bluuebunny/crossref_metadata_2025 huggingface dataset:
Cuticular morphology of larval mountain midges (Diptera: Deuterophlebiidae): implications for the phylogenetic relationships of Nematocera
Authors: Courtney Gregory W.
Published: August 2008

The cuticular structure of larval mountain midges (Diptera: Deuterophlebiidae) is described, with emphasis on cranial and mouthpart morphology. Homologies are suggested for musculature and external features of the head capsule. External morphology of the thorax and abdomen is described, and a system for deuterophlebiid larval chaetotaxy is presented. Also included is a discussion of the feeding behaviour of deuterophlebiid and blepharicerid larvae, and how differing morphological characteristics influence mechanisms of food acquisition. Larval morphology of the Deuterophlebiidae and other Nematocera provides support for (i) a sister-group relationship between the Deuterophlebiidae and Blephariceridae; (ii) a monophyletic Blephariceromorpha (sensu Wood and Borkent) composed of the Nymphomyiidae + (Deuterophlebiidae + Blephariceridae); and (iii) a sister-group relationship between the Blephariceromorpha and Psychodomorpha (sensu Wood and Borkent).
Intrapopulation variation in mineral profiles of feathers of Spruce Grouse
Authors: Bortolotti Gary R. , Szuba Kandyd J. , Naylor Brian J. , Bendell James F.
Published: August 2008

We used instrumental neutron-activation analysis to determine the concentrations of Br, Mn, Cl, Al, and Na in primary feathers 1, 9, and 10 of Spruce Grouse (Dendragapus canadensis) in four jack pine (Pinus banksiana) forests in northern Ontario. Our objective was to see if there were consistent trends in intrapopulation variation of mineral profiles among populations. Except in the case of Na concentration, there were significant sources of variation attributable to age (adult versus chick) and sex in all forests, and there were large differences among study sites. Yearling and adult grouse that recruited to the breeding population differed in the elemental composition of their feathers from long-term residents of the same age. Information on intrapopulation variation, which traditionally has confounded studies of geographic variation, may have useful applications in research and management. If trends are repeatable and predictable, feather profiles may be used to identify the age or sex of a bird and the origin of recruits on a microgeographic scale.
Parasites of arctic grayling, Thymallus arcticus (Pallas), stocked into Michigan lakes
Authors: Muzzall Patrick M.
Published: August 2008

Grayling (Thymallus arcticus) stocked into seven lakes and one river in northern Michigan were examined for parasites in October and November 1987 and 1988. Grayling were 1 + year of age and were in the lakes for at least 140 days. Of 154 grayling examined, 66% were infected with at least one of the following parasites: Crepidostomum sp., Diplostomum sp., Ornithodiplostomum sp., Proteocephalus sp., Cystidicoloides tenuissima, Spiroxys sp., Pomphorhynchus bulbocoll, and Trichophrya sp. Diplostomum sp., Ornithodiplostomum sp., and Po. bulbocolli had high prevalences and mean intensities in three separate lakes. Trichophrya sp. infected a high percentage of grayling from two lakes. Factors associated with these parasites becoming established in stocked grayling are discussed.
Male parental care in a population of Red-winged Blackbirds, 1983–1988
Authors: Beletsky Les D. , Orians Gordon H.
Published: August 2008

The proportion of male Red-winged Blackbirds (Agelaius phoeniceus) among populations that assist females in feeding nestlings is highly variable. We report our observations from a 6-year study of male redwings feeding offspring in a Washington State population, and compare our findings with those from other North American regions. We found that nests at which males fed offspring fledged significantly more young than other nests on the same territories. However, less than 10% of breeding males each year fed nestlings, and it remains unclear why more males do not do so.
Lack of myoglobin function in the isolated perfused buffalo sculpin (Enophrys bison) heart
Authors: Nichols J. W. , Weber L. J.
Published: August 2008

The contribution of myoglobin to cardiac performance and O2 consumption was investigated using an isolated perfused buffalo sculpin (Enophrys bison) heart preparation. Dose–response studies at ambient (150 Torr)(1 Torr = 133.322 Pa) O2 tensions were conducted as a means of selecting an oxidizing agent with high activity toward myoglobin, while minimizing the possibility of toxic side effects. Treatment with 10.0 μM phenylhydroxylamine oxidized greater than 95% of intracellular myoglobin but did not affect pulse pressure, peak dP/dt, or heart rate. The functional importance of myoglobin was investigated by perfusing electrically paced hearts with 10.0 μM phenylhydroxylamine at physiological (32 Torr) O2 tensions. Inactivation of myoglobin by oxidation with phenylhydroxylamine had no effect on cardiac performance or O2 consumption.
The Eimeria (Apicomplexa: Eimeriidae) of Serpentes, with descriptions of three new species from colubrid snakes
Authors: Upton Steve J. , McAllister Chris T.
Published: August 2008

Three new species of Coccidia (Apicomplexa: Eimeriidae) are described from snakes collected in Texas, U.S.A. Oocysts of Eimeria papillosum sp.nov. were found in Salvadora grahamiae lineata and are cylindrical, 32.0 × 18.0 (28.8–35.2 × 16.0–20.4) μm, with an outer wall studded by numerous papules. A micropyle and oocyst residuum are absent but a polar granule is present. Sporocysts are ellipsoid, possess a sporocyst residuum, and lack a Stieda body. Oocysts of Eimeria serpenticola sp.nov. were found in Thamnophis proximus rubrilineatus and are ellipsoid, 20.3 × 17.5 (18.4–22.4 × 15.8–19.8) μm, with a smooth, thin wall. A micropyle and oocyst residuum are absent but a polar granule is present. Sporocysts are elongate and possess a sporocyst residuum and Stieda body. Oocysts of Eimeria striatula sp.nov. were recovered from Virginia striatula and are spherical, 12.5 (11.2–15.2) μm, with a thin wall. A micropyle and oocyst residuum are absent but a polar granule is present. Sporocysts are elongate and possess a Stieda body and few granules within the sporocyst. A table is provided listing the more than 50 named species of eimerians reported to infect members of the suborder Serpentes.
Demographic responses of small mammal populations to a herbicide application in coastal coniferous forest: population density and resiliency
Authors: Sullivan Thomas P.
Published: August 2008

This study was designed to assess the demographic responses of small mammal populations to herbicide-induced habitat alteration in a 7-year-old Douglas-fir plantation near Maple Ridge, British Columbia, Canada. Populations of the deer mouse (Peromyscus maniculatus), Oregon vole (Microtus oregoni), Townsend chipmunk (Eutamias townsendii), and shrews (Sorex spp.) were sampled in control and treatment habitats from April 1981 to September 1983 and from April to October 1985. Recolonization of removal areas by these species was also monitored in both habitats. There was little difference in abundance of deer mice, Oregon voles, and shrews between control and treatment study areas. Chipmunk populations appeared to decline temporarily on the treatment areas relative to controls. Recolonization by voles was not affected by habitat change, but for deer mice was lower on the treatment than control area. Both deer mouse and Oregon vole populations were at comparable densities on control and treatment areas in the second and fourth years after herbicide treatment. The proportion of breeding animals and average duration of life were similar in control and treatment populations of deer mice and voles. These small mammal species should be able to persist in areas of coastal coniferous forest that are treated with herbicide for conifer release.
The aquatic Oligochaeta from the People's Republic of China
Authors: Brinkhurst R. O. , Sang Qi , Yanling Liang
Published: August 2008

Limnodrilus amblysetus sp.nov. (Tubificidae) is described and compared with other Chinese Limnodrilus species as well as Limnodrilus silvani which is recorded from California and Oregon, U.S.A. The presence of other previously known Chinese species is confirmed. Polymorphism in the development of dorsal chaetae, already known for the Naididae and for Tubificinae (Tubificidae), is now suspected for Rhyacodrilinae (Tubificidae). The oligochaete fauna of China resembles that of India, Japan,and the eastern Soviet Union. Some tropical and subtropical Naididae may yet be discovered from the southern provinces, some cold-water Tubificidae and Lumbriculidae from the northeast and those elevated parts of the far west of China that are not deserts.
Egg surface morphology, development, and evolution in the Congrogadinae (Pisces: Perciformes: Pseudochromidae)
Authors: Mooi Randall D. , Winterbottom Richard , Burridge Mary
Published: August 2008

The Congrogadinae consists of 19 species of elongate fishes which reach a maximum length of about 40 cm. They occur primarily in the coral reefs and sea-grass meadows of the Indo-West Pacific. Mature ovarian eggs were found to possess hooked, multi-armed projections distributed equidistantly over their surfaces. Each projection has a central pedicel perpendicular to the chorion which raises it above the egg surface. A few of these hooks give rise to long filaments. The numbers of hooks, arms per hook, and filaments vary among taxa. Hook size and shape changes with egg size. On eggs 70 μm in diameter, hooks begin as small, button-shaped knobs about 2 μm across, gradually becoming stalked and composed of four V-shaped subunits. These eventually form a cruciform structure, about 200 μm across, which bears recurved hooks; these occur on eggs over 3000 μm in diameter. Hooks stop increasing in size before the egg attains its maximum diameter. Filaments increase in length as the hooks grow, reaching a final length of at least 7500 μm. In extruded eggs, the filaments (but not the hooks) come loose from the chorion to tangle with the hooks and filaments of adjacent eggs. This forms an egg mass which is probably guarded by the male. Although the data are prone to homoplasy, two alternative cladograms based on egg surface morphology were constructed. Changes to cladograms existing in the literature involved the genera Halimuraena, Haliophis, Halidesmus, and Blennodesmus. These genera might be monophyletic, based on the occurrence of the hooks in deep pits. The monophyly of the subgenus Congrogadoides is further corroborated by the predominance of three-armed hooks on their egg surfaces.
Hymenolepis nana induced mastocytosis in mice
Authors: Novak M. , Sokolies R. B. , Pip E.
Published: August 2008

Mice inoculated with 1000 Hymenolepis nana eggs did not show any significant mucosal mast cell (MMC) increases in duodena containing mature cysticercoids on day 4 of primary infection. However, on day 12, with adult worms in the ileum, prominent mucosal mastocytosis was seen in the ilea and, to a lesser degree, in the duodena; mastocytosis was due primarily to the intraepithelial MMC population. When the primary infection was terminated on day 4 (at the tissue phase) by administration of the anthelmintic drug praziquantel, the development of challenge cysticercoids was drastically impaired. Termination of primary infection after day 12 (luminal phase) resulted in improved development of challenge cysticercoids, but their excystment was aborted as the majority of them were still present in duodenal villi on day 12 of challenge. No adult worms were recovered from any of the challenged mice. MMC numbers on day 4 of challenge were comparable to those seen in duodena on day 12 of primary infection, but their numbers declined on day 12 of challenge and were comparable to those present in challenged ilea.
Assessing the effects of positive buoyancy on rainbow trout (Oncorhynchus mykiss) held in gas supersaturated water
Authors: Shrimpton J. M. , Randall D. J. , Fidler L. E.
Published: August 2008

We examined the effects of swim bladder overinflation associated with dissolved gas supersaturation on rainbow trout (Oncorhynchus mykiss). The change in swim bladder volume with increased swim bladder pressure was measured in fish subjected to a decrease in ambient pressure. An expansion of swim bladder volume occurs that is related to the excess swim bladder pressure. The volume change results in a decrease in density and positive buoyancy in the fish. Small fish are adversely affected when exposed to gas supersaturated water because of the high swim bladder pressure required to force gas out the pneumatic duct. Changes in behaviour and depth distribution of fish held in gas supersaturated water were measured in a 2 m deep observation column. A large change in density caused small fish to increase depth and compensate for the swim bladder expansion. Although swim bladder inflation occurs for all sizes of trout held in gas supersaturated water, the impact is greatest for small fish and they must compensate by seeking depth. However, adequate depth to compensate for positive buoyancy may not always exist. In such a case, fish must swim continuously in a head down position to overcome excess buoyancy. The power necessary for a fish to swim with an overinflated swim bladder is greatest for small fish that show the largest change in density.
Eulimdana florencae n.sp. (Nematoda: Filarioidea) from Micropalama himantopus (Aves: Charadriiformes): evidence for neonatal transmission, ephemeral adults, and long-lived microfilariae among filarioids of shorebirds
Authors: Bartlett Cheryl M. , Anderson R. C.
Published: August 2008

Eulimdana florencae n.sp. from Stilt Sandpipers (Micropalama himantopus (Bonaparte)) (Charadriiformes: Scolopacidae) at Little Quill Lake, Saskatchewan, and Gem, Alberta, Canada, differs from its closest congener (Eulimdana pseudolari) by the lack of a cleft at the posterior extremity of the female. In addition, the microfilaria of E. florencae has a long, attenuated tail unlike that of any previously described species. Adult worms occurred in neck tissues and microfilariae in skin. Seven of 17 juvenile (less than 2 months old) Stilt Sandpipers were infected; four contained mixed sex infections and in two of these birds microfilariae were present in both the female worms and the host's skin. The remaining three infected juvenile birds contained only adult male or only adult female worms. Eight of 12 adult birds were infected; six contained only skin-inhabiting microfilariae, one contained microfilariae plus a single adult female (probably senescent), and one contained a single male. Support is provided, therefore, for a recent hypothesis predicting that Eulimdana spp. are often acquired early in life by scolopacid shorebirds, that postreproductive adult worms are ephemeral, and that the skin-inhabiting microfilariae are long-lived.
Three simultaneous and independent approaches to the characterization of a new species of Labeo (Teleostei, Cyprinidae) from West Africa
Authors: Paugy D. , Guégan J.-F. , Agnèse J.-F.
Published: August 2008

A new species of Labeo (Cuvier, 1817) is defined and described from the Upper Niger River and Upper Senegal (Baoulé) River basins. Although it is diagnosed as a new species, there is some overlap with two other sympatric species, L. coubie and L. senegalensis, in identifying characters. This overlap is sufficient to introduce the alternative possibility that the putative new species is a hybrid. Three separate techniques were used to test the two competing hypotheses: morphological/morphometric analysis, chromosomal/enzymological analysis, and comparative parasitology. These complementary studies were carried out simultaneously but essentially independently, to minimize any scientific bias during the investigation. It was established that the three species can be distinguished by a combination of mouth morphology and meristics (notably gill raker counts). Though all three have the same chromosome number (2N = 50), the new species can be identified allelically by four homozygous loci that are not present in L. coubie and L. senegalensis. This genetic result indicates that the new species is sexually isolated from the other two. Also, calculations of Nei's genetic distance produce an index which is shorter between L. coubie and L. senegalensis than between either of these two and the prospective new species. All three species can be further separated by their specific monogenean gill-parasite complement: L. coubie (five Dogielius spp., seven Dactylogyrus spp.); L. senegalensis (two Dogielius spp., five Dactylogyrus spp.); Labeo roseopunctatus n.sp (1 Dogielius sp., one Dactylogyrus sp.). As a result of these investigations, the idea of hybridism is rejected and a formal taxonomic description of Labeo roseopunctatus n.sp. is included in this paper.
Effects of exercise training and coronary ablation on swimming performance, heart size, and cardiac enzymes in rainbow trout, Oncorhynchus mykiss
Authors: Farrell A. P. , Johansen J. A. , Steffensen J. F. , Moyes C. D. , West T. G. , Suarez R. K.
Published: August 2008

Rainbow trout, Oncorhynchus mykiss, were exercise trained for 28–52 days. Trained fish were 13% larger and swam 12% faster in an aerobic swimming test. Training induced cardiac growth that was isometric with body growth, since ventricle mass relative to body mass was constant. The proportions of compact and spongy myocardia in the ventricle were also unchanged by training. Trained fish had significantly higher levels of citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase in both compact and spongy myocardium. Ligation of a 0.5- to 1.0-cm section of the coronary artery produced only a temporary interruption of coronary flow to the compact myocardium because new vessels grew around the ligation site in the majority of fish during the 28- to 52-day experiment. Nonetheless, coronary ligation resulted in a significantly smaller (17%) proportion of compact myocardium with lower levels of citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase. Exercise-induced increases in the levels of these enzymes in the compact myocardium were prevented by coronary ligation. The decrease of enzymes in the compact myocardium as a result of coronary ligation was compensated for by a 30% increase in the levels of the aerobic enzymes citrate synthase and β-hydroxyacyl CoA dehydrogenase and a 32% increase in the mass of spongy myocardium. As a result of these compensations and coronary regrowth, chronic coronary ligation did not affect maximum prolonged swimming speed. These experiments clearly reveal that cardiac plasticity allows compensatory changes that are necessary for the heart to maintain adequate oxygen delivery to exercising skeletal muscle. The compensatory changes were isometric increases in heart mass or proportionately larger increases in heart mass and compact tissue if the coronary artery was ligated and an increase in metabolic enzymes associated with ATP generation, namely, citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase.
Water uptake from plant tissue by the egg pedicel of the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae)
Authors: Byrne David N. , Cohen Allen C. , Draeger Erich A.
Published: August 2008

Proof is provided that the egg pedicel of Trialeurodes vaporariorum (Westwood) serves as a conduit for water from plant tissue into the egg. Movement was demonstrated by using tritiated water to irrigate plants supporting whitefly eggs and later measuring tritiated water activity in the eggs. Calculations showed that approximately 50% of the mass of a mature egg consists of water imbibed from plant tissue. Eggs were also weighed at intervals of 5 min and 1, 4, 8, 24, and 48 h after being oviposited. The increase in their mass (47%) over time agrees with the calculations involving tritiated water uptake.
Eimeria caretta sp.nov. (Apicomplexa: Eimeriidae) from the loggerhead sea turtle, Caretta caretta (Testudines)
Authors: Upton Steve J. , Odell Daniel K. , Walsh Michael T.
Published: August 2008

Eimeria caretta sp.nov. (Apicomplexa: Eimeriidae) is described from the feces of a stranded loggerhead turtle, Caretta caretta (Testudines), rescued from the Atlantic coast near Jensen Beach, Hutchinson Island, Martin County, Florida. Oocysts are subspherical to ellipsoidal, 24.5 × 22.0 (21.4–28.0 × 18.4–24.0) μm, with a smooth, bilayered wall. Micropyle, polar granule, and oocyst residuum are absent. Sporocysts are ovoid, 14.3 × 8.9(12.8–16.0 × 8.2–10.0) μm, and possess a Stieda body but no substieda body. The Stieda body is unusual in that 12–20 long, thin filaments project from its surface. Sporozoites are elongate, each with two refractile bodies. The sporocyst residuum consists only of scattered granules. This coccidian is most similar to Eimeria filamentifera Wacha and Christiansen 1979 from the common snapping turtle, Chelydra serpentina, but differs because it possesses more numerous and elongate filaments associated with the Stieda body and lacks an oocyst residuum.
Plasma electrolytes, gill aluminum content, and gill morphology of juvenile Atlantic salmon (Salmo salar) and brook trout (Salvelinus fontinalis) indigenous to acidic streams of Nova Scotia
Authors: Lacroix G. L. , Hood D. J. , Belfry C. S. , Rand T. G.
Published: August 2008

Plasma electrolytes and gill [Al] were determined and gill morphology and histology were examined in Atlantic salmon (Salmo salar) parr and brook trout (Salvelinus fontinalis) from feral populations in acidic streams of southwest Nova Scotia. Plasma [Na+] and [Cl−] were lowest in fish from streams with the lowest pH levels, but there were no correlations between plasma [Na+] or [Cl−] and exchangeable [Al] in streams for both species. Gill [Al] increased exponentially with increasing exchangeable [Al] in water, but was less than 100 μg/g dry weight in both species. There were no correlations between plasma [Na+] or [Cl−] and gill [Al] for both species, and plasma [Na+] and [Cl−] were ultimately linked to low pH. Scanning electron microscopy of gills showed normal primary and secondary lamellae, with few signs of fusion or hyperplasia, only a slight amount of mucus, regular chloride cell crypts, and epithelial cells with distinct microridges. Histology of gill sections showed few lesions in the primary lamellae but some focal histologic lesions in the secondary lamellae of greater than 50% of fish, regardless of ambient pH or [Al]. The histopathology included hypertrophy of individual epithelial, mucous, and chloride cells, clubbing of tips of secondary lamellae, and localized epithelial hyperplasia. These features were focal and not comparable to the extensive morphological changes or histologic lesions usually attributed to high [Al] at low pH. Dissolved organic carbon concentrations greater than 5 mg/L in the acidic streams apparently afforded protection against Al effects at concentrations of at least 360 μg total Al/L.
Food availability, growth, and heritability of body size in nestling tree swallows (Tachycineta bicolor)
Authors: Wiggins David A.
Published: August 2008

I studied the effects of food deprivation on the growth, final size, and inheritance of body size in nestling tree swallows (Tachycineta bicolor). Each experimental brood was divided into deprived and fed nestlings. Deprived nestlings showed relatively poor growth during the experimental stage (days 5–8), but were not significantly different in size from either their nestmates or control young at day 16. Parents of experimental broods did not compensate by increasing their food delivery rate. Heritability estimates of tarsus length were similar for deprived and fed nestlings. For control nestlings, tarsus length was significantly heritable at days 9 and 16, and bill length was heritable at day 16. There were no significant heritability estimates for wing length or body mass. Small sample sizes and single-parent–offspring regression likely inflated the standard errors associated with the heritability estimates. The mechanism that allowed deprived nestlings to grow as large as control and fed nestlings remains unknown.
Observations on the birth of a beluga whale (Delphinapterus leucas) in the St. Lawrence Estuary, Quebec, Canada
Authors: Béland Pierre , Faucher Annick , Corbeil Patrice
Published: August 2008

Several white adult beluga whales (Delphinapterus leucas) were observed to act together with a mother and calf. Underwater sound recordings, group behaviour, and calf appearance and behaviour strongly suggest that the birth had occurred during the observation period. Grey juveniles associated with the group remained at a distance during the whole event. The birth occurred in July during the presumed peak calving season, in a main channel of the St. Lawrence Estuary, home to an endangered population of belugas.
Effet de la lune sur l'activité des pétrels (classe Aves) aux îles Salvages (Portugal)
Authors: Bretagnolle V.
Published: August 2008

Correlations between lunar phase and behaviour have been studied in five different species of petrels (Cory's Shearwater, Calonectris diomedea; Little Shearwater, Puffinus assimilis; Bulwer's Petrel, Bulweria bulwerii; White-faced Storm Petrel, Pelagodroma marina; and Madeiran Storm Petrel, Oceanodroma castro) during 20 nights. Quantitative data on the activity of birds (number of calls per time unit, proportion of nests visited, and number of birds in flight by night), relatively to their breeding status and the phase of the moon, suggest that moonlight may affect primarily the activity of the nonbreeders, especially in the smaller species. The results are compared with those for other species of petrels and possible causes of moon avoidance, such as increased predation risk, are discussed.
On the statistical analysis of niche overlap data
Authors: Manly Bryan F. J.
Published: August 2008

It has recently been suggested that problems with the statistical analysis of niche overlap data can be overcome by computing overlaps between randomly paired individuals. This allows a test for temporal changes in the overlap between two populations. In this paper, it is suggested that this test relies too heavily on random pairing. It is argued that a better test is one based on an analysis of variance of niche overlaps between all possible pairings that can be made at the same time, with the significance level being determined by bootstrapping.
A model of dispersion and regulation of brood mite (Tropilaelaps clareae) parasitism on the giant honeybee (Apis dorsata)
Authors: Burgett D. M. , Rossignol P. A. , Kitprasert C.
Published: August 2008

We observed that the distribution of the parasitic brood mite Tropilaelaps clareae Delfinado and Baker on the giant honeybee, Apis dorsata F., in northern Thailand, is aggregated and fits a negative binomial distribution if parasite-associated host mortality is presumed. Because no brood mortality was directly observed, we propose to account for this presumed host mortality through the removal of infested late-instar larval brood or pupae, along with their parasites, by worker nurse bees. An ability of bees to detect infected brood, as a function of the number of parasites associated with the host, correlates significantly with observed data. We show how such a prophylactic strategy could regulate parasite density, because parasite mortality would increase more rapidly than brood host mortality. Finally, we suggest that the potential tendency for the parasite population to be less aggregated, to evade bee defensive behaviour, may be counteracted by an advantage to sexual reproduction. The predicted degree of aggregation that would result in the maximal number of sexual encounters closely matches the degree of aggregation derived from the observed data.
Extirpation and transplantation of the brain of the snail Helix aspersa: a study of the survival of the animal and the implant
Authors: Gomot Philippe , Gomot Lucien , Marchand Claude-Roland , Colard Claude
Published: August 2008

Dormant, hibernating snails whose brains (supraoesophageal cerebral ganglia and associated dorsal bodies) were removed by surgery continued to live retracted in their shells. The remaining ganglia of the circumoesophageal ring did not regenerate in the 12 months following the removal of the brain. The transplanted brains in the haemocoel (auto- or allo-graft) were not rejected and many of their cerebral neurosecretory cells and the endocrine dorsal bodies appeared normal structurally and functionally, as evidenced by ultrastructural and immunocytochemical studies. The data from these experiments demonstrate the possibility of studying by in vivo culture methods the roles of cerebral ganglia and endocrine dorsal bodies on the control of reproduction under different temperature regimes.
The photoreceptors and visual pigments in the retina of the white sturgeon, Acipenser transmontanus
Authors: Sillman A. J. , Spanfelner M. D. , Loew E. R.
Published: August 2008

The photoreceptors in the retina of the white sturgeon, Acipenser transmontanus (Chondrostei), were studied by means of scanning electron microscopy, in situ microspectrophotometry, and spectrophotometric analysis of visual pigment extracts. The white sturgeon retina is simple in that it contains only two morphologically distinct photoreceptors. The retina is dominated by rods with large outer segments, but there is a substantial population (40%) of single cones. Evidence was found for only one rod visual pigment and one cone visual pigment. Peak spectral absorbance (λmax) of the rod pigment is near 539 nm, whereas λmax of the cone pigment is near 605 nm. Both visual pigments are porphyropsin types with chromophores based on vitamin A2. No detectable rhodopsin based on vitamin A1 is ever present, regardless of season or light regimen. The results are discussed in terms of the sturgeon's behavior, as well as the implications for the evolution of color vision.
Metabolic organization in swimming muscle of anadromous coregonines from James and Hudson bays
Authors: Couture Patrice , Guderley Helga
Published: August 2008

The metabolic organization of swimming muscles from anadromous cisco (Coregonus artedii) and lake whitefish (Coregonus clupeaformis) sampled in two rivers presenting different regimes of migratory difficulty and temperature was compared. Cisco muscle showed an increased aerobic capacity in the river where the fishes' migration is longer, as shown by the activities of several enzymes and by the proportion of red muscle in their swimming muscle. Lake whitefish, generally larger than cisco, did not show any compensation for the difficulty of migration. For both species, latitudinal differences in thermal regime were not correlated with differences in aerobic capacity. As estimated from published allometric equations, scaling effects can account for only a small proportion of the interstation variation in the aerobic enzyme activities of cisco. Our results suggest that because cisco are smaller than lake whitefish in these rivers, and thus are more affected by the degree of difficulty of the prereproductive migration at a given temperature, cisco have compensated by increasing the aerobic capacity of their swimming musculature in populations facing greater swimming requirements.
Diving depths and diet of Cassin's Auklet at Reef Island, British Columbia
Authors: Burger Alan E. , Powell David W.
Published: August 2008

Diving depths of Cassin's Auklets (Ptychoramphus aleuticus) breeding at Reef Island, Queen Charlotte Islands, British Columbia, were measured with miniature gauges attached to the birds. Maximum diving depths of 22 birds averaged 28 m, with a mode of 40 m. A time-at-depth recorder showed that one auklet dived to 29 m, but spent 80% of its time underwater at 3–13 m. Food delivered in gular pouches to chicks contained mainly euphausiids (predominantly Thysanoessa spinifera) and juvenile fish (Ammodytes hexapterus), with lesser amounts of copepods, amphipods, small pandalid shrimps, Brachyura larvae, and ctenophores. Euphausiid meals were most common during spring tides. Auklets that delivered significant amounts of euphausiids appeared to have dived deeper than those that delivered fish.
Effects of radio collars on wild mice, Mus domesticus
Authors: Pouliquen Odile , Leishman Michelle , Redhead Trevor D.
Published: August 2008

Experiments were conducted in the laboratory and in the field to test the effects of radio collars (1.7–1.9 g) on wild house mice (Mus domesticus). There was a decrease in the activity of the collared animals in the laboratory immediately after collar attachment. There were no adverse effects on social interactions in the laboratory, nor on survival for 4–5 days in the field. Provided that the collar is well adjusted, there should be no need to keep wild animals captive for more than 1 h after collar attachment. These results are consistent with those of other researchers on the effect of transmitters on some species of small mammals.
Evolutionary aspects of hybrid dysgenesis in Drosophila
Authors: Kidwell Margaret G.
Published: August 2008

Hybrid dysgenesis results from the movement of specific transposable elements following hybridization between populations having different element complements. The phenotypic and molecular properties of P, I, and hobo elements in Drosophila are briefly described to provide a background for discussion of the evolutionary significance of the phenomenon of hybrid dysgenesis. It is argued that most mobile element systems are apt to produce dysgenic traits, but that other properties of the P–M and I–R systems of hybrid dysgenesis, such as nonreciprocity and tissue specificity, will be more restricted in their occurrence. There is good evidence that mobile elements may move between both closely and distantly related species in the genus Drosophila, but it is not known whether this type of event is frequent enough to have evolutionary consequences. It appears to be unlikely on theoretical grounds that hybrid dysgenesis acts directly as a postmating reproductive isolating mechanism. The ubiquity of mobile elements and the observed high frequency of insertional mutations induced by them suggest that these elements could contribute to increased population genetic variability, which may differ from that produced by other natural mutagens. However, there is no direct evidence that this variability has long-term evolutionary significance. Although there is currently little clear evidence for hybrid dysgenesis in other insect genera, it is premature to conclude that this phenomenon is restricted to a few mobile element families in Drosophila.
Acoustic recognition signals: barriers to hybridization in Homoptera Auchenorrhyncha
Authors: Claridge M. F.
Published: August 2008

The biological, or isolation, concept of species is compared with the recognition concept of Paterson. Specific-mate recognition signals are in practice equated with premating isolating mechanisms. Acoustic signals are dominant in specific-mate recognition systems of Homoptera Auchenorrhyncha. Recording and analysis of the signals give some of the best data for species discrimination in these insects. The morphological species Nilaparvata lugens, the brown planthopper, includes two morphologically indistinguishable biological species associated respectively with rice, Oryza, and the weed grass, Leersia hexandra. These planthopper species are sympatric over large areas of Asia and Australia. Populations of the two differ significantly in pulse repetition frequencies of male and female calls, but each also shows geographical variation for the same characteristics. These data are more consistent with theories of speciation involving sexual selection than with the recognition concept of species.
The control of gene flow across a narrow hybrid zone: a selective role for chromosomal rearrangement?
Authors: Shaw D. D. , Marchant A. D. , Arnold M. L. , Contreras N. , Kohlmann B.
Published: August 2008

Independent molecular, biochemical, and cytological markers have been used to assess the evolutionary status of a narrow hybrid zone between two genomically distinct taxa of the grasshopper Caledia captiva. Despite the extreme narrowness (<1 km) of the hybrid zone when assessed in terms of its chromosomal profile, other diagnostic nuclear and cytoplasmic markers are found at high frequencies in populations up to 400 km beyond the chromosomal limits of the zone. These data suggest that the hybrid zone is very old and capable of moving while still retaining its narrow chromosomal profile. The data also suggest that the chromosomal rearrangements are the principal components maintaining this narrow hybrid zone and that strong selective forces, acting upon the structure of the genome, are involved. Analysis of chromosomal variation has revealed that the Moreton taxon has a complex chromosomal cline in which every chromosome changes from metacentric to acrocentric or telocentric along the cline. We argue that the chromosomal rearrangements which are involved in maintaining the narrow hybrid zone are themselves playing an adaptive role within the population, both as homo- and hetero-zygotes. A model is presented to explain these patterns of genomic change along environmental gradients as an adaptation, probably at the cellular level, to establish a temporal synchrony of events during embryogenesis.
Trigonocotyle sexitesticulae sp.nov. (Eucestoda: Tetrabothriidae): a parasite of pygmy killer whales (Feresa attenuata)
Authors: Hoberg Eric. P.
Published: August 2008

Trigonocotyle sexitesticulae sp.nov. is described from specimens collected from pygmy killer whales (Feresa attenuata) in Florida. This species is differentiated from other Trigonocotyle species by the minute overall dimensions of the scolex (372–523 μm wide), strobila (maximum 13.7 mm long in a pregravid specimen), and cirrus sac (40–54 μm in length), an unusual number of testes (6), and the configuration of the scolex and genital atrium. Among other species of Trigonocotyle the dimensions of the scolex, strobila, and cirrus sac far exceed those of T. sexitesticulae, and there are typically > 20 testes in each proglottid. Examination of some specimens of Trigonocotyle globicephalae Baer, 1954 during the present study revealed inconsistencies in previous descriptions with respect to the structure of the scolex, numbers of testes, and dimensions of the cirrus sac. In addition, Trigonocotyle prudhoei Markowski, 1955 appears to represent a composite in which the original description was based on specimens of Trigonocotyle sp. and Strobilocephalus triangularis (Diesing, 1850).
Cardiorespiratory responses of skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), and bigeye tuna (Thunnus obesus) to acute reductions of ambient oxygen
Authors: Bushnell Peter. G. , Brill Richard W. , Bourke Robert E.
Published: August 2008

Cardiorespiratory responses to acute reductions of ambient oxygen were measured in skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), and bigeye tuna (Thunnus obesus). Prevented from swimming by a spinal injection of lidocaine, fish were placed in seawater flowing at a velocity equivalent to their normal swimming speed. Ventilation volume [Formula: see text], heart rate, cardiac output, mouth gape, and inspired water and exhalant water oxygen partial pressures ([Formula: see text] and [Formula: see text], respectively) were simultaneously measured during periods of full oxygen saturation (normoxia) and brief (ca. 3–4 min) periods of reduced oxygen (hypoxia). During hypoxia, [Formula: see text] ranged from 140 to 50 mmHg. [Formula: see text] during normoxia was significantly different in skipjack, yellowfin, and bigeye tunas (6.7, 3.9, and 1.5 L∙min−1∙kg−1, respectively) and paralleled differences in oxygen consumption (740, 455, and 322 mg O2∙kg−1∙h−1). All three species were sensitive to [Formula: see text], and mild hypoxia [Formula: see text] elicited significant cardiorespiratory adjustments, including increased mouth gape and [Formula: see text] and reduced heart rate. Cardiac output was maintained until [Formula: see text] reached 95 mmHg, but at lower oxygen levels it too began to decrease. Therefore, the three tuna species studied appear as sensitive to hypoxia as other marine teleosts and show cardiorespiratory adjustments at [Formula: see text] values well above those eliciting swimming speed changes.
Investigation of food habit and niche relationships in a cyprinid community
Authors: Litvak Matthew K. , Hansell Roger I. C.
Published: August 2008

Study of the gut contents of a cyprinid community by means of frequency occurrence and back-predicted biomass data indicated that Pimephales promelas has a benthic food habit, consuming a high proportion of detritus and associated invertebrates. Phoxinus eos and Phoxinus neogaeus both consumed prey from the benthos and throughout the water column. A large portion of their diet also consisted of detritus, but less than that of Pimephales promelas. The community food niche was analyzed in multidimensional niche space, using principal coordinate analysis, and an algorithm for a community perspective on the multidimensional niche was used. Pimephales promelas had the smallest niche, with a high proportion of its niche hypervolume in intersection with the two Phoxinus species. Phoxinus eos had the second largest niche and was the "middle competitor" in this community. Phoxinus neogaeus had the largest niche and was overlapped the least in the community. Comparison with previous studies of food habit suggests that competition was occurring at the time of the study.
Wear and tear of mouthparts: a critical problem in stream animals feeding on epilithic algae
Authors: Arens Werner
Published: August 2008

A large number of stream-dwelling animals feed on epilithic algae and must scrape or brush off food that is firmly attached to rough stones. The mouthparts of these highly specialized alga grazers are equipped with brushes, rakes, gouges, excavators, and rasps. Because they scrub across the rough substratum, these different types of feeding apparatus all become extremely worn down after a short time. The delicate bristles of brushes, the prongs of rakes, and the fine structures of rasps abrade swiftly, and often completely disappear after having been used for removing epilithic algae from stones. The blades of gouges and the scoops of excavators also wear down, but in this case abrasion usually causes only the shortening of these relatively solid tools and does not so strongly impair their effectiveness. Specific adaptations have been evolved to deal with the problem of wear. Either the grazing animals are able to repair their mouthparts frequently, or their feeding apparatus is constructed in such a way that its effectiveness is guaranteed for a long time despite the wear. Typical defects arising from use, and adaptations to wear, were studied comparatively by scanning electron microscopy of different alga grazers: insects of different orders (Ephemeroptera: Rhithrogena, Epeorus, Ameletus, Baetis, Lepeorus; Plecoptera: Brachyptera; Coleoptera: Limnius; Diptera: Liponeura, Oxycera), the isopod Ligia italica, the snail Ancylus fluviatilis, and the tropical fish Garra taeniata. Laboratory experiments with mayfly larvae showed that the mouthparts wear down when they are used to scrape a rough substratum. There was no evidence that moulting intervals were shortened by abrasion of feeding structures in mayfly larvae.
Clutch size of anadromous and freshwater threespine sticklebacks: a reassessment
Authors: Snyder Randal J.
Published: August 2008

There is conflicting evidence in the literature regarding the size-specific fecundity of anadromous and freshwater threespine sticklebacks (Gasterosteus aculeatus L.). To examine this question, I reared offspring of threespine sticklebacks collected from an inland location along the Navarro River, Mendocino County, California, and compared their initial clutch size and egg size with data obtained earlier for two other stickleback populations (an anadromous and a coastal freshwater population) from the same drainage. Size-specific clutch size was lower and eggs were larger in the inland population compared with the two populations studied previously. When wild-caught threespine sticklebacks are compared, fecundity of anadromous forms should usually be higher due to their higher size-specific fecundity as well as their larger average size at maturity. The eggs of anadromous sticklebacks may also be smaller than those of typical freshwater sticklebacks, since there is evidence of negative phenotypic correlations between egg size and clutch size in these fish.
Flight speeds of parent birds feeding nestlings: maximization of foraging efficiency or food delivery rate?
Authors: McLaughlin Robert L. , Montgomerie Robert D.
Published: August 2008

We examined the flight behaviour of female Lapland longspurs (Calcarius lapponicus) foraging during the nestling period to determine whether they flew at speeds maximizing the overall rate of energy delivery to their nestlings (VY), or at speeds maximizing the distance travelled per unit energy expended (Vmr), as predicted by different models. The average flight speed of females was slower when they flew to closer feeding sites, suggesting that acceleration was an important component of these flights. We therefore included the cost of acceleration into the flight-speed models. Longspurs flew slightly faster, on average, than our predicted speeds for maximizing the distance travelled per unit energy expended (Vmr) but substantially lower than our predicted speeds for maximizing the overall rate of energy delivery to nestlings (VY). The fact that longspurs did not fly faster at times of increased food availability is also consistent with maximizing the distance travelled per unit energy expended, but not with maximizing the overall rate of energy delivery. Based on other studies of parent birds feeding young, we expected that longspurs would adjust their flight speeds to maximize the overall rate of energy delivery to their young. Instead, their flight behaviour was more consistent with maximizing foraging efficiency (the ratio of energy collected to energy spent).
Description of Xironogiton victoriensis n.sp. from British Columbia, Canada, with remarks on other species and a Wagner analysis of Xironogiton (Clitellata: Branchiobdellida)
Authors: Gelder Stuart R. , Hall Lee Ann
Published: August 2008

Xironogiton victoriensis n.sp. is described from the crayfish Pacifastacus leniusculus leniusculus on Vancouver Island, British Columbia, Canada. Collections of P. l. leniusculus from Goldstream River, and Colquitz Creek, Victoria, and Burdette Creek, Burnaby, Vancouver, in southwestern British Columbia yielded Cambarincola fallax, C. gracilis, C. montanus, and Xironogiton kittitasi. Specimens of each species of Xironogiton have been examined and a taxonomic key for the genus has been constructed. The information was also used in a Wagner analysis of Xironogiton which showed the genus to be a monophyly.
Relocation of nest sites by female deer mice, Peromyscus maniculatus borealis
Authors: Sharpe Sean T. , Millar J. S.
Published: August 2008

Nest-sites of female Peromyscus maniculatus borealis were monitored during 1985 and 1986 in the Kananaskis Valley, Alberta, Canada. Nest-site relocation by breeding overwintered adults and young of the year was common. There was no significant difference in the distance moved between years and sites or among reproductive-status groups. Nest relocations were most common in 1985, when population density was approximately half that in 1986. There were no differences in the numbers of relocations per season due to site or age. Females in breeding condition moved 3 times more frequently than did nonbreeders, which were young of the year. Relocations were most frequent at parturition and during early lactation, and thus may serve as a predator-avoidance mechanism. Some relocations by females may have served to leave former nest sites to offspring from previous litters.