bluuebunny/crossref_metadata_2025 huggingface dataset:
Wolves, elk, and bison: reestablishing the "landscape of fear" in Yellowstone National Park, U.S.A.
Authors: Laundré John W , Hernández Lucina , Altendorf Kelly B
Published: April 2011

The elk or wapiti (Cervus elaphus) and bison (Bison bison) of Yellowstone National Park have lived in an environment free of wolves (Canis lupus) for the last 50 years. In the winter of 1994-1995, wolves were reintroduced into parts of Yellowstone National Park. Foraging theory predicts that elk and bison would respond to this threat by increasing their vigilance levels. We tested this prediction by comparing vigilance levels of elk and bison in areas with wolves with those of elk still in "wolf-free" zones of the Park. Male elk and bison showed no response to the reintroduction of wolves, maintaining the lowest levels of vigilance throughout the study ([Formula: see text]12 and 7% of the time was spent vigilant, respectively). Female elk and bison showed significantly higher vigilance levels in areas with wolves than in areas without wolves. The highest vigilance level (47.5 ± 4.1%; mean ± SE) was seen by the second year for female elk with calves in the areas with wolves and was maintained during the subsequent 3 years of the study. As wolves expanded into non-wolf areas, female elk with and without calves in these areas gradually increased their vigilance levels from initially 20.1 ± 3.5 and 11.5 ± 0.9% to 43.0 ± 5.9 and 30.5 ± 2.8% by the fifth year of the study, respectively. We discuss the possible reasons for the differences seen among the social groups. We suggest that these behavioural responses to the presence of wolves may have more far-reaching consequences for elk and bison ecology than the actual killing of individuals by wolves.
The potential for invertebratevertebrate intraguild predation: the predatory relationship between wolf spiders (Gladicosa pulchra) and ground skinks (Scincella lateralis)
Authors: Rubbo Michael J , Townsend, Jr. Victor R , Smyers Scott D , Jaeger Robert G
Published: April 2011

Intraguild predation is described as predation among organisms that exploit similar resources. As wolf spiders (Araneae, Lycosidae) are generalist predators that share habitat and food resources with the ground skink Scincella lateralis, we conducted a series of laboratory experiments to determine if wolf spiders are capable of preying upon ground skinks. Wolf spiders (Gladicosa pulchra) successfully preyed on skinks during 3 of 20 encounters, but did not overtly respond to chemical stimuli from the skinks. Skinks employed antipredatory behaviors (i.e., immobility) when exposed to visual and chemical stimuli from spiders, providing evidence that they recognize spiders as predators prior to an encounter. In an additional experiment, the hypothesis that increased skink movement would lead to an increase in spider attacks was tested. Skinks exhibited high levels of movement in this experiment, with spider predation occurring during 4 of 10 encounters. The presence of structural refugia played a significant role in this predatorprey interaction by increasing the amount of time required for a spider to prey upon a skink. Our results indicate that G. pulchra can prey upon S. lateralis, and that skinks may recognize cues deposited on the substrate by spiders. These data indicate that these two species may interact in an ecologically meaningful manner.
Differential habitat use and reproductive patterns of frugivorous bats in tropical dry forest of northwestern Costa Rica
Authors: Stoner Kathryn E
Published: April 2011

To determine if frugivorous bats in tropical dry forest differentially use a particular habitat and if this use is related to their reproductive patterns, I monitored populations from one site from January 1994 to January 1997 in Parque Nacional Palo Verde in northwestern Costa Rica. Abundance, reproductive condition, sex ratio, age-classes, and recapture data were compared across seasons and years. During 56 nights of sampling, 13 species of frugivores and 5 nectarivores were captured (N = 998). Carollia perspicillata, Artibeus jamaicensis, and Sturnira lilium were significantly more abundant in 1994 than in 1995 or 1996. Carollia perspicillata and A. jamaicensis were captured year-round, but there were peaks of abundance in the dry season and the middle of the rainy season. Sixteen percent of 244 adult female C. perspicillata and 20% of 87 A. jamaicensis were reproductive, principally in February through June. Forty-three percent of 28 adult female S. lilium were reproductive from February to June and in October and December. Fifty-four percent of 26 adult female Centurio senex were reproductive between December 1995 and February 1996. Few subadults were captured at this site. Sex ratios were significantly different across seasons for C. perspicillata and A. jamaicensis. Seventy-three C. perspicillata were recaptured and 25 (34%) of these were recaptured after more than 4 months. The results of this study indicate that the abundance of some tropical frugivorous bats varies between years and (or) over seasons at a particular site within tropical dry forest.
The allometry of density within the space used by populations of mammalian Carnivora
Authors: Smallwood K Shawn
Published: April 2011

The relationship between body mass and population density has been used to develop theory of how energy is used in ecosystems. The usual allometric density slope, 0.75, was reduced to near zero among species of mammalian Carnivora after Smallwood and Schonewald and Blackburn and Gaston adjusted density estimates by the sizes of the corresponding study areas. In this paper, I restricted the allometric analysis to density estimates made at or near the threshold area, which is the species-specific minimum area likely to support a population. I excluded densities estimated from subpopulations and "megapopulations", thereby removing biases of study design that had previously confused the allometry of population density. Density at threshold area declined with increasing body mass. The population's mass density did not relate to threshold area, within which carnivore species averaged 9 kg/km2. The spatial intensity of oxygen consumption did not relate to body mass, but assuming that species with smaller threshold areas occur at more locations than species with larger threshold areas, one must conclude that smaller bodied species use more energy from the environment than do larger bodied species. Furthermore, threshold area and density at threshold area were most responsive to female brain mass, which provides an ecological allometry that links spatial scale, sensory perception, parental care, life-history attributes, basal metabolic rate, and body mass.
Interactions between Bacillus thuringiensis and parasitoids of late-instar larvae of the spruce budworm (Lepidoptera: Tortricidae)
Authors: Schoenmaker Astrid , Cusson Michel , Frankenhuyzen Kees van
Published: April 2011

We investigated interactions between Bacillus thuringiensis Berliner var. kurstaki and parasitoids that attack late instars of the eastern spruce budworm, Choristoneura fumiferana (Clemens). In a petri-dish arena, females of Tranosema rostrale rostrale (Brishke) (Hymenoptera: Ichneumonidae) were able to discriminate between untreated fourth instars and fourth instars that had been given a known dose of a commercial product (Foray 48B). When the choice tests were conducted before host mortality due to B. thuringiensis had occurred among treated larvae (24 h post ingestion), the parasitoid attacked untreated larvae more readily. When females were given a choice between control larvae and treated larvae that were still alive 72 h post ingestion, they were able to discriminate between the two only when the larvae had been treated with at least a 50% lethal dose. Under laboratory conditions, female T. r. rostrale were thus able to detect and avoid treated larvae that exhibited a lethal response to the pathogen, and to a lesser extent larvae that had survived pathogen exposure. The ability of the latter was not apparent under field conditions. When treated and untreated larvae were exposed for 1 week to a complex of indigenous parasitoids in the field, there was no difference between treatments in the rates of parasitism by either T. r. rostrale or Actia interrupta Curran (Diptera: Tachinidae). Parasitism averaged 91% for larvae in the control treatment compared with 92% for larvae treated with Foray 48B. The field data suggest that spruce budworm larvae that survive exposure to B. thuringiensis are just as likely to be parasitized as unexposed, healthy larvae. This means that prolonged development of late-instar spruce budworm larvae after treatment with B. thuringiensis could possibly result in increased attack rates by parasitoids.
An evaluation of territory mapping to estimate fisher density
Authors: Fuller Todd K , York Eric C , Powell Shawn M , Decker Thomas A , DeGraaf Richard M
Published: April 2011

We evaluated winter-territory mapping as a method for estimating fisher (Martes pennanti) density in a 210-km2 survey area in north-central Massachusetts in 1994 and 1995 by comparing estimates with simultaneous camera markresight estimates. Assuming intrasexual territoriality and accounting for all occupied habitat, territories of resident radio-marked fishers were mapped (mean = 54% of all territories in the study area), and those of unmarked resident fishers were identified from tracks and photographs. The total number indicated a population of 40 (19/100 km2) and 49 (23/100 km2) residents for 1994 and 1995, respectively. Results from replicated automatic-camera capturemarkresight surveys suggested slightly higher total numbers and densities of fishers in 1994 (44.5; 21/100 km2) and 1995 (52.9; 25/100 km2), but these estimates likely also included nonresident juveniles. Territory mapping and automatic-camera markresight methods resulted in very similar population estimates, but both require large numbers of radio-marked fishers to effectively detect small population changes (e.g., such as the 20% observed in this study). Individually marking animals would enhance markrecapture estimates.
Densities of breeding birds and changes in vegetation in an Alaskan boreal forest following a massive disturbance by spruce beetles
Authors: Matsuoka Steven M , Handel Colleen M , Ruthrauff Daniel R
Published: April 2011

We examined bird and plant communities among forest stands with different levels of spruce mortality following a large outbreak of spruce beetles (Dendroctonus rufipennis (Kirby)) in the Copper River Basin, Alaska. Spruce beetles avoided stands with black spruce (Picea mariana) and selectively killed larger diameter white spruce (Picea glauca), thereby altering forest structure and increasing the dominance of black spruce in the region. Alders (Alnus sp.) and crowberry (Empetrum nigrum) were more abundant in areas with heavy spruce mortality, possibly a response to the death of overstory spruce. Grasses and herbaceous plants did not proliferate as has been recorded following outbreaks in more coastal Alaskan forests. Two species closely tied to coniferous habitats, the tree-nesting Ruby-crowned Kinglet (Regulus calendula) and the red squirrel (Tamiasciurus hudsonicus), a major nest predator, were less abundant in forest stands with high spruce mortality than in low-mortality stands. Understory-nesting birds as a group were more abundant in forest stands with high levels of spruce mortality, although the response of individual bird species to tree mortality was variable. Birds breeding in stands with high spruce mortality likely benefited reproductively from lower squirrel densities and a greater abundance of shrubs to conceal nests from predators.
What's hot and what's not: defining torpor in free-ranging birds and mammals
Authors: Barclay Robert MR , Lausen Cori L , Hollis Lydia
Published: April 2011

With the development of small implantable data loggers and externally attached temperature-sensitive radio transmitters, increasing attention is being paid to determining the thermoregulatory strategies of free-ranging birds and mammals. One of the constraints of such studies is that without a direct measure of metabolic rate, it is difficult to determine the significance of lowered body temperatures. We surveyed the literature and found that many different definitions have been used to discriminate torpor from normothermy. Many studies use arbitrary temperature thresholds without regard for the normothermic body temperature of the individuals or species involved. This variation makes comparison among studies difficult and means that ecologically and energetically significant small reductions in body temperature may be overlooked. We suggest that normothermic body temperature for each individual animal should be determined and that torpor be defined as occurring when the body temperature drops below that level. When individuals' active temperatures are not available, a species-specific value should be used. Of greater value, however, are the depth and duration of torpor bouts. We suggest several advantages of this definition over those used in the past.
Distaplia alaskensis sp.nov. (Ascidiacea, Aplousobranchia) and other new ascidian records from south-central Alaska, with a redescription of Ascidia columbiana (Huntsman, 1912)
Authors: Lambert Gretchen , Sanamyan Karen
Published: April 2011

Alaskan ascidians are incompletely known and rarely sampled. The Smithsonian Environmental Research Center recently conducted an extensive survey of harbors and marinas for nonindigenous species at major marine traffic sites on the Kenai Peninsula and Prince William Sound in Alaska. Collections made during summer 1998 and 1999 included 12 species of ascidians, one of which is a new species of Distaplia, D. alaskensis. We consider it indigenous, though it could be cryptogenic because it was collected only from marina floats and no neighboring natural subtidal areas have ever been sampled. All the other species are natives except Botrylloides violaceus. This aggressive invader from Japan has recently spread rapidly along both coasts of the U.S.A. and Canada as well as in many other parts of the world, and is here reported from Alaska for the first time. Ascidia columbiana (Huntsman, 1912), synonymized in 1924 by Hartmeyer under Ascidia callosa, has now been shown to be a valid species, based on differences in morphology and reproductive mode; a redescription of A. columbiana is included here. Several species collected in 2000 at the Sitka Sea Farm mariculture facility near Sitka are also included. Because all these collections are from areas never before sampled for ascidians, all are new records for these species.
Phylogeography and genetic characteristics of a putative secondary-contact zone of the loggerhead shrike in central and eastern North America
Authors: Vallianatos M , Lougheed S C , Boag P T
Published: April 2011

The loggerhead shrike (Lanius ludovicianus) is found throughout North America in grassland and open scrub habitats. We previously described four loggerhead shrike management units found in central and eastern North America within the geographic ranges of three subspecies, L. l. migrans, L. l. ludovicianus, and L. l. excubitorides. A contact zone has been suggested to occur between L. l. migrans and L. l. excubitorides. The present study uses mitochondrial DNA sequence data to explore historical, ecological, and geographical factors that may have played a role in the genetic differentiation of these four management units, and examines the evidence for and characteristics of the migransexcubitorides contact zone. Geographically discrete, monophyletic clades were not evident, but the distribution of haplotypes (especially those exceeding 10% overall frequency) indicated some phylogeographic structure that perhaps reflects an intermediate stage of differentiation between paraphyly and reciprocal monophyly. The contact zone between L. l. migrans and L. l. excubitorides is supported by the mixing of haplotypes unique to each of the hybridizing populations and intermediate frequencies of common haplotypes. We interpret these patterns as possibly reflecting the impact of both glacial refugial dynamics and anthropogenic changes to habitat in eastern North America.
Systematics of the AtlanticMediterranean soles Pegusa impar, P. lascaris, Solea aegyptiaca, S. senegalensis, and S. solea (Pleuronectiformes: Soleidae)
Authors: Borsa Philippe , Quignard Jean-Pierre
Published: April 2011

Nucleotide-sequence variation at the cytochrome b locus was investigated in five Solea species, with a re appraisal of meristic data and a review of allozyme data pertinent to their systematics. Solea aegyptiaca, considered a synonym of Solea solea, and Solea (Pegusa) impar, considered a synonym of S. (P.) lascaris, are shown to be valid species according to the morphological, phylogenetic, genotypic, and biological species definitions. The validity of the genus Pegusa was examined in the light of both allozyme and cytochrome b gene sequence data.
Parasites of Loligo gahi from waters off the Falkland Islands, with a phylogenetically based identification of their cestode larvae
Authors: Brickle Paul , Olson Peter D , Littlewood D. Timothy J , Bishop Antony , Arkhipkin Alexander I
Published: April 2011

One thousand and ninety-six longfin Patagonian squid, Loligo gahi, were collected from waters off the Falkland Islands over a period of 1 year and 4 months and examined for helminths. Cestode and Anisakis sp. (Nematoda) larvae were present throughout the study, but occurred at low rates. The pooled data showed prevalences of 5.75 and 2.46%, respectively. An adult digenean, Derogenes varicus, was found in a single instance and was thus considered an accidental infection. Parasite parameters were not significantly correlated with either host sex or seasonality. Stomach contents of the squid revealed a highly varied diet, although krill, amphipods, and chaetognaths were the dominant prey items. To aid in the identification of the cestode larvae, a subsample of 14 plerocercoids was characterized for the D2 variable region of the nuclear lsrDNA gene and compared with both published cestode lsrDNA sequences as well as that of six additional adult tetraphyllidean cestode species sequenced herein. Direct sequence comparison showed that 12 of the 14 plerocercoids were identical with each other and differed by a single transition (of a total of 658 base pairs) from the tetraphyllidean Clistobothrium montaukensis, and another plerocercoid differed by two transitions from the trypanorhynch Grillotia erinaceus. The remaining pleroceroid sequence was identified through phylogenetic analysis as being closer to the tetraphyllidean Ceratobothrium xanthocephalum than to any other taxon analyzed, but may not be congeneric, given its relatively high degree of divergence from C. xanthocephalum.
A new species of large and highly contractile hydroid in the genus Candelabrum (Hydrozoa: Anthoathecatae) from southern Oregon, U.S.A.
Authors: Hewitt Chad L , Goddard Jeffrey HR
Published: April 2011

A new species of hydroid, Candelabrum fritchmanii, is described from Cape Arago, Oregon, U.S.A. Specimens were collected from the intertidal region underneath boulders. This new species' standing with respect to other members of the genus is discussed. The claspers in the blastostylar region of the new species show similarities to the North Atlantic Candelabrum cocksii. However, three specimens had multiple, connected polyps at varying stages of development and the cnidome differs between C. cocksii and the new species, leading to the erection of a new species. The polyp cnidome consists of desmonemes, heteronemes (microbasic mastigophores and homotrichous microbasic euryteles), and stenoteles and the actinula cnidome consists of desmonemes, haplonemes (atrichous isorhizas), and stenoteles. Emendations to the family, subfamily, and genus diagnoses are presented to accommodate these findings. Observations are also presented on actinula development and the ensnaring, predatory feeding behavior of the highly contractile polyp.
THE SALIVARY GLAND CHROMOSOMES OF TWO SIBLING SPECIES OF BLACK FLIES INCLUDED IN EUSIMULIUM AUREUM FRIES
Authors: Dunbar Robert W.
Published: April 2011

Two closely related dichromosomic sibling species of Eusimulium "aureum" were segregated cytologically in populations sampled from the Toronto area. The known range of these two so far included southern Ontario and Quebec, and New York State. Both siblings have extremely similar salivary gland chromosomes but they differ by four homozygously rearranged regions, all in the first chromosome, and in the degree of chromosomal polymorphism. Although sympatric over a wide range, the two siblings do not interbreed as evidenced by the failure to find critical heterozygous loops for the interspecific inversions, and the absence of common intraspecific inversions. Therefore the siblings represent two biologically distinct species.
PARASITES OF SOUTH PACIFIC FISHES: I. INTRODUCTION, AND HAEMATOZOA
Authors: Laird Marshall
Published: April 2011

During 1952–54, fishes were collected and examined for parasites (particularly those of the blood and gills) at various localities ranging from Sydney, Australia, through the island groups of Melanesia to Tarawa, Gilbert and Ellice Islands Colony. Most of the specimens were obtained by poisoning intertidal zone pools on coral reefs or rocky coasts, the remainder being from fresh-water or brackish sources. A total of 1121 fishes of at least 122 species, 63 genera, and 27 families were dealt with. This paper, the first of a series detailing the findings, includes a complete list of the material, an account of the techniques employed, and new host and locality records for Haemogregarina bigemina Laveran and Mesnil and H. mugili Carini.
STUDIES IN THE MODE OF ACTION OF ROYAL JELLY IN HONEYBEE DEVELOPMENT: I. CHANGES OCCURRING IN FRESH ROYAL JELLY DETERMINED BY CARTESIAN DIVER RESPIROMETRY
Authors: Dixon S. E. , Shuel R. W.
Published: April 2011

Holter's Cartesian diver technique was used, with divers ca. 200 microliters volume, to study changes in royal jelly. Studies indicated that oxygen was consumed by fresh royal jelly, a phenomenon which was inhibited under an atmosphere of nitrogen. This activity diminished rapidly within a period of hours. Royal jelly held at room temperature for 6 to 8 hours showed no activity. No activity was found in fresh royal jelly which had been stored at −18 °C. Cyanide did not inhibit this oxidation. The significance of the above results is discussed.
PARASITES OF NYMPHAL AND ADULT GRASSHOPPERS (ORTHOPTERA: ACRIDIDAE) IN WESTERN CANADA
Authors: Smith R. W.
Published: April 2011

The taxonomy, distinctive features, life histories, seasonal occurrence, incidence of parasitism in different hosts and at different times, and the economic significance of 23 species of primary parasites of grasshoppers are described. Three species of hyperparasites are similarly discussed. The information is based on field collections made in Western Canada in 1938 to 1953 and on laboratory studies at Belleville in 1939 to 1955.
CRYPTIC SPECIATION IN THE VERNALIS GROUP OF CYCLOPIDAE
Authors: Price J. L.
Published: April 2011

Breeding experiments performed on the descendants of 30 separate populations of Cyclops vernalis Fischer show a pattern of positive and negative results indicating the existence of seven reproductive isolates. Most of these isolates vary morphologically, but they differ in the nature and degree of this variation. They are, for the most part, not easily indentifiable but the one which varies the least is shown to be referable to C. brevispinosus Herrick, a species which had been placed in the synonymy of C. vernalis. No attempt is made to name the six other isolates.In addition to their experimentally demonstrated reproductive isolation and differences in morphological variability, the isolates are regarded as species on the basis of differences in their ability to serve as first intermediate hosts for the tapeworm Triaenophorus crassus Forel.
SOME OBSERVATIONS ON CRISTISPIRA IN THE CRYSTALLINE STYLE OF SAXIDOMUS GIGANTEUS DESHAYES AND IN THAT OF SOME OTHER LAMELLIBRANCHIATA
Authors: Berkeley C.
Published: April 2011

The occurrence of a spirochaete of the genus Cristispira in the crystalline style of Saxidomus giganteus Deshayes is recorded. The distribution of the organisms in the style, and the possible reasons for their absence in the anterior region of it, are discussed. It is found to be a facultative anaerobe. Observations are recorded on the infection of newly regenerated styles, and occurrences of Cristispira in styles of species of Lamellibranchiata other than Saxidomus giganteus, and of their absence elsewhere, are summarized.
The spectral sensitivity of Hydra carnea L. Agassiz (1850)
Authors: Ellis Virginia L.
Published: April 2011

The spectral sensitivity of Hydra carnea was investigated by growth rate and action spectrum studies. The rate of asexual growth was measured over a 40-day period for animals cultured under white, blue, green, and red lights of equal intensity. The growth rate was greatest under red light and slowest under blue; the rate under white light was similar to that under green light. The action spectrum, measured as the reaction times to light stimuli of various wavelengths, varied according to the light under which the animals were cultured. For H. carnea that had been cultured in the dark, the reaction time was shortest at 650 nm and longest at 450 nm when lights of equal intensity were used. This differs from the results of an earlier study with H. pirardi, which showed maximum sensitivity to blue light. Animals cultured under blue, green, and red lights showed a decreased sensitivity, indicated by an increased reaction time, to the light under which they were cultured as compared to animals cultured in the dark.
Aspects of iron metabolism in a freshwater mussel
Authors: Hobden David J.
Published: April 2011

Estimations of the total iron content of tissues of Elliptio confirm that this animal concentrates iron. During starvation, tissue mass decreases more than total iron and an apparent increase in iron content results. Most iron is contained in the viscera and mantle, while muscular tissue contains least.59Fe injected into the visceral mass was rapidly translocated to the gills and mantle where much of it accumulated in tissue that acted as a 'kidney of accumulation'. The 59Fe did not become fully incorporated into the physiological iron pool in 10 days, nor was it rapidly excreted. There is little metabolic turnover of elemental iron.This iron store is much greater than needed in known enzyme systems. It may indicate hyperactivity of an uptake mechanism or the lack of an adequate excretory mechanism.
A histochemical study of glycogen metabolism in developing cartilage and bone
Authors: Townsend F. J. , Gibson M. A.
Published: April 2011

The distribution of glycogen, phosphorylase, and glycogen synthetase was studied during the early development of cartilage and bone in the chick. The relative amounts of each of these substances was related to cellular activity. Cellular activity was assessed by measuring the rate of matrix deposition and by a study of the ground substance with the toluidine blue and alcian blue histochemical methods. In both cartilage and bone, there is a close correlation between the relative amounts of glycogen within the cells and the rate of matrix deposition. Also, the intensity of the phosphorylase reaction parallels the use of glycogen by the cells. Glycogen synthetase gave the most intense reaction during the early stages of chondrification but could not be demonstrated, with certainty, during the ossification process. In both cartilage and bone there appears to be a direct correlation between cellular activity, in terms of matrix synthesis, and the synthesis and degradation of glycogen by the cells.
Nematodes from aspen cankers in Colorado and New Mexico
Authors: Massey Calvin L. , Hinds Thomas E.
Published: April 2011

Nematodes were discovered in the necrotic tissues of Cenangium and Ceratocystis cankers of aspens during a study of the etiology of these diseases. One new genus and three new species of nematodes were recovered: Bealius bisulcus n. gen., n. sp., Entaphelenchus brevigulonis n. sp., Neodiplogaster columbanus n. sp., and Cylindrocorpus rifflei n. sp. The nematodes Acrostichus concolor Massey 1962, Panagromacra margaretae Massey 1964, Plectonchus wyganti Massey 1964, and Mononchoides adjunctus Massey 1966, were also collected from the cankers. All nematodes appear to be insect associates or parasites, and were probably carried to the diseased trees by various species of Epurea. It is believed that the worms may be a factor in the etiology or pathogenesis of the cankers.
Freshwater ostracodes of Canada. Part I. Subfamily Cypridinae
Authors: Delorme L. D.
Published: April 2011

The subfamily Cypridinae is represented in Canada by 21 species belonging to the eight genera Cypris, Chlamydotheca, Cypricercus, Megalocypris, Cyprinotus, Dolerocypris, Eucypris, and Isocypris. Of note is the presence of the neotropical species Chlamydotheca arcuata (Sars) in Holocene sediments at a latitude of 54°. The genus Cypricercus is represented by five species of which one, Cypricercus deltoidea, is a new form.
The relationship of social vocalizations to surface behavior and aggression in the Hawaiian humpback whale (Megaptera novaeangliae)
Authors: Silber Gregory K.
Published: April 2011

Humpback whale (Megaptera novaeangliae) social vocalizations (nonsong sounds) were clearly related to whale group size and surface activity. Social sounds occurred almost exclusively in groups containing three or more whales and were rarely heard near single whales, pairs, or cow–calf groups. Large groups (3 to 20 individuals) vocalized at an overall mean rate of 43.1 ± 55.52 sounds per whale/h. Group size changed frequently and a dramatic increase in vocalization rate resulted when a new whale entered a group. Large groups engaged in flurries of surface activity, such as breaching, flipper- and tail-slapping, and underwater bubbling. Aggressive encounters resulted from male–male interaction. Social sounds probably acted to demonstrate aggression or agitation as adult males competed for temporary social dominance within the group and for proximity to the female. Likewise, visual displays may have been used as threats in close quarters and were apparently produced in conjunction with sounds to convey levels of aggression. Although other studies suggested that surface activity increased with group size, I found a negative correlation between activity and group size, both in the group as a whole and per individual. In contrast, social vocalizations per group increased with group size while the vocalization rate per individual did not vary significantly with increasing group size.
Myxosporean parasites of marine fish from the continental shelf off Newfoundland and Labrador
Authors: Khan R. A. , Bowering W. R. , Burgeois C. , Lear H. , Pippy J. H.
Published: April 2011

Bile from 2793 marine fish of 28 species from the northwestern Atlantic Ocean was examined for myxosporean parasites. Twenty-two fish species were infected, some with one to three species of the six different genera observed. Six of 7 littoral and all of 16 demersal or benthic species were infected whereas 5 epipelagic or mesopelagic forms were apparently uninfected. Variations in prevalence of some species of parasites in fish hosts originating from different geographical areas of the continental shelf suggests a potential use in separating stocks on the basis of geographical location, parasite identity, and (or) migratory habits.
Historical and ecological sources of variation among lake populations of threespine sticklebacks, Gasterosteus aculeatus, near Cook Inlet, Alaska
Authors: Francis Richard C. , Baumgartner Jeffrey V. , Havens Allan C. , Bell Michael A.
Published: April 2011

Multivariate analyses of morphological variation of Gasterosteus aculeatus from 24 lakes in a recently deglaciated region north of Cook Inlet, Alaska, were performed. Presence or absence of the pelvis most effectively discriminates among populations. Intralocality character correlations generally were similar to interlocality correlations, but the among-locality relationship of body depth with other morphometric variables was different from its relationships within localities, which suggests that genetic reorganization during the evolution of these populations has broken the expected correlated response of body depth with other variables. Variation within different suites of covarying morphological characters is best explained by either historical processes (phylogeny, gene flow) or the present distribution of environmental variables (adaptation). The set of populations studied must have been derived from marine Gasterosteus within the past 13 000 years and have diverged markedly within a relatively short period of time. Rapid and extensive diversification appears to characterize Gasterosteus from recently deglaciated regions.
Quantitative observations on populations of the lungworm Oslerus osleri (Cobbold, 1889) in coyotes (Canis latrans Say)
Authors: Polley Lydden
Published: April 2011

Total adult Oslerus osleri populations were recovered from all the tracheal and bronchial nodules present in 27 coyote carcasses from Saskatchewan, Canada. The parasites were sexed and counted. Twenty-one of 27 coyotes contained fewer than 10 nodules and 18 of the animals were infected with fewer than 50 parasites. One hundred of the total of 186 nodules contained fewer than five parasites. The relationship between the number of parasites (x) and the number of nodules (y) in individual coyotes was well described by the regression equation [Formula: see text]. This equation reflects a curvilinear relationship in which the rate of nodule formation decreases as parasite numbers increase above approximately 100.
Response of cruiser and ambusher entomopathogenic nematodes (Steinernematidae) to host volatile cues
Authors: Lewis Edwin E. , Gaugler Randy , Harrison Robert
Published: April 2011

Two species of entomopathogenic nematodes, an ambush forager (Steinernema carpocapsae) and a cruising forager (S. glaseri), were assayed for their responses to volatiles associated with Galleria mellonella (Insecta: Lepidoptera). The responses of entomopathogenic nematodes to six host-associated volatile treatments were assayed. Live G. mellonella, live G. mellonella with the cuticular hydrocarbons removed, live G. mellonella with carbon dioxide removed, dead G. mellonella, dead G. mellonella with the cuticular hydrocarbons removed, and volatiles from S. exiqua feces were assayed in a Y-tube choice aparatus. Steinernema glaseri were attracted only to treatments producing carbon dioxide. Steinernema carpocapsae showed no significant response to any treatments tested. To assess the directionality of the response toward live G. mellonella, net average movement per nematode after 5, 10, and 20 min was measured for both nematode species. The assay method was based on the "quadrant plate" bioassay, with a 9 cm Petri dish containing 2% agar. Steinernema carpocapsae showed little directionality of response, whereas S. glaseri was attracted to carbon dioxide. We conclude that carbon dioxide attracts S. glaseri to areas likely to hold hosts. Ambush foragers are less influenced by cues associated with hosts or their habitat.
Interspecific aggression and spatial relationships in the salamandersPlethodon kentuckiandPlethodon glutinosus: evidence of interspecific interference competition
Authors: Marvin Glenn A
Published: April 2011

Competitive interactions among widely sympatric species of terrestrial plethodontid salamanders have received little attention. I investigated whether interspecific interference competition for space occurs between one such pair of species, Plethodon kentucki and P. glutinosus. Encounters between heterospecific adults in the laboratory resulted in aggressive interactions as often as did encounters between conspecific adults. However, intense aggression (bite-holds) occurred more often during pairings between conspecifics, indicating that interference competition is greater among individuals of the same species. Plethodon glutinosus was dominant more often than P. kentucki during encounters with heterospecifics in the laboratory. During a second laboratory experiment, both species preferentially used large cover sites in single-species control groups, whereas P. kentucki used small cover sites significantly more often in mixed-species experimental groups, indicating competitive exclusion of P. kentucki by the larger P. glutinosus. In natural habitats, individuals of both species were usually found alone under cover objects, and the extent of home-range overlap did not differ between conspecifics and heterospecifics. My results indicate that these species compete for space and defend territories against heterospecifics as well as conspecifics. Greater intraspecific than interspecific interference competition may permit coexistence if the former is more important in limiting the population growth of each species.
Habitat use by muskoxen (Ovibos moschatus) in winter in an alpine environment
Authors: Nellemann Christian
Published: April 2011

Muskoxen (Ovibos moschatus) were introduced into a relatively snow-rich alpine environment in Norway far outside their natural polar distribution 40 years ago. Habitat choice in winter by the muskoxen was compared with topographical characteristics and snow and vegetation distributions. The density of fecal-pellet groups was approximately 1500/ha in the exclusively used Dryas heath, more than 30 times greater than that observed in the only two other heath communities, lichen heath and Juncus heath. Juncus heath had a standing graminoid biomass of ca. 30 g/m2, but 50-60 cm of hard snow. Lichen heath had shallow snow (<<40 cm) and low graminoid biomass (<<4 g/m2) and was used primarily for resting and rumination. Muskoxen clearly selected Dryas heath on calcareous rock located on very steep slopes (>>27°), which offered the only available areas with shallow snow (ca. 20 cm) and available graminoids (ca. 10 g/m2). %Integrated ram hardness% values were <<200 kg cm in Dryas heath compared with 1500-2500 kg cm in the only other two heath communities. Dryas heath occupied ca. 1% of the entire study area, but was used intensively by muskoxen. A strong preference for very steep slopes with shallow snow indicates that muskoxen show little plasticity in adapting to more snow-rich environments.
Regulated changes in body mass and muscle mass in molting Blue-winged Teal for an early return to flight
Authors: Brown Richard E , Saunders David K
Published: April 2011

During the breeding season, Blue-winged Teal (Anas discors) undergo cyclic changes in body mass (Mb) and pectoral- and leg-muscle mass coincident with the simultaneous molt of all flight feathers. These conformational changes cannot be attributed to nutritional or metabolic demands, nor can they be a use-disuse phenomenon. A reduction of >>18% in body mass from premolt values produces wing loadings (Mb/wing area) nearly equal to those seen premolt, allowing these birds to regain flight capability, although the flight feathers are <<75% of premolt length and area. A reduction of >>30% in flight-muscle mass represents about half of the total reduction in Mb; however, the lowest power necessary for flight, calculated for five different periods during the breeding season, is found at 75% of feather regrowth. Reduction in Mbcoupled with a >>40% increase in leg-muscle mass during the flightless period should permit these birds to achieve higher swimming speeds. The temporal and mechanical relationships of these conformation adjustments suggest that they are programmed or regulated to (i) permit the earliest possible return to flight after the molt-related flightless period and (ii) provide for faster predator-avoidance speeds across or under the water during the flightless period.
Mate and sperm competition during multiple-male spawnings of Atlantic salmon
Authors: Mjølnerød I B , Fleming I A , Refseth U H , Hindar K
Published: April 2011

The influence of sperm competition and individual mating behaviour in an externally fertilizing species of fish, the Atlantic salmon (Salmo salar), is estimated from video observations of multiple-male spawnings and subsequent paternity analyses. One male dominated the paternity during polygamous spawnings, fathering more than 80% of the progeny in a single nest. Behavioural analyses of the spawnings showed that the first-mating male had sperm precedence in 6 out of 10 cases. In three of the other spawnings, sperm limitation likely influenced individual success, as the first-mating male had participated in a large number of spawnings. In the final, nearly simultaneous spawning, male size was more important than the 0.6-s difference in spawning times. Thus, male fertilization success can be influenced by a variety of factors, including sperm precedence, male size, and spawning history.
A new molecular technique for identifying field collections of zebra mussel (Dreissena polymorpha) and quagga mussel (Dreissena bugensis) veliger larvae applied to eastern Lake Erie, Lake Ontario, and Lake Simcoe
Authors: Claxton W Trevor , Boulding Elizabeth G
Published: April 2011

The veliger larvae of two introduced species of bivalves, the zebra mussel (Dreissena polymorpha) and the quagga mussel (Dreissena bugensis), are difficult or impossible to tell apart morphologically. We have developed specific dreissenid polymerase chain reaction (PCR) primers from dreissenid bivalve DNA sequences, which amplify a region of the cytochrome c oxidase subunit I mitochondrial gene. Non-dreissenid mtDNA, as found in field-collected veliger samples, was not amplified by these new PCR primers. The DNA sequence of this region distinguishes zebra mussel from quagga mussel larvae. Restriction digests of this region using the enzyme ScrFI showed no intraspecies variation in restriction pattern. We used this technique to distinguish the species of veliger larvae collected in eastern Lake Erie, Lake Ontario, and Lake Simcoe. In our limited study, no quagga mussel larvae were found in Lake Simcoe, suggesting that this mussel species has not yet spread to the Kawartha Lake system. No zebra mussel larvae were found in either Lake Erie or Lake Ontario. These preliminary results add to the growing evidence that the quagga mussel is replacing the zebra mussel in parts of the lower Great Lakes.
Costs of reproduction in female moose (Alces alces) as measured by means of phenotypic correlations
Authors: Sand Håkan
Published: April 2011

The costs of pregnancy and lactation in terms of subsequent body growth and fecundity were studied by comparing different reproductive categories of Swedish female moose (Alces alces) during 1989-1992. Non-reproducing females and females that experienced gestation but not lactation were significantly heavier than females in the same reproductive category prior to reproduction. Production of one offspring and subsequent lactation during the summer and early autumn were also associated with an average annual increase in carcass mass, although this was less pronounced than in females that only experienced gestation. By contrast, production of two offspring and successful rearing of both to the autumn resulted, on average, in a reduction of carcass mass (7%) relative to that of females in the same reproductive category prior to reproduction. In female moose, while body growth was affected by the costs of lactation, future fecundity was not. Instead, future fecundity was related most strongly to the number of offspring produced during the current year. This positive association could not be attributed to variation in individual quality in terms of age or carcass mass. The ultimate consequences of reproduction in female moose seem to strongly influence the patterns of growth: adult females will alternate between gain and loss of body mass among years, depending on the number of offspring produced and successfully reared through the lactation phase.
Nutrition and the energetic tactics of muskrats (Ondatra zibethicus): morphological and metabolic adjustments to seasonal shifts in diet quality
Authors: Campbell Kevin L , MacArthur Robert A
Published: April 2011

Basal metabolic rate (BMR), serum thyroxine (T4) concentration, lean organ mass, and body composition were measured in 94 captive, seasonally acclimatized muskrats (Ondatra zibethicus) between May 1991 and April 1992. Seasonal measurements of oxygen consumption, body water content, and mass were obtained from an additional 124 captive or free-ranging animals in 1994-1995. Mass-independent BMRs (kJ · kg-0.67· h-1) and serum T4concentrations (nmol · L-1) varied significantly over the year (P << 0.0001), with mean values in February exceeding July values by 31.1 and 77.2%, respectively. These variables tracked seasonal changes in the neutral detergent soluble (NDS) content of broadleaf cattails (Typha latifolia), the dominant food of muskrats in the study population. From July through February, alimentary tract, liver, spleen, and heart masses increased, while kidney mass declined. Body fat stores varied significantly over both years, with peak values measured in February. However, lean body and pelt masses exhibited little seasonal variation (P >> 0.05). Stepwise multiple regression and principal component analyses suggested that variation in BMR was associated most closely with changes in heart and alimentary tract masses. Annual variations in basal energy expenditure, serum T4concentration, and organ masses of wild muskrats appear to be linked to seasonal changes in forage NDS content and energy intake, and may be important factors relating to the annual pattern of fat accretion and mobilization in this semiaquatic rodent.
The relative roles of hunger and size asymmetry in sibling aggression between nestling ospreys, Pandion haliaetus
Authors: Machmer Marlene M , Ydenberg Ronald C
Published: April 2011

The food-amount hypothesis, proposed to account for sibling aggression in brood-reducing bird species, predicts that broods will be aggressive when hungry, and that as a result, senior siblings will be able to take a greater share of the total available food. We performed a field experiment to test these predictions in ospreys, Pandion haliaetus. Broods were removed from their natal nests and subjected to a series of experimental trials. Each trial consisted of a 3.5-h starvation period followed by a feeding or sham-feeding treatment designed to manipulate the hunger of the nestlings. Following treatment, broods were placed in a viewing nest along with a fish. While the viewing-nest mother fed the fish to the brood, we recorded food allocation and aggresssion. Each of 10 broods experienced a number (one to six) of feeding and sham-feeding treatments over a period of 2 days and was then returned to its natal nest. Broods were slightly but significantly more aggressive after sham-feeding treatments, and senior siblings took a greater share of the meal. The tremendous variation in the level of sibling aggression observed between broods was inversely related to brood mass asymmetry but not to condition, suggesting that siblings adjusted the rate of aggression according to the level of competition within their broods.