bluuebunny/crossref_metadata_2025 huggingface dataset:
Group structure in wood bison: nutritional and reproductive determinants
Authors: Komers Petr E. , Messier François , Gates Cormack C.
Published: July 2008

Sexual segregation in ungulates has been documented for many species including bison. However, male and female bison do not differ in their pattern of habitat selection. In the present study we observed that a fraction of bison groups did not have young (<2 years) despite the presence of males and females. The male to female ratio in these groups was 2.4. We call them adult groups, in contrast to mixed groups, where young were present and the male to female ratio was 0.4. The proportion of cows with young (mothers) in a group was negatively correlated with the male to female ratio, suggesting that mothers associated more often with other cows than with bulls. Before the rut, cows without young (non-mothers) spent less time feeding than either mothers or bulls. However, mothers and non-mothers did not differ in the number of steps per minute they took while grazing, and both types of cows stepped faster than bulls. We suggest that cows feed more selectively than bulls and that the differing foraging strategies result in temporal but not spatial segregation of the sexes. Possibly as a result of similar nutritional demands, mothers tended to aggregate, forming nursery groups. We suggest that the formation of nursery groups can also serve to protect calves through a dilution effect of predation. Whether mothers actually prefer to associate with other mothers remains to be investigated.
Surface and underwater observations of cooperatively feeding killer whales in northern Norway
Authors: Similä Tiu , Ugarte Fernando
Published: July 2008

Killer whales (Orcinus orca) feeding on herring (Clupea harengus) were observed both from the surface and underwater. We refer to one of the feeding techniques used by killer whales as the carousel method, whereby whales cooperatively herded herring into a tight ball close to the surface. During herding and feeding, whales swam around and under a school of herring, performing much lobtailing and porpoising. When the herring were gathered into a tight ball whales often swam with the white underside of their body towards the fish and emitted large bubbles close to the surface. While feeding, whales spent more time circling around the ball of fish than eating. Ball formation is a known defence mechanism used by schooling fish, and the effort by killer whales appeared to be directed towards keeping the ball very dense and close to the surface. The whales stunned their prey by slapping the edge of the school with the underside of their flukes and then ate the stunned fish one by one. The tail slaps created a loud banging sound which could have been either a by-product or an aid to stunning the prey.
Stegotricha enterikos gen.nov., sp.nov. (class Phyllopharyngea, order Rhynchodida), a parasitic ciliate in the digestive gland of Pacific oysters (Crassostrea gigas), and its distribution in British Columbia
Authors: Bower S. M. , Meyer G. R.
Published: July 2008

Stegotricha enterikos gen.nov., sp.nov. is found in the lumen of the digestive gland tubules of Pacific oysters (Crassostrea gigas (Thunberg, 1793)), where it multiplies by transverse binary fission. Nondividing stages have an elongated ovoid body (49.8 ± 10.3 μm long and 18.1 ± 3.4 μm wide) covered by about 16 evenly spaced, slightly oblique kineties (ciliary rows), except for a small naked area on one side of the posterior end. One kinety, associated with the naked area, is unusual, with cilia spaced two to three times as far apart as in the other somatic kineties. A cytopharyngeal structure composed of radially arrayed overlapping sheets of microtubules occurs at the anterior end and occasionally encompasses extrusomes. The centrally located macronucleus is large (about 16 × 12 μm) and the micronucleus (about 2.5 μm in diameter) is either posterior or anterior to the macronucleus. Except for the extent of ciliation, S. enterikos is most closely affiliated with the family Ancistrocomidae. Instead of creating a new family, we suggest that the diagnosis of the Ancistrocomidae be expanded to include ciliates with complete ciliation. Stegotricha enterikos was found in 2.5–72.5% of the oysters (n = 40) sampled between November 1985 and March 1990 from 35 localities in British Columbia. Most infections (86%) were light (1–9 ciliates per wet mount of digestive gland tissue). However, there was no evidence of pathogenesis in 22 oysters with heavy infections (more than 25 ciliates per wet mount).
Predatory behavior of a social spider, Stegodyphus sarasinorum (Araneae: Eresidae): why attack first?
Authors: Willey Marianne B. , Jackson Robert R.
Published: July 2008

Stegodyphus sarasinorum Karsch is a Sri Lankan social spider that exhibits communal predation and feeding. A spider's feeding time is dependent on its position in the feeding sequence, with early feeders feeding longer than those arriving later. Feeding time per spider does not decrease with increasing group size when compared with a given feeding position, temporally speaking. The first spider to feed is the only individual whose feeding time is not shortened by conspecifics.
Functional morphology of toadfish sonic muscle fibers: relationship to possible fiber division
Authors: Fine Michael L. , Bernard Barbara , Harris Thomas M.
Published: July 2008

Sexually dimorphic sonic muscles, which vibrate the swimbladder for sound production in the oyster toadfish (Opsanus tau), are among the fastest vertebrate muscles. Previous work has shown that sonic muscle fibers are smaller in males, have an unusual morphology, and increase in number and size for life. We now report evidence consistent with the hypothesis that mature, presumably postmitotic, sonic fibers divide, and suggest that division, which returns fibers to small energy-efficient units, is necessary because mitochondria are excluded from the fiber's contractile cylinder. Large fibers, potential candidates for division, develop fragments of contractile cylinder separated by channels of an expanded sarcoplasmic reticulum; these channels can assume the appearance of the sarcoplasm (glycogen granules and mitochondria) beneath the sarcolemma. Measurements indicate that contractile cylinder diameter does not increase with fish size and that diameters are approximately 21% larger in females (p < 0.0001). Fiber fragmentation, possible division, and the presence of smaller fibers with smaller diameter contractile cylinders in males are seen as adaptations for repeated rapid contraction and fatigue resistance during production of the male's courtship boatwhistle call.
Ecology of isolated open-formation Tropidurus (Reptilia: Tropiduridae) in Amazonian lowland rain forest
Authors: Vitt Laurie J.
Published: July 2008

Ecological, morphological, and life-history characteristics of three as yet undescribed populations of open-formation Tropidurus species in Rondônia and a population of Tropidurus oreadicus in Pará, Brazil, that are isolated on rock outcrops completely surrounded by lowland tropical forest were compared with similar characteristics of a eurytopic open-formation close relative, Tropidurus hispidus, and a crevice-adapted close relative, Tropidurus semitaeniatus, from an open-formation (caatinga) habitat in northeastern Brazil. Individuals of the isolated Amazonian populations do not enter the forest, but escape into narrow crevices on rock outcrops when disturbed. They are restricted to the only habitat patch in tropical forest similar to open-formation habitats, granitic rock outcrops. The outcrops maintain cerrado and caatinga vegetation and published paleoecological data indicate that the forested area surrounding the outcrops in Rondônia was cerrado in the recent past. Individuals in the isolated Tropidurus populations are morphologically flattened compared with T. hispidis, clutch size is reduced, and relative clutch mass is reduced, as is observed in other crevice-adapted species of lizards. Females deposit eggs under granitic cap rocks, like the flattened lizard T. semitaeniatus. The most parsimonious explanation for the set of characteristics shared by these four isolated lizard populations is that natural selection has led to an adjustment of behavior, morphology, and certain life-history characteristics in response to the high ecological risks associated with entering surrounding forest. It remains unclear whether this occurred once (which assumes a common ancestor), followed by canalizing selection, or the populations converged independently on similar morphology and ecology (which assumes different ancestors). The direction of divergence in behavior, morphology, clutch size, relative clutch mass, and nesting behavior in isolated populations of Tropidurus species remains unknown.
Glochidium morphology of the freshwater pearl mussel (Margaritifera margaritifera) and glochidiosis of Atlantic salmon (Salmo salar): a study by scanning electron microscopy
Authors: Nezlin L. P. , Cunjak R. A. , Zotin A. A. , Ziuganov V. V.
Published: July 2008

The morphology of glochidia of the freshwater pearl mussel Margaritifera margaritifera L. and the development of the cyst for 50 days after glochidial infection of wild and hatchery-reared Atlantic salmon (Salmo salar L.) parr were studied using scanning electron microscopy. The microvillar surface of the inner epithelium of the glochidium, which may function in nutrition, respiration, and osmoregulation, is described. Glochidia were found to have five sensory tufts as well as marginal ciliary bands which are believed to function in directing water currents. After artificial infection of salmon parr, cyst formation was the result of shape change and migration of gill epithelial cells, but not hyperplasia. The process of cyst formation lasted from 9 to 12 h. No mortality of salmon parr occurred during the experiment. Based on our study, glochidia appear to have a negligible effect on the gills of Atlantic salmon, its preferred fish host. These results are discussed in the context of the possibility of a mutually beneficial coexistence of Atlantic salmon and pearl mussels in northern European rivers such as the Varzuga River in Russia.
Diversity and zoogeography of the non-oceanic Crustacea of the Galápagos Islands, Ecuador (excluding terrestrial Isopoda)
Authors: Peck Stewart B.
Published: July 2008

Fifty-three species of adult crustaceans (excluding Isopoda) are now known from a diversity of non-oceanic habitats on the Galápagos Islands. These include hypersaline, brackish, and fresh coastal and inland surface waters, anchialine subterranean waters, and terrestrial habitats above the high-tide line such as supralittoral beach wrack and upland leaf litter. The faunal assemblage is physiologically defined by evolving away from the ancestral marine environment, before or after reaching the Galápagos Islands. It is taxonomically diverse and includes Notostraca, Conchostraca, Anostraca, Ostracoda (Myodocopa and Podocopa), Copepoda (Calanoida and Cyclopoida), Tanaidacea, Amphipoda, and Decapoda (Caridea, Anomura, and Brachyura). All members of the fauna (or their progenitors) have dispersed across an oceanic gap of at least 1000 km and have colonized the archipelago by three principal methods: (1) as swimming pelagic larvae or adults that dispersed passively by being carried through the sea; (2) through passive transport of nonswimming forms by rafting in or on floating debris on the sea surface; and (3) through passive biological transport of propagules by birds or insects. There is no direct evidence for the aerial (wind) transport of desiccation-resistant dormant stages such as eggs, but it is possible that this has occurred. Twenty-eight species are native and 25 are endemic. The supralittoral species and those in both temporary and permanent surface waters are generally native and widespread in the Americas. Three amphipod genera and one crab genus are endemic. Subterranean (anchialine) waters contain a high percentage of (often eyeless) endemics. The largest evolutionary shift is represented by an upland terrestrial amphipod that has evolved in situ from an ancestral supralittoral species.
Effects of ectoparasites on breeding success of great tits (Parus major) and pied flycatchers (Ficedula hypoleuca) in an air pollution gradient
Authors: Eeva Tapio , Lehikoinen Esa , Nurmi Jorma
Published: July 2008

Numbers of ectoparasitic blow fly (Protocalliphora azurea) larvae (Diptera: Calliphoridae), adult and larval hen fleas, Ceratophyllus gallinae (Siphonaptera: Ceratophyllidae), and other nest-dwelling insects were counted from the nests of the great tit, Parus major, and the pied flycatcher, Ficedula hypoleuca, in southwestern Finland around a factory complex emitting large quantities of sulphuric oxides and heavy metals. Protocalliphora azurea larvae were more frequently found in the nests of P. major than in those of F. hypoleuca. The prevalence of P. azurea larvae tended to be lower in polluted areas. The number of P. azurea larvae correlated positively with nest size and brood size of P. major. This may be caused by difficulties in sanitation of large and crowded nests. The numbers of fleas and their larvae were negatively affected by moisture in the nests. Nests of F. hypoleuca contained more adult fleas in polluted areas. This may indicate reduced resistance of birds exposed to heavy metals, but other possibilities are also discussed. We found a detrimental effect of P. azurea larvae on the growth of P. major nestlings, and an effect of fleas on mortality of F. hypoleuca nestlings, but these effects were not enhanced by air pollution. We conclude that the ectoparasites studied, at densities observed in our study area, are of minor importance in determining the breeding success of these two bird species.
Helminth infracommunities of Podarcis pityusensis and Podarcis lilfordi (Sauria: Lacertidae) from the Balearic Islands (western Mediterranean basin)
Authors: Roca V. , Hornero M. J.
Published: July 2008

A survey of the helminth communities of Podarcis pityusensis (Boscá, 1883) and Podarcis lilfordi (Günther, 1874) (Sauria: Lacertidae) from the Pityusic and Gimnesic islands, respectively, in the Balearic Islands, Spain, was conducted. Both host species harbour similar though not identical helminth infracommunities. An analysis of the patterns of diversity for all helminths revealed that both lizards have depauperate isolationist infracommunities, possibly as a result of factors such as host ectothermy, the simplicity of their digestive canal, low vagility, and generalist feeding.
Metabolic responses to dehydration by liver of the wood frog, Rana sylvatica
Authors: Churchill Thomas A. , Storey Kenneth B.
Published: July 2008

The metabolic responses by the liver to the evaporative loss of up to 60% of total body water were quantified in spring-collected wood frogs, Rana sylvatica, a freeze-tolerant species. Dehydration stimulated rapid hyperglycemia, liver glucose levels rising 3.8-fold to 90 nmol/mg protein (9.9 μmol/g wet mass) by the time that 10% of total body water had been lost. Glucose accumulation occurred at the expense of liver glycogen reserves, which fell over the course of dehydration, and was supported by a 5.8-fold increase in the activity of glycogen phosphorylase a in the liver, made up of increases in both the total phosphorylase activity expressed and the percentage of the enzyme in the active form. Analysis of changes in the levels of glycolytic intermediates in the liver over the course of dehydration showed sharp increases in glucose-6-phosphate and fructose-6-phosphate during the period of active glucose synthesis but no change in the levels of fructose-1,6-bisphosphate or triose phosphates. This indicated that an inhibitory block on glycolysis at the phosphofructokinase reaction helped to promote the diversion of glycogenolysis into glucose export. When water loss exceeded 10%, cellular energetics were affected; ATP levels fell progressively between 25 and 60% dehydration, but a concomitant drop in the total adenylate pool held the energy charge stable at 0.7–0.8 up to 35% dehydration. At extreme dehydration (50 and 60%), metabolic indicators of hypoxia stress appeared in the liver: lactate accumulated and the energy charge fell. The data show that a primary response to whole-body dehydration in wood frogs is the activation of liver glucose synthesis and this suggests that the production of glucose as a cryoprotectant during freezing in this species is probably derived from a pre-existing amphibian volume-regulatory response to dehydration.
Contrasting patch choosing by anthophilous ambush predators: vegetation and floral cues for decisions by a crab spider (Misumena vatia) and males and females of an ambush bug (Phymata americana)
Authors: Greco Carlos F. , Kevan Peter G.
Published: July 2008

Field-collected individuals of Misumena vatia and Phymata americana were compared experimentally as to the kind of vegetation and flower cues they use to choose a hunting site, by introducing them into choice arenas with variously manipulated natural stems of three species of plant and with artificial flowers. Misumena vatia showed a strong preference for stems with flowers or leaves or both; P. americana did not prefer normal stems as strongly and it did not show a statistically significant preference among the various manipulated patches. Both predators discriminated among Solidago canadensis, Daucus carota, and Cirsium arvense, showing a clear preference for the first. Misumena vatia showed a clear preference for yellow artificial flowers on wooden sticks when given a choice of four different colours. Phymata americana preferred yellow or blue to white or red, showing no discrimination between colours of the same group (yellow vs. blue or white vs. red). Misumena vatia took the longest time (ca. 43 min) to complete its choice of stem; female and male P. americana took 18 and 15 min, respectively. In all the experiments P. americana showed sexual diethism, the females being more choosy than the males. The ranking of discrimination from greatest to least was as follows: M. vatia, females of P. americana, and males of P. americana. We suggest that both species of predators have different strategies of patch choice and that in the case of P. americana, males and females have different patterns of patch selection, the males searching not only for prey but also for mates.
Seasonal variation in the metabolic rate of harp seals: unexpected energetic economy in the cold ocean
Authors: Renouf Deane , Gales Rosemary
Published: July 2008

The metabolic rate of nine harp seals was measured chronically over a 12-month period using indirect calorimetry. The extent to which the seals' oxygen consumption was predicted by the allometric equation relating basal metabolic rate to body mass depended upon how the former was operationally defined and on the breeding status, sex, and age of the animal. There were large seasonal changes in the oxygen consumption of adult males and reproductive females when metabolic rate was defined as the lowest hourly mean [Formula: see text] in, typically, 23 h of measurement. From April until August, the males' metabolic rate averaged as much as 83% higher than the allometric prediction from body mass, but for the rest of the year their oxygen consumption was not different from the expected value for mammals. Pregnant and pseudopregnant females showed a brief spring elevation in metabolic rate, but otherwise their oxygen consumption was well below that predicted by allometry. In one female who spontaneously aborted some 7 months after insemination, [Formula: see text] increased to the value for mammals shortly thereafter, to a level resembling that of the only female who was not pregnant and who showed no seasonal variation in oxygen consumption. The immature seals' records are highly variable, showing no clear intra-annual pattern; however, their metabolic rates were lower than expected for young mammals. All seasonal shifts were in the opposite direction to the large changes in body mass exhibited by these seals. The effect of these findings in reducing the calculated impact of harp seals on the North West Atlantic fishery is discussed.
Comparative ultrastructure of the spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis (Cestoda, Anoplocephalidae, Inermicapsiferinae), intestinal parasites of rodents in Senegal
Authors: Bâ Cheikh Tidiane , Marchand Bernard
Published: July 2008

Spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis are filiform and tapered at both extremities. The anterior extremity exhibits an apical cone of electron-dense material and two helical ridges. The axoneme, of the 9 + "1" pattern, is surrounded over part of its length by a sheath of electron-dense material. At the posterior extremity the cytoplasm contains electron-dense material. In regions III and IV of the spermatozoa the cytoplasm is subdivided into compartments of electron-lucent material limited by irregularly spaced walls of electron-dense material. The sperm nucleus is a compact cord wound in a spiral around the axoneme. Cortical microtubules are helically arranged down the length of the spermatozoa except at the posterior extremity where they run parallel to the spermatozoon axis. In I. madagascariensis, cortical microtubules may not extend as far as the posterior extremity of the spermatozoa; the dense periaxonemal material exists in regions I to IV of the spermatozoon and the nucleus never coils more than once around the axoneme.
Some effects of starvation on the lipid and skeletal muscle layers of the winter flounder, Pleuronectes americanus
Authors: Maddock D. M. , Burton M. P. M.
Published: July 2008

Winter flounder, Pleuronectes americanus, were starved during the summer feeding season. The condition factor of starved fish declined over the starvation period and was lower than that for fed or wild fish. Starvation resulted in a decrease of the hypodermal lipid layer under the lateral line. White muscle water content was higher in fish in the starved state, reaching 94.6%. White muscle fibres were atrophic in appearance in starved fish, with decreased cross-sectional area, increased intercellular spacing, and increased space between myofibrils. Red muscle, located in a wedge under the lateral line, was conserved in starvation. Depletion of fat reserves and the ability to utilize white muscle protein as an energy store during starvation are indicated.
Redescription of Parastenocaris brevipes Kessler and description of a new species of Parastenocaris (Copepoda: Harpacticoida: Parastenocarididae) from the U.S.A.
Authors: Reid Janet W.
Published: July 2008

Parastenocaris brevipes Kessler is redescribed and its presence in North America is established through comparison of specimens from the U.S.A., Finland, and Germany. Parastenocaris wilsoni Borutskii, Parastenocaris starretti Pennak, Parastenocaris biwae Miura, and Parastenocaris sp. 2 Strayer (Strayer, D.L. 1988. Stygologia, 4: 279–291.) are assigned to the synonymy of P. brevipes. Biwaecaris Jakobi is a synonym of Parastenocaris Kessler. Some North American records of P. brevipes or P. starretti refer in fact to P. brevipes, other records to a presently undescribed species. Newly verified records of P. brevipes include Massachusetts, Michigan, New Hampshire, New York, Virginia, and Wisconsin in the U.S.A., and Lake Biwa, Japan. Parastenocaris trichelata, new species, is described from Virginia, U.S.A. The taxon is distinguished in both sexes by the combination of the long slender caudal ramus with all setae inserted in the distal half and by the medial spine of the leg 1 basipodite, and in the male by the leg 4 with slender hyaline endopodite and 3 spines on the basipodite medial to the endopodite. The new species little resembles any known North American parastenocaridid, nor is it assignable to any presently defined species-group in the genus.
Patterns of dispersion of aquatic insects colonizing artificial substrates in a southern Ontario stream
Authors: Rutherford Jane E.
Published: July 2008

Modified artificial turf substrates were readily colonized by stream invertebrates, supporting 20 or more taxa after 10 or 22 days in the stream. Of the individuals present, 50–80% belonged to four taxa: Hydropsychidae, Hydroptila sp. (larvae and pupae), Rheotanytarsus sp., and Baetidae. All four taxa displayed significantly aggregated patterns of dispersion (as shown by Clark–Evans–Donnelly indices) on most of the 6 substrates. The hydropsychids and the Hydroptila sp. pupae appeared to have the highest degree of aggregation, especially at high densities; both taxa occupied about the same areas on the substrates, forming discrete bands of occupation at the upstream and downstream edges as well as along a narrow band near the middle of the substrates. Weakly positive (but generally nonsignificant) Φ2values (intertaxon association indices based on presence–absence data) coupled with negative Iaivalues (intertaxon association indices based on joint abundances) for the Hydropsychidae – Rheotanytarsus sp. and Hydroptila sp. – Rheotanytarsus sp. pairings indicate that Rheotanytarsus sp. occupies quite different areas of the substrates than either the hydropsychids or Hydroptila sp. pupae, suggesting that competition for space may be important amongst these sessile taxa.
An endemic groundwater fauna in unglaciated eastern North America
Authors: Strayer David L. , May Sarah E. , Nielsen Pamela , Wollheim Wilfried , Hausam Sharon
Published: July 2008

Invertebrates specialized for life in groundwater (stygobionts) are diverse and widely distributed in Europe but poorly known in North America. A survey of the invertebrate fauna at 14 sites in eastern North America shows that unglaciated ancient terrain in eastern North America contains a rich fauna of stygobionts. Several groups of stygobionts (the polychaete Troglochaetus sp., an undescribed genus of aphanoneuran annelid, a possibly undescribed family of oligochaetes, bathynellacean crustaceans, and microcerberid isopods) are reported for the first time from eastern North America. Stygobionts are infrequent north of the glacial border, suggesting that they have not yet been able to disperse into glaciated terrain. The extraordinarily slow dispersal rates implied by these distributions have important ecological ramifications. The few stygobionts found north of the glacial border may have survived glaciation in subglacial refugia.
Mother–pup reunions in harp seals, Phoca groenlandica: cues for the relocation of pups
Authors: Kovacs Kit M.
Published: July 2008

This study was designed to examine how female harp seals (Phoca groenlandica) solve the orientation problems they face when returning to their pups from the water in a pack-ice environment. Data were collected during the breeding seasons of 1992 and 1993 in the Gulf of St. Lawrence, Canada. During 31 h of observations, 73 returns of females were documented. Most return paths of females from the water originated at the access point closest to their pup (88%), indicating good underwater orientation capabilities. The mean path length was 1.3 ± 2.2 times the length of a direct line between the water access point and the pup, and most females were clearly oriented toward their pup upon leaving the water. Most return paths (84%) terminated in a nursing session with the pup. Prior to nursing, naso–naso contact was made by the mother–pup pair. Only 26% of return paths were directed toward a calling pup, the rest were spontaneously performed to a silent, unmoving pup. The mean duration of calling prior to the appearance of the female was 7.3 ± 7.2 min (N = 18). Mothers returning to a vocalizing pup did not have more direct return paths than those returning to a silent pup (Mann–Whitney U test, U = 422, P = 0.19). Although pups were remarkably sedentary in the absence of their mothers, approximately half of females returning to their pup (32/73) were approached by it. Only 7% of paths (5/73) of females involved contact with a foreign pup. Likewise, pups rarely approached females other than their mother. Females were able to return directly to sleeping, silent (or dead) pups that were not visible from the origin of the path and were able to return to locations where they had last left the pup without the pup itself acting as a stimulus. Thus, it appears that harp seal mothers use multimodal sensory cues to return to their pups in the pack-ice environment. At long distances spatial information appears to be of primary importance and can be used exclusively by females to return to specific positions on the ice. Visual and auditory cues emitted by pups may ease the task of relocation, although they must be considered of secondary importance. Pups appear to recognise their mothers at a distance. At close range, olfactory cues provide the definitive means of individual identification within mother–pup pairs.
Age-, size-, and sex-specific infection ofAnodonta piscinalis(Bivalvia: Unionidae) withRhipidocotyle fennica(Digenea: Bucephalidae) and its influence on host reproduction
Authors: Taskinen Jouni , Valtonen E. Tellervo
Published: July 2008

A Rhipidocotyle fennica infection in Anodonta piscinalis was studied during 1987–1989 in Lake Saravesi, central Finland. The overall prevalence was 32.3% (n = 1157). Only mature clams, ≥ 3 and ≥ 4 years old in the littoral and sublittoral zones, respectively, were infected. According to log-linear models constructed for the mature clams, there was a statistically significant interaction between prevalence and age of the host, between prevalence and habitat, and between age of the host and habitat; prevalences were higher among old specimens and in the littoral zone than among young clams or in the sublittoral zone. Logit models showed that prevalence increased linearly with host size in both habitats. A relationship between clam growth and infection was also found: fast-growing clams were more often infected or infected clams had grown faster. The quantity of sporocyst tubules increased with the age of the host. Prevalence was higher among female clams than among males. It was estimated that over 50% of mature females in the littoral zone were infected. It was also estimated that there was a 31% reduction in the number of glochidium-bearing clams in the littoral zone of Lake Saravesi due to infection with this parasite.
Winter use of food by fenced voles (Microtus pennsylvanicus)
Authors: Bergeron Jean-Marie , Jodoin Louise
Published: July 2008

Meadow voles (Microtus pennsylvanicus) were housed in fenced plots over the winter to establish whether intense grazing in the summer could affect their winter diet and thereby reduce their chances of survival. Intense grazing in the summer was simulated by removing 14% of the fall biomass. In November 1992, voles were introduced into two clipped plots and two unclipped plots. Two other plots were used to follow changes in biomass not associated with intense grazing. In January 1993, population densities and chemical constituents of fecal samples were significantly reduced as a result of experimental and winter environmental conditions. Over time, the vole feces contained increasing proportions of phenolics and neutral detergent solubles, and their diet became more diversified. These effects were more evident in the clipped plots, suggesting that the removal of fall biomass caused a rapid decline in vole numbers and the increased use of low-quality food during winter.
Winter range arrival and departure of white-tailed deer in northeastern Minnesota
Authors: Nelson Michael E.
Published: July 2008

I analyzed 364 spring and 239 fall migrations by 194 white-tailed deer (Odocoileus virginianus) from 1975 to 1993 in northeastern Minnesota to determine the proximate cause of arrivals on and departures from winter ranges. The first autumn temperatures below −7 °C initiated fall migrations for 14% (95% confidence interval (CI) = 0 – 30) of female deer prior to snowfall in three autumns, but only 2% remained on winter ranges. During 14 autumns, the first temperatures below −7 °C coincidental with snowfalls elicited migration in 45% (95% CI = 34 – 57) of females, and 91% remained on winter ranges. Arrival dates failed to correlate with independent variables of temperature and snow depth, precluding predictive modeling of arrival on winter ranges. During 13 years, a mean of 80% of females permanently arrived on winter ranges by 31 December. Mean departure dates from winter ranges varied annually (19 March – 4 May) and between winter ranges (14 days) and according to snow depth (15-cm differences). Only 15 – 41% of deer departed when snow depths were >30 cm but 80% had done so by the time of 10-cm depths. Mean weekly snow depths in March (18 – 85 cm) and mean temperature in April (0.3 – 8.1 °C) explained most of the variation in mean departure dates from two winter ranges (Ely, R2 = 0.87, P < 0.0005, n = 19 springs; Isabella, R2 = 0.85, P = 0.0001, n = 12 springs). Mean differences between observed mean departure dates and mean departure dates predicted from equations ranged from 3 days (predictions within the study area) to 8 days (predictions for winter ranges 100 – 440 km distant).
Spatial distribution, habitat utilization, and social interactions of humpback whales,Megaptera novaeangliae, off Hawai'i, determined using acoustic and visual techniques
Authors: Frankel A. S. , Clark C. W. , Herman L. M. , Gabriele C. M.
Published: July 2008

Acoustic and visual methods were used to track and observe humpback whales off the island of Hawai'i. Sixty-two singing whales were located acoustically in water depths from 10 to 305 fathoms (mean 126 fathoms; 1 fathom = 1.828 m). This indicates that singers are not confined within the 100-fathom contour, although nearshore waters had a higher density of singers. The separation distance between singers (mean 5.1 km) was found to be significantly greater than that between nonsinging singletons (mean 2.1 km), supporting the hypothesis that song functions to maintain spacing between singers. The mean speed of singers determined from visual data was 1.79 km/h and from acoustic data 1.6 km/h. Some singers actively swam while singing. Other singers continued singing while affiliating with or being joined by other whales. The correlation between breaching and the cessation of singing suggests that the sounds of aerial behavior can convey information to other whales. These observations suggest the need to expand the traditional interpretations of the behavior of singing humpback whales obtained from visual observations alone.
Evidence for a trade-off between defensive morphology and startle-response performance in the brook stickleback (Culaea inconstans)
Authors: Andraso Gregory M. , Barron James N.
Published: July 2008

It is generally believed that predation pressure may drive the evolution of long spines, a robust pelvic girdle, and a deep body in sticklebacks (Pisces: Gasterosteidae). However, the lack of such traits in environments under intense predation pressure suggests that there may be a limit to which these apparently defensive structures benefit sticklebacks. In some environments, well-developed defensive structures may not increase stickleback survival, but may actually reduce fitness if there is a cost associated with them. This paper focuses on a trade-off between defensive morphology and escape-response performance in the brook stickleback (Culaea inconstans). Our study of four populations of brook stickleback reveals that the population with the largest pelvic girdles and deepest bodies has a poorly developed escape response (i.e., small displacement, low maximum velocity, and low acceleration), while the population with the smallest pelvic girdles and shallowest bodies has a highly developed escape response. The two populations with intermediate defensive structures are intermediate in escape-response performance. Consideration of predation regimes in different environments may help us understand selection pressures that favor heavily versus poorly armored stickleback morphs.
A comparative study of the fish parasites Proteocephalus exiguus and P. percae (Cestoda: Proteocephalidae): morphology, isoenzymes, and karyotype
Authors: Hanzelová Vladimira , Šnábel Viliam , Špakulová Marta , Králová Ivica , Fagerholm Hans-Peter
Published: July 2008

The two closely related cestodes Proteocephalus exiguus (= P. neglectus) and P. percae, parasites of coregonid and salmonid fishes and of perch, respectively, were compared using morphological, biochemical, and cytogenetic methods. Three morphological forms of similar appearance were observed in both P. exiguus and P. percae. Although the two species were strikingly similar in general morphological appearance, some of the features analyzed morphometrically (width of scolex, diameter of apical organ, length and width of hermaphroditic proglottis, length of cirrus sac) exhibited consistent differences. Fixed genetic differences distinguish the species at five loci in EST, GOT, and PGM enzymes. Nei's interspecific genetic distance was 0.305. Both species have 18 chromosomes with comparable absolute lengths. However, the morphology of most chromosome pairs differed. On the basis of these results, discriminative characteristics for P. exiguus and P. percae are given.
Trophic dynamics of two sympatric species of riparian spider (Araneae: Tetragnathidae)
Authors: Williams D. Dudley , Ambrose Laura G. , Browning Laura N.
Published: July 2008

Four species of Tetragnatha were found along the banks of Duffin Creek, Ontario: T. versicolor Walckenaer, T. elongata Walckenaer, T. laboriosa Hentz, and T. straminea Emerton. However, only the first two species were common; together they represented 91% of all species of spiders observed. Highest densities of T. elongata occurred in July, a time when numbers of T. versicolor were at their lowest. Growth rates differed between the two species. Both species were more common (2–3 times) on the east bank of the river than on the west. The locations (in three dimensions) of individual spiders along the banks were similar for both species, although T. elongata frequented shrubs overhanging the river more than T. versicolor, which was found farther away from the water's edge. The mean number of prey caught by T elongata was significantly higher than that caught by T. versicolor. Webs caught most prey when located 2–4 m from the water's edge, both in annual vegetation (grass level to a height of about 0.5 m) and in tall shrubs (1.5–2 m). Large numbers of prey were caught also in webs spun in shrubs and tree branches that hung over the water surface at a height of 1–2 m. The number of prey caught was not related to web diameter. Maximum prey capture by T. elongata coincided with the time of maximum total insect emergence in the river. Although the insect taxa found in the webs reflected those that were emerging in greatest numbers, typically chironomids and mayflies, other commonly emerging taxa (e.g., caddisflies and stoneflies) were conspicuously absent. The minimum estimate of the proportion of total insect emergence from this river that is captured by these two spider species is 0.2%.
Two new Canadian species of the genusTricorythodesUlmer, with additional studies on other North American species (Insecta, Ephemeroptera: Leptohyphidae)
Authors: Alba-Tercedor Javier , Flannagan John
Published: July 2008

Two new mayfly species (Tricorythodes mosequs n.sp. and T. cobbi n.sp.) are described from the Assiniboine River, Manitoba, Canada. Taxonomic knowledge of the North American species of the genus Tricorythodes is summarized. The type material of T. stygiatus McDunnough, T. atratus (McDunnough), and T. peridius Burks was studied and additional characteristics of these species are described. New drawings of the genitalia of these species are presented. Tricorythodes peridius and T. atratus are considered to be junior synonyms of T. allectus (Needham). A key to the imagines of Tricorythodes in Canada is included.
Seasonal variation in body mass and composition of eastern coyotes
Authors: Poulle Marie-Lazarine , Crête Michel , Huot Jean
Published: July 2008

Fat and protein reserves were estimated from body mass and the kidney and femur fat index for 135 coyotes (Canis latrans) of different ages and both sexes. These coyotes were collected in southeastern Quebec during five trapping periods between summer 1990 and autumn 1991. Coyotes were 27–28% heavier during autumn–winter than during summer: 16.0 versus 12.5 kg for males and 14.0 versus 11.0 kg for females. This mass gain consisted of 0.6–0.7 kg of protein and 1.5–2.0 kg of fat (water accounted for the balance). The mean fat percentage varied widely among individuals but did not differ according to sex or age. It varied according to trapping period and almost doubled from summer to autumn (10 versus 18%), did not change significantly from late October to late March, but then decreased from winter to summer. It appears that fat deposits accumulated by coyotes during autumn were not used progressively during the winter. However, they allowed the coyotes to survive during brief periods of food shortage. Furthermore, spring and summer seemed to be periods of relative food scarcity for coyotes, because they lost 16–17% of their protein mass from late winter to summer. Only 41% of the 39 females old enough to reproduce ovulated, but no relationship was apparent between this low fertility rate and the body composition of the females.
Brooding strategies in solitary ascidians: Corella species from north and south temperate waters
Authors: Lambert Charles C. , Lambert Ilsa M. , Lambert Gretchen
Published: July 2008

Corella inflata from the northwest Pacific coast of North America and Corella eumyota from southern New Zealand are both ovoviviparous solitary ascidians with very different methods of brood retention. Corella inflata eggs are covered with large follicle cells that are responsible for flotation. The floating eggs are trapped in the upwardly situated atrial chamber, where development ensues. Corella eumyota eggs have small follicle cells and do not float; the follicle cells produce a viscous glue that causes the eggs and embryos to stick to each other and to the right atrium. The follicle cells are not sticky when removed from the ovary but become so in about 15 min. In C. inflata, development to hatching requires 24–26 h at 13 °C and metamorphosis begins 17 h later. Corella eumyota tadpoles hatch at about 25 h at 15 °C and begin metamorphosis 11 h later. Both species retain the tadpoles well beyond hatching and release tadpoles fully competent to metamorphose. In C. inflata the tadpoles swim down and out of the atrium; C. eumyota tadpoles somehow break free of the glue-encrusted vitelline coat and swim out the atrial siphon. Tadpoles of both species swim vigorously when released and then rapidly metamorphose. Most tadpoles metamorphose in 15–20 min. Since both species spawn around dawn, tadpoles are released during the night.
Patch choice in the anthophilous ambush predator Phymata americana: improvement by switching hunting sites as part of the initial choice
Authors: Greco Carlos F. , Kevan Peter G.
Published: July 2008

Optimal foraging theory predicts that foragers with an imperfect knowledge of the environment will invest time sampling the foraging area. The ambush bug Phymata americana Melin appertains to this category of foragers because it has shown, in previous studies, apparently nonoptimal behaviour in choosing patches while crawling on the ground. Even so, we hypothesize that, atop the canopy where they normally seek prey, they can easily switch to a better position. To examine this hypothesis and to test the prediction of optimal foraging theory, adult male and female ambush bugs were released in an experimental arena containing six different kinds of patches of Solidago canadensis: (1) normal, leafy stems with inflorescences, (2) bare stems without inflorescences, (3) leafy but deflowered stems, (4) normal stems with ambush bugs of the opposite sex in the inflorescences, (5) normal stems with dead house flies (Musca domestica) (prey) hanging over the flower, and (6) normal stems with dead honeybees (Apis mellifera) (prey) hanging over the flower. The bugs showed only weak discrimination in choosing a stem from the ground. However, once atop the canopy (stems or inflorescences), the bugs switched quickly to other patches, significantly improving their situation. These results suggest that this ambush predator has some ability to recognize not only vegetation and floral cues, but also the presence of other insects in flowers, i.e., prey and the opposite sex. Sexual diethism is also indicated.
Physiological responses of neonatal white-tailed deer reflective of maternal dietary protein intake
Authors: Sams Michael G. , Lochmiller Robert L. , Hellgren Eric C. , Payton Mark E. , Varner Larry W.
Published: July 2008

Previously, we observed a strong correlation between immunity parameters of neonatal white-tailed deer (Odocoileus virginianus) fawns and probability of survival in an overpopulated herd. As a result, we monitored age-related changes in neonatal fawn physiology, with an emphasis on measures of passive immune transfer, to test the hypothesis that maternal protein malnutrition adversely influences the vigor and immunocompetence of newborn fawns. Body mass and physiological data were collected from 55 neonatal fawns (1–28 days old) born to captive does on either a high-protein (16%) or low-protein (6.5%) diet during the latter half of gestation through lactation (15 March – 1 September). The study was conducted over two breeding seasons (1992 and 1993), with does receiving the same diet the second year to assess diet × year interactions. We found little evidence of compromised immunocompetence of neonatal fawns born to protein-malnourished does in either year. The absence of any sign of suppressed in utero development suggested that the nutritional deficiencies of the diet regime we used may not have been chronic enough to mirror conditions that exist in the wild. Birth mass, hematology, and serum chemistries of fawns suggested that low-protein diets caused reductions in maternal nutritional status by the second year. The results of this study and those of preliminary field observations suggested that compromised immunocompetence of neonatal fawns may be manifested only during chronic malnutrition, when the protein reserves of does become depleted or insufficient.
A new species of Phreodrilidae (Oligochaeta),Astacopsidrilus nacerisp.nov., from Morocco (North Africa), with notes on the biogeography of the family
Authors: Giani Narcisse , Martin Patrick , Juget Jacques
Published: July 2008

Previously only known in Australia and mainly ectoparasitic, the genus Astacopsidrilus has been found in groundwaters of North Africa (Morocco) for the first time. The characteristics of Astacopsidrilus naceri sp.nov. include two setae in ventral bundles, one simple-pointed and one bifid with the upper tooth reduced, deep spermathecal vestibules running to the dorsal wall of the body, with muscular attachment in which the female funnel is probably involved, and sperm organised into thin, elongated, and spirally coiled bundles. The location of the new species in North Africa extends the distribution of the family above the Tropic of Cancer. Compilation of records known thus far supports a pan-Gondwanian origin of the family. The occurrence of the family in refuges above the Tropic of Capricorn led us to assume that the species is a relict in this geographical zone and to predict the existence of the family in groundwaters of Arabian Peninsula.