bluuebunny/crossref_metadata_2025 huggingface dataset:
Circulatory responses of seals to periodic breathing: heart rate and breathing during exercise and diving in the laboratory and open sea
Authors: Fedak M. A. , Pullen M. R. , Kanwisher J.
Published: March 2009

In terms of a seal's success as a predator, the ability to spend a high fraction of time submerged and yet remain in a steady state is at least as important as that to make long dives. This aspect of seal physiology has received much less attention than has the ability to dive for extended periods and yet is important to the context in which dive-related morphological and physiological specializations are considered. We found, in seals exercising in the laboratory, that as [Formula: see text] increased, heart rate during breathing bouts was high and unchanging. Heart rate during dives was 25 to 33% of the rate during breathing and was insensitive to metabolic rate. However, the fraction of time seals spent breathing and overall average heart rate increased with exercise. We have confirmed these patterns using very high frequency and acoustic telemetry in freely diving harbour seals in the open sea. Heart rate at the surface was virtually constant at 120 beats/min and independent of dive duration. While the seals were diving, heart rate fell to 40 beats/min. Average heart rate depended almost entirely on the proportion of time spent below the surface and only to a minor extent on dive length. The exceedingly low heart rates seen during forced dives in the laboratory were never observed at sea.
Forced and voluntary diving in ducks: cardiovascular adjustments and their control
Authors: Jones David R. , Furilla R. A. , Heieis M. R. A. , Gabbott G. R. J. , Smith F. M.
Published: March 2009

Diving ducks submerge voluntarily for less than 1 min yet, in forced dives in the laboratory, redhead ducks can endure at least 8 min underwater. This is much longer than a dabbling duck of the same body mass can endure and is a result of the quicker onset of oxygen-conserving cardiovascular responses in divers. Oxygen conservation during forced dives is indicated by a profound bradycardia as blood flow is restricted to cerebral and central cardiovascular areas. In voluntary dives, on the other hand, heart rate is frequently above resting rates, and blood flow is preferentially directed to the working muscles of the hind limbs. Profound bradycardia only occurs in unrestrained ducks when they are trapped underwater. Since leg movements cease within 30 s after ducks are trapped, blood flow must at that time be directed away from the working muscles, as in the "classical" oxygen-conserving dive response. Cardiovascular adjustments to forced diving are caused by stimulation of nasal receptors in diving ducks. In dabblers, arterial chemoreceptor stimulation is crucial to the response, although an intact barostatic system may be necessary for development of profound bradycardia. Baroreceptors are essential for the cardiac response observed when dabblers are trained to dive for food, although neither baro-, chemo-, nor naso-receptors appear to have much to do with the cardiac adjustments to voluntary submergence in diving ducks. Nevertheless, in divers, cardiac adjustments to dabbling and forced, voluntary, and trapped dives are linearly related on a plot of dive (trapped) against the logarithm of predive (pretrap) heart rate. This relationship is due to a similar increase in vagal activity, of some 50% of maximum, in all types of diving manoeuvers. Phychogenic factors, long thought to be important in cardiac responses to forced diving, would appear to underpin this relationship.
Pressure and the diver
Authors: Kooyman Gerald L.
Published: March 2009

In the last few years a large number of depth recordings have added a substantial amount of information about diving depths in aquatic tetrapods. Many dive to at least 200 m on occasion, and some to > 1000 m. The high pressures at such depths may necessitate special adaptations for responding to compression and gas exchange. Effective compensation has been experimentally explained in only a few cases for seals. For example, the seal's respiratory system, because of the unusual compliance of the chest, easily yields to high ambient pressures. This causes compression collapse of the lung and low gas exchange. The result is low blood N2 tensions no matter what the dive depth. Somewhat similar adaptations exist for sea snakes, but the adaptations of sea turtles and birds remain unknown.
Control of the respiratory mode in air-breathing fishes
Authors: Smatresk Neal J.
Published: March 2009

The transition from water breathing to air breathing for most bimodally breathing fishes appears to be critically dependent on sensory information from three major sets of peripheral receptors. Dominant control over the respiratory mode arises from stimulation of oxygen-sensitive chemoreceptors. Stimulation of internally oriented chemoreceptors generally increases both aquatic and aerial respiration, while stimulation of external chemoreceptors may shift the ventilatory emphasis from water to air breathing. Air-breathing organ mechanoreceptors may help to reflexively stimulate or inhibit air breathing upon deflation or inflation of the air-breathing organ, and probably play a major role in matching ventilation to perfusion in the air-breathing organ. Waterborne irritants or emersion stimulate defense receptors that may override control priorities set by other receptors, and inhibit branchial ventilation in favor of air breathing. While there is still little detailed information about the distribution and characteristics of these sensory receptors, it seems likely that similar sets of receptors control the respiratory mode in most air-breathing fishes, and that differences in the central integration of this sensory information may best account for the great variability of respiratory reflex responses in this diverse group of animals.
Endocrine regulation of carbohydrate metabolism in hypometabolic animals
Authors: Musacchia X. J.
Published: March 2009

Experimental hypothermia and natural hibernation are two forms of hypometabolism with recognized physiological changes, including depression of endocrine and metabolic functions. To better understand functional changes, helox (i.e., helium and oxygen (80:20) mixtures) and low ambient temperatures have been used to induce hypothermia in hamsters and rats. Both clinical and biological survival, i.e., survival without recovery and survival with recovery from hypothermia, respectively, are related to depth and length of hypothermia. In the rat, body temperatures of 15 °C for periods greater than 6–10 h greatly restrict biological survival. The role of glucocorticoids in enhancing thermogenic capacity of rats was assessed using triamcinalone acetonide. In the hamster, treatment with cortisone acetate prolonged both clinical and biological survival. Hypothermic hamsters continue utilizing circulating glucose until they become hypoglycemic and die. Hypothermic rats do not utilize glucose and respond with a significant hypoinsulinema. The role of endocrines in the regulation of carbohydrate homeostasis and metabolism differs in hibernation and hypothermia. Glucocorticoids influence the hypothermic response in both species, specifically by prolonging induction of hypothermia in rats and by prolonging survival in hypothermic hamsters.
Does song deter territorial intrusion in White-throated Sparrows (Zonotrichia albicollis)?
Authors: Falls J. Bruce
Published: March 2009

The role of the song of the White-throated Sparrow (Zonotrichia albicollis) as a deterrent to potential intruders was assessed by removing territorial males of the white-striped morph and replacing them with loudspeakers playing back their songs. Following removals, intrusions of new singing birds were both delayed and fewer in inner zones of playback territories, as compared with similar areas of control territories that had no playback. In peripheral zones (outside the area defined by loudspeakers), or after playback ended (after 2 days), there were no significant differences between playback and control territories. During the playback period, intrusions were reduced within 10 m of speakers but not at greater distances. Thus, song tends to inhibit territorial intruders from singing and thereby asserts the resident male's dominance. To achieve this effect, I suggest that a resident needs to sing to some extent throughout its territory. These results are compared with those obtained in studies of the Great Tit (Parus major).
Overwintering habitats of coho salmon (Oncorhynchus kisutch) and other juvenile salmonids in the Keogh River system, British Columbia
Authors: Swales S. , Caron F. , Irvine J. R. , Levings C. D.
Published: March 2009

Catches of overwintering juvenile coho salmon (Oncorhynchus kisutch) in the Keogh River system, Vancouver Island, were higher in two small (8 and 25 ha), shallow (mean depth 2 – 3 m) lakes and their outlet and inlet streams than in the main river, where steelhead trout (Salmo gairdneri) were predominant. Dolly Varden char (Salvelinus malma), cutthroat trout (Salmo clarki), and threespine stickleback (Gasterosteus aculeatus) were also present in the lakes. The distribution of coho salmon in the lakes was restricted largely to areas close to the bank, with few fish being captured in offshore areas or in mid-water. Apparent differences in the abundance of coho salmon between the two lakes may have been related to differences in fish community composition, with sticklebacks being particularly numerous in Misty Lake, where catches of coho salmon were lower than in Long Lake. The population density and biomass of coho salmon overwintering in Long Lake were estimated to be 176 fish/ha and 1.14 kg ha−1, respectively. The mean length of coho salmon in the lakes was greater than that of coho salmon in the tributary streams and main river, and the mean length of the salmon in the lakes generally increased with distance away from shore.
Fates and movements of meadow voles (Microtus pennsylvanicus) following a population decline
Authors: Mihok Steve , Lawton Todd , Schwartz Bill
Published: March 2009

The movements of 24 meadow voles were monitored with radiotelemetry during summer 1985 near Pinawa, Manitoba, to ascertain fates following a severe winter population decline. Low breeding season survival of 22% per month resulted in the persistence of low numbers through spring 1986. Despite densities of only a few individuals per hectare, voles were captured in both meadows and forests. Some voles first caught in forests (mostly males) moved over large areas (up to 4 ha), including both meadow and forest habitat. In contrast, voles captured in meadows were sedentary, often confining their movements to small areas of 0.1–0.2 ha. Radiotransmitters were recovered from 18 of 19 voles that died during the study. Five voles (28%) appeared to have died in situ; six voles (33%) may have been taken by an unusually clean predator or scavenger. Fates of the remaining voles were uncertain. No direct evidence of predation by small mustelids was found to support the hypothesis that these predators account for the persistence of low density following population declines.
Dynamique spatio-temporelle des déplacements de macroinvertébrés dans une grande rivière
Authors: Cellot Bernard , Bournaud Michel
Published: March 2009

The movements of macroinvertebrates in the Rhône River were studied by using suspended artificial substrates that were immersed for 7 days at three depths near a bank and at the centre of the channel at Jons (27 km upstream of Lyon, France). Sampling was carried out monthly on an annual cycle, from December 1978 to March 1980. The 93 taxa found were distributed as follows: chironomid larvae (Diptera), 34.4%; Hydropsyche spp. (Trichoptera), 24.9%; Oligochaeta, 15.7%; Gammarus fossarum and (or) G. pulex (Crustacea), 15.0%; others, 10.0%. Correspondence analysis revealed and summarized the hierarchy of the spatio-temporal variations in fauna. The first level of variation is seasonal and shows contrasts between some summer species (e.g., Ephemerella ignita, Leuctra fusca) and the pool of organisms that subsist during winter. The second level of variation is due to seasonal hydrological conditions. The large flow rate during winter and at the beginning of the summer instigates the drift of rheolithophilous (e.g., Psychomyia pusilla) or limnophilous (Asellus aquaticus) taxa, which results in a more intense spatial homogenization of the fauna. The first increase in flow rate after a slower regime, although minor, has a "washing out" effect on the backwaters connected with the main stream (parapotamic area). On the other hand, the slower flow rate at the end of summer is favourable to some extent for some lentic taxa (Planaria), particularly near the banks. A third level of variation, less important, concerns transverse movements (between bank and channel) and the effects of emptying and cleaning the upstream reservoir.
Differential development of the rostrum and mandible of the swordfish (Xiphias gladius) during ontogeny and its possible functional significance
Authors: McGowan C.
Published: March 2009

The swordfish, with its much shortened mandible and long thin snout, commences life with mandibles that extend to the tip of the snout. The radical change in jaw proportions occurring during ontogeny has been known since Cuvier's time, and although many descriptive accounts have been given, there have been few attempts to quantify the changes taking place. Bivariate analyses of snout, head, and mandibular growth were conducted upon published larval data, and upon unpublished adult data for 336 individuals. Mandibular growth conforms to simple negative allometry in larvae, and the same appears to be true for adults, but the growth of the snout and head is complex, with significant departures from linearity when logarithmically transformed data are plotted against body size. The disproportionate development of the upper and lower jaws results primarily from the retarded growth of the mandible, rather than from the accelerated growth of the snout. The possible functional significance of the abbreviated mandible is briefly discussed in terms of the cutting efficiency of the sword and the potential for seizing freshly injured prey..
Effects of food availability on larval development and inter-instar predation among larvae of Libellula lydia and Libellula luctuosa (Odonata: Anisoptera)
Authors: Wissinger Scott A.
Published: March 2009

I conducted two types of laboratory experiments with larvae of the dragonflies Libellula lydia and L. luctuosa. In one experiment I varied the number of Daphnia magna fed daily to these larvae to determine the effect of food availability on growth and survivorship. The time spent in each instar decreased dramatically with increased food availability, but the number of molts did not vary and the size at each molt was only slightly affected. Mortality was low in all but the lowest feeding treatment, despite 2- to 5-fold differences in instar duration. These results suggest that the number and size of instars are determinate in these species, and that starvation is an unlikely cause of larval mortality in nature. In a second experiment I used naturally co-occurring size combinations of L. lydia and L. luctuosa to determine how inter-odonate predation varies as a function of larval size difference. For both intra- and inter-specific combinations, (i) little or no predation occurred between larvae similar in size, (ii) some predation always occurred when larvae differed by more than two instars, and (iii) the number of larvae consumed increased dramatically as a function of instar difference. The proportional difference between the labial (gape) width of the larger instar and the head width of the smaller instar was a good estimator of inter-odonate predation rates across all instar and species combinations. Together these results suggest that the effects of inter-odonate competition and predation can be disentangled in the field by manipulating the instar structure of experimental populations.
Revision of the genus Eustrongylides Jägerskiöld, 1909 (Nematoda: Dioctophymatoidea) of piscivorous birds
Authors: Measures Lena N.
Published: March 2009

The genus Eustrongylides Jägerskiöld, 1909 (Nematoda: Dioctophymatoidea) is revised based on examination of adult E. tubifex from experimentally infected Common Mergansers (Mergus merganser) and specimens of Eustrongylides spp. from various museums. Only three species are considered distinguishable: E. tubifex (Nitzsch in Rudolphi, 1819) Jägerskiöld, 1909 (the type species), E. ignotus Jägerskiöld, 1909, and E. excisus Jägerskiöld, 1909. All three species are redescribed. Eustrongylides perpapillatus Jägerskiöld, 1909 is regarded as a synonym of E. tubifex. Eustrongylides formosensis Sugimoto, 1933, E. indicus Ali, 1971, E. phalacrocoracis Johnston and Mawson, 1941, E. plotinus Johnston and Mawson, 1941, E. tricolor Sugimoto, 1931, and E. excisus amoyensis Hoeppli, Hsü, and Wu, 1929 are regarded as synonyms of E. excisus. Nine additional species are considered species inquirendae.
Cestodes of the genus Hymenolepis Weinland, 1858 sensu stricto from pocket gophers Geomys and Thomomys spp. (Rodentia: Geomyidae) in Colorado and Oregon, with a discriminant analysis of four species of Hymenolepis
Authors: Gardner Scott Lyell , Schmidt Gerald D.
Published: March 2009

Cestodes found to represent previously undescribed members of the genus Hymenolepis s.str. (Yamaguti 1959) were recovered from pocket gophers, Geomys bursarius (Shaw), in northeastern Colorado. Hymenolepis weldensis n.sp. and Hymenolepis geomydis n.sp., not occurring together in any individual host, were found in 3 and 8%, respectively, of pocket gophers examined for helminths. The life cycle of H. weldensis was completed in the laboratory using beetles, Tenebrio molitor (L.), as intermediate hosts, and pocket gophers of three genera (Geomys, Thomomys, and Pappogeomys) as definitive hosts. Development of H. weldensis did not occur in laboratory rats, Rattus norvegicus (Berkenhout). Morphologic relationships four species of Hymenolepis (H. diminuta, H. tualatinensis, H. weldensis, and H. geomydis) were analyzed using multiple discriminant function analysis, which clearly allocated individual cestodes to the respective groups and discriminated species.
Red cell magnesium in rainbow trout
Authors: Houston A. H. , Gray J. D.
Published: March 2009

In vivo erythrocytic magnesium concentration was significantly correlated with red cell potassium level and potassium equilibrium potential, but not with specimen weight, plasma magnesium, red cell sodium and chloride, or chloride equilibrium potential. To examine the relationship between magnesium and potassium, potassium levels were manipulated in vitro with catecholamine, furosemide, ouabain, and valinomycin. Over a wide range of normal and supranormal potassium concentrations, a significant correlation between magnesium and potassium levels was evident. However, depletion of potassium following exposure to ouabain and valinomycin led to a shift from the normal high potassium/low sodium relationship to a high sodium/low potassium state with progressive increases in magnesium content. Correlation of magnesium with potassium was lost, and a significant correlation with red cell sodium, but not with sodium equilibrium potential, was evident. Red cell magnesium concentration appears, therefore, to be influenced by the preponderant univalent cellular cation rather than potassium per se.
Proisotoma rainieri Folsom, 1937 (= lsotoma kisoana Yosii, 1939) syn. nov. An epitokous species of Collembola (Isotomidae)
Authors: Fjellberg Arne
Published: March 2009

Examination of type specimens of both taxa prove that the Japanese Isotoma kisoana is a junior synonym of the Nearctic Proisotoma rainieri. Reproductive specimens from Alberta and Oregon are epitokous with prolonged abdominal macrochaetae and transformation of some of the setae on the anal valves to thick spines. The transformation is more pronounced in females than in males. Other cases of epitoky among isotomid Collembola are briefly discussed.
Microhabitat preference and coexistence of ectoparasitic arthropods on Alaskan seabirds
Authors: Choe Jae C. , Kim Ke Chung
Published: March 2009

The population structure and distribution patterns of ectoparasitic arthropods on four species of Alaskan seabirds (common murre (Uria aalge), thick-billed murre (Uria lomvia), black-legged kittiwake (Rissa tridactyla), and red-legged kittiwake (Rissa brevirostris)) were studied and interspecific interactions were examined. In most ectoparasite populations on murres and kittiwakes, females predominated. This pattern may be attributable to differences in activity, behavior, and mortality between the sexes of the ectoparasites. Except for feather mites, adults of most ectoparasites were less abundant than immatures. The extremely high relative abundance of immature ticks was probably due to the high fecundity of these organisms and predation pressure. Distribution patterns of adults differed significantly from those of immatures in most louse and tick populations. Populations of lice (Quadraceps obliquus (Mjöberg), Quadraceps ornatus (Grube)) and ticks (Ixodes uriae White) on murres and kittiwakes were highly clumped. The degree of clumping was lower among ectoparasites on murres than among those on kittiwakes. Murres aggregate more and thus provide more opportunities for their ectoparasites to disperse to new host individuals. Ticks were the dominant group of ectoparasites in most body regions. On the wings, however, mites were much more abundant. The wings provided the largest surface area and supported the highest ectoparasite species diversity and population density. The louse and tick populations exhibited distinct patterns of spatial distribution on the host, largely as a result of their distinct preferences for certain microhabitats. However, close competition appears to occur between Q. obliquus and I. uriae on murres, and between the two feather mites, Alloptes (Alloptes) sp. and Laronyssus martini (Trouessart), on kittiwakes.
Design of exogenous fuel supply systems: adaptive strategies for endurance locomotion
Authors: Weber Jean-Michel
Published: March 2009

The prolonged performance of submaximal exercise depends on the adequate supply of exogenous fuels (e.g., hepatic glucose) to slow down the use of endogenous substrates (e.g, intramuscular fat or glycogen) and delay their depletion. This paper investigates the adaptive strategies available to vertebrates for increasing the rate of exogenous fuel supply in endurance locomotion. Two steps can be defined for the design of a "good" system: (i) the choice of oxidizable fuels and storage sites that maximize the rate of energy transfer to the working muscle and (ii) the provision of adequate regulatory mechanisms which alter substrate fluxes rapidly in response to work of different intensities. The principal oxidizable fuels used by vertebrates (free fatty acids (FFA), glucose, and lactate) are examined to determine the major constraints on maximal supply rates. The delivery of albumin binding sites to adipose tissue represents a specific constraint on FFA transport to working muscles. Furthermore, because the supply of all exogenous fuels is probably limited by membrane transport, animals requiring the rapid use of oxidizable substrates to sustain locomotion can follow two strategies: (i) switch to endogenous substrates whenever possible to avoid this constraint and (ii) evolve different transmembrane fuel carriers or augment the density of existing ones to increase maximal rates of substrate translocation across cell membranes.
Limits and constraints in the scaling of oxidative and glycolytic enzymes in homeotherms
Authors: Hochachka P. W. , Emmett B. , Suarez R. K.
Published: March 2009

It is now empirically well established that basal and maximum rates of O2 uptake in homeotherms scale approximately to the 0.75 power; log–log plots of mass-specific metabolic rates versus body mass yield slopes of −0.20 to 0.25. Recent studies of 10 mammalian species and 1 hummingbird species indicate that marker enzymes of mitochondrial metabolism (citrate synthase, for example) scale inversely with body mass. Hummingbirds and shrews are near the upper limit in the degree to which the oxidative capacity of heart and skeletal muscles can be elevated; further increases in mitochondrial volume densities would sacrifice myofilament or sarcoplasmic reticulum volume densities. Whales weighing about 105 kg may be near the limit at the opposite extreme because their mass-specific resting metabolic rates are predicted to be approaching those of hypometabolic ectotherms. In contrast to oxidative enzyme scaling patterns, enzymes normally operative in muscle anaerobic glycolysis, such as lactate dehydrogenase, scale directly with body mass. Hummingbirds and shrews are considered to have reduced muscle lactate dehydrogenase levels near a lower limit commensurate with buffering of cytosolic redox, a distinctly aerobic lactate dehydrogenase function. How much anaerobic glycolytic potential can be packed into muscle cells in the largest mammals is unknown; this upper limit appears to be set by a compromise between myofilament volume densities and the combined volume densities of glycogen granules, intracellular buffering components, and glycolytic enzymes.
Inheritance of metasomal pile colour variation in the bumble bee Bombus rufocinctus Cresson (Hymenoptera: Apidae)
Authors: Owen Robin E. , Plowright R. C.
Published: March 2009

The bumble bee Bombus rufocinctus Cresson exhibits two metasomal pile colour dimorphisms. One involves the expression of either red or black pile on terga 2 and 3, and the other, yellow or black pile on terga 4 and 5; thus, four phenotypes are possible. Data gathered from 107 colonies showed that the dimorphisms have a genetic basis and are independent, yet neither can be accounted for by a single gene locus. The simplest hypothesis to account for the red/black dimorphism is that of two interacting gene loci. Geographical variation of morph frequencies in queens is also described.
Black bear predation of white-tailed deer neonates in the central Adirondacks
Authors: Mathews Nancy E. , Porter William F.
Published: March 2009

Bear predation has recently been recognized as a significant mortality factor affecting free-ranging cervid populations in North America. This report documents three probable incidents of black bear predation on neonate white-tailed deer in the central Adirondack Mountains of New York during June of 1986 and 1987. Black bear predation on free-ranging white-tailed deer has not been previously reported in the northeastern United States.
Habitat separation in tortoises and the consequences for activity and thermoregulation
Authors: Wright J. , Steer E. , Hailey A.
Published: March 2009

Habitat use, daily activity times, and body temperatures of sympatric Testudo hermanni and Testudo graeca in summer were studied at four coastal sites in northeastern Greece. There was significant habitat separation at each site, with T. graeca occupying more open habitat. The two species had similar daily activity periods and body temperatures in habitats of similar structural complexity, coastal heath and mixed heath. Testudo hermanni occupying pine plantations and broadleafed woodland had lower body temperatures, and morning and evening activity periods shifted towards midday, compared with sympatric T. graeca in coastal heath. Habitat separation was studied throughout the year at one site, where T. hermanni were absent from coastal heath in spring; however, some T. hermanni moved into this habitat in summer. Testudo graeca occupied only coastal heath all year, so that habitat separation was least in summer. Less movement of T. hermanni into coastal heath occurred in a dry year, decreasing competition during periods of low food supply. The distribution of T. graeca in northern Greece is described. It is an eastern species which occupies a variety of habitats in Asia Minor, where it is the only tortoise. There is a cline of habitat use, such that moving westwards, T. graeca becomes progressively limited to more open habitats; the other habitats are occupied by T. hermanni. This pattern is discussed in relation to the evolutionary history of Mediterranean tortoises.
Seasonal aspects of sodium, potassium, and water balance in the predaceous diving beetle Dytiscus verticalis
Authors: Frisbie Malcolm Pratt , Dunson William A.
Published: March 2009

A previous study showed that food availability i the laboratory can dramatically affect sodium balance of the predaceous diving beetle Dytiscus verticalis. Because this species inhabits small ponds that dry up in the summer, it seemed likely that wild beetles would undergo annual changes in ody ion content. Seasonally collected predaceous diving beetles were analyzed for dry body mass, body water, body sodium and potassium, hemolymph sodium concentration, and hemolymph osmolality. Beetles varied in all characteristics over a 16-month period, and variation was seasonally cyclic for body water, body sodium, hemolymph sodium, and hemolymph osmolality, but not for dry mass and body potassium. A laboratory experiment and two field-enclosure experiments determined possible mechanisms underlying these cycles. Beetles in enclosures with food had greater dry mass than nonfed beetles in enclosures, but not greater than that of wild beetles. The number of tadpoles killed by beetles in enclosures correlated well with beetle dry mass. Because food availability directly affects dry mass, wild beetles must not suffer seasonal periods of food limitation. Body sodium and potassium levels also appear related to food availability, but not closely enough to explain the seasonal variation in sodium, the nonseasonal variation in potassium, and the nonparallel variation in the two cations. Food intake can be important for increasing both hemolymph sodium concentration and hemolymph osmolality, but these characteristics can be regulated independently of food intake and of each other. Seasonal variation in hemolymph sodium was out of phase with body sodium variation, suggesting that sodium supply is not the cause of hemolymph sodium cycles. Hemolymph osmolality was greatly increased in winter months, perhaps reflecting elevated levels of free amino acids in the hemolymph.
Pre-hatch and post-hatch brood amalgamation in North American Anatidae: a review of hypotheses
Authors: Eadie John McA. , Kehoe F. Patrick , Nudds Thomas D.
Published: March 2009

Two forms of brood amalgamation occur frequently in several species of North American waterfowl: (i) pre-hatch brood amalgamation, whereby a female lays her eggs in the nest of another female and the recipient thereafter provides all further care of the eggs and resulting offspring, and (ii) post-hatch brood amalgamation, whereby a female abandons or loses her young to another female after hatch, and the recipient subsequently tends the foster young. Some authors have viewed these behaviours as accidental or aberrant and of little evolutionary significance. More recently, a number of alternative hypotheses have been suggested. However, few of these hypotheses have been contrasted as viable alternatives and tested in the field, largely because an appropriate theoretical framework is lacking. We analyze the frequency of occurrence of brood amalgamation in North American anatids. We also review the hypotheses that have been proposed to explain these behaviours and erect a theoretical framework which applies to the evolution of both pre-hatch and post-hatch brood amalgamation, and which may apply to species other than those of the Anatidae. Finally, we show that the occurrence of brood amalgamation in North American waterfowl may be associated with low relative resource availability and K-type life-history traits.
Body temperature patterns in black-tailed prairie dogs in the field
Authors: Bakko Eugene B. , Porter Warren P. , Wunder Bruce A.
Published: March 2009

Body temperatures (Tb) of black-tailed prairie dogs (Cynomys ludovicianus) were monitored in the field for 1 year. A daily Tb rhythm was evident during all months that animals were monitored. Diurnal high Tb was always greater than nocturnal low Tb. An annual Tb pattern was evident with summer Tb > winter Tb. The maximum range in Tb over the year was 5.8 °C, between August diurnal Tb (39.3 °C) and January nocturnal Tb (33.5 °C). The greatest difference between average high and low Tb in 1 month occurred in January (2.8 °C). Torpor was never observed. The lowest recorded Tb in any individual animal was 31.0 °C during nighttime hours in January. Males exhibited higher Tb than females at all hours during the prebreeding period in January, while females showed greater Tb than males during the breeding period in February for 15 of 24 h. Significant differences in Tb were not observed between males and females at other times of the year. The daily and annual Tb patterns observed result in energy and water savings.
Distinctive vocalizations from mature male sperm whales (Physeter macrocephalus)
Authors: Weilgart Linda S. , Whitehead Hal
Published: March 2009

Groups of sperm whales (Physeter macrocephalus) were tracked acoustically off the Galapagos Islands between February and April 1985. In total, 716 h were spent in visual or acoustic contact with the whales, during which time vocalizations were recorded for 5 min/h. Distinctive loud, ringing clicks, called "slow clicks," were highly correlated with the presence of mature male sperm whales. Slow clicks were distinguished from usual clicks by their slower repetition rate or interclick interval, their longer duration, and, usually the presence of intensity peaks at about 1.8 and 2.8 kHz. Between clicks of individual males (identified by photographs of natural markings), there were differences both in interclick intervals and in the pattern of emphasized frequencies. These differences, however, were not distinct enough to allow us to reliably distinguish one male's clicks from those of another. We hypothesize that slow clicks may be a sign of a mature or maturing male and may inform other sperm whales on the breeding grounds of its competitive ability and maturity.
Limiting effects of snow on seasonal habitat use and diets of caribou (Rangifer tarandus groenlandicus) on Coats Island, Northwest Territories, Canada
Authors: Adamczewski J. Z. , Gates C. C. , Soutar B. M. , Hudson R. J.
Published: March 2009

The insular population of barren-ground caribou (Rangifer tarandus groenlandicus) on Coats Island, Northwest Territories, is ultimately limited by winter food resources. This study was undertaken to assess forage biomass available during summer and to determine the effects of snow on forage availability in winter. Vegetation was low in density and diversity, but provided ample forage of high quality in summer for the 2000–2500 caribou existing on the island. Aboveground green biomass averaged only 50–60 g∙m−2 in mesic and wet meadows, the most productive habitats. Caribou fed almost exclusively in meadows throughout the snow-free period; willows (Salix spp.) constituted 80–90% of rumen contents in caribou collected during the summer. Lichens were scarce and were a major food only at the beginning and end of winter. During mid and late winter, hard-packed snow averaged 4000–9000 g∙cm−2 in hardness and 50–80 cm in depth on all low-lying vegetation. Under these conditions, caribou cratered only where snow was less than 10–20 cm deep; consequently feeding was limited to the slopes of wind-blown ridges and the tops of high-centre polygons. Forage available under these winter conditions was drastically reduced in quantity and quality compared with forage available in summer. During winter 1983 – 1984, snow accumulated rapidly and prolonged deep snow cover was associated with high calf mortality.
The influence of wax deprivation on temporal polyethism in honey bee (Apis mellifera L.) colonies
Authors: Fergusson Linda A. , Winston Mark L.
Published: March 2009

Various levels of wax deprivation in honey bee (Apis mellifera) colonies induced shifts in the temporal pattern of division of labour in worker honey bees. The most extreme wax stress induced an earlier onset of foraging, and an increase in comb building and the production of wax scales. Moderate wax stress induced only an increase in comb building and production of wax scales. No significant differences in development of hypopharyngeal gland acinal diameter were found, suggesting that production of wax and brood food and associated behaviour patterns develop and decline independently. The graded changes in behavioural response to various levels of stress found in this study support the concept of a reserve labour force in honey bee colonies, which can respond to stress through shifts in caste ontogeny.
Vitamin A modification of the positional information of blastema cells during limb regeneration in the axolotl Ambystoma mexicanum
Authors: Scadding Steven R.
Published: March 2009

Vitamin A is known to cause proximodistal duplication of parts of the limb during limb regeneration in amphibians. The objective of this study was to investigate the nature and location of the cellular changes induced by vitamin A when it causes this duplication in the axolotl Ambystoma mexicanum. When axolotls were treated with retinol palmitate by immersion for 14 days before limb amputation, proximodistal duplications were still observed in subsequent regenerates of limbs amputated after vitamin A treatment was discontinued. This observation suggests that some characteristic of the cells is changed by vitamin A and that exogenous vitamin A need not be present while the limb is regenerating. When a limb that was induced to undergo proximodistal duplication by vitamin A was reamputated 49 days later through the original mid radius–ulna amputation plane, it regenerated a limb of normal structure. A regeneration blastema transplanted from a vitamin A treated axolotl to an untreated axolotl regenerated on the host limb stump, producing a limb with proximodistal duplication; this indicates that the blastema cells underwent some change by the early to mid cone stage, which was expressed later when the blastema redifferentiated into a new limb. Conversely, when an untreated blastema was transplanted onto a vitamin A treated axolotl from which the forelimb blastema had been removed, proximodistal duplications developed. This result is interpreted to mean that the stump cells, although morphologically of the radius–ulna level, were proximalized by the prior vitamin A treatment and still displayed proximal positional values, leading to intercalation of missing proximodistal structures. These results are consistent with the hypothesis that vitamin A brings about a temporary change in the positional information of the limb stump and blastema cells, and that when the vitamin A treatment is discontinued, there is a gradual return to normal positional values over a period of several weeks.
Multiannual fluctuations in precipitation and population dynamics of the montane vole, Microtus montanus
Authors: Pinter Aelita J.
Published: March 2009

The montane vole, Microtus montanus, exhibits multiannual fluctuations in population density in northwestern Wyoming. Multiannual fluctuations in precipitation during May were also observed in the area. For data from the past 19 years, there is a significant negative correlation (r = −0.61, p < 0.01) between precipitation during May and vole population dynamics. Furthermore, there was a correlation between cycle phases of May precipitation and of population density. Peak precipitation in May (1970, 1974, 1977, 1980, 1984) was correlated in the same year with the decline phase in the population cycle. A trough in the May precipitation cycle (1969, 1973, 1976, 1979, 1983, 1985) was correlated in the same year with a population peak. It is hypothesized that spring precipitation may contribute to the population dynamics of Microtus montanus in north-western Wyoming by influencing the survival and reproductive success of these rodents at a critical time, the onset of the breeding season.
A review of primary setae and pores on legs of larval Dytiscidae (Coleoptera)
Authors: Nilsson Anders N.
Published: March 2009

Based on the study of 88 species of Dytiscidae, the number, shape, and position of setae and pores present on legs of first-instar larvae are described. Differences between genera, tribes, and subfamilies are emphasized. Observations from four other adephagan families are included for the establishment of the ancestral system of the family Dytiscidae. Within this family, the subfamily Hydroporinae shows the smallest deviation from the ancestral system: in Laccornis oblongus (Steph.) only the absence of a single seta on the trochanter. When possible, the ancestral setae and pores are homologized for the studied taxa. Within the Adephaga, the Dytiscidae is characterized by the presence of 10 or more primary setae on the femur and by the submedian or distal position of the first ancestral seta on the tibia. The most important characters found are presented in a dichotomous key and the polarity is determined for a set of 13 characters. The character distribution is presented and some problems with respect to phylogeny are discussed.
Some aspects of reproduction in a Lake Erie population of Blanding's turtle, Emydoidea blandingii
Authors: MacCulloch Ross D. , Weller Wayne F.
Published: March 2009

A Lake Erie population of Emydoidea blandingii produced clutches of slightly greater relative mass than those of other emydids. Regression analyses showed that both clutch mass and relative clutch mass were significantly related to both female mass and female size, while clutch size was also related to female size. Mean egg mass was not related to either clutch size or female size.
Cardiac growth in rainbow trout, Salmo gairdneri
Authors: Farrell A. P. , Hammons A. M. , Graham M. S. , Tibbits G. F.
Published: March 2009

Relative ventricular mass, percent compact myocardium, total protein, DNA content, and myocyte size were determined for rainbow trout, Salmo gairdneri, ranging in size from 10 to 2000 g. Ventricular mass, ventricular total protein, and DNA content increased linearly with body size. The DNA to protein ratio was reduced slightly over a 100-fold range of body size. Myocyte size increased with heart size. However, the estimated 1.7-fold increase in myocyte volume for a 10-fold increase in heart weight was incompatible with a corresponding 10-fold increase in total protein. Since DNA content increased 10-fold it is suggested that long-term cardiac growth in rainbow trout involves both hyperplasia and hypertrophy.
Epizootiology of blood parasite infections in passerine birds from central New Jersey
Authors: Kirkpatrick Carl E. , Suthers Hannah B.
Published: March 2009

One or more genera of hematozoa were found in blood smears of 204 (29.3%) of 697 birds representing 59 species. Parasites included Leucocytozoon spp. (16.6% prevalence), Haemoproteus spp. (9.9%), Plasmodium spp. (3.0%), Trypanosoma spp. (4.2%), and microfilariae of filariid nematodes (1.0%). Of 353 birds (48 species) tested for trypanosomiasis by blood culture, 141 (39.9%) were found to be positive. Several new host–parasite associations were identified. Prevalences were lowest in the summer and highest in the spring. During the summer, hatching-year birds were found to be infected less frequently than were older birds. Ground-feeding birds were infected with Leucocytozoon spp. at a significantly higher rate than were birds that characteristically feed above ground. Although the vertical stratum preferred for foraging was significantly associated with that of nesting, no significant association between preferred nesting stratum and prevalence of Leucocytozoon spp. infection among locally breeding birds was found. The results of this study, when compared with those of others, indicate that the epizootiology of avian hematozoan infections may vary greatly according to the locality studied. An examination of the effects of blood sampling (whether by nail clipping or jugular venipuncture) on the birds revealed no significantly adverse effect of sampling on bird survival.
Foraging dive patterns of humpback whales, Megaptera novaeangliae, in southeast Alaska: a cost–benefit analysis
Authors: Dolphin William Ford
Published: March 2009

The foraging behavior of humpback whales (Megaptera novaeangliae) summering in southeast Alaska was studied from 1979 to 1984 using surface observations, a 120-kHz echo sounder, and remotely operated underwater cameras. Considerations of foraging costs as well as profits appear to play a dominant role in determining feeding dive patterns of the whales. The energy costs of diving, based on observed blow rates, estimated tidal volume, and O2 extraction efficiency, have previously been shown to increase with increasing depth of dive during foraging episodes. Time spent diving into and returning from a prey patch, and time spent at the surface recovering from a dive represent the time costs of foraging. The percentage of time available for actual capture of prey decreased with increasing depth of dive. Thus, time and energy costs were highly correlated with the depth of the target prey patch. In conjunction with acoustic scans, the underwater cameras made possible the accurate determination of potential prey patch depths, densities, and vertical extent. Prey patches were ranked using a derived weighted density value and associated time and energy expenditure required of the whales to feed upon the patch (viz., gain–cost representation). Foraging models incorporating prey patch density value and time and energy costs of diving resulted in the best fit when compared with observed foraging patterns of the humpback whales.
Baroreceptor activity in muskrats (Ondatra zibethica) during nasal stimulation
Authors: Douse M. A. , Jones David R.
Published: March 2009

Nasal stimulation with water (simulated dive) in anesthetized muskrats (Ondatra zibethica) caused a significant increase in cardiac interval (209 ± 8 to 1370 ± 280 ms; mean ± SE) and decrease in mean arterial blood pressure (86 ± 8.6 mmHg to 75.7 ± 7.9 mmHg; 1 mmHg = 133.32 Pa). Baroreceptor activity, recorded from the peripheral end of a cut sinus nerve, stopped during the prolonged initial diastolic interval and in 3 of 10 fibres was absent for the first three heartbeats. Chemoreceptor activity did not change at the start of the nasal stimulation. As nasal stimulation continued, mean arterial blood pressure significantly increased (to 118.1 ± 9.5 mmHg), while cardiac interval decreased (to 740 ± 102 ms). This resulted in an increase in baroreceptor activity comparable with that seen during a similar increase in blood pressure in a pressor test. An increase in chemoreceptor activity also occurred during the latter part of nasal stimulation. Two types of efferent activity were recorded from the central end of a cut sinus nerve. One efferent responded to nasal stimulation with an immediate increase in neural activity, while activity of the other efferent halted. These responses would be expected to inhibit rather than foster baroreceptor activity in the intact nerve. The results suggest that there is no facilitation of the baroreflex engendered by changes at the receptor level that might contribute to the initiation of the dive bradycardia.
The occurrence, structure, and development of microbranchiospines among the tilapias (Cichlidae: Tilapiini)
Authors: Beveridge M. C. M. , Briggs M. R. P. , Northcott M. E. , Ross L. G.
Published: March 2009

The microbranchiospine morphology in a range of tilapiine species belonging to the three principal genera (Oreochromis, Sarotherodon, and Tilapia) was investigated using light and scanning electron microscopy. The structure and development of the microbranchiospines is described in detail; significant differences in presence, number, and morphology are observed between species and between size classes. The systematic value of microbranchiospines is also briefly discussed.