bluuebunny/crossref_metadata_2025 huggingface dataset:
Sexual size dimorphism in bighorn sheep (Ovis canadensis): effects of population density
Authors: LeBlanc Mylène , Festa-Bianchet Marco , Jorgenson Jon T
Published: April 2011

Sexual dimorphism is an important characteristic of many mammals, but little is known about how environmental variables may affect its phenotypic expression. The relationships between population size, body mass, seasonal mass changes, and sexual mass dimorphism were investigated using 22 years of data on individually marked bighorn sheep (Ovis canadensis) on Ram Mountain, Alberta. The number of adult ewes was artificially maintained low from 1972 to 1981 and then allowed to increase. The body mass of males from 0 to 7 years of age was negatively affected by population density. Female body mass was negatively affected by population density up to 2 years of age. As the number of ewes increased, sexual mass dimorphism of sheep aged 27 years declined. Population density had a negative effect on seasonal mass changes of young males and females. Density also had a weak but significant positive effect on yearly mass gain of 2-year-old females, suggesting compensatory growth. Females appear to compensate for resource shortages early in life, while males show a lifelong negative effect. We suggest that these sexual differences are due to the greater flexibility of resource allocation to growth or reproduction by females than by males.
Distribution and behavior of ice worms (Mesenchytraeus solifugus) in south-central Alaska
Authors: Shain Daniel H , Mason Tarin A , Farrell Angela H , Michalewicz Lisa A
Published: April 2011

The ice worm, Mesenchytraeus solifugus ssp. rainierensis, is the only known annelid that survives in glacier ice. We report the locations of eight ice worm populations in south-central Alaska, including the northern- and western-most extent of known ice worm habitation. All ice worms identified in this study inhabit coastal glaciers proximal to the Gulf of Alaska. They were found in a variety of habitats including level snowfields, steep avalanche cones, crevasse walls, glacial rivers and pools, and hard glacier ice. Ice worms were not found on all coastal glaciers nor were they found in Alaska's interior (the Alaska Range). Ice worms on Byron Glacier, Alaska, totaled ~30 million and were distributed on seven distinct avalanche cones. They displayed a diurnal cycle, appearing on the glacier surface several hours before sunset and penetrating back into the glacier shortly after sunrise. Experiments suggest that ice worms preferentially penetrate the glacier beneath surface algae, Chlamydomonas nivalis, to a depth between 15 and 100 cm and resurface at a proximal location. Lateral movement of ice worms on the glacier surface can reach speeds of ~3 m/h. Ice worms on Byron Glacier avoided light, but did not respond preferentially to different wavelengths in the visible spectrum. Finally, ice worms displayed an unexpected attraction to heat.
Life at the river's edge: ecology of Kentropyx altamazonica in Brazilian Amazonia
Authors: Vitt Laurie J , Sartorius Shawn S , Avila-Pires Teresa Cristina S , Espósito Maria Cristina
Published: April 2011

The teiid lizard Kentropyx altamazonica was studied at two localities in the Brazilian Amazon region, one in Amazonas (Rio Ituxi) and the other in Rondônia (Rio Formoso). This lizard is linearly distributed along water courses, where it carries on most activities in well-lit, warm microhabitats. Activity does not occur on days with cloud cover. Late morning and midday activity predominates on sunny days. Body temperatures of active lizards were 35.9 ± 0.37°C (mean ± SE) and were higher than substrate or air temperatures at the point of capture and higher than overall temperatures in the habitat. Although a variety of prey types are eaten, spiders, grasshoppers and crickets, roaches, and insect larvae dominate the diet. Larger lizards eat larger prey but also include small prey in their diets. Absolute and relative prey sizes were greater for lizards at the Rio Ituxi than for those in Rondônia, but lizard stomachs were equally full, suggesting that prey types available varied between sites. Males reach larger body sizes than females and have relatively larger heads. Although K. altamazonica is similar in ecology to other Amazonian Kentropyx species, it is more closely associated with water than the others.
Prolonged copulation and the internal dynamics of sperm transfer in the water strider Aquarius remigis
Authors: Campbell Veronique , Fairbairn Daphne J
Published: April 2011

Copulations lasting much longer than required to effect insemination are common throughout the Insecta, but their adaptive significance remains obscure. We address the hypothesis that prolonged copulations benefit male Aquarius remigis (Hemiptera, Gerridae) by influencing sperm use and storage following insemination. We describe the gynatrial complex of females and document sperm location immediately following 32 naturally terminated and 25 artificially terminated copulations. We also examine sperm storage in 22 females isolated from males for 210 days. Our results demonstrate that insemination occurs at the end of copulation, and therefore that prolonged copulation is not a post-insemination mate-guarding tactic, as was previously assumed. Sperm are transferred in a coherent, coiled mass and move rapidly to the spermathecal tube, the primary storage organ. However, a few sperm move directly to the fecundation canal and hence should be capable of immediate fertilization. Prolonged copulation is associated with increased filling of the spermathecal tube, which may indicate some form of copulatory courtship or sperm loading by males during the prolonged pre-insemination phase. We discuss this new interpretation of prolonged copulation in A. remigis in the context of the overall costs and benefits of prolonged copulation for both sexes under the natural conditions of polygynandry.
Inbreeding in the field: an experiment on root vole populations
Authors: Gundersen Gry , Aars Jon , Andreassen Harry P , Ims Rolf A
Published: April 2011

We used a field experiment with replicate populations of a particular geographic race of root voles (Microtus oeconomus) with different degrees of inbreeding to test whether inbreeding effects were expressed in demographic parameters. This geographic race had been shown to exhibit reduced reproductive rates in the laboratory resulting from inbreeding depression. There were no effects of inbreeding on population growth rate or any demographic parameter. Inbred animals grew less than outbred animals early in the summer, but this had no demographic consequences. Our study is one of the few to compare the performance of the same species in the laboratory and in the field with respect to the extent of inbreeding depression. More such comparisons will be needed to determine whether inbreeding is detrimental more often in the field than in the laboratory.
Feeding ecology of the long-eared owl (Asio otus) in northern Italy: is it a dietary specialist?
Authors: Bertolino Sandro , Ghiberti Elena , Perrone Aurelio
Published: April 2011

The feeding ecology of the long-eared owl (Asio otus) in the Stupinigi Natural Park, northwestern Italy, was investigated for 1 year. Owls fed seasonally on three main prey categories. Mice (Murinae) constituted the bulk of the diet from September to March, with voles (Arvicolinae) and birds as secondary prey. During the breeding season, birds became preeminent, constituting about half of the prey ingested. Dietary overlap between the overwintering period and breeding season was low. Food-niche breadth was low in autumn and winter but increased markedly from May to August. A comparison of our results with those of eight other European studies showed that the long-eared owl in Italy has a more varied diet. The diet in Italy and Spain (southern Europe) is based on at least three prey groups and differs from that described for areas in central and northern Europe, where only species of voles are the main prey. Our results show that the long-eared owl is an adaptable predator that expands its food niche in the presence of diversified prey. This adaptability contrasts with the picture of a specialized predator.
EFFECTS OF ACCLIMATIZATION AND SEX ON RESPIRATION AND THERMAL RESISTANCE IN TRIBOLIUM (COLEOPTERA:TENEBRIONIDAE)
Authors: Edwards D. K.
Published: April 2011

Some effects have been studied of prolonged exposure to nonoptimal temperatures on respiration and thermal resistance in the flour beetle Tribolium confusum Duval.Adult beetles maintained at 18 °C. and 38 °C. for a number of months exhibited changes in the location and form of the temperature–respiration curve compared with that of control insects at 30 °C. Insects from 18 °C. showed increased survival ability at −3 °C., but there was no respiratory compensation during acclimatization. Changes in the sign of respiration–weight regression in the experimental groups was probably related to differences in sensitivity to temperature between lighter and heavier individuals.Control 30° males survived exposure to −3 °C. better than corresponding females. This survival difference at the low temperature was eliminated by prolonged maintenance of the insects at 18 °C. Insects from 18 °C. possessed a higher water content and a lower dry weight than controls. A discussion is presented dealing with the influence of the ratio of active to inactive weight on respiration per unit weight.The temperature–respiration curves were adequately expressed in the double-logarithmic form. The constants in this equation were used comparatively among the different experimental groups.
PARASITES OF SOUTH PACIFIC FISHES: III. TREMATODES FROM THE SOLOMONS AND NEW HEBRIDES, WITH A DESCRIPTION OF DAITREOSOMA PARVA N. SP. (MONOGENEA) FROM GUADALCANAL
Authors: Laird Marshall
Published: April 2011

Daitreosoma parva n.sp. (Monogenea: Dactylogyridae) was discovered in gill smears from four of five glassies, Ambassis miops Günther (Centropomidae), from fresh-water pools on Guadalcanal, British Solomon Islands Protectorate. Only two species of Daitreosoma were known previously, both of them parasitizing Therapon spp. (Theraponidae) from the Thomson River, Queensland. D. parva n. sp., measuring from 133 to 145 μ by from 38 to 41 μ (av., 139 by 39 μ), is only about one-quarter the length and width of its congeners. It also differs from these in details of the haptorial structures and genitalia, notably in that the testis is ventral to the ovary. An encysted metacercaria of Stephanostomum sp. (Digenea: Acanthocolpidae) is also recorded from the gills of A. miops. One of 12 mullets, Mugil oligolepis Bleeker (Mugilidae), from a tidal stream on the island of Aneityum, New Hebrides, had an example of an undetermined species of Microcotyle (Monogenea: Microcotylidae) on its gills.
THE EFFECTS OF RADIATION ON THE HABITAT TEMPERATURES OF SOME POPLAR-INHABITING INSECTS
Authors: Henson W. R.
Published: April 2011

The relationship between habitat temperature, ambient temperature, and radiation for a series of insectan habitats on poplar leaves is shown to be highly specific. A series of these relationships is described and the possible ecological significance of the findings is discussed. The amount of heating experienced is shown to be influenced by the size and shape of the structure, and its absorptivity and ventilation.
SOME BIOLOGICAL REQUIREMENTS AND HOST–PARASITE RELATIONS OF ENTAMOEBA INVADENS
Authors: Meerovitch Eugene
Published: April 2011

A hypothesis explaining the processes leading to the encystation of E. invadens is presented. It is suggested that E. invadens can live in turtles as a harmless commensal because the conditions necessary for its encystation and the completion of its life cycle are available in the intestinal lumen of turtles. As these conditions are not present in snakes, the amoebae feed on the mucous secretion of the snakes' intestinal epithelium, and invade the tissues.
REDESCRIPTION OF CHORIOPTES TEXANUS, A PARASITIC MITE FROM THE EARS OF REINDEER IN THE CANADIAN ARCTIC
Authors: Sweatman Gordon K.
Published: April 2011

Chorioptes texanus, which was first described by Hirst and collected from the bodies of domestic goats in Texas, is redescribed from the ears of semidomesticated reindeer in the Canadian Arctic.
TRANSMISSION OF LEUCOCYTOZOON BONASAE CLARKE TO RUFFED GROUSE (BONASA UMBELLUS L.) BY THE BLACK FLIES SIMULIUM LATIPES MG. AND SIMULIUM AUREUM FRIES
Authors: Fallis A. M. , Bennett G. F.
Published: April 2011

Specimens of Simulium aureum, S. latipes, S. venustum, and S. rugglesi feed on ruffed grouse although relatively few engorged specimens of the two latter species were obtained. S. aureum and S. latipes are suitable hosts for Leucocytozoon bonasae as shown by infections produced in grouse following injections of sporozoites removed from the salivary glands of these flies. The parasitaemia in grouse infected naturally and experimentally was relatively low and no gross signs of disease were noted in any of the infected birds.
PREFERRED TEMPERATURE OF RAINBOW TROUT (SALMO GAIRDNERI RICHARDSON) AND ITS UNUSUAL RELATIONSHIP TO ACCLIMATION TEMPERATURE
Authors: Garside E. T. , Tait J. S.
Published: April 2011

The modal preferred temperatures of rainbow trout acclimated to 5 °C, 10 °C, 15 °C., and 20 °C. were determined photographically to be 16 °C, 15 °C., 13 °C, and 11 °C., respectively. The final preferendum was 13 °C. The phenomenon of decreasing preferred temperature with increasing acclimation temperature has not been reported for any other species of fish.
HELMINTH PARASITES OF REPTILES, BIRDS, AND MAMMALS OF EGYPT: V. Avian Cestodes
Authors: Mahon June
Published: April 2011

Twenty-nine species of cestodes are recorded from birds in Egypt, including two new species—Raillietina (Fuhmannetta) malakartis (Davaineinae) and Neyraia parva (Paruterininae). There are several new host records.
MEASUREMENT OF SOME PHYSIOLOGICAL PARAMETERS IN RAINBOW TROUT (SALMO GAIRDNERII)
Authors: Schiffman R. H. , Fromm P. O.
Published: April 2011

Data on physiological parameters such as hematocrit, hemoglobin, erythrocyte count and size, organ weights, body-water weight, plasma and blood volumes are given for hatchery-raised Salmo gairdnerii. Methods for obtaining the above data using fingerlings varying in weight from 9 to 29 g are discussed. Mean values reported are as follows: hematocrit 31.8; hemoglobin 6.51 g/100 ml blood; R.B.C. count 1.11 million/mm3; R.B.C. length 14.67 μ. Kidney, liver, and spleen weights as well as total body water, and plasma and blood volumes were found to be statistically valid factors of body weight. Straight-line regression equations are given for each. A comparison of these data with recent summaries of similar data is given and possible reasons for discrepancies are discussed.
Histological and histochemical observations on the testes of Byrsothria fumigata Guer and Gromphadorhina portentosa Schaum
Authors: Lūsis Oskars , Sandor Thomas , Lehoux Jean-Guy
Published: April 2011

Testes of two species of cockroaches have been examined histologically and histochemically. Groups of secretory cells have been found in the neck part of each testicular tube. The substance secreted by these cells is of a lipoprotein nature. Droplets of other secretory material are found among the developing gametes during spermatogenesis as the product of the tubule and they are either mucoprotein or mucopolysaccharide. The significance of the secretory materials has been discussed and a comparison of the neck cells with similar structures in other insects has been made.
Diaptomus (Leptodiaptomus) connexus Light 1938 in Alberta and Saskatchewan
Authors: Anderson R. Stewart
Published: April 2011

The occurrence of Diaptomus connexus Light 1938 in Alberta is reported. Comparative examination of specimens from Saskatchewan indicate that the species occurs there also. Specimens of D. siciloides Lilljeborg 1889 from widespread parts of North America were examined comparatively and consistent differences between the two species were found. Some observations and comments on the ecology and distribution of the two species are presented.
Reflection of ratfish skin (Hydrolagus colliei)
Authors: Arnott H. J. , Nicol J. A. C.
Published: April 2011

A study of the physical basis of the coloration of the shiny integument of the chimaeroid Hydrolagus colliei (ratfish) is presented. The metallic sheen is caused by reflection of light from platelets in the skin that are oriented mostly vertically. They lie in a layer of oriented reflecting cells in the dermis. Additionally, there is a stratum argenteum in the subdermis and in the peritoneum. The oriented reflecting layer is 4 to 11 cells deep; the cells contain about 12 flat crystals regularly stacked above each other. Each crystal lies in a crystal chamber, delimited by a chamber membrane; the chamber is enclosed in a crystal sac bounded by a unit membrane. Cells of the stratum argenteum also contain crystals in crystal sacs. Estimates are made of crystal thickness from interference colors, and of spacing from electron micrographs. The superposed thin lamellae are about one-quarter wavelength thick; the organization is one that could produce high reflectivity by constructive interference. There is a medley of colors, but the overall hue is unsaturated and gold.
Blood viscosity and optimal hematocrit in a deep-diving mammal, the northern elephant seal (Mirounga angustirostris)
Authors: Hedrick Michael S. , Duffield Deborah A. , Cornell Lanny H.
Published: April 2011

Elephant seals offer a unique opportunity to examine rheological characteristics of blood because of the normally high hematocrits in this species. A comparison of blood viscosity of the elephant seal with that of a terrestrial mammal (rabbit; HCT = 35%) reveals a threefold increase in viscosity of elephant seal blood over that of rabbit blood due to the high hematocrit (HCT = 65%). While the increased hematocrit of elephant seal blood reflects increased oxygen storage capacity, blood oxygen transport may actually be reduced by the effects of increased blood viscosity on blood flow. Elephant seal plasma viscosity was also higher than that of rabbit plasma; this was associated with a higher concentration of plasma proteins. There were no apparent differences in the viscous properties of the red blood cells of the two species. The theoretically optimal hematocrit was determined in vitro for reconstituted blood from each species and compared with the observed in vivo hematocrit. It was found that the observed hematocrit of the elephant seal lies far to the right of the predicted hematocrit for optimal oxygen transport, while the rabbit hematocrit was identical with the predicted value. These results suggest that elephant seals have increased oxygen storage capacity at the expense of optimizing oxygen transport. The observed increase in hematocrit and viscosity may be of importance in considering the diving behavior and energetics of elephant seals.
Distribution of two species of Kudoa (Myxozoa: Multivalvulida) in the offshore population of the Pacific hake, Merluccius productus (Ayres, 1855)
Authors: Kabata Z. , Whitaker D. J.
Published: April 2011

Samples of pacific hake (Merluccius productus), a total of 581 fish, were collected along its distribution range from California to Vancouver Island. The fish were examined for prevalence and intensity of infection with Kudoa thyrsitis and K. paniformis (Myxozoa). Fish age 4+ (and older) were more heavily infected than those age 3+, the most heavily infected part of the fish being the dorsal musculature directly behind the head. Although the prevalence of infection with K. thyrsitis increased in a northerly direction, its intensity was markedly lower than the intensity of infection with K. paniformis. Fish of comparable age and size were twice as heavily infected with K. paniformis off California as those taken off Vancouver Island. Fish infected with K. thyrsitis appeared to show a much stronger reaction to the presence of the parasite by producing relatively more black pseudocysts than those infected with K. paniformis. Reasons for this fact and for the observed pattern of parasite distribution are discussed.
Kinematics of lake sturgeon, Acipenser fulvescens, at cruising speeds
Authors: Webb Paul W.
Published: April 2011

Lake sturgeon, 15.7 cm in total length, have a 2-min critical swimming speed of 38.6 ± 4.2 cm∙s−1 (2.45 body lengths∙s−1) at 15 °C. Tail beat frequency (ƒ, Hz), amplitude (a, cm), and propulsive wavelength (λ, cm) increased linearly with swimming speed (U, cm∙s−1), according to the following equations: ƒ = 1.67 + 0.07 U, a = 3.2 + 0.020 U, and λ = 11.0 + 0.039 U. Tail depth and the cosine of the angle of the tail with the axis of motion were independent of swimming speed with mean values of 1.96 ± 0.08 cm and 0.7 ± 0.08, respectively. Swimming kinematics were generally similar to those of teleosts and anuran larvae, implying that body and caudal fin propulsive movements are conservative among actinopterygians and tetrapods. Swimming patterns did not provide for interactions between median fins that are considered to be important to shark swimming. The thrust generated by swimming sturgeon averages 82% that of trout of similar size, although the surface area of sturgeon is substantially lower. Therefore, drag per unit area of sturgeon is 3.5 times that of other actinopterygians, presumably because of the presence of scutes.
The eggshell of Drosophila melanogaster. II. New staging characteristics and fine structural analysis of choriogenesis
Authors: Margaritis Lukas H.
Published: April 2011

The characteristics of the stages of choriogenesis have been identified using light and electron microscopy. Nine stages have been discerned (11A, 11B, 12A, 12B, 12C, 13A, 13B, 14A, 14B), replacing the four stages used so far (11, 12, 13, 14). Characteristics used to determine the stage of the choriogenesis include (a) the size of oocyte as compared with the whole follicle, (b) the length of the chorionic appendages, and (c) the fine structure of the chorionic layers at the main shell and at the specialized regions. Factors a and b were detected by dark-field light microscopy on living follicles, whereas factor c was studied with electron microscopy. At stage 11A the vitelline membrane has just been completed. At stage 11B the follicle cells secrete the wax layer and the respiratory appendages start to form. Stage 12A follicles secrete endochorion at the anterior pole and the appendages elongate, whereas at stage 12B the main shell follicle cells start to secrete endochorion complex. Stage 12C shows initiation of pillar formation at the main shell and 150 μm long appendages. Stage 13A is characterized by 200 μm long appendages and formation of endochorionic cavities at the main shell, through the participation of a "flocculent" material. At stage 13B the endochorionic "roof is formed, which is completed at stage 14A by the simultaneous formation of the "roof network." The last stage, 14B, exhibits 300 μm long appendages and the secretion of exochorion over the entire follicle. The above stages are accompanied by region-specific formation of specialized structures which include the respiratory appendages, the operculum, the posterior pole, the micropyle, and the collar.
Northeast Pacific holothurians of the genus Parastichopus with a description of a new species, Parastichopus leukothele (Echinodermata)
Authors: Lambert Philip
Published: April 2011

Discriminant analysis is used to determine the most reliable ossicle characters for distinguishing three known species of the stichopodid genus Parastichopus from the northeast Pacific (P. californicus (Stimpson, 1857), P. johnsoni (Théel, 1886), and P. parvimensis (H. L. Clark, 1913)) and a proposed new species. The new species, Parastichopus leukothele, is described and a key to the four species is presented. In life P. leukothele has a distinctive bright orange skin with rust-brown patches and small, white, dorsal papillae. Tables with large disks (mean diameter > 100 μm) and few spines on the spires (mean < 12) distinguish this new species from others in the genus Parastichopus. Parastichopus leukothele occurs on the continental shelf from California to British Columbia.
Étude des protéines vitellines de l'hémolymphe et de l'ovaire chez le Crustacé Décapode Carcinus maenas; incidence du parasite Sacculina carcini (Crustacé Rhizocéphale)
Authors: Andrieux Nicole , Frescheville Jacques de , Herberts Charmaine
Published: April 2011

We have performed electrophoretic, immunochemical, and immunoautoradiographic analyses of vitellin proteins from the ovary and hemolymph of healthy crabs of the species Carcinus maenas during vitellogenesis. The same study was performed in parasitized crabs and in the parasite, Sacculina carcini. In unparasitized crabs, there are two vitellin proteins in the ovary. They are immunologically similar, but their electrophoretic mobility is different. One (primary vitellin) is synthesized in the ovary throughout the ovarian cycle. The other (secondary vitellin) exists in the ovary only during secondary vitellogenesis and is partially of endogenous origin. From primary vitellogenesis, we observed in the hemolymph only one vitellogenic protein, homologous to secondary vitellin, of which it is the exogenous precursor. The ovary and hemolymph of parasitized crabs contain the same proteins as those of unparasitized females during primary vitellogenesis. The large quantities of these proteins, observed when the ovarian development is stopped, suggest inhibition of the control of their synthesis and of absorption of the vitellogenin by the gonad. Secondary vitellin was never observed. Sacculina has two vitellin proteins present in the ovary, integument, and hemolymph. These proteins show no electrophoretic or immunochemical similarity to those from the host. At least one has a dual origin, exogenous and endogenous. The roots of the parasite contain neither the crab's vitellin proteins nor those from Sacculina, and do not seem to be a site of transfer or of synthesis for these substances.
Costs and benefits to Red-breasted Mergansers nesting in tern and gull colonies
Authors: Young Andrew D. , Titman Rodger D.
Published: April 2011

The costs and benefits to Red-breasted Mergansers (Mergus serrator) nesting in a Common Tern (Sterna hirundo) colony and a Herring Gull (Larus argentatus) and Great Black-backed Gull (L. marinus) colony were studied from 5 June to 17 August 1984 on islands off the east coast of New Brunswick. Merganser nests outside larid colonies were preyed upon significantly more than nests in the tern colony while no difference was found with nests in the gull colony. Nests in the tern colony were more densely concentrated and more likely to be abandoned. Clumped nests in the tern colony were not initiated in greater synchrony than dispersed nests. The merganser–gull nesting association is discussed. We postulate that the protective benefit for merganser nests in tern colonies accounts for the evolution of the nesting association.
Comparative ultrastructural features of the sporozoite of Lankesterella minima (Apicomplexa) in its anuran host and leech vector
Authors: Tse Bikeung , Barta J. R. , Desser S. S.
Published: April 2011

The ultrastructural features of sporozoites of Lankesterella minima (Apicomplexa) from erythrocytes of the bullfrog (Rana catesbeiana) and from the salivary cells of the leech vector (Batracobdella picta) were compared. Two notable differences were observed. Firstly, the intraerythrocytic sporozoites were more regular in outline and usually assumed a slightly flexed position within a closely applied parasitophorous vacuole. Sporozoites in the salivary cells were more irregular in shape and were often reflexed sharply in their mid or posterior region. Secondly, although the sporozoites in both hosts contained pre- and post-nuclear dense bodies, these were more numerous and approximately twice the diameter in parasites from the leech. These morphological differences may reflect the maturation and attainment of infectivity of the sporozoites in the tissues of the leech vector.
Systematic relationships of Propelops, with a modification of family-group taxa in Phenopelopoidea (Acari: Oribatida)
Authors: Norton Roy A. , Behan-Pelletier Valerie M.
Published: April 2011

Relationships of the oribatid mite genus Propelops, whose members are common in the litter of North American coniferous forests, are assessed using the principles of phylogenetic systematics; characters of both adults and newly discovered immatures are analyzed. The closest relatives of Propelops are among the Phenopelopidae (despite the lack of specialized mouthparts previously used to characterize the family) rather than the Ceratozetidae, as commonly suggested. A new phenopelopid subfamily, Propelopinae, is proposed to include Propelops. The phenopelopid genus Tectopelops Jacot, 1929 is considered a junior subjective synonym of Eupelops Ewing, 1917. Unduloribatidae, most commonly included among the Oribatelloidea, is transferred to the Phenopelopoidea, and new diagnoses are presented for all phenopelopoid family-group taxa.
Escape gaits of white-tailed deer, mule deer, and their hybrids: body configuration, biomechanics, and function
Authors: Lingle Susan
Published: April 2011

Characteristics of body configuration in the escape gaits of white-tailed deer, mule deer, and their hybrids were examined to evaluate mechanical features of these gaits that pertain to their function. Landing and takeoff angles, angles of limb and vertebral flexion, and neck and back attitudes were calculated using data digitized from high-speed films. Galloping white-tailed deer had the most horizontally directed flexion in their necks, backs, and forelimbs. Combined with features of limb timing, the summation of velocities of these body segments results in a faster gallop for white-tailed deer than for galloping mule deer and hybrids. Stotting mule deer attain considerable horizontal velocity which may be conserved between strides. The bound, used by hybrids, appears to be a slow and mechanically inefficient gait for deer, primarily due to biomechanical factors stemming from the coupled forelimb landing and associated steep body position. These limitations present the possibility that hybrids have ineffective responses to predators, which could lower their viability relative to that of white-tailed and mule deer.
Function of the mite pockets of lizards: a reply to E.N. Arnold
Authors: Bauer Aaron M. , Russell Anthony P. , Dollahon Norman R.
Published: April 2011

Arnold's critique misidentifies the goals of Bauer et al. (A. M. Bauer, A. P. Russell, and N. R. Dollahon, 1990. Can. J. Zool. 68: 1196–1201). Because Arnold's premise is that adaptation is responsible for the evolution of mite pockets, his arguments are necessarily panselectionist. Although available evidence regarding putative acarodomata is ambiguous, the argument of Bauer et al. that phylogenetic or structural constraint is responsible for the presence of integumentary pockets in at least some gekkonid lineages remains the most robust working hypothesis. Arnold's arguments regarding the damage-ameliorating function of mite pockets are not supported by data from either the hosts or the parasites.
Thyroid hormone dynamics during the nursing period in harbour seals, Phoca vitulina
Authors: Haulena Martin , Aubin David J , Duignan Padraig J
Published: April 2011

The postnatal period in phocid seals is metabolically demanding, requiring mobilization of maternal energy stores, which are then transferred via the milk for subsequent deposition in the pup. Thyroid hormones may be important modulators of these processes, and so we monitored circulating levels of free and total thyroxine (T4), triiodothyronine (T3), and reverse T3 (rT3) in 13 free-ranging female harbour seals (Phoca vitulina) and their pups for up to 25 days post partum. Early total and free T4 levels, percentage of free T4, total and free T3 levels, rT3 levels, and rT3:T3 ratios were significantly higher in pups than in mothers. Total and free T4 levels, percentage of free T4, free T3 and rT3, levels, and rT3:T3 ratios in pups decreased significantly over the lactation period, while maternal total and free T4 levels increased significantly. Our findings highlight the dynamic nature of thyroid hormones and their involvement in regulating metabolism throughout this important period. This is the first report examining free T3 and rT3 levels in phocid seals.
Swimming speeds and activity levels of consumers at various resource and consumer densities under predation risk
Authors: Johansson Frank , Leonardsson Kjell
Published: April 2011

We tested the following predictions concerning a consumer in a three-level trophic system (resource-consumer-predator): (i) speed is a hump-shaped response and activity level an asymptotic response to increasing resource densities, and (ii) speed increases and activity level declines and then increases with increasing consumer density. Green sunfish (Lepomis cyanellus) were used as predators, mosquitofish (Gambusia affinis) as the consumers, and Daphnia pulex as the resource. Speeds and activity levels of mosquitofish showed the predicted response as a function of resource and consumer densities. No differences in speed or activity level were found between the sexes. The functional response of the consumers was type II for three of the four consumer densities used. The behavioural responses implied an increase in encounter rates with prey at low prey densities, a property that has the potential to stabilise predator-prey systems.
Intra- and inter-sexual aggression in the ground skink (Scincella lateralis)
Authors: Akin Jonathan A
Published: April 2011

Differences in reproductive investment between males and females can be a basis for both intra- and inter-sexual conflict. In a series of laboratory experiments, I staged intra- and inter-sexual contests for food between pairs of adult ground skinks (Scincella lateralis). Males were significantly more aggressive than females. Size asymmetry between contestants significantly affected intrasexual behavior between females, as smaller individuals exhibited avoidance behaviors more frequently than larger individuals. Aggression was more prevalent in intersexual contests than in intrasexual contests, and males bit females significantly more often than females bit males. Females captured significantly fewer prey in the presence of a male than in control tests, but showed more avoidance behaviors in intersexual contests than did males. These results suggest that intersexual conflict may be important in social interactions in ground skinks, particularly with respect to spatial distribution.
Tadpole bullies: examining mechanisms of competition in a community of larval anurans
Authors: Faragher Sarah Grimké , Jaeger Robert G
Published: April 2011

We examined interference competition during interspecific interactions of larval anurans to determine its importance. We conducted laboratory experiments to examine behavioral and chemical interference competition between tadpoles of the southern leopard frog (Rana utricularia) and those of the green treefrog (Hyla cinerea). Water preconditioned byR. utricularia tadpoles significantly decreased the growth and increased the mortality of H. cinerea tadpoles compared with control treatments. In addition, R. utricularia tadpoles inhibited the feeding rate ofH. cinerea tadpolesby harassing them, and these interactions significantly decreased the growth and increased the mortality of theH. cinerea tadpoles. Rana utricularia tadpoles apparently use both chemical interference and aggressive behavior in securing a competitive advantage over H. cinerea tadpoles, and the H. cinerea tadpoles suffer from these interactions. Intraspecific chemical and behavioral interference competition also significantly decreased the growth of larval H. cinerea. In natural ponds, R. utricularia tadpoles that inhibit the growth and increase the mortality of H. cinerea tadpoles may increase their own chances of survival and metamorphosis, while H. cinerea tadpoles that avoid interactions with conspecifics and with R. utricularia tadpoles may increase their own chances of survival and metamorphosis.
Seasonal dive behaviour of lactating New Zealand fur seals (Arctocephalus forsteri)
Authors: Mattlin R H , Gales N J , Costa D P
Published: April 2011

The dive behaviour of 18 female New Zealand fur seals (Arctocephalus forsteri) from Taumaka, Open Bay Islands, New Zealand (43°52'S, 168°53'E), was recorded during early (summer; December-February), mid (autumn; March-May), and late (winter; June-August) lactation. Mean dive depth, dive duration, and bottom time for dives >=6 m in depth increased from summer through winter. Variation in individual seal dive behaviour within a season accounted for approximately 11, 9, and 11% of the observed difference between seasons in dive depth, dive duration, and bottom time, respectively. Seasonal dive data (mean ± 1 SD) were as follows: summer: dive depth 30 ± 37 m, dive duration 1.4 ± 1.1 min, and bottom time 0.5 ± 0.6 min; autumn: dive depth 54 ± 47 m, dive duration 2.4 ± 1.3 min, and bottom time 1.0 ± 0.8 min; winter: dive depth 74 ± 64 m, dive duration 2.9 ± 1.5 min, and bottom time 1.2 ± 1.1 min. Maximum recorded dive depth was 274 m for a 5.67-min dive in autumn. Maximum duration was 11.17 min for a dive to 237+ m in winter. New Zealand fur seals are the deepest diving fur seal species reported thus far. The estimated theoretical aerobic dive limit was exceeded on 18.4% of dives (range of individual values 0.2-57.8%). Females (n = 12) were ashore about 1.8 days at a time during February through November, and this increased to about 4.3 days during December and January. Average time spent away from the rookery ranged from 3 to 15 days.
The station-holding performance of the plaicePleuronectes platessaon artificial substratum ripples
Authors: Gerstner Cynthia L , Webb Paul W
Published: April 2011

The ability to maintain position in a current (station-holding) was determined for the plaicePleuronectes platessa on a simple form of habitat structure, substratum ripples. Twelve sinusoidal combinations of ripple wavelength and amplitude were tested, with wavelengths approximating 0.5, 1, 2, and 5 times fish total length. Although ripple flow patterns varied, all provided regions of retarded flow in the ripple troughs. Therefore, ripples affected station-holding performance in the following three ways: (1) directly, by providing regions of retarded flow, thus creating flow refuges, (2) indirectly, by interfering with behaviors deferring the onset of active swimming, and (3) indirectly, by providing opportunities for new behaviors deferring swimming. The direct effects of retarded flow on performance versus\i indirect effects via swim-deferring behavior were evaluated. Flow retardation was measured as the velocity ratio (utrough/ufree-stream), where utroughis the velocity measured 0.5 cm from the bottom of a trough and ufree-streamis the velocity measured 10 cm above ripple crests. At a velocity ratio >0.4, direct flow-retardation effects were most important in determining observed performance. At a velocity ratio <0.4, indirect interference affected performance. Performance of plaice was maximized on ripples with wavelengths approximately twice their total body length.
Home-range sizes and altitude selection for arctic foxes and wolverines in an alpine environment
Authors: Landa Arild , Strand Olav , Linnell John DC , Skogland Terje
Published: April 2011

We compared the use of space and habitat by wolverines, Gulo gulo, and arctic foxes, Alopex lagopus, on the Snøhetta plateau and surrounding mountains in south-central Norway. The arctic foxes used smaller annual home ranges than the wolverines, whose home ranges were among the largest yet reported for the species. In both species, resident males used larger home ranges than resident females. Arctic foxes used a much narrower, and higher, range of altitudes than wolverines, always above the tree line. Wolverines used lower altitudes in winter than in summer. Female wolverines showed pronounced seasonal peaks in their use of the peripheral areas of their home ranges. Both species showed an ability to cross at least some transportation corridors (road, rail, human settlements) in the area. The habitat available at Snøhetta appears suitable for arctic foxes and does not explain the failure of the population to recover during 67 years of protection. Because of predation on domestic sheep, wolverines will probably be confined to a series of core conservation areas (CCA). At present densities (0.28-0.36 wolverines per 100 km2), the CCA surrounding Snøhetta can contain from 36 to 50 wolverines.
Comparative feeding behaviour and niche organization in a Mediterranean duck community
Authors: Green Andy J
Published: April 2011

Feeding behaviour of the Marbled Teal, Marmaronetta angustirostris, Mallard, Anas platyrhynchos, Garganey, Anas querquedula, and Ferruginous Duck, Aythya nyroca, in the Göksu Delta, Turkey, was compared from 10 July to 6 August 1995. Almost all individuals observed were postbreeding adults and juveniles. Marbled Teal fed closest to the surface (mean depth within the water column 8.4 cm), chiefly by bill dipping (66%) and gleaning (14%). Garganey fed at a mean depth of 9.1 cm, mainly by bill dipping (57%) and neck dipping (35%). Mallards fed at greater depths (mean 31.8 cm), mainly by upending (tipping 46%) and neck dipping (41%). Ferruginous Ducks fed at the greatest depths (mean 38.4 cm), chiefly by diving (76%). Marbled Teal moved most frequently between feeding events and Mallards moved least frequently. As in previous studies of dabbling ducks, the largest species (Mallard) upended more and fed deeper in the water column. However, Mallards used shallower microhabitats than smaller dabbling ducks. Dabbling and diving duck guilds were not discernible in either horizontal (feeding habitat) or vertical (feeding behaviour) niche dimensions, and the Mallard and Ferruginous Duck were related in both dimensions. Niche overlaps between species pairs along the two dimensions were negatively correlated (r = -0.71, P = 0.12), supporting niche complementarity.
Results of low-frequency playback of M-sequence noise to humpback whales,Megaptera novaeangliae, in Hawai′i
Authors: Frankel A S , Clark C W
Published: April 2011

The behavior of humpback whales, Megaptera novaeangliae, exposed to playback of low-frequency sounds, was examined to test whether animals would respond to this signal when received sound levels exceeded 120 dB re: 1 µPa. The source signal was an M-sequence (essentially a sine wave with a series of phase reversals) centered at 75 Hz with a 30-Hz bandwidth. Behavior and movements of whales were described before, during, and after playback. Eighty-five trials were conducted, of which 50 had an experimental condition of M-sequence playback. Thirty-four were no-sound controls and a single trial used a playback of the Alaska humpback whale feeding call. The received playback sound level at the whales ranged from ambient level ( approx 90 dB) to 130 dB re: 1 µPa (60-90 Hz). A comparison revealed no difference in whale tracks and bearings between control and playback conditions. Behavior rates were examined statistically using independent variables describing pod composition, nearby vessels, and playback sound level. Natural variables of pod composition were the most important factors predicting behavior rates. Vessels had a larger impact and affected more behavioral variables than playback. A slight increase in the duration and distance between successive surfacings was found as the received playback sound level increased. Eleven playbacks in which whales passed within the 120-dB isopleth yielded only three potential responses (one movement away and two toward the sound source) and eight nonresponses. Overall, subtle responses to M-sequence playbacks could only be detected statistically, but the biological significance of these responses is uncertain.
An increase in habitat complexity reduces aggression and monopolization of food by zebra fish (Danio rerio)
Authors: Basquill Seán P , Grant James WA
Published: April 2011

We tested the predictions that an increase in the structural complexity of a habitat causes both a decrease in aggression and the monopolization of resources. Groups of three zebra fish (Danio rerio) were allowed to compete for food in a complex habitat with simulated vegetation and in a simple habitat with no vegetation. As predicted, both the levels of aggression by the dominant fish (P = 0.050) and the coefficient of variation of the amount of food eaten within a group (P = 0.020), a measure of food monopolization, were lower in the complex habitat than in the simple one. Fish that chased competitors more frequently ate more food in both habitats, but the relationship was stronger in the simple than in the complex habitat. Our results suggest that aggression is less useful as a mode of competition in habitats with greater structural complexity. Manipulating the structural complexity of the habitat may be a practical way of controlling the intensity of aggression and resource monopolization in groups of animals.
Latitudinal variation in testis size in six species of North American songbirds
Authors: Pitcher Trevor E , Stutchbury Bridget JM
Published: April 2011

Six songbird species were studied to determine how testis size varies in relation to latitude, using data from breeding areas at latitudes 7°N to 69°N. Three of the species (Carpodacus mexicanus, Vireo olivaceus, Geothylpis trichas) exhibited a significant positive relationship, one (Passerculus sandwichensis) a significant negative relationship, and two (Agelaius phoeniceus, Spizella passerina) no significant association between relative testis mass and latitude. These results suggest that sperm competition may also vary latitudinally, likely in response to geographic variation in breeding season length, extrapair mating intensity, and social mating system.
Predicting body fat and body mass in moose with ultrasonography
Authors: Stephenson Thomas R , Hundertmark Kris J , Schwartz Charles C , Ballenberghe Victor Van
Published: April 2011

Lipids are the primary energy store of the body and estimation of these reserves provides an indication of nutritional status in moose (Alces alces). Estimates of total body fat enhance our understanding of reproductive potential, survival rate, energy balance, and nutritional carrying capacity. We developed predictive equations of total body fat and body mass from ultrasonographic fat measurements for application in live animals. We detected a strong linear relationship (r2 = 0.96) between ingesta-free body fat and rump fat thickness measured by ultrasonography. Rump fat thickness was measurable over a range of body fat levels (5.8-19.1%). Rump fat mass (r2 = 0.92) and kidney fat mass (r2 = 0.95) were curvilinearly related to ingesta-free body fat level. For adult females, total length and chest girth were not related to body mass. Ingesta-free body fat, however, explained 81% of the variability in body mass, and ultrasonically measured rump fat thickness predicted body mass (r2 = 0.80).
Estimating mean body masses of marine mammals from maximum body lengths
Authors: Trites Andrew W , Pauly Daniel
Published: April 2011

Generalized survival models were applied to growth curves published for 17 species of cetaceans (5 mysticetes, 12 odontocetes) and 13 species of pinnipeds (1 odobenid, 4 otariids, 8 phocids). The mean mass of all individuals in the population was calculated and plotted against the maximum body length reported for each species. The data showed strong linearity (on logarithmic scales), with three distinct clusters of points corresponding to the mysticetes (baleen whales), odontocetes (toothed whales), and pinnipeds (seals, sea lions, and walruses). Exceptions to this pattern were the sperm whales, which appeared to be more closely related to the mysticetes than to the odontocetes. Regression equations were applied to the maximum lengths reported for 76 species of marine mammals without published growth curves. Estimates of mean body mass were thus derived for 106 living species of marine mammals.