effects of pregnenolone, progesterone, and ACTH on corticosterone secretion of bank vole (Clethrionomys glareolus) adrenals in tissue culture
Authors: Tähkä Klaus M. , Kahri Arvi I. , Voutilainen Raimo , Wallgren Henrik
Published: August 2008

Possible sex-specific differences in the basal as well as the pregnenolone-, progesterone-, and ACTH-induced glucocorticoid secretion of bank vole adrenals was studied in tissue culture by column and gas–liquid chromatography. The adrenals were cultured for 12 days and the medium was replaced after 6 days. The main glucocorticoid in this species, as in many other rodents, seems to be corticosterone since no cortisol was detected. During the first 6 days of cultivation, the administration of pregnanes (20 μg as a single dose) as well as ACTH (0.1 IU∙mL−1∙day−1) induced a marked increase (P < 0.01 or P < 0.001) in the corticosterone secretion in both sexes. The basal as well as the pregnenolone- and the ACTH-induced secretion of corticosterone was significantly (P < 0.02 or P < 0.01) greater in female than male adrenals. These functional differences were almost totally abolished after 12 days of culture. This study suggests that despite the existence of a 3β-hydroxysteroid dehydrogenase negative juxtamedullary zone (at least by histochemical criteria), female adrenals have a greater capacity to convert endogenous as well as exogenous precursors to corticosterone than male adrenals. This is at least partly due to sex differences in the activity (per gland) of the steroidogenic enzymes distal to cholesterol side-chain cleavage, 3β-hydroxysteroid Δ5-Δ4-isomerase in particular.
Étude expérimentale in situ des effets de la densité et de la quantité de nourriture chez le gastéropode Bithynia tentaculata (Mollusca: Prosobranchia)
Authors: Gilbert Eric , Vincent Bruno , Roseberry Luc
Published: August 2008

Experiments in a natural environment on the Gastropod Bithynia tentaculata showed that adult density and available food have significant effects on the growth of smaller adults and newborns. Mean length of the new generation at the end of the experiment incresed as adult densities decreased from the initial value and as food abundance increased. The only case of interaction between these two factors can be explained by an increase in the number of young brought about by the addition of food when density was low and by the influence of the density of these young on their growth. Different combinations of density and food can produce the various types of length–frequency histograms observed in a natural environment and during the past 8 years in the St. Lawrence River. There was no significant correlation between these two factors and the adult mortality rate, but density did have a significant effect on the mean number of young per adult.[Journal translation]
Reproduction of a fingernail clam in contrasting habitats: life-history tactics?
Authors: Bailey Robert C. , Mackie Gerald L.
Published: August 2008

In a population of a semelparous fingernail clam (Pisidium casertanum) inhabiting an ephemeral pond, litter size was larger and generation time was shorter than that of a conspecific population in a lake. This agreed with the r–K selection model, which predicts selection for a shorter generation time and larger litter sizes in relatively unstable habitats. Cage experiments at varying densities, however, revealed that considerable phenotypic variability in litter size may be environmentally induced. These results indicate that this and other comparative studies of intraspecific variation in the life-history traits of fingernail clams cannot conclude that varying evolutionary tactics are present until simpler hypotheses of environmentally induced variation are dismissed.
The population biology of Culaea inconstans, the brook stickleback, in a small prairie lake
Authors: Moodie G. Eric E.
Published: August 2008

Density, female reproductive effort, diet, and morphology of a population of Culaea inconstans were monitored over a 4-year period. Density varied from near extinction to 2.4 fish/m2. There was evidence that growth and female reproductive effort were inversely correlated with density. Females may spawn every 3 days when food is abundant. Fecundity ranged from 104 eggs per female when density was greatest, to 451 eggs per female the year density was least. The species is capable of large scale prespawning migrations, which may result in an immigrant to resident ratio of 0.5–8:1, depending on resident density. Regular immigration coupled with periodic extinction of populations occupying unstable habitats may account for the apparent lack of local morphological adaptation which seems to characterize this species. Despite substantial variation in density, significant variation in annual growth, and different levels of predation, there was no important variation in gill raker means or the number of dorsal and pelvic spines over the course of the study.
Foraging strategies of the mole (Parascalops breweri Bachman, 1842). I. The distribution of prey
Authors: Jensen I. M.
Published: August 2008

The distribution of potential prey for moles in their burrows was compared with that in untunnelled areas. There was little evidence that surface tunnels acted as pitfall traps for invertebrates. There was some suggestion of reduced arthropod biomasss in and around the tunnels, possibly because of predation. Earthworm biomass was significantly lower in soil surrounding tunnels than in control areas, but this was shown not to be the result of predation.
Seasonal moulting patterns in three fur bearing mammals: the European badger (Meles meles L.), the red fox (Vulpes vulpes L.), and the mink (Mustela vison). A morphological and histological study
Authors: Maurel Daniel , Coutant Christian , Boissin-Agasse Line , Boissin Jean
Published: August 2008

Seasonal changes in the fur of three species of mammals at the adult stage, the European badger, the red fox, and the mink, were studied in the field. The badger had only one seasonal change of pelage during the summer and the fall (from July to December), and there was no seasonal variation of hair density. The fox moulted in the spring (between the end of April and the end of August) and again in the fall, but the fall change consisted only in the regrowth of a new fine undercoat that combined with the summer fur to form a denser winter coat. In the mink, the spring and fall moults were very distinct and gave rise to characteristic summer and winter coats that differed in density and number of fine hairs per surface unit. The histological study revealed a similarity in skin composition among the three species, but the relative importance of the different components (sebaceous glands, adipose tissue, keratine layer) varied with each species' way of life. Seasonal follicular activity was correlated with seasonal regrowth of the pelage; the active anagen phase was very long (badger, 5 months; fox, 4 months; mink, 2 months in the spring and 3 months in the fall). During the other part of the annual cycle, telogen, the hair follicles were in a resting phase. Differences in the annual moulting processes between the three species are discussed in terms of adaptive characteristics.[Journal translation]
Male territoriality and mating success in Nannothemis bella (Uhler) (Odonata: Libellulidae)
Authors: Lee Rupert C. P. , McGinn Patrick
Published: August 2008

Observations of territorial behaviour of male Nannothemis bella indicated that females only laid eggs on males' territories after copulating with the territory holder. Results of daily censuses of marked individuals on a study area suggested that a distinct subpopulation within the male population never retained a territory for more than 1 day on the study area. Such males tend to die or emigrate sooner than do males that hold a territory on the study area for more than 1 day at some time in their lives. Further observations of territorial behaviour showed that males holding territories for less than 1 day achieved copulations at significantly lower overall rates while on those territories than did males that retained territories for more than 1 day. We infer that all males attempt to hold territories for as long as possible, but under conditions of high population density a male must have a relatively high intrinsic "territory-holding ability" in order to hold a territory for more than 1 day. Census data indicated that males emerging late in the season were less likely to retain a territory for more than 1 day than males emerging earlier.