bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of parasitism by Romanomermis culicivorax (Nematoda: Mermithidae) on growth and development of Aedes vexans (Diptera: Culicidae) in laboratory and field tests
Authors: Galloway T. D. , Brust R. A.
Published: March 2009

Parasitism by Romanomermis culicivorax caused symptoms typical of starvation in Aedes vexans larvae in both field and laboratory experiments. Infected larvae were reduced in size, moulting at each instar was delayed, there was a failure to develop significant fat body, and secondary pigmentation occurred in later instars. Excluding samples taken after the onset of pupation of uninfected larvae, mean percent infection ranged from 7.2 to 18.8, 12.4 to 24.8, 9.2 to 23.2, and 38.0 to 49.0% when preparasites were applied at 10 000, 20 000, 50 000, and 100 000 m−2 to artificial field pools, respectively. Of 2786 parasitic juvenile nematodes encountered in dissected larvae during the field trial, 2.0% were melanized.
Isolation and purification of Eimeria bovis (Apicomplexa: Eimeriidae) first-generation merozoites
Authors: Reduker David W. , Speer C. A.
Published: March 2009

By using a simple procedure involving meront disruption, centrifugation, and a nylon wood column, large numbers of viable Eimeria bovis first-generation merozoites were obtained from experimentally infected calves. More than 109 highly purified merozoites were obtained from a single calf inoculated 15.5 days earlier with 1.5 × 106 sporulated oocysts of E. bovis.
Synchronous diving by surf scoter flocks
Authors: Schenkeveld L. E. , Ydenberg R. C.
Published: March 2009

We studied the diving and surfacing synchrony of foraging flocks of wintering surf scoters (Melanitta perspicillata). Our data support the hypothesis that synchronous diving is an adaptation that reduces kleptoparasitism by glaucous-winged gulls (Larus glaucescens), which frequently attend foraging flocks. We developed a statistical method for measuring and comparing synchrony between flocks, and applied it to videotape records of 30 flocks. The results show that diving and surfacing are highly synchronous, and that there is a large variation between flocks in the degree of synchrony exhibited. The most pronounced effect is for surfacing synchrony to be higher in the presence of gulls. This seems to arise because individual birds curtail their dives so that less synchrony is lost between diving and surfacing during a group dive. This curtailment of dive length may lead to a reduction in the average size of prey captured.
Social behaviour of the golden-mantled ground squirrel (Spermophilus lateralis)
Authors: Ferron Jean
Published: March 2009

The social interactions of golden-mantled ground squirrels (Spermophilus lateralis) observed during a 2-year study in the Rocky Mountains of Alberta under natural conditions are described and quantitatively analyzed. Agonistic interactions were common for all age and sex groups, except among littermates before dispersal. Among adults, cohesive and recognitive behaviours were restricted almost exclusively to male–female interactions. For young, cohesive and recognitive behaviours occurred with other young (mainly littermates) and with the mother. This species can be categorized as "asocial" according to G. R. Michener's classification of social organization in ground squirrels.
The effects of adult removal on dispersal of yearling yellow-bellied marmots
Authors: Brody Alison K. , Armitage Kenneth B.
Published: March 2009

The relative importance of adult–yearling interaction and individual behavioral phenotypes on dispersal of yearling yellow-bellied marmots was investigated. Two marmot colonies near Gothic, Colorado, were studied; one was treated as an experimental colony from which all adults were removed, while the second was left undisturbed. Analysis of dispersal patterns and behavioral observations indicated that agonistic behavior between adults and yearlings is not necessary for dispersal to occur. Dispersal of male yearlings appears to be independent of adult–yearling interactions, although dispersal of female yearlings probably is mediated by social interactions. Individual behavioral phenotypes could not be used to predict which animals dispersed nor the relative timing of their departure. Dispersal can be viewed as an important mating strategy; for yearling males it is likely to be the only option available for reproductive success.
The effect of temperature on rate of egg and larval development in populations of Argia vivida Hagen (Odonata: Coenagrionidae) from habitats with different thermal regimes
Authors: Leggott Mark , Pritchard Gordon
Published: March 2009

The hypothesis was tested that isolated populations of Argia vivida living in habitats with different thermal regimes would show similar rates of egg and larval development when reared at any constant temperature. Eggs from three populations developed and hatched normally over the temperature range 12.5–32.5 °C, but development rates at 15 and 20 °C were faster in a population from a habitat with daily and annual fluctuations in temperature (Deep Creek, Idaho) than in a population from a more stable geothermal regime (Banff, Alberta), which were in turn faster than in a population from a geothermal site with damped annual fluctuations (Albert Canyon, British Columbia). However, differences between slope or intercept values for the regressions of development time on temperature from the three sites were not statistically significant. Growth rates for Deep Creek larvae were also generally higher than for Banff larvae at all temperatures in all instars, but few of these differences were statistically significant. An estimate of 2600 degree-days above 11.25 °C for completion of egg and larval development leads to prediction of a 1-year life cycle at Banff, a 2- or 3-year life cycle at Deep Creek, and a 3-year life cycle at Albert Canyon.
Proventricular lesions associated with natural and experimental infections of Dispharynx nasuta (Nematoda: Acuariidae)
Authors: Rickard Lora G.
Published: March 2009

Dispharynx nasuta (Rudolphi, 1819) was found in the proventriculus of 7 of 11 species of birds examined from Florida. Raised lesions with multifocal petechial hemorrhages, excess mucus, mononuclear infiltrate, and epithelial desquamation were consistently seen in these birds. Nematode larvae originating from eggs obtained from a northern cardinal, Cardinalis cardinalis (L.), were fed to an adult brown-headed cowbird, Molothrus ater (Boddaert), and mature adults established within the proventriculus. The lesion produced was similar to those found in the naturally infected birds. Nematode larvae originating from eggs obtained from a blue jay (Cyanocitta cristata (L.)), American crow (Corvus brachyrhynchos Brehm), boat-tailed grackle (Quiscalus major Vieillot), northern cardinal, and wild turkeys (Meleagris gallopavo (L.)) were fed to young broad-breasted white domestic turkey poults. Larvae originating from northern cardinal and wild turkey established in the domestic turkeys; however, mature adults were found in only one bird after 12 weeks. Proventriculi from the domestic turkeys had a mixed mononuclear and granulocytic infiltrate, villar necrosis, and abscesses in the submucosa.
Electrophoretic and hybridization comparison of Glossina morsitans morsitans, G. m. centralis, and G. m. submorsitans (Diptera: Glossinidae)
Authors: Gooding R. H.
Published: March 2009

Two colonies of Glossina morsitans morsitans Westwood, two colonies of Glossina morsitans submorsitans Newstead, and one colony of Glossina morsitans centralis Machado, each originating from a different geographic location, were compared genetically and by their ability to hybridize. There were marked asymmetries in results of intersubspecific hybridization. Most F1 males were sterile but most F1 females were fertile. Nei's mean genetic identity (based on 12 loci) and four hybridization indices (based upon proportion of females fertilized, puparia produced per fertilized female, F1 adults per fertilized female, and proportion of females fertilized in backcross experiments) yielded the same results: intrasubspecific similarities are greater than intersubspecific similarities, and G. m. centralis is more similar to G. m. morsitans than it is to G. m. submorsitans. Evidence is presented indicating that a phenogram based upon allele frequencies is as good as phenograms based upon hybridization as a means of representing relationships among tsetse flies.
A parasite survey of juvenile chum salmon (Oncorhynchus keta) from the Nanaimo River
Authors: Whitaker D. J.
Published: March 2009

The sequence of parasite acquisition in a cohort of juvenile chum salmon, Oncorhynchus keta (Walbaum), during their first few months of life is presented. Although no parasites were found in fish collected as downstream migrants, six of the species found in fish collected from other locations were of freshwater origin. Marine species were acquired shortly after entrance into the sea and prevalence and intensity increased with time. Ecological factors influencing the acquisition of the different species found are discussed.
Ldh-4 allozyme variability in North American sockeye salmon (Oncorhynchus nerka) populations
Authors: Withler R. E.
Published: March 2009

Allozyme variation at the Ldh-4 locus was surveyed in 66 populations of sockeye salmon (Oncorhynchus nerka) over the North American range of this species. Two alleles, Ldh-4100 and Ldh-4115, were present in populations over the species range, but frequencies of the Ldh-4115 allele exceeding 5% were restricted to some populations in northern British Columbia and Alaska. Ldh-485 present at frequencies less than 10%, was virtually confined to populations of the Skeena River drainage. Likelihood ratio analysis revealed significant variation in Ldh-4 allelic frequencies among major geographic regions, among smaller areas within regions, and among populations within the Nass and Stikine River drainages. Selective and zoogeographic factors which may explain the distribution of the Ldh-4115 allele in North American sockeye populations are discussed.
Redescription of Lophoura gracilis (Wilson, 1919) (Copepoda: Sphyriidae) from Synaphobranchus kaupi in the Northwest Atlantic Ocean
Authors: Hogans William E. , Dadswell Michael J.
Published: March 2009

The mesoparasitic copepod Lophoura gracilis is redescribed from eight female specimens recovered from synaphobranchid eels captured at 600 m on the Scotian Shelf. This is the first documentation of L. gracilis since the original description. We conclude that L. gracilis is a valid species distinct from the other North Atlantic representatives of this genus.
The effect of 17β-estradiol on spontaneous ovulation in the goldfish, Carassius auratus
Authors: Pankhurst N. W. , Stacey N. E.
Published: March 2009

Sexually mature female goldfish were treated daily with 17β-estradiol in oil (2 μg∙g body weight−1) or given a single silastic pellet containing 17β-estradiol (50 μg∙g−1) and held under conditions which promote spontaneous ovulation. Levels of 17β-estradiol were found to be significantly elevated by the treatments during the period prior to ovulation. However, neither of the 17β-estradiol treatments had any effect on gonadotropin levels or the number of fish ovulating. A decline in the level of serum 17β-estradiol does not appear to be a critical requisite for the occurrence of the preovulatory gonadotropin surge in goldfish.
Loss of protein from spermatozoa of Atlantic salmon (Salmo salar L.) because of cryopreservation
Authors: Yoo Bong Y. , Ryan Mary A. , Wiggs A. James
Published: March 2009

Proteins of Atlantic salmon (Salmo salar L.) spermatozoa were lost into the seminal fluid during storage at −80 °C. Addition of glycerol or dimethylsulfoxide reduced but did not completely prevent loss of sperm proteins. Of the two, glycerol more effectively fostered retention of sperm proteins, especially those of higher molecular weight. Some of the proteins lost during storage were surface labelled via lactoperoxidase-mediated iodination. More protein species were labelled in frozen than in fresh spermatozoa. The massive loss and extensive labelling of sperm proteins with 125I are taken together as an indication of damage to salmon sperm membranes during freezing, storage, and thawing.
Architecture of the pectoralis muscle of the Japanese quail (Coturnix japonica): histochemical and ultrastructural characterization, and distribution of muscle fiber types
Authors: Rosser B. W. C. , George J. C. , Frombach S. K.
Published: March 2009

The muscle fibers in the pectoralis muscle of the Japanese quail (Coturnix japonica) are classified as fast-twitch glycolytic (FG), fast-twitch oxidative-glycolytic (FOG), and slow-tonic on the basis of their histochemical and ultrastructural characteristics. There is an increasing proportion of FOG/FG fibers along a superficial to deep gradient throughout the entire belly of the muscle. Slow-tonic fibers are present in low numbers, and are restricted to a tiny area located in the deepest fasciculi of the cranial third of the muscle. This distribution of muscle fiber types is typical of those vertebrate muscles adapted to a locomotory function. The slow-tonic fibers are alkali-stable and acid-stable when preincubated for myofibrillar adenosine triphosphatase (mATPase) activity. Slow fibers in the chicken pectoralis and mouse soleus muscle, both types previously described as alkali-labile, acid-stable for mATPase activity, cannot be distinguished from each other or Japanese quail slow-tonic fibers on the basis of several ultrastructural characteristics: Z-line width, metabolic differences, or fusion of myofibrils. While mammalian slow fibers have one large motor end plate, all avian slow fibers have small multiple motor end plates. Mammalian slow fibers are slow-twitch, and avian slow fibers are probably slow-tonic. More complex secondary synaptic clefts distinguish mammalian from all avian fiber types.
A quantitative analysis of ferric iron in butterflyfish teeth (Chaetodontidae, Perciformes) and the relationship to feeding ecology
Authors: Motta Philip Jay
Published: March 2009

Despite much work on the iron compounds found on invertebrate and vertebrate teeth, no interspecific quantitative analyses of iron compounds in fish teeth have ever been conducted, nor in any vertebrate has such a study related the iron concentrations to the feeding ecology. This study reveals that ferric iron exists on the tooth cap of eight species of chaetodontid butterflyfishes. The iron layer appears early in tooth development and is darkest, and presumably more concentrated, towards the tooth tip. There are significant differences among the eight species, with those that feed on harder prey having more iron than those that feed on softer-bodied prey. Furthermore, there exist differences among the species that correlate with the degree of morphological specialization for feeding on hard-bodied prey. The iron layer, which has been shown by others to be harder than the underlying enameloid, probably represents a specialization to harden the teeth, resisting abrasion and cracking.
Activity budgets and group size of caribou during spring migration
Authors: Duquette Laurel S. , Klein David R.
Published: March 2009

Activity budgets and group size of caribou were described throughout the early spring migration in 1982 and 1983. Pregnant cows were the predominant cohort under observation. Activity budgets and group size of migrating caribou are compared with data from nonmigrating caribou and reindeer to test the hypothesis that the spring migration of pregnant cow caribou will occur with minimal disruption of the normal grazing pattern to ensure maintenance of body condition. The average proportion of time migrating caribou spent feeding, lying, standing, and walking was 61, 28, 1, and 9%, respectively, in 1982 and 64, 24, 1, and 11%, respectively, in 1983. Grazing was consistently the dominant activity throughout migration while lying time was negatively correlated with walking time. Migrating caribou spent more time grazing and walking and less time standing and lying than nonmigrating caribou and reindeer during this season. Discrete caribou groups were difficult to identify because mixing of caribou between groups was common. Groups were identifiable at four study sites and group size ranged from 8 to 393 caribou. At three study sites, caribou were associated with aggregations of 500+ animals. Large social aggregations may be important for stimulating migratory movements through the process of social facilitation.
A simple model of optimal territory size for drift-feeding fish
Authors: Grant James W. A. , Noakes David L. G.
Published: March 2009

A simple model of optimal feeding-territory size is developed for drift-feeding fish by modifying Hixon's (M. A. Hixon. 1980. Am. Nat. 115: 510–530) model for energy maximizers. Our model predicts that territory size should vary directly with food density when the fish is subject to time constraints, and directly with intruder pressure when the fish is subject to processing constraints. These unique predictions arise because any food not immediately eaten is carried downstream out of the territory. Our model also predicts that territory size should vary inversely with intruder pressure when the fish is subject to time constraints, and inversely with food density when the fish is subject to processing constraints. The qualitative predictions of the model are not affected by changes in the shape of the cost or benefit curves, unlike other simple models. A review of studies of salmonid territory size indicates that most are inadequate tests of the model because (i) food was not presented in a natural manner, (ii) ration levels were not controlled at levels that were clearly above or below a maximum daily ration, and (iii) the confounding effects of intruder pressure were not controlled. Future experiments will have to incorporate these factors to distinguish between the competing predictions posed by this and previous models.
Habitat use by foraging insectivorous bats
Authors: Furlonger C. L. , Dewar H. J. , Fenton M. B.
Published: March 2009

We monitored echolocation calls to measure the activity of insectivorous bats at study sites in southwestern Ontario during the summer of 1985, relying on feeding buzzes to identify foraging activity. Eptesicus fuscus was the most common and widespread species in the area, while Lasiurus cinereus and Lasiurus borealis were widespread. Species in the genus Myotis were more restricted in their distribution, being more common in an area with potential hibernacula. None of the species foraged exclusively in one habitat and all species exploited concentrations of insects around lights. Only E. fuscus made significant use of lights as foraging sites in urban areas while in town and rural areas all of the species foraged around lights.
Morphological differences among females of four species of stickleback (Gasterosteidae) from New Brunswick and their possible ecological significance
Authors: Delbeek J. Charles , Williams D. Dudley
Published: March 2009

Fifteen morphological characters were measured from females of four species of stickleback (Gasterosteidae) collected from the east coast of Canada. Significant differences were found between the species for 12 of these characters. All four species were found to differ significantly in their gill raker number. Gasterosteus had the greatest number of gill rakers followed by Pungitius and Apeltes. A significant negative correlation between gill raker number and prey size was demonstrated; Gasterosteus fed to a greater extent on smaller, planktonic prey, while Pungitius and Apeltes fed on larger, benthic prey. Gasterosteus were found also to have larger pectoral and caudal fin areas, and shorter but wider caudal peduncles, than Pungitius and Apeltes. The larger fins of Gasterosteus are probably a reflection of their increased swimming ability in response to the pelagic phase of their life histories. The longer, narrower caudal peduncles of Pungitius and Apeltes are probably an adaptation to life in weedy habitats where high manoeuverability is desired. The significance of these characters, as well as mouth height, pelvic fin length, body depth, gut length, head length, and pectoral fin length, are further discussed with respect to observed differences in diet, habitat, and life histories.
A study of Enterogyrus sp. (Monogenea) parasitizing the foregut of captive Pomacanthus paru (Pomacanthidae) in Georgia
Authors: Cone D. K. , Gratzek J. B. , Hoffman G. L.
Published: March 2009

A species of Enterogyrus Paperna, 1963 (Monogenea: Ancyrocephalidae) parasitizing the foregut of a captive Pomacanthus paru (Pomacanthidae) in Georgia was studied in situ both histologically and with scanning electron microscopy. The worms are found at the junction of the esophagus and stomach and arrange themselves with their main body axis directed perpendicular to longitudinal folds in the foregut wall. They cling to host tissue principally by blades of the pair of large dorsal hamuli and apparently rely little on the action of the pair of small ventral hamuli and the 14 marginal hooks. It is argued that this adhesive attitude allows unrestricted movement when peristaltic waves move along the gut and the worm thereby maintains a stable footing. The body tegument is unusually thick (2 to 5 μm) for the worm's size. Dorsally it is smooth and devoid of microvilli. Ventrally it is thrown into transverse folds having small microvilli and unique round to oval papillae that measure up to 7 μm in diameter. Evidently the modified tegument is an adaptation to life in the foregut, possibly serving to protect worms from digestive enzymes. The study represents the first report of Enterogyrus from a marine host.
Dive behavior and estimated energy expenditure of foraging humpback whales in southeast Alaska
Authors: Dolphin William Ford
Published: March 2009

The ventilatory and dive behaviors of humpback whales were studied during July–September 1982–1984 in the area of Frederick Sound, Alaska. Oxygen utilization and energy expenditure were estimated based upon observed blow rates and calculated tidal volume during foraging at identified depths between 0 and 120 m. Duration of dive, duration of surfacing, and number of blows per surfacing were all strongly correlated with depth of dive. Dives tended to be short (57.4% were less than 2.8 min in duration) and shallow (84.6% were to depths of less than 60 m). Humpback whales dived and returned to the surface directly, which allowed for calculation of the time spent at depth in different diving situations. The percent of time spent at the surface tended to increase with increasing depth of dive and exhibited a marked increase at depths surpassing 60 m. The lowest oxygen utilization rate was found during dives 41–60 m in depth. Oxygen utilization per ventilation–dive cycle was strongly and positively correlated with depth of dive. It is postulated that dives to depths of 41–60 m (4–6 min in duration) represent the aerobic limit of humpback whales. Dives exceeding these limits result in anaerobic metabolism and, consequently, an inefficient use of time and energy resources.
Dehydration tolerance in Awassi fat-tailed sheep
Authors: Laden S. , Nehmadi L. , Yagil R.
Published: March 2009

Young Awassi sheep were subjected to 5-d periods of complete water restriction in metabolic cages. During water deprivation there were steady declines in food intake and faeces and urine excretion. The blood haematocrit and urine and plasma osmolalities increased. There was a decline in blood and faecal water. As dehydration progressed, urinary excretion of osmotically active substances was greatly reduced. When drinking water was presented following 5 d of restriction it took 24 h to replace water losses and for urine to be excreted. Faecal water did not return to normal within 24 h. The sheep were as capable of withstanding dehydration as the other small desert ruminants that are mentioned in the literature. The dehydrated sheep relied on faecal and renal water conservation to survive. The sheep are not rapid replenishers of water losses, nor are they rapid reabsorbers of water, making their stay at water holes longer than that of goats.
Tissue responses and organogenesis during regeneration in the oligochete Limnodrilus hoffmeisteri (Clap.)
Authors: Cornec Jean-Pierre , Cresp Jean , Delye Paule , Hoarau Fred , Reynaud Georges
Published: March 2009

Ultrastructural study of regeneration initiated by tail amputation in Limnodrilus hoffmeisteri revealed the accumulation and fate of the stimulated cells. It was found that the components involved in regeneration are stem cells or dedifferentiated cells supplied by each layer. Blastocytes that migrate along the nerve cord are responsible for the formation of septa in regenerates, while neuroblasts of epidermal origin give rise to the central nervous system.
Predator–prey interactions in a stream: a combined field and laboratory study of Paragnetina media (Plecoptera) and Hydropsyche sparna (Trichoptera)
Authors: Feltmate Blair W.
Published: March 2009

Substrate size selection, upper and lower substrate surface colonization, and net spinning were examined for the caddisfly Hydropsyche sparna in the presence and absence of the predaceous stonefly Paragnetina media. In the laboratory, I found that when stoneflies were present, caddisflies selected larger substrate and spun fewer nets. Upper and lower surface colonization of substrate did not change as a function of P. media presence. Laboratory findings were consistent with observations made of H. sparna and P. media in the Credit River, Ontario, during midsummer 1983. Based on Hess sample collections, I observed a significant negative correlation between stonefly and caddisfly densities.
Salinity during embryonic development influences the response to salinity of Gasterosteus aculeatus L. (trachurus)
Authors: Belanger Gilbert , Guderley Helga , FitzGerald Gérard J.
Published: March 2009

Individual male sticklebacks established nests, courted females, and cared for their fertilized eggs at 0 or 20‰ salinity. The time to hatching was shorter at 0 than at 20‰. One-week-old fry that hatched in freshwater had a significantly lower mortality after 96 h in freshwater than fry that hatched in brackish water. Fry that hatched at 20‰ grew little in freshwater and had their highest growth rates at 28‰, while fry that hatched at 0‰ showed little variation in growth rates at intermediate salinities and had reduced growth at 28‰. The mean duration of fanning bouts and the total duration of fanning was significantly greater at 0 than at 20‰, particularly toward the end of the incubation period, but the aggressive behavior did not differ between the two hatching salinities.
The next 25 years: vertebrate systematics
Authors: Nelson Joseph S.
Published: March 2009

Systematics, defined here as the study of the evolutionary history of life, plays a vital role in biology. Together with studies of evolutionary mechanisms, it gives special meaning to biology; it is the unifying force in biology. As a result of recent developments in techniques useful to systematics and in philosophical approaches to systematics, it will be possible for vertebrate systematics to make major advances. Comparative morphological studies of extant and extinct species will play the dominant role in our understanding of the overall pattern of vertebrate phylogeny. For extant species, data from immunological, electrophoretic, and amino acid sequence studies will be important, but the major advances will come from studies of mitochondrial DNA and DNA–DNA hybridization. Examples of phylogenetic controversies that should be resolved in the next 25 years concern the following: the ancestral group of jawed vertebrates, the relationships of Latimeria, the ancestral group of tetrapods, the interrelationships of birds and mammals to each other, and the closest living relatives of man. Both cladistic and synthetic classifications will survive; each serves a useful purpose in translating phylogenetic ideas. Systematics, together with evolution, is a fundamental aspect of biology and should be included in the undergraduate program of all biology students; all biology departments should have a research program in systematics involving graduate students and staff. In addition, museums are a vital part of biology departments, in both their teaching and research functions, and their existence within universities must be nourished.
The next 25 years: vertebrate physiology and biochemistry
Authors: Randall David
Published: March 2009

Predicting the future accurately is at best difficult: general trends are often self-evident, specific predictions are often wrong. In the next 25 years in vertebrate physiology and biochemistry I anticipate an increase in the importance of multidisciplinary group approaches, with such groups working on problems of a broad integrative nature. I think that physiology and biochemistry will play a larger role in contributing answers to many of the controversial issues in general biology, for example, enlarging the functional base for evolutionary theory. I think that the administration of science in general is becoming more rigid and research directives more centralized, resulting in less freedom of action for individual scientists in Canada. Vertebrate physiology and biochemistry, however, continue to be very active and will continue to be so over the next 25 years.
Animal decision making and its ecological consequences: the future of aquatic ecology and behaviour
Authors: Dill Lawrence M.
Published: March 2009

It is virtually impossible to predict the next 25 years of research in aquatic ecology and behaviour with any accuracy. However, by identifying those areas that are the current frontiers of the discipline it is possible to guess at the most likely research developments over the next decade. From my own biased perspective, the research programme most likely to be productive in the near future is that of behavioural ecology, which studies, among other things, animal decision making in an ecological context. I focus on situations in which animals must make decisions under conflicting objectives, e.g., to simultaneously maximize net energy intake while minimizing risk of predation. New data on guppies (Poecilia reticulata) are presented and the recent literature is reviewed to support the notion that animals in such situations behave so as to maximize fitness. Habitat choices, ontogenetic habitat shifts, and the phenomena of vertical migration and downstream drift are beginning to be considered in this general evolutionary framework, with novel results, and this trend will undoubtedly continue. Extension of the logic of trade-offs to the community level leads to a number of new insights about the processes that shape community structure, and affirms the need for aquatic ecologists of the future to have a thorough understanding of animal behaviour, and a working knowledge of such tools of evolutionary ecology as optimality reasoning and game theory.
Demography and ecology of the arctic hare (Lepus arcticus) in southwestern Newfoundland
Authors: Hearn Brian J. , Keith Lloyd B. , Rongstad Orrin J.
Published: March 2009

We determined demographic attributes of an arctic hare (Lepus arcticus) population in the Southern Long Range Mountains of Newfoundland. Twenty-four adult hares were livetrapped, radio collared, and monitored from July 1981 through July 1984. From livetrapping and an aerial census we estimated mean density at about 1 adult/km2. A single litter was born annually and natality averaged 3.0 young/female. Mean dates of conception and parturition were 19 April and 8 June, respectively. Annual survival rate of radio-collared adults was 0.78; calculated 1st-year survival rate of juveniles was 0.15. Natural mortality was mainly from red foxes (Vulpes vulpes). One-year-old individuals comprised 18% of 68 adult hares shot in May. Sex ratios were biased towards males in both trapped and shot samples. Summer home range size of three adult females (52–69 ha) averaged half that of three adult males (116–155 ha). Movements increased in March and April with onset of breeding activity. It is unlikely that winter food shortage affected survival, as hares collected in May had both kidney fat and relatively high levels of bone marrow fat. Annual differences in these condition indices were, however, reflected in several reproductive parameters. We hypothesize that the single litter and small litter size which combine to give Newfoundland arctic hares the lowest reproductive potential of any known hare population are a consequence of (i) the late spring that delays onset of breeding until April, and (ii) the shorter day length in April and hence lower gonadotrophin levels at this southernmost limit of distribution. We believe that predation on juveniles is the paramount limitation on growth of this arctic hare population, and primarily responsible for the stabilization at low densities.
Jusheyus shogunus gen. et sp. nov. (Siphonostomatoida: Eudactylinidae), a gill parasite of the bass Polyprion oxygeneios (Percichthyidae) from Coffs Harbour, Australia
Authors: Deets Gregory B. , Benz George W.
Published: March 2009

Jusheyus shogunus gen. et sp. nov. (Siphonostomatoida: Eudactylinidae) is described from female and male specimens found parasitic on gills of the bass Polyprion oxygeneios from Coffs Harbour, Australia. Morphologically the new species is unique in having dorsal styliform processes projecting from the first free thoracic somite. Ecologically the new species is unusual among eudactylinids in being a parasite of teleost rather than elasmobranch fishes.
An ultrastructural and histochemical study of the secretory granules in the salivary gland cells of the Drosophila melanogaster species subgroup: phylogenetic relationships and evolutionary aspects
Authors: Thomopoulos G. N.
Published: March 2009

The morphology of the secretory granules and the distribution of "neutral" complex carbohydrates in these structures of the larval salivary gland cells of six species belonging to the melanogaster subgroup of Drosophila were examined at the ultra-structural level. The secretory granules of each species show a unique morphology. The species of the melanogaster subgroup can be subdivided into two complexes (the melanogaster and the yakuba complexes) on the basis of the existence of filamentous or granular material in their secretory granules. In the former complex belong the species Drosophila melanogaster, Drosophila simulans, and Drosophila mauritiana, whose secretory granules consist mainly of filamentous material, and in the latter complex belong the species Drosophila yakuba, Drosophila teissieri, and Drosophila erecta, whose secretory granules consist of granular material. A phylogeny of the six species, in which D. erecta is regarded as the most primitive, is presented. It is proposed that the morphology of the secretory granules at the ultrastructural level, combined with the distribution of complex carbohydrates in them, can be used as an additional criterion for the classification of the Drosophila species.
Reply to Watson and Moss (1987)
Authors: Bergerud A. T.
Published: March 2009

In our original paper (Bergerud, A. T., Mossop, D. H., and Myrberget, S. 1985. Can. J. Zool. 63: 2240–2248) we presented a precise diagram of two major hypotheses on the mechanics of change in ptarmigan numbers: H1, territorial limitations determine breeding numbers, and H2, breeding success determines breeding numbers. We accepted H2 based on a review of the literature and the reanalysis of 11 population studies. Watson and Moss (Watson, A., and Moss, R. 1987. Can. J. Zool. 65: 1043–1047) have not provided a rebuttal to H2 based on data or reanalysis; we believe their arguments are largely semantic. We have pointed out several weaknesses in their choice of study areas and study populations, the most serious being the problems of ingress and egress that confound an understanding of how reproductive and mortality rates change numbers. Further progress requires that they clarify their views; if they still believe in H1, they should state what they will accept as a valid disproof of their territorial model.
Répartition tissulaire d'acide ribonucléique chez la planaire Dugesia tigrina: étude histochimique au fluorochrome acridine-orange
Authors: Sarnat Naomi Beth , Sarnat Harvey B.
Published: March 2009

The distribution of nucleic acids, particularly of ribonucleic acid, was studied in the organs and cells of the turbellarian Dugesia tigrina, using the fluorochrome acridine orange as a histochemical marker. The cells showing the strongest ribosomal fluorescence are neoblasts and nerve cells with the exception of their axons. Secretory cells such as intestinal epithelial cells and vitelline cells also exhibit an orange–red fluorescence, though not as strong. Muscle fibers, both somatic and pharyngeal, show very little RNA fluorescence. Other organs are intermediate in intensity of fluorescence. This new method may serve as a useful tool for the histochemical study of peptide and protein synthesis in the lower metazoans. Examples of applications are embryonic development and growth, states of nutritional deprivation, and regeneration.
Turnover rates of glucose and lactate in rainbow trout during acute hypoxia
Authors: Dunn J. F. , Hochachka P. W.
Published: March 2009

Turnover rates of glucose and lactate in trout during hypoxic exposure were undertaken to determine the rates of flux of these metabolites into and out of the blood. This measurement provides a more quantitative indication of rates of metabolite flux than do simple concentration values. Specific activity decay curves were obtained from control rainbow trout (Salmo gairdneri) plasma, and from trout subjected to 3 h of hypoxia. Glucose turnover remained constant at 10.7 μmol∙min−1∙kg−1, while lactate turnover increased from 2.8 ± 0.4 μmol∙min−1∙kg−1 to 20.6 ± 6.8 μmol∙min−1∙kg−1. It is argued that the increase in lactate turnover rate emphasizes the fact that anaerobic glycolysis is activated, and that the lack of increase in rates of glucose turnover provides evidence for endogenous fuel sources for glycolysis.
External scarring of whitefish, Coregonus nasus and C. clupeaformis complex, from the western Northwest Territories, Canada
Authors: Reist J. D. , Bodaly R. A. , Fudge R. J. P. , Cash K. J. , Stevens T. V.
Published: March 2009

Up to 40% of whitefish (Coregonus nasus and C. clupeaformis) sampled during spawning migrations from the area of the Mackenzie Delta, N.W.T., had external scars. Percent frequency of scarred individuals varied geographically from the Mackenzie mainstem and tributaries, where 20% were scarred, to Anderson river (2%), Cox Lake (16%), and Alaska (0–7%). Within the Mackenzie system fish captured at mainstem locations had approximately twice the frequency of scarring than did fish from tributary locations. Scars were classified as either slash or round type. Both scar types were located more frequently on the left side of the fishes and below the lateral line. Details of orientation and location on the body provided clues permitting the assignment of putative causation. Small round scars were restricted to locations with connections to the Arctic Ocean and were probably caused by the marine parasitic copepod Coregonicola or by Arctic lampreys (Lampetra japonica). Larger round scars were either the result of attacks by lampreys or by previous gill net capture. Unequal distribution and orientation on the body of slash scars indicated previous capture in gill nets or predation attempts by bears, birds, or piscivorous fishes.
The significance of winter activity by the big brown bat (Eptesicus fuscus): the influence of energy reserves
Authors: Brigham R. Mark
Published: March 2009

I tested the hypothesis that big brown bats (Eptesicus fuscus) found active during winter months may be forced into activity because of reduced energy reserves. I compared the masses and fat reserves of big brown bats found active with inactive (torpid) bats at a hibernaculum, throughout the winter. Active bats were significantly lighter that those in the hibernaculum during the same period. Active bats had significantly lower fat reserves and lean dry mass than inactive individuals. The majority of bats found active were lighter than the predicted mass of bats leaving hibernation in April. The forearm length of active individuals was significantly shorter than inactive bats. Inactive individuals lost mass throughout the winter while there was no significant correlation between the mass of active bats and the date of capture. The data are consistent with the hypothesis that bats may become active at a critically low energy reserve, possibly to find food.
Parasitism of a frugivorous fly, Rhagoletis cornivora, by the wasp Opius richmondi: relationships to fruit and host density
Authors: Juliano Steven A. , Borowicz Victoria A.
Published: March 2009

Recent evidence indicates that characteristics of both host plants and herbivorous insects influence attack of herbivores by natural enemies. We assessed experimentally the effect of fruit density of Cornus amomum (fruits/m3) on percent parasitism of a specialist frugivore, Rhagoletis cornivora (Diptera: Tephritidae), by Opius richmondi (Hymenoptera: Braconidae). We also examined correlations of parasitism by O. richmondi with number and density of R. cornivora (larvae/m3) in the plant. Parasitism of R. cornivora by O. richmondi was not significantly affected by manipulations of fruit density, indicating that relative size of the fruit crop has little effect on parasitism of the frugivore. Percent parasitism by O. richmondi increased with both number and density of developing R. cornivora in the plant. These results indicate that spatial distribution of R. cornivora larvae is related to risk of parasitism. Rate of parasitism of R. cornivora declined from 66.7 to 18.2% over the active season. These spatial and temporal relationships may have influenced the searching and oviposition behavior of R. cornivora.
The effects of Plagiorchis noblei (Trematoda: Plagiorchiidae) metacercariae on the behavior of Aedes aegypti larvae
Authors: Webber R. A. , Rau M. E. , Lewis D. J.
Published: March 2009

Third-instar mosquito larvae (Aedes aegypti (L.)) infected with the metacercariae of the digenean Plagiorchis noblei Park exhibited significant behavioral changes. Larvae infected with more than three metacercariae were less active, spent more time suspended from the surface of the water, and spent less time in the bottom half of the water column than did uninfected control larvae. In contrast, larvae infected with one or two metacercariae were more active and spent less time suspended from the surface of the water. Such lightly infected larvae spent more time in the bottom half of the water column than the more heavily infected larvae. Since cercariae of P. noblei generally settle to the bottom of the water column, lightly infected larvae thus may be rendered more susceptible to superinfection. In contrast, heavily infected larvae may be removed from further exposure. Furthermore, heavily infected larvae may be more susceptible to surface-feeding predators. These behavioral changes of the insect host may facilitate the transmission of P. noblei both to the second intermediate and definitive host.
Dietary niche relationships among cervids relative to winter snowpack in northwestern Montana
Authors: Jenkins Kurt J. , Wright R. Gerald
Published: March 2009

We compared diets of white-tailed deer (Odocoileus virginianus ochrourus), Rocky Mountain elk (Cervus elaphus nelsoni), and Shiras moose (Alces alces shirasi) during two winters in the North Fork of the Flathead Valley, Montana. Diets of white-tailed deer contained the greatest proportions of low-lying evergreen shrubs, as well as high proportions of coniferous browse. Elk selected greater proportions of grasses than did white-tailed deer or moose, whereas moose consumed the greatest proportion of deciduous shrubs. Deep snow in 1982 increased the similarity of diets chosen by white-tailed deer, elk, and moose. In 1982, white-tailed deer and elk consumed more total browse, and moose more coniferous browse, as deep snow covered the preferred forages. Increased dietary overlap and energy limitations suggested a potential for interspecific competition during harsh winters.
Characteristics of successful nest sites for marsh-nesting common terns
Authors: Storey Anne E.
Published: March 2009

The relationship between nest site characteristics and nest success during tidal flooding was studied in six New Jersey colonies of marsh-nesting common terns (Sterna hirundo). Most colonies were on high ground with a northeast water exposure, and almost all nests were on mats of dead vegetation. Terns nested on the thickest areas of the mats and, whether nesting on mats or on the ground, they selected nest sites with low vegetation density. The characteristics of successful nests differed with the height and date of the flood tide, and with wind direction. In the 1975 flood, nests on high ground were more successful, whereas nests in tall grass and on large mats successfully survived tidal flooding in 1976. Because grass height and ground height are negatively correlated in the marsh, it is difficult for the terns to maximize both characteristics when selecting a nest site. The large mats associated with flood survival in 1976 were also associated with higher prédation rates, indicating a further complication in selecting a safe nest site. Data from these floods were compared with floods studied by other researchers to further test whether certain nest site characteristics are associated with nest success in different types of floods.
Phylogenetic analysis of the higher classification of the Nematoda
Authors: Adamson Martin L.
Published: March 2009

Inglis (W. G. Inglis. 1983. Aust. J. Zool. 31: 243–255) divided Nematoda into three classes: the Enoplea, Rhabditea, and Chromadorea. Although most nematologists agree as to the limits of each of these groups, there is much disagreement as to how the groups relate to one another. Some authors group the Chromadorea with the Rhabditea, others group the Chromadorea with the Enoplea, and still others treat the three as independently derived taxa. In the present study I examine characters upon which various versions of the classification are based to identify plesiomorphic and derived character states. These are used to construct a phylogenetic tree using the Wagner algorithm. The analysis suggests that the Enoplea are best treated as the sister group to the Chromadorea–Rhabditea. The Chromadorea appear to be paraphyletic, consisting of several lineages forming a grade between the Enoplea and Rhabditea.
Redescription of Clavellisa cordata Wilson, 1915 (Copepoda: Lernaeopodidae) from anadromous clupeids in eastern Canada
Authors: Rubec L. A. , Hogans W. E.
Published: March 2009

The male and female of Clavellisa cordata Wilson, 1915 are described from the gills of blueback herring (Alosa aestivalis), alewife (Alosa pseudoharengus), and American shad (Alosa sapidissima) collected in New Brunswick. The female differs from the original description in the presence of uropods, the apical armature of the first antennae, second antennae, and first maxillae, the presence of secondary teeth on the mandibles, and several additional processes on the maxillipeds. The male differs in the presence of uropods and in the detailed morphology of the various appendages, in particular the maxillipeds. Distinctive features of Clavellisa spinosa, another species occurring in the northwestern Atlantic, are briefly discussed. Differences between Clavellisa cordata and a closely related species, Clavellisa emarginata, occurring in the northeastern Atlantic, are listed. The present redescription of Clavellisa cordata represents a northern range extension and three new Canadian host records.